IV. Environmental Impact Assessment of Livestock Production in Mixed Rainfed Systems in Temperate Zones (MRT) (excluding Africa)

1. Introduction
2. MRT Environmental Impacts
3. Conclusions and Recommendations Relative to MRT-Environment
4. MRT-Environmental Impact Case Study
5. References

1. Introduction

1.1 Description of MRT Production System

1.1.1 Geographic Distribution

Mixed farming systems in true temperate zones (MRT) are the dominant AZ-LS category for most of the northern hemisphere (Table IV.1). Countries in the former U.S.S.R. collectively account for 47 percent of the agricultural land in this category. This category is significant in the southern hemisphere only in Australia, New Zealand, Argentina, and Chile. It accounts for 26.3 percent of the world’s human population, 17.4 percent of its pasture land, and 43.4 percent of its arable land. Its agricultural lands consist of almost equal parts arable and pasture land, and it supports a population density of.8 ha/capita.

1.1.2 Livestock Resources

The MRT supports almost one-fourth of the world’s cattle and one-fifth of its sheep and goats (Table IV.2). As with agricultural land, countries of the former U.S.S.R. account for more than one-third of the cattle and sheep. Most of the goats (55 percent), however, are found in China. Based on livestock unit equivalents, cattle account for 86 percent of the feed demand generated by the three types of livestock in the MRT.

1.1.3 to 1.1.7 (See Sere 1994)

1.2 Current Trends

1.2.1 Livestock Resources and Production

Cattle numbers, both beef and dairy, have declined significantly over the past decade. Despite these declines in stocks, beef and dairy milk production have continued to increase. Sheep stocks increased slightly, led by increases in Australia and Europe. New Zealand and the United States, however, showed significant reductions in numbers over the past decade. Goat numbers also showed increases over almost the entire production zone. Poultry meat production increased dramatically over the past decade as it became the meat of choice in many OECD countries.

1.3 Overview of Key Indicators

1.3.1 Direct Indicators

1.3.1.1 Pesticide/Herbicide Residues in Water

Pesticide levels in water from rangelands are minimal and generally poorly documented. Most monitoring sites are associated with water systems where cropland is a major component of the landscape, masking any potential loading from rangelands. The primary source of pesticides from rangelands would be associated with runoff from sites where external parasites are controlled. Location of such sites needs to consider overland flow issues and downslope filtering of runoff and grazing of run-on areas to minimize pesticide loading in watershed systems.

1.3.1.2 Pesticide Use and Residues

Extensive testing of pesticide residues in meat from grazing animals reared or imported into the U.S. and Europe indicated that few environmental hazards exist to consumers. Mean residues have been at 0.23 percent of acceptable daily intake levels with violative rates associated with inspections at less than 0.43 percent. The emerging concern of pesticide residues in meat products is primarily in consumption of processed by-products and crop residues not destined for human consumption. More education, special care of feeding nontraditional feedstuffs, and subsequent monitoring needs to be given special focus as nonhuman consumptive crop by-products are considered for feedstuff.

1.3.1.3 Vegetation Ground Cover--Overstory-Understory Relationships

Understory forage production generally increases dramatically when woody overstory is removed due to increased incoming radiation, reduced rainfall interception in tree canopies and ground litter, reduced transpirational demand from the woody vegetation, and release of soil nutrients concentrated under the woody canopy. The degree of response pre- and postclearing of overstory will depend on the relative impact of overstory on the above factors and the nature of the rainfall events. As a general rule, herbaceous production declines as tree canopy cover, basal area, or density increases. Resulting allometric equations of these relationships are allowing grazingland managers to strategically plan ahead and adjust livestock numbers in anticipation of future stand clearings and/or closures. However, such predictions are not suitable for within-year operational adjustments.

1.3.1.4 Soil Fertility

In grazed environments, grazing animals redistribute nutrients and speed up nutrient cycling. Depending on the degree of human interaction, humans exert some control on distribution of nutrients and the degree of external nutrient input via supplemental feeds. When viewing livestock-cropping interactions, the human decision process is a critical component to understanding soil fertility impact, particularly as the forage selection process becomes less animal driven. Animal manuring systems involve either a) direct animal input through rotational nighttime holding or staking on croplands or b) off-site grazing or seeding with transfer to the cropland system. In the former case, nutrient input is wholly dependent on the quality of adjacent grazing lands and amount of supplemental feed. Additional factors, such as handling and storage of the manure, are important in the second system. In any case, manure management system are considered poor when the import of nutrients and organic matter exceeds export. Excessive leakage of nutrients in positive balanced systems through runoff and leaching in deep drainage and lateral flow (interflow) creates serious environmental problems, particularly with water-quality issues. When animals graze pasture lands, losses through leaching may occur due to uneven distribution of feces and urine. As dietary crude protein rises and rumen solubility rises in forage/feed, urine nitrogen losses will rise in proportion of total nitrogen excretion. Volatilization of nitrogen from urine patches can be as much as 10-25 percent degree of soil surface moisture, degree aeration, and inherent nitrogen concentration. Imbalances in feeds with excessive rumen degradable protein will result in excessive urination and volatilization of ammonia. The rate of ammonia volatilization is influenced by ammonia concentration in the manure, temperature, and wind speed. In general, 10 percent of urine-N volatilizes in temperature climates, and 25 percent is lost through utilization in subtropics and tropical climates. The negative effects of ammonia volatilization can be odor, nitrogen enrichment, and acidification of soil and surface water. Acidification can lead to mobilization of aluminum ions, which are toxic to fish, and reduce nutrient uptake in plants. The principal concern for leaching is nitrogen conversion to nitrates in the nitrification process. Period of manure application can have a major effect on nitrate leaching. Saturation losses are more of a problem in mixed-rainfed temperate zones, while excess removal a greater problem in the mixed-rainfed humid zone. Manure is not a major problem in livestock grassland, humid, and temperate zones, given the extensive nature of grazing in these zones and limited concentration of stock and subsequent application on grazingland.

1.3.1.5 Methane Emissions

Over the past 150,000 years, earth processes have produced stable concentrations of 600 to 700 ppbv during warm interglacial periods and about half as much during the major ice age. Currently, global methane concentration is approximately 1700 ppbv, or more than double those levels. Domestic animals account for approximately 14 percent of the current methane generated. Cattle, sheep, goats, water buffalo, equine, and camels account for 71 percent, 9 percent, 3 percent, 8 percent, 2 percent and 1 percent of global animal emissions, respectively. Of the four agroecological zones discussed in this document, the livestock grassland temperate zone emits the lowest amount of livestock-source methane (2.237 Tg/yr). Emissions were very similar across the other zones with the mixed-rainfed temperate yielding the highest levels. If water buffalo are added to the mixed rainfed humid zone there would be little difference between MRT, MRH, and LGH (13.554, 12.659, 13.427 Tg/yr, respectively for cattle, sheep, and goats). Since cattle comprise the largest source of methane among the domestic ruminants, emissions followed the same trends as overall methane emissions. However, sheep were the greatest methane source in the MRT, while goats were the highest in the MRH. Over the past 200 years livestock methane emissions have simply replaced wild-animal emissions in the LGT and, to a more limited extent, in the other zones. Environmental programs designed to expand wetlands (21 percent), wild ruminant populations (7 percent) coupled with expanding landfills (7 percent), coal mining (6 percent), and oil and gas drilling (8 percent) will account for more than 49 percent of the current global methane emissions in the future. The contribution of livestock to global methane emissions is projected to decline relative to human-made sources, given the limited capacity to greatly expand livestock populations and limited acreage to expand high methane-emitting rice paddies.

1.3.1.6 Waste-Manure--Soil Fertility

The principal concern of manure application on soil fertility focuses on nutrient balance relative to amounts applied. Nutrients of particular concern are primarily nitrogen (N) and phosphorus (P) with secondary concern for potassium (K) and to a lesser degree copper (Cu) and zinc (Zc). Although not a nutrient per se, organic matter is another manure input to soils that can affect both soil fertility and physics. The fertilizer efficiency of animal manure is dependent upon, a) kind and class of animal supplying the manure; b) nature of forage and concentrate feeds consumed by the animal, including extent of degradable nutrients; c) housing, rearing, collection, processing, and storage techniques; d) rate and method of application; e) type of crops receiving the manure; f) characteristics of soil (depth, cation exchange capacity, pH, current nutrient levels, organic matter, etc.); and g) other cultural inputs such as irrigation and commercial fertilizer. Given lower temperatures, higher stocking densities, and external fed inputs associated with livestock-grazing pastures in the mixed-rainfed temperate agroecological zone, issues of nutrient leaching are more of a concern in this zone. Given the high human populations associated with much of the mixed-rainfed humid zone, livestock manure is a scarce commodity which requires integration with other soil fertility management strategies to adequately meet the fertility needs of crops. Derived pastures in the mixed-rainfed temperate and humid zones have a high capacity to take external nutrients from manure. Generally, the combined effects of animal offtake and harvesting of hay maintains nutrient loads in the soil below saturation levels. This is particularly true for the rainfed mixed humid zone where temperatures are higher. Nutrient loading via livestock manure generally is in balance for the livestock grassland temperate and livestock grassland humid (native pastures). However, evidence is growing that these systems can experience significant degradation once these ecosystems form erosion cells, accelerating nutrient and water loss from the system.

1.3.1.6 Waste-Manure--Methane Emissions

Very few studies are available related to methane emissions of livestock manure from grazingland conditions. However, methane emission rate have been shown to be strongly influenced by the internal temperature of the pat. Emissions occur from 10 to 40⁰ C, increasing exponentially above 25⁰ C. Overall, emissions from feces were found to be insignificant compared to those from the rumen. However, methane emissions are significant from swampy cesspit areas or runoff accumulation areas where high concentrations of livestock occur.

1.3.1.7 Concentrate Feed Demand--Soil Fertility

The primary effect of concentrate feeds on soil fertility occurs as nutrient return via the feces and urine of fed animals. This effect is particularly apparent in highly concentrated livestock situations where desired high productivity requires external nutrient input. The agroecological zones with greatest external nutrient input is the mixed rainfall temperate zone, representative of both high cropland development and livestock concentrations. In extensive rangeland conditions, animals tend to concentrate nutrients near watering points, holding pens, and thermal shelters (natural and artificial). During the period when feeding winter supplemental feeds, nutrients tend to be concentrated in loafing areas, particularly when animals anticipate feeding activities. It has been well established that reducing feeding frequently forces animals to graze over larger areas, reducing nutrient concentration in feeding areas. There is little evidence that feeding of concentrate supplements on rangelands causes excessive nutrient loading on rangelands. There is some concerns that nutrient loading due to feeding concentrate feeds to animals stocked at high densities on fertilized-derived pastures might lead to excessive nitrogen loading. Reducing nitrogen excretion must be evaluated in terms of meeting nutrient requirements in the rumen and at the tissue level of metabolism so that productivity, animal health, and profitability are not compromised.

1.3.2 Indirect Indicators

1.3.2.1 Livestock Productivity

An evaluation of technologies and innovations related to feed production, storage, and use, with particular emphasis on ruminant-animal systems in particular, shows there is a multitude which can readily be transferred and adopted by both developed and developing countries. Imagination, time lag in adoption, and institutional constraints are the principal limits to expanded animal productivity rather than the traditional ones of land, labor, and capital. There are a vast number of genetic-oriented, animal health, reproduction and nutrition technologies and related management techniques available and ones which will become available in the next decade.

1.3.2.2 Livestock Feeds and Feeding

A host of technologies related tofeeds and feeding need considerably more attention. Many advances are being made as a result of biotechnology and genetic engineering. Many compounds available are being developed to promote growth and feed efficiency, such as anabolic steroids, somatotropins, antimicrobial agents, and feed additives. Furthermore, farm animals wastes, such as poultry litter, hog excrement, and cattle manure, are being used increasingly as feedstuffs. Many nonconventional feed resources, such as straw, hay, and crop residues, have methods developed for them which can be used to improve digestibility and nutritional content. Considerable decrease in cost of feedstuffs can be obtained by using simple least-cost ration techniques. In addition, a variety of plants, such as azolla and leucaena, deserves much more attention.

Table IV.1. Human Population and Hectares of Arable and Pasture Land in the Mixed Farming Rainfed Temperate Zones (excluding Africa and Tropical Highlands)

			Human Pop. (mill)	% of Natl. Total	Pasture Land (mill ha)	% of Natl. Total	Crop Land (mill ha)	% of Natl. Total
OECD
	North America:
		Canada	25.1	94.4	19.0	67.9	41.9	91.3
		United States	151.7	60.7	64.0	26.8	139.3	74.2
	South Pacific:
		Australia	5.0	29.4	20.0	4.8	8.9	19.0
		New Zealand	3.2	94.1	6.7	48.9	0.4	100
	Europe:
		Austria	7.7	100	2.0	100	1.5	100
		Belgium -Luxembourg	10.4	100	0.7	100	0.8	100
		Denmark	5.1	100	0.2	100	2.6	100
		Finland	5.0	100	0.1	100	2.5	100
		France	56.7	100	11.2	100	19.2	100
		Germany	79.5	100	5.3	100	12.0	100
		Greece	9.9	98.0	3.6	67.9	3.8	97.4
		Ireland	3.4	97.1	4.1	87.2	0.8	88.9
		Italy	57.7	100	4.9	100	12.0	100
		Netherlands	14.9	100	1.1	100	0.9	100
		Norway	4.2	100	0.1	100	0.9	100
		Portugal	9.3	93.9	0.5	62.5	2.3	71.9
		Spain	37.5	96.2	6.3	61.2	18.0	89.6
		Sweden	8.6	100	0.6	100	2.8	100
		Switzerland	6.0	53.8	0.6	37.5	0.3	75.0
		United Kingdom	57.0	98.3	10.0	89.3	6.0	90.9
		Yugoslavia (former)	23.8	100	6.4	100	7.7	100
	Asia:
		Japan	123.5	100	0.7	100	4.6	100
CSA
	Argentina		7.0	21.7	4.7	3.3	0.2	0.8
	Chile		7.2	54.5	7.2	53.3	2.1	52.5
ASIA
	China		323.7	29.0	60.8	15.2	26.2	27.1
	Mongolia		0.2	9.1	2.1	1.7	1.4	100
	North Korea		8.7	39.0	0	0	1.4	70.0
	South Korea		3.3	7.7	0	0	0.5	23.8
E. EURO. & CIS
	Albania		3.3	100	0.4	100	0.6	100
	Bulgaria		8.8	100	2.0	100	3.9	100
	Czechoslovakia		15.6	100	1.6	100	5.0	100
	Hungary		10.3	100	1.2	100	5.1	100
	Poland		38.3	100	4.1	100	14.4	100
	Romania		23.2	100	4.8	100	9.4	100
	U.S.S.R.		281.3	100	327.3	100	224.4	100
Total			1,436.1		584.3		583.8
% of World MRT			85		94		95
% of World Total			26.3		17.4		43.4

Table IV.2. Numbers of Head of Cattle, Sheep and Goats in the Mixed Farming Rainfed Temperate Zones (excluding Africa and Tropical Highlands)

			Cattle (mill)	% of Natl. Total	Sheep (mill)	% of Natl. Total	Goats (mill)	% of Natl. Total
OECD
	North America:
		Canada	8.7	77.7	0.4	50.0	0	0
		United States	46.1	53.3	1.4	12.3	0.1	5.3
	South Pacific:
		Australia	8.1	34.9	19.6	11.5	0	0
		New Zealand	6.3	77.7	21.9	37.8	0.3	27.3
	Europe:
		Austria	2.6	100	0.3	100	0	0
		Belgium - Luxemb.	3.3	100	0.2	100	0	0
		Denmark	2.2	100	0.1	100	0	0
		Finland	1.4	100	0.1	100	0	0
		France	20.4	100	11.1	100	1.2	100
		Germany	19.1	100	4.1	100	0.1	100
		Greece	0.5	83.3	5.0	57.5	3.0	56.6
		Ireland	4.9	83.1	4.8	82.8	0	0
		Italy	8.7	100	10.8	100	1.2	100
		Netherlands	4.5	100	1.7	100	0	0
		Norway	1.0	100	2.2	100	0.1	100
		Portugal	0.9	69.2	3.6	64.3	0.6	66.7
		Spain	4.1	80.4	16.0	66.7	1.7	45.9
		Sweden	1.7	100	0.4	100	0	0
		Switzerland	0.9	47.4	0.1	25.0	0	0
		Yugoslavia(former)	4.7	100	7.6	100	0	0
	Asia:
		Japan	4.4	100	0	0	0	0
CSA
	Argentina		3.8	7.5	0.8	2.8	0.4	12.1
	Chile		1.6	48.5	3.2	48.5	0.2	33.3
ASIA
	China		9.9	12.9	17.6	15.5	23.4	23.8
	Mongolia		0.7	25.9	2.0	14.0	0.5	10.0
	North Korea		0.3	23.1	0.1	25.0	0.1	33.3
	South Korea		0.1	4.8	0	0	0	0
E. EURO. & CIS
		Albania	0.6	100	1.6	100	1.1	100
		Bulgaria	1.6	100	8.1	100	0.4	100
		Czechoslovakia	5.1	100	1.1	100	0.1	100
		Hungary	1.6	100	2.1	100	0	0
		Poland	10.0	100	4.2	100	0	0
		Romania	6.3	100	15.4	100	1.0	100
		U.S.S.R.	118.3	100	138.4	100	6.6	100
Total			314.4		306.0		42.1
	% of World MRT		101.5**		84.7*		84.7*
	% of World Total		24.4		20.3*		20.3*

* Sheep plus goats
** E.E. and CIS estimates in Sere’s report are 58.5 mill less than the WRD source used herein.

2. MRT Environmental Impacts

2.1. Range Utilization

2.1.1. Direct Indicators

2.1.1.1 Soil Structure

See Sections III-2.1.1.1 and V-2.3.1.2.

2.1.1.2 Soil Erosion

See Sections II-2.1.1.2 and V-2.2.1.1.

2.1.1.3. Pesticide/Herbicide Residues in Water

Pesticide levels in water from rangelands are minimal and generally poorly documented. Most monitoring sites are associated with water systems where cropland is a major component of the landscape, masking any potential loading from rangelands. The primary source of pesticides from rangelands would be associated with runoff from sites where external parasites are controlled. Location of such sites needs to consider overland flow issues and downslope filtering of runoff and grazing of run-on areas to minimize pesticide loading in watershed system.

Also, see Sections II-2.1.1.3 and III-2.1.1.3.

2.1.1.4. Pesticide Use and Residues

The issue of pesticide use and residues relative to grazing animals and the environment must consider the dynamics of the system and ascertain impacts. Also, food safety issues arise over concern that consumption of food products derived from grazing animals may contain harmful levels of chemicals. An extensive review on the subject was conducted by Byers (1994), Craigmil (1994), Lefferts (1994), and Winter (1994) in a study commissioned by the U.S. National Cattlemen's Association entitled "Cattle on the Land" (Byers 1994). The issue was also reviewed by Cheeke (1993).

Principal concerns of the residue issue relate to use of pesticides for control of external parasites, anthelmintics as deworming agents, hormones for growth regulation, antibiotics for disease control, trace minerals (Se), vitamins, and pesticide consumption in crop residues. At issue is residue levels in animal foods consumed and dispersal of chemicals in the environment through excretion or direct discharge in the environment.

External applied pesticides can be stored in body fat, detoxified, and excreted in the urine, or excreted intact in the feces. Once excreted, the chemicals can be detoxified by soil microbes, volatilized into the atmosphere, dispersed into water, or photooxidized upon exposure to sunlight. Extensive testing of beef in the U.S., representing temperate grassland systems, mixed farming temperate systems, and humid grassland systems, found that mean residues were.23 percent of acceptable daily intake levels, with chlorinated hydrocarbons comprising the largest contribution about the low levels (FDA 1990).

Prevalence of pesticides of food animal origin have been relatively uncommon in the U.S. in recent years. Ritchie (1994) reports that NRMP and FSIS violative rates (percent of samples) for all pesticides and anthelminitcs in the U.S.:

Animal Kind/Class	NRMP	FSIS
Bull	na	0.0%
Steer and Heifer	.24 to.43%	0.0%
Calves	.26 to.31%	na
Cows	.22 to.24%	.23%
Swine	na	.68%
Market hogs	.09to.32%	na
Sows	.23 to.86%	na
Sheep	na	.26%
Lambs	.61%	na
Goat	na	.26%
Chickens	.24 to.63%	0 to.54%
Turkey	0.0%	.19 to.53%
Ducks and geese	na	0.0%

Since 1986 reported rates have declined further for fifty-three compounds in the following classes: chlorinated hydrocarbons, organophosphates, carbamate, and benimidazales. Among these the most common class used with grazing animals are the organophosphates and carbamates. In a national study in 1983 the violative rate was zero for organophosphates. Carbamates seldom appear as volatile residues (USDA-FSIS 1988). The U.S. monitoring system would indicate that given the inspection system in place and husbandry practices applied that pesticide residue in meat products from grazinglands is well within safe limits. Several European countries have reported major declines in organophosphates since 1980 (Arino 1991, Venant et al. 1989, Herrera et al. 1994).

Of concern is nonpoint source pollution associated with application of pesticides for external parasite control. Three application methods are used, spraying, dipping, and injection. Spraying's primary risk is associated with localized soil contamination, which could be released off-site via runoff events or leaching into groundwater supplies. The degree of impact depends on the level of soil detoxification, soil infiltration/macropore flow, photooxidation, and runoff dilution with subsequent filtering and off-site detoxification. Therefore, location of application sites relative to the degree of "ecosystem" leakiness is at issue.

Placement of treatment locations becomes more critical as the frequency of treatment increases. Those sites located in drainages or in outflow-inflow transitions increase risk of water loading with pesticides. The degree to which a treatment site contributes will also depend on the frequency of runoff events relative to treatments, with increasing runoff diluting the effects. The sequence of downslope sinks and filters will ultimately dictate the degree of environmental impact.

Soil with high water tables and high infiltration, or macropore flow, poses a potential problem for local groundwater loading with pesticides. Typically, livestock-spraying or dipping activities are located near human dwellings and their supporting water wells. Serious consideration needs to be given to both slope position and soil permeability when locating livestock-handling facilities.

Oil-based acaracides present an additional problem in that dispersion into the soil at loafing and bedding sites or at nighttime concentration areas can move these chemicals over a wider area. This dispersion can be a beneficial effect if detoxification occurs or greater dilution occurs in runoff. Sprayed or dipped livestock that stand in open water ponds or running water in streams can also present chemical transfer points, particularly if the animals are still wet from spraying or dipping. Use of volume control and cement, drip-return catchments at treatment sites would help maintain residues at a localized site.

Chlorinated hydrocarbons (DTT and its analogs chlordane, heptachlor, aldrin, dieldrin, mirex, toxaphene, and lindane among others) have been largely discontinued or severely restricted because of suspected carcinogenic effects and long half-lives of several months in mammals and up to several years in arid soils. Tests of meats imported into the U.S. indicate no significant differences in domestic meats with respect to residue violations.

Although anthelmintics have not been linked to any significant residue problems in meat products, there is some concern that they may disrupt nutrient cycling due to residue levels in feces, which retard the decomposition process. Madsen et al. (1990) studied the effects of ivermectin (22, 23-dihydroavermectin B1) on dung-dwelling Diptera-Cyclorrhapha, dung beetle larvae (Aphodins spp.), and earthworms and houseflies (Musca domestica).

The dung-dwelling larvae of Diptera-Cyclorrhapha were lower in pats from treated dairy heifers grazing temperate pastures in Denmark. Larvae of Aphodins were suppressed for one day after excretion post-treatment. Cyclorrhapha were lower than the controls up to thirty days after treatment. Earthworms were not affected. Most dung-breeding insects were negatively affected. Most dung-breeding insects are secondary species which invade the dung at a relatively late stage, feeding on nondecomposed plant material. The filter feeding on particulate organic matter of this group results in high mortality by ivomectin (Wall and Strong 1987, Schmidt 1983).

Nutrient cycling in pastures could be impacted by using ivomectin. In high-yield tropic pastures, dung is dispersed within 24 hours (Coe 1977, Heinrich and Bartholomew 1979). In cool temperate grasslands, dung requires approximately one grazing season to break down with maximum deterioration in late fall. Ivomectin remains active in dung pats up to sixty days after injection with the greatest impact on insects and least impact on dung beetles and earthworms (Madsen et al. 1990).

Pesticides form residues in supplemental feeds, and crop residues are also another entry point in the food chain. Given that most crops for humans do not have excessive levels of harmful chemicals that would place the population at risk, it is the consumption of processed by-products and crop residues not destined for human consumption that is the greatest concern, particularly herbicides. Special attention needs to be paid to this area of concern.

2.1.2 Indirect Indicators

2.1.2.2 Socioeconomic Indicators about Feeds and Feeding

2.1.2.2.1 Crop and Forage Production Technologies: Summary

Animal agriculture is, of course, dependent on crop and forage techniques. Thus, assessment of what is ahead in animal agriculture is highly related to understanding changes in feedstuffs production.

Biotechnology, discussed at length in other sections, opens the door for rapid increases in plant improvement through recovery of desirable plant genotypes from tissue culture, protoplast fusion, and cloning. Recombinant DNA facilitates the direct manipulation of an organism's genetic material to produce offsprings with desired characteristics. Although use of DNA is still in the early stages of development, DNA will be widely applied in the 1990s to agriculture.

Plant-breeding work includes increased photosynthetic efficiency, seeds produced by genetic engineering, seed treatment, plant growth regulators, salt tolerance, and introduction of polyacetylenes and nitrogen-fixing organisms.

Some of the more exciting agronomic practices include no-till (zero tillage), custom prescribed tillage, forage quality improvement through management, hydroponics, multiple cropping, intercropping, and improved water conservation practices.

Mechanization is an important new area to reduce costs of animal feedstuffs. Innovations include solar bin buildings, improved engine, draft and tractive efficiency, integrated control harvesting, and computer-controlled spot application of herbicides on weeds. Many of these technologies will have as much impact on very small plots typical of countries in Asia as on the largest farms in North America.

Data management and coordination techniques are an important aspect in the new scientific revolution for agriculture as a whole and personal computers are the key hardware. A virtual information explosion has taken place in the past five years due to the greatly expanded use of computers for data analysis and dissemination of information. Computer ownership has also led to improved management practices on the part of both farmers and researchers, resulting in a type of psychological synergy.

Review of animal and crop technological change leads to a conclusion that management is the central variable for effective adoption of them. This conclusion is reinforced by recognition that the shelf life of each technology and product is becoming shorter as greater knowledge about basic processes is acquired. The net result is that a continual information flow to producers is needed because technologies are constantly changing. However, when taken as a whole--and in combination with the synergistic effects--the impact will be enormous.

2.1.2.2.2 Feedstuffs Availability and Use

Rangeland and extensive pasture areas of the world differ considerably regarding management strategies related to feed and feeding. Furthermore, distance from market, transportation infrastructure, and cost/price relationships of feedstuffs and animals sold are major constraining factors on feasibility of feeding practices. Clearly, management abilities, extension education availabilities, and capital resources are also constraints. For example, a producer in a very short growing season, with no economic potential of growing or purchasing inputs for the long winter, has very few management options available. In contrast, producers in semitropical, agroecological zones with markets nearby have an abundance of potential production strategies. In effect, there is a wide variety of feeds and feeding practices that vary from quite primitive to very intensive.

Major advances are being made in feedstuffs and their use. Many of the advances are the result of biotechnology and genetic engineering. To a large extent, producers in developing countries can benefit almost as much as those in developed countries even though the research and product-development technique are often quite sophisticated. As discussed in other sections of this report, knowledge is becoming paramount in adapting to and adopting technologies. The following discussions highlight this observation.

2.1.2.2.3 Compounds to Promote Growth and Feed Efficiency

The various compounds currently used to promote growth, such as anabolic steroids and ionophores, will continue to be used. But there is a host of new products also being developed. This section begins with a discussion on growth promotants and feed-efficiency enhancers currently in use and proceeds to emerging technologies such as somatotropins and beta-agonists. They are included in this section because they are so closely tied to feeding management and strategies.

2.1.2.2.3.1 Anabolic Steroids

Some steroids (any of numerous naturally occurring fat-soluble organic compounds) act as vitamins while others act as hormones. The anabolic steroids used to promote growth are estrogens and progesterone (female sex hormones) and androgens (male sex hormones). First approved for use in livestock in 1954 in the United States, they are only used in beef cattle and sheep. Their widespread use, almost exclusively as an implant, includes 70 percent of stocker cattle and 90 percent of feedlot cattle in the United States. Anabolic steroids are the principal growth promotants used. They have not been shown to be effective in swine or poultry.

The mechanisms by which steroids act in cattle are not known but it is postulated that estrogens and somatotropins are additive, and act independently. Current research is focusing on using combinations of steroids and delivery mechanisms as well as experimenting on pregnant ewes and cows in the hope of increasing growth potential of offspring (a process known as imprinting). Anabolic steroids and all other types of hormones are banned in the EEC for political reasons. Considerable testing has taken place in China, but there is virtually no use made of them commercially, mainly because of the rudimentary cattle industry structure.

2.1.2.2.3.2 Somatotropins

A somatotropin is a protein hormone produced by the pituitary gland, a very small gland located at the base of the brain that affects growth and other physiological processes, such as lactation in dairy cows. The objective in work with somatotropins is to elevate natural levels using genetic engineering techniques to increase production. (A hormone is a chemical produced by one organ or cell and transported to another to cause a biological effect.) Hormones can be steroids, proteins, peptides, or modified amino or fatty acids.

All major livestock species produce somatotropins, with each unique to the species. Evidence also exists that some nonvertebrate animals, such as shellfish, produce somatotropins. Differences in the amino acid sequence of proteins lead to species specificity. Somatotropins affect growth rate, feed efficiency, milk yield, and the proportions of fat and protein in the body. They also affect glucose metabolism by increasing glucose production by the liver. This additional glucose is available for such uses as increased growth or milk production. Furthermore, somatotropins redirect nutrients (primarily glucose) away from fat synthesis to provide energy for lean tissue accretion.

2.1.2.2.3.2.1 Bovine Somatotropin

Only a small number of studies using somatotropin to increase growth in growing cattle have been conducted, although research in this field is increasing. Comparison of results is tenuous but, on average, daily weight gain increases by 12 percent, feed conversion is improved by 9 percent, carcass lean content is increased by 9 percent, and carcass fat is decreased by 15 percent.

Bovine somatotropin (bST) has been shown to increase milk production by about 12 percent, although response varies with stage of lactation and nutritional status. The ratio of nutrients required by cows given bST does not change. However, the cow will consume more feed to accommodate the increased milk production.

2.1.2.2.3.2.2 Ovine Somatotropin

Both bST as well as ovine somatotropin (oST) are effective in sheep. Average daily weight has increased by 18 percent, feed efficiency improved by 14 percent, carcass lean content increased by 10 percent, and carcass fat content was decreased by 15 percent.

2.1.2.2.3.2.3 Somatotropin-Related Technologies

So far, the discussion has focused on exogenous administration of somatotropin. Other research is being carried out to increase endogenous production and secretion. One approach is through the growth hormone-releasing factor (GRF), which is another protein hormone that acts on the pituitary gland. Administration of GRF has been shown to be effective; the drawback is production of sufficient quantities and ways of administration for commercial use.

Another related technology is to deactivate somatostatin, a compound that inhibits release of somatotropin from the pituitary gland. This method has been shown to be effective in cattle. A third method being investigated is to increase the effectiveness of somatotropin by coupling it with a monoclonal antibody specific for somatotropin. This technique is in its basic stages.

2.1.2.2.3.3 Beta-Agonists

Beta-agonists, compounds similar to epinephrine (adrenaline), can be used as growth promotants and also to enhance carcass leanness in meat-producing animals. They were not approved for use in the United States until early 1993. These compounds, which are also called repartitioning agents, redirect nutrients away from the formation of fat tissue to muscle growth.

2.1.2.2.3.4 Antimicrobial Agents

Antimicrobial agents, which include antibiotics (naturally occurring substances) and chemotherapeutics (chemically synthesized substances), are a traditional way used for the past forty years to promote growth. They are added to livestock feed in low concentrations to suppress or inhibit the growth of microorganisms. Although much is known about antibiotics, it is not known exactly how antimicrobial agents stimulate growth, but the most widely accepted hypothesis is that they control subclinical disease, thus helping animals to more closely reach their genetic potential. Current research is focusing on development of new antimicrobials, safety aspects, and more efficient methods of delivering them. Growth rates in beef cattle have been shown to increase up to 5 percent, while feed efficiency has improved up to 7 percent.

2.1.2.2.3.5 Nutrition

Feed is the major cost component in livestock production. Consequently, technologies and production methods which can reduce cost, and thus increase profits, are welcomed. Improvements in feed efficiency, i.e. a lower quantity of feed consumed per unit of weight gain, as well as faster gain, are also goals. There is a cornucopia of technologies being developed, only a few of which are now discussed.

Feed additives to improve digestibility of feedstuffs are increasingly being used. Sodium bicarbonate in rations has been shown experimentally to increase weight gain by 14 percent through increasing feed intake by 8 percent and maintaining a neutral ruminal pH. Plastic pellets can even be used as a substitute for roughage. Experiments have shown that 50 g of the pellets compare favorably with 1.9 kg of hay, and they can be recycled. Genetic manipulation of ruminal bacteria is in its infancy, but as the ruminal fermentation patterns become better understood, it will be possible to boost the rate at which the rumen breaks down cellulose from the current 70 percent to nearly 99 percent. The result will be improvements in feed conversion to milk. Microflora developed through genetic engineering will be used to metabolize raw feedstuffs more efficiently into nutrients.

Wastes from animals such as poultry litter, hog excrement, and cattle manure are increasingly being used as cattle feedstuffs. Recent attention given to ensiling these wastes with other material, such as corn forage or grass hay, has yielded promising results. Rumen-regulating drugs to improve feed digestibility and absorption along with expanded feed intake are being investigated. Other emerging nutritional techniques are treatment of straw with a urea-based liquid protein supplement. Research in the United Kingdom has shown that dairy cattle can maintain yields in the warm season by feeding grazing animals a supplement of brewers' grains and treated straw. Straw, hay, and crop residues treated with hydrogen peroxide have been shown to improve dramatically digestibility of these low-value feeds. Use of these nonconventional feed resources, along with the use of ammonia, which is now a well known practice that is being adopted more generally in many countries, is discussed in another section.

Mineral use is consistently overlooked in most of the world. Serious consequences of inadequate mineral nutrition are reductions in daily gain and reproduction as well as increased health costs and higher mortality. Although there continues to be identification of mineral deficiencies and there are emerging technologies in testing and evaluation procedures, it is clear that management, education, and provision of quality products are the limiting factors. In fact, proper mineral and vitamin use as well as adequate nutrition are constraints to effective use of many emerging technologies.

2.1.2.2.4 Feed Price and Ration Optimization

Some of the most serious considerations in development of a country's feed industry are quality control improvement and optimal use of ingredients. The purpose of this section is to quantitatively demonstrate the extent to which feed resources can be misallocated and to show the impact from utilizing least-cost rations. The example that follows is for pigs, but the principles, and probably most of the results, apply to ruminants as well.

The first approach taken is to show the misallocation of feedstuffs by evaluation of relative values of Chinese feedstuffs. The data, presented in Table IV-3 for August, 1986, are based on government fixed prices in Beijing. A swine ration analysis and relative value computer program from the Iowa State University Cooperative Extension Service was modified and used to determine the relative values. Values are based on the standard approach of calculating nutrient content of the feed based on energy, lysine, and phosphorus content of each ingredient. These values, in turn, are based on the prices and composition of maize, soybean meal, and dicalcium phosphate, also a standard industry practice in evaluating feedstuffs.

Review of the relative value tables shows considerable disparities between feedstuffs, indicating that prices have not been set according to relative feeding values. For example, data for August, 1986, based on government maize price of $8.65 per 100 kg in Beijing (the free price in August, 1986, was $12.97) show that the relative value of government-priced wheat bran was $9.80 per 100 kg. (From this point all feed-related values are expressed in terms of 100 kg unless otherwise indicated.) The actual price was $5.95, which means that a $3.85 advantage existed in favor of wheat bran over maize. Rapeseed cake had a $5.99 advantage, while peanut cake (groundnut cake) had a $6.08 disadvantage.

Data are not presented, but there was a great diversity in the effect on price advantage when the free market maize price (about 50 percent higher than the government price) was used in place of the government corn price. Low-protein feedstuffs were heavily affected, while there was relatively little impact on high-protein ones. For example, the absolute advantage of barley shifted from a negative ($-3.01) to a positive ($0.61) per 100 kg, indicating it became a more economical feedstuff than maize when based on the free maize price. But, imported fishmeal only changed from $-16.14 to $-13.75, a much smaller percentage change.

Analysis of relative values using Beijing data for June, 1992, revealed that while discrepancies still existed between the actual and feeding values, the gap was generally closer. The only notable exceptions were cabbage and fishmeal. The analysis indicated that the flow of information about prices had improved.

Analysis of relative value data for Japan and the United States for the same time period indicates there was very little, and in most instances no relative, advantage or disadvantage among feedstuffs. The reason is feedstuffs are widely traded daily in these countries, and, as soon as an advantage appears for a feedstuff, demand for it immediately increases, driving up the price. The same situation holds in other commercially developed countries. In contrast, even in the early 1990s there was no published price data for feedstuffs in China and virtually no use made of relative value analysis. In fact, only very limited use was made of least-cost feed formulation. Equally as important is recognition of the great fluctuation throughout the country in feedstuffs availability and quality.

The impact of least-cost ration formulation is another indication of the misallocation of feed resources. A typical finishing ration for hogs weighing 60 to 90 kg containing 12.13 percent protein and 1,366 kcal of energy recommended by some researchers in Chengdu would have cost $12.73 per 100 kg in August, 1986, assuming free market-priced maize (Table IV-4). A least-cost ration computer program was used to choose a similarly balanced ration. The result is one based mainly on dried sweet potatoes, rice bran, maize, and cottonseed meal, which would have cost $8.53, i.e., only about three-quarters that of the recommended one, which was 62 percent maize. Maximal utilization constraints were placed on sweet potatoes, rice bran, and cottonseed meal to conform with nutritional recommendations.

A comparison between a standard-recommended ration and a least-cost ration is useful because it demonstrates the extent to which the cost of mixed feed can be decreased by use of least-cost formulation in certain situations. The data are for 1986, but observation shows that analytical similarities existed in the early 1990s. Evaluation of both Tables IV-3 and IV-4 reveal the importance that by-product and nonconventional resources have in feeds. They also show the importance of knowledge in the process.

2.1.2.2.5 By-Product and Nonconventional Feed Resources

Worldwide there is a long history of adeptly utilizing what are now called nonconventional feed resources (NCFR), crop residues, and by-product feeds. But as animal feeding has modernized, the use of NCFRs, relative to total feed consumed, has diminished rapidly. However, there will continue to be an important place for NCFRs, residues, and by-product feeds, and they can be expected to make an important contribution to development of the livestock industry. The purpose of this section is to describe NCFRs and by-products.

The term NCFR has been defined by Devendra (1992) as "all those feeds that have not been traditionally used in animal feeding or are not normally used in commercially produced rations for livestock." Thus, the term "new" feeds has increasingly been applied to NCFRs. A problem in the definition is the difficulty in distinguishing between traditional feeds and NCFRs. For example, rice straw and water hyacinth have long been used in China and much of Asia as major feedstuffs, yet at the world level they are considered NCFRs. The problem then is application of a widely used term to an individual country.

Rather than attempt to develop new terminology, the term NCFR is explained by what it is and is not. NCFR, as used in this report, means all feedstuffs not commonly found in commercially produced rations used in modern-type feeding systems. Thus, minor ingredients such as spent brewers' grains and molasses are not considered NCFRs. Rather, they are designated by-products. In addition, ingredients bought and sold internationally, such as fishmeal, are named by-products. The definition of NCFR has certain drawbacks, but it is consistent with international terminology. Some of NCFR characteristics include:

· their being end products of production and consumption that have not been used or recycled or salvaged (an example is rice straw);

· their mainly being organic, but often found in a solid, slurry, or liquid form (azolla is an example of a plant);

· their economic value often being less than the value in alternative uses (an example is cassava for animal rather than human use);

· their usually being excellent sources of fermentable carbohydrates when derived from feed crops (an example is sweet potato);

· many containing an abundance of sugar, which is high in energy (banana rejects and pineapple pulp are examples);

· many having bulky, poor quality cellulosic roughages with high crude fiber and low nitrogen but which can be utilized by ruminants (rice straw and maize stover are examples);

· some having deleterious effects;

· many, if not most, requiring much more research on ways to utilize them most efficiently and economically.

Devendra (1987), who has researched and written widely on the topic, follows a slightly different classification scheme than the one adopted for this report. He feels there are three main categories of feeds, apart from the primary commodity: crop residues, agroindustrial by-products (AIBP), and NCFRs. Crop residues are defined as mainly fibrous materials that are by-products of crop cultivation. Agroindustrial by-products refer more to by-products derived in the industry due to processing of the main products. Thus, according to Devendra, they include molasses, rice bran, and pineapple waste. To him, NCFRs refer to all those feeds that have not traditionally been used in animal feeding and are not normally used in commercially produced rations for livestock. But he also states that NCFRs include feed material from AIBP. Definitions and classifications of feedstuffs are open to discussion. But the important point is that a definition has been established which permits common utilization of terms in this report.

Table IV-5 sets out nutritional characteristics for many of the crop residues and NCFRs. Of special interest is the wide variability in protein. For example, while cassava leaves are quite high in protein (about 25 percent on a dry matter basis), sugarcane tops only have 3.8 percent protein and pineapple waste 4.9 percent. In contrast, poultry litter ranges between 40 and 46 percent. An important aspect of economic analysis of these feedstuffs is to place them on a relative value basis and, since collection often involves considerable labor, also on a delivered basis.

The feedstuffs termed by-products are relatively well known. Brewers' grains, a by-product of the malting industry mostly for beer making, is one by-product which merits expanded discussion. Barley is generally the grain used. Throughout the world, spent grains, as brewers' grains are also called, are normally sold wet. Once removed from the extraction vessel, brewers' grains ferment rapidly. As a consequence, fresh brewers' grains already contain the volatile products typical of ensiled grains when they reach the farm. A related feedstuff is distillers' grains from alcohol or liquor production.

Spent grains have a wide range of crude protein (CP), 17-30 percent, although the mode is 20.4 percent. In effect, the spent grains are much higher in CP than the original grain, which has a protein content of about 10.6 percent. Metabolizable energy (ME) of spent grains averages 10.4 Mcal with a range of 9.2 to 11.3 Mcal, whereas there is 2.7 Mcal in barley.

Brewers' grains are an excellent feed for cattle and sheep. For example, dairy cattle can be fed as much as 30 kg per head per day of wet brewers' grains with no apparent ill effect. They can also be given generously to cattle on fattening rations, up to 20 kg per day for large animals. Despite brewers' grains not being recommended for pigs due to their fibrous nature, these are the main animals to which they have been fed. The reason is that the dairy and beef feeding industries are quite small and not always located near breweries. However, when available, they are used by dairy farms. Beer production increased very rapidly during the 1980s in response to expanded consumer incomes. The brewing industry can be expected to continue growing, thus providing a substantial new source of by-products for animals.

2.1.2.2.6 Nonconventional Feed Resources Described

The purpose of this section is to describe a number of NCFR which have considerable potential as animal feedstuffs for pasture or range-oriented producers. Because of their importance, green manure crops, treated straw, leucaena, azolla, and poultry litter are discussed in detail.

2.1.2.2.6.1 Green Manure Crops

Many green manure crops, such as azolla, vetches, clover, sesbania, mung beans, and alfalfa, are also either entirely or partly used for livestock feeds. For example, alfalfa is a very popular animal fodder whose roots are used as fertilizer and whose leaves and stalks are fed to animals. Shrubby fatseindingo (Amapha fruiticosa) is planted to improve soil fertility and structure. Its leaves serve as animal fodder, and it is also mixed with other organic materials in making compost. Red and white clovers are used as animal feeds and manure recycled back to the clover fields as a basal fertilizer for crops.

2.1.2.2.6.2 Ammonia Treated Straw, Fodders, and Hay

Straw is quite indigestible, thus limiting both the amount ingested and its feeding value. It is also low in protein content and deficient in many minerals, but because it is relatively cheap and plentiful, straw has received considerable attention from animal scientists throughout the world. A substantial portion of hay produced in every country is of relatively low quality due to improper curing or to adverse conditions after harvest. Finally, the stovers from maize and sorghum are abundant in most countries covered by this report.

The principal straws treated are rice, wheat, and barley. Sodium hydroxide is one possible treatment method but is seldom used. Urea can also be used, but while it raises the protein content, there is a limited effect on palpability. Ammonia has emerged as the preferred on-farm method in some countries where straw, hay, and stovers are treated because ammonia is relatively safe and cheap, and it also increases energy and the protein content.

2.1.2.2.6.3 Leucaena

Leucaena (Leucaena leucocephala) is a tropical and semitropical legume found extensively in warm climates. This tree crop is easily propagated and, if not kept pruned or harvested regularly, will grow into a small tree. It is cultivated or used as a house hedge in much of Southeast Asia. In other countries, such as China, it is mainly found along roadsides, ditches, or other noncropped areas.

Farmers generally feed leucaena fresh in a cut-and-carry system to all types of livestock. The leaves are occasionally fed dry, but because of collection and transport costs, leucaena has not developed into a principal crop in any area. However, research is warranted on this NCFR because it does not require nitrogen (and only minor amounts of phosphorus, potassium, and minor elements) because of its nitrogen-fixing ability and high ME.

One main constraint to leucaena's feeding value is presence of the toxic amino acid mimosin as well as tannins. These ingredients are presently a deterrent to its use in poultry diets. Also, sheep suddenly fed relatively high levels tend to lose their wool. Goats seem to adapt quickly when fed only a leucaena and chopped rice straw diet and thrive with no deleterious effects.

A method of intercropping based on leucaena known as alley cropping has become popular in several tropical countries. The idea is to plant leucaena in rows with another crop in between which then benefits from the nitrogen-fixing aspect of leucaena. Goats have been used to harvest the leucaena in some areas. Overall, this tree crop seems to have much potential in warm areas.

2.1.2.2.6.4 Azolla

Azolla, a crop little known outside China although there are many varieties from around the world, is widely grown along China's southeast coast as an animal feed, a green manure crop and as a source of nitrogen. This tiny aquatic fern has a symbiotic association with a nitrogen-fixing blue-green algae, genus Anabaena.

There are nine varieties of azolla in the world:

1. A. microphylla from South America,
2. A. nilotica from Sudan and Burundi in Africa,
3. A. carolina from the United States,
4. A. imbricata from China,
5. A. imbricata indo from India,
6. A. rubra from Japan,
7. A. mexicana from Mexico,
8. A. filiculoides from the United States,
9. A. pinnata from the Ivory Coast.,

Nitrogen content of azolla varies with season and variety. Growth and nitrogen content are greatest when grown under high temperatures. On a dry-matter basis azolla has 2.5 to 5.5 percent nitrogen. It yields 135 kg of nitrogen per ha in paddy fields and thus needs no chemical nitrogen except when soils are poor.

Use of azolla as an animal feed is expanding in China. It is fed fresh to poultry and pigs and can also be fed to ruminants. The crude protein content varies from 11 to 16 percent (dry-matter basis). In a cultivation experiment at Doudian Village in the western suburbs of Beijing, azolla yielded 50 metric tons (fresh weight) per ha of water surface on the approximately 20 ha of ponds in the village. Yield on a dry-weight basis is 19.5 metric tons, which is about twice that of alfalfa (dry-weight basis) in that area (Simpson et al. 1994b).

Azolla has generally been used only as a supplement in animal feeds since the nutrient content of droppings is higher when animals are also fed with grain crop by-products. The common practice with azolla has been to first satisfy farmer's fertilizer requirements and then to use it as a green feedstuff for animals.

2.1.2.2.6.5 Poultry Litter

Poultry litter, i.e., poultry manure, provides both a good fertilizer and feedstuff. The quantity of litter available will grow rapidly as consumption of poultry products expands and especially as a larger proportion of birds are kept in commercial operations. Poultry litter is an excellent fertilizer, but high nitrate levels preclude continual extensive use on cropland. Regardless of how useful litter is as a fertilizer, as poultry operations in China become more concentrated and expand in size, increasing attention will be given to feeding it.

The presence of a substantial amount of fiber in poultry litter precludes its extensive use in broiler diets. Furthermore, high nitrate and urea levels limit its use to not more than 10 percent of the nitrogen component of the ration. Excessive use can cause toxicity because of excessive ammonia. Poultry litter has essentially no use for laying hens as it is too low in energy. It cannot be fed to dairy cattle due to toxic residues. The high fiber content precludes use in swine rations. However, while use is quite limited in swine and poultry, poultry litter is an excellent feed for beef cattle. The main constraint is the high calcium content (about 10 percent) which becomes a limiting factor, as beef cattle rations should only have about 3 percent calcium.

The United States is an example of a country in which poultry litter use for animal feed has grown rapidly. Published data are not available, but discussions with specialists indicate that about 1 to 2 percent of all poultry litter was being used as feedstuffs in the early 1990s. The major limiting factors are distance between poultry operations and cattle feedlots and relatively cheap alternative feeds. However, as environmental guidelines become stricter there will be increased pressure to expand the use for feeding.

Composting for feedstuffs is another use of poultry litter that may have considerable application in China. The technique is used to convert manure to stable products using microorganisms. Thermophylic bacteria in aerobic fermentation use the nonprotein nitrogen in manure to synthesize protein. Studies in the Netherlands show that bulls fed maize silage with 20 percent of the product grew as well as bulls fed 100 percent maize silage. Composted poultry manure can also be used with straw as a substrate for growing mushrooms.

2.1.2.2.7 Discussion on By-Products and NCFR

Substantial and adequate general information and, to a lesser extent, qualitative data on individual feeds are now available for most Asian countries. Furthermore, tables of feed composition for both conventional and nonconventional feedstuffs applicable to much of Asia now exist. Unfortunately, research in China as well as in other Asian countries has tended to focus on isolated feeding trials and determination of feed composition rather than centering on economic analyses. Efforts to extend laboratory work to real farm situations have been on a small scale in Asia and have not been altogether convincing.

There are a number of good reasons why NCFR are presently underutilized not only in China but in all other Asian countries. Production is scattered and the quality produced is low, especially for processing. Few researchers have attempted to utilize fibrous feeds in the untreated form in combination with other ingredients. But there is evidence that supplementation of fibrous feeds (such as straw) with leguminous forages may be just as physically effective and more cost effective than chemical pretreatment (Devendra 1992). Nevertheless, there is often a high cost of collection, and in many cases processing plants would have to be modified, e.g., to collect blood in slaughter plants. In addition, there is a general unawareness of the feeding value from NCFR and a tendency to feel that many of the products are for disposal and not utilization. Finally, there is a lack of managerial and technical skills to properly utilize the feeds. Devendra (1992) also points out that limitations on the end use of the final product is a constraint, along with uncertainty about marketability of the end products. For example, few producers really know how to effectively utilize processed food wastes, such as pineapple waste from canning.

2.1.2.2.8 Implications of Feeds and Feeding Relative to Livestock-Environmental Interaction

Most technological advances associated with feeds and feeding for animals using grazinglands have focused on improvement of digestibility of feedstuff through direct treatment or manipulation of gastrointestinal microflora, creation of more adapted derived pasture species, application of animal metabolic modifiers, improved use of crop/food by-products, and improved genetics of domestic stock. Implicit in these trends is the replacement of existing grazinglands with more adapted derived-pasture species in a strategic manner, manipulation of metabolic rate and nutrient partitioning in ruminants, more diverse use of more exotic feedstuff and processed food by-products, and emergence of domestic animals with transgenic characteristics to use existing forage resources more efficiently. In each of these cases, intensification of management inputs will have to emerge to capture investments in these new technologies. Implicit in these trends are landholders with sufficient capital or credit worthiness to convert existing lands, purchase veterinarian/commercial animal products, or properly acquire and feed advanced feed products. Special attention will have to be paid when applying metabolic agents, given the higher emerging requirements for such things as milk production or greater partitioning to protein at the expense of energy. In both cases, traditional supplementation programs will have to be altered to take advantage of these processes in the animal. Otherwise, greater wastage and lower animal production may be the result. A positive effect on the environment may be more efficient use of protein with less nitrogen excretion onto grazinglands or waste processing facilities. Critical to this process will be application of analytical tools which better characterize nutrient balance of grazingland animals and mediation with least-cost, biologically optimal feedstuff. In all cases, greater economic well-being of landholders and improved training in the application of these technologies will be required for widespread adoption.

Table IV-3. Actual price, relative feeding values, and economic advantage of swine feedstuffs based on government prices of maize, Beijing, August, 1986, and June, 1992

Ingredient	August, 1986				June, 1992
	Relative values				Relative values
	Actual $/100 kg	$/kg	$/100 kg	$/100 kg adv.	Actual $/100 kg	$/kg	$/100 kg	$/100 kg adv.
Azolla, wet	0.54	0.004	0.37	-0.17	0.33	0.00	0.29	-0.04
Barley	11.89	0.089	8.88	-3.01	10.00	0.07	6.89	-3.11
Bonemeal	10.37	0.175	17.46	7.19	13.33	0.16	15.88	2.54
Blood meal	32.48	0.415	41.52	9.04	33.33	0.32	32.25	-1.08
Brewers' grains, wet	1.62	0.025	2.47	0.85	1.67	0.02	1.94	0.28
Cabbage	0.54	0.007	0.70	0.16	10.00	0.01	0.55	-9.45
Corn gluten meal	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Cottonseed meal	10.81	0.144	14.38	3.57	6.67	0.11	11.35	4.69
Dicalcium phosphate	29.73	0.297	29.73	0.00	29.00	0.29	29.00	0.00
Distillers' grains	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Fishmeal, domestic	29.73	0.229	22.92	-6.81	46.67	0.19	18.57	-28.10
Fishmeal, imported	48.65	0.349	34.90	-13.75	53.33	0.28	28.17	-25.16
Golden fishgrass, wet	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Maize, state price	8.65	0.087	8.65	0.00	6.67	0.07	6.67	0.00
Peanut (groundnut) cake	20.00	0.139	13.92	-6.08	10.00	0.11	10.90	0.90
Flaxseed meal	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Rapeseed cake	10.27	0.163	16.26	5.99	9.17	0.13	12.92	3.76
Sorghum, govt.	8.11	0.083	8.35	0.24	10.00	0.06	6.49	-3.51
Sorghum, free	13.51	0.083	8.35	-5.16	0.00	0.06	6.49	0.00
Starch industry by-product	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Soybean meal	20.27	0.203	20.27	0.00	15.83	0.16	15.83	0.00
Sweet potato and vine, wet	0.00	0.000	0.00	0.00	0.00	0.00	0.00	0.00
Sweet potato vines, dry	4.59	0.062	6.21	1.62	0.00	0.05	5.23	0.00
Tofu (beancurd) waste	1.62	0.015	1.52	-0.10	0.00	0.01	1.18	0.00
Wheat bran, govt.	5.95	0.098	9.80	3.85	5.00	0.08	7.83	2.83
Wheat bran, free	6.49	0.098	9.80	3.31	10.00	0.08	7.83	-2.17

Source: Simpson et al. 1994b

Ingredient	Protein	Price	Price advantage	Composition
				Recommended	Least cost1
	Pct	$/100 kg		Pct
Cottonseed meal	33.80	7.56	6.91	-	10.00
Dicalcium phosphate	0.00	20.52	0.00	1.20	-
Dry silkworm powder	53.90	32.44	-6.62	1.00	-
Lysine	0.00	378.00	0.00	0.28	-
Maize, free market	8.60	13.52	0.00	62.10	30.93
Methionine	0.00	324.00	0.00	0.12	-
Peanut meal	43.90	19.45	-3.08	-	2.24
Premix	77.00	77.00	0.00	-	-
Rapeseed meal	36.40	8.64	8.12	8.00	1.83
Rice bran	12.10	5.40	8.90	24.00	15.00
Salt	0.00	3.24	0.00	0.30	-
Sweet potato, dry	3.90	5.41	7.67	-	40.00
Wheat bran, free milk	14.40	10.81	1.58	3.00	-
	Analysis
Total ingredients (pct)				100.00	100.00
Ration costs ($/100 kg)				12.73	8.53
Protein (pct)				12.13	12.13
Energy (kcal)				1,366.00	1,350.00

Source: Simpson, Xu and Miyasaki, 1994.

¹ Cottonseed meal set at maximum of 10 percent, rice bran at 15 percent, and sweet potatoes at 40 percent.

Feed source	Moisture	Crude protein1	Crude fiber	Organic matter digestibility
	Percent
Crop residues2
Cassava leaves	73.6-78.8	21.7-26.6	8.1-23.2	55.1-61.0
Groundnut vines	71.3	9.2	24.1	60.0-68.0
Maize stover	12.8-16.3	5.0	28.3	61.0
Pigeon pea forage	71.1-74.8	20.0-25.6	17.6-22.6	47.2-55.4
Rice strawe	9.0-9.2	3.3-4.5	28.8-33.6	48.1-56.4
Sugarcane tops	72.0	3.8	38.0	43.0
Sweet potato vines	99.3	13.3	17.2	60.2
By-products3
Bagasse	3.9-4.7	2.9-6.9	10.3-39.3	49.0
Brewers' grains	9.8-10.8	24.0-27.4	15.9-17.1	60.0
Cocoa pod husks	89.6	6.0	31.5	45.0
Coconut cake2	10.0	18.0	12.0	78.0
Coffee seed hulls	8.0	6.9	45.6	31.0
Molasses	25.4	1.6	-	108.0
Palm kernel cake4	5.7	14.2	20.2	66.8
Palm oil mill effluent	78.0-89.0	9.6	11.5	58.1-64.2
Palm press fiber	13.8	4.0	36.4	30.8
Pineapple waste	6.8	4.9	20.8	76.0
Poultry litter	6.4	40.4-45.7	18.0-21.2	54.2
Rice bran	9.3-11.4	11.4-17.4	10.4-20.0	62.0
Rice hulls	6.7-9.7	1.5-2.8	14.3-41.4	37.0
Wheat middlings	12.7	20.5	9.0	69.0-71.4

Source: Adapted from Devendra (1992).
¹ Dry matter basis.
² Includes nonconventional feeds.
³ Expeller pressed.
⁴ Solvent extracted.

See Section V-2.1.2.4.

2.1.2.5 Population

See Section V-2.1.2.5.

2.1.2.6 Microeconomics

See Section III-2.1.2.6.

2.2 Forest Utilization

2.2.1 Direct Indicators

2.2.1.1 Soil

2.2.1.3 Vegetation Ground Cover

See Sections II-2.2.1.4 and V-2.2.1.3.

2.2.1.3.2 Overstory-Understory Relationships

In mixed oak-woodlands of California, it was revealed that herbage under the canopy of blue oak (Quercus douglasii) was approximately 40 percent greater than herbage growing under live oak (Quercus wislizenii) and 10 percent greater than associated interspace openings (Ratcliff et al. 1991). Herbage under Pinus sabiniana and Ceanothus cuneatus was 45 percent and 38 percent less, respectively, than blue oak understory. The relationship varied with range site (water-holding capacity and stability of moisture and nutrients) across the landscape. In this case, woody plant control should be conducted in a selective manner to increase herbage available and to maintain diversity of species available to herbivores.

In cleared forestland which is subsequently replanted with trees, herbage release declines as tree canopy, basal area, or density increases. Lewis (1989) and Tapia et al. (1990) cited an extensive number of studies which developed regression relationships between one of these three attributes and yield of understory herbage. Understanding the typical response of declining herbage supply to increasing woody plant cover allows grazing managers to plan ahead and adjust livestock numbers in anticipation of future clearings and closures. As expected, all these studies indicated that regression equations were found to be better suited for long-term strategic planning rather than within-year operational adjustments.

2.3 Crop-Livestock Interactions

2.3.1. Direct Indicators

2.3.1.1. Soil Fertility

The best way to understand crop-livestock interactions as they affect soil fertility is to understand nutrient cycles and balance in the cropping system relative to the role of the animal. In grazed environments, grazing animals redistribute nutrients and speed up nutrient cycling. Depending on the degree of human interaction, humans exert some control on distribution of nutrients and the degree of external nutrient input via supplemental feeds (Stuth et al. 1993).

Cropping systems which incorporate animal wastes are almost exclusively human-controlled processes. Areas selected for grazing or forage/concentrates brought to the animal is largely determined by humans (Stuth et al. 1993). Therefore, when viewing livestock-cropping interactions, the human decision process is a critical component to understanding soil fertility impact, particularly as the forage-selection process becomes less animal driven.

Nutrient cycles describe major pools, inputs, outputs, and transformations (Wilkerson and Stuedemann 1992). Pool sizes, flows between pools, system size, and time scales describe nutrient use and movement within specific crop-livestock systems. Nutrients are either added, lost, transformed, transported, or reused (cycled).

Animal manuring systems involve either a) direct animal input through rotational nighttime holding or staking on croplands or b) off-site grazing or seeding with transfer to the cropland system. In the former case, nutrient input is wholly dependent on the quality of adjacent grazing lands and amount of supplemental feed. As the quality of surrounding forage increase, manure quality of surrounding forage increases, and manure quality increases as well. Addition factors such as handling and storage of the manure are important in the second system. In any case, manure management systems are considered poor when the import of nutrients and organic matter exceeds export. Excessive leakage of nutrients in positive balanced systems through runoff and leaching in deep drainage and lateral flow (interflow) creates serious environmental problems, particularly with water quality issues.

A generalized nutrient cycle for cropping-livestock systems can be found in figure 1.

<???> Image Figure 1. Nutrient cycling in grazed ecosystems.

When animals graze pasturelands, losses through leaching may occur due to uneven distribution of feces and urine. For examples, N-levels in urine patches can be as high as 200 to 250 kg/ha (Vander Meer and Meenwissen (1989). As dietary crude protein rises and rumen solubility rises in forage/feed, urine nitrogen losses will rise in proportion to total nitrogen excretion.

Volatilization of nitrogen from urine patches can be as much as 10 to 25 percent degree of soil surface moisture, degree aeration, and inherent nitrogen concentration. Urine excretion of nitrogen is proportionally high in more intensive livestock operations, given the higher sustained quality of the pasture and high external nutrient inputs in the form of roughages, stored forages, and concentrate feeds. Imbalances in feeds with excessive rumen-degradable protein will result in excessive urination and volatilization of ammonia.

The rate of ammonia volatilization is influenced by ammonia concentration in the manure, temperature, and wind speed In general, 10 percent of urine-N volatilizes in temperature climates, and 25 percent islost through utilization in subtropics and tropical climates (Brandjes et al. 1995). The negative effects of ammonia volatilization can be odor, nitrogen enrichment, and acidification of soil and surface water. Acidification can lead to mobilization of aluminum ions, which are toxic to fish, and reduction of nutrient uptake in plants.

Steffens and Benedetti (1993) outlined important nitrogen pathways of animal manures in soils after application. Once applied to the soil, soil organic nitrogen in the feces (20 to 85 percent) is mineralized to ammonia; the remaining ammonia (15-85 percent) is either volatilized into the atmosphere, absorbed by clay minerals, fixed by soil fauna, or undergoes nitrification. Soil fauna in turn mineralize nitrogen into ammonia which goes to soil organic matter, clay minerals, plants, or back to soil fauna.

The principal concern for leaching is nitrogen conversion to nitrates in the nitrification process. Where manure is applied to crops or pasture, leaching losses of nitrates can be noted at levels above 150 kg/ha depending on clay content. However, nitrate leaching can occur more readily in urine patches because of the highly localized levels of nitrogen (up to five times). This is particularly true on well-drained, sandy soils where grazing is concentrated (high stock density).

Period of manure application can have a major effect on nitrate leaching. Nitrate accumulates in the soil after crop removal through nitrogen mineralization from soil organic matter and readily decomposed crop residues and manure. Nitrogen leaves residues in the period after cropping and the next harvested crop, accumulated due to limited plant demands. If no cover crops are applied to capture nitrates after harvest, partitioning between leaching and denitrification is influenced by the rate of nitrate formation, the balance of precipitation, and evaporation (soil moisture balance, the amount of soil organic matter, and soil drainages characteristics. Fresh animal excreta do not contain nitrogen in the form of nitrates. If not aerated, nitrates do not form until applied to soil via microbiological nitrification.

Phosphorus is a primary nutrient of concern; it is a major limiting factor in semiarid cropping systems. Along with nitrogen, phosphorus is an excessive nutrient in large-scale manure applications for intensive cropping systems, leading to eutrophication of water. Soils can hold a finite amount of phosphorus (saturation level). It is generally believed that leaching occurs when phosphorus saturation exceeds 25 percent. Typical manure phosphorus content is between 0.15 and 1.25 percent phosphorus. Typical grassland levels are 0.17 to 0.35 percent, while animals on high quality temperate pastures or animals receiving large amounts of concentrate feeds can be .35 to 1.25 percent.

Saturation losses are more of a problem in mixed-rainfed temperate zones, while excess removal a greater problem in the mixed-rainfed humid zone. Manure is not a major problem in livestock grassland humid and temperate zones, given the extensive nature of grazing in these zones and limited concentration of stock and subsequent application on grazingland. Some expectations exist in the livestock grassland temperate zone where grazing and cropland are recipients of feedlot manures. In these cases, saturation issues arise similar to the mixed-rainfed temperate and humid zones, except volatilization will be more of an issue due to greater windspeeds and higher temperatures.

The role of livestock in impacting soil fertility is largely related to the degree of mechanization, population density, and cultural attitude toward use of animals and animal excreta in cropping systems. Crop-livestock farmers generally cannot keep sufficient numbers of animals or manage these animals in a way to provide enough manure to sustain fertility requirements of cultivated crops. Other techniques must be combined with manuring to maintain soil fertility, including fallowing, growing legumes, incorporation of crop residues, and use of chemical fertilizers.

The availability of animal numbers to manure crops adequately is largely dependent on availability of adjacent grazinglands. As population density increases, pressure to expand cropping onto grazinglands ultimately marginalizes traditional stock growers forcing even more conversion of grazingland, particularly rangelands, to cropland. As these pressures increase, manuring becomes more necessary, until fallowing periods become so short that labor-intensive farming gives way to mechanization. This process marginalizes the value of manure as farmers shift to cash crops with less residue forage value to local stock, and rely more on commercial fertilizer.

Of concern in that scenario is the impact on remaining rangelands. Soil nutrients are removed from the grazingland system via manure if the animals are not paddocked on cropland. Nutrients deposited via feces at concentration areas are moved onto cropping areas. Typically, crop expansion on to rangelands begins with more fertile range or ecosites with high moisture capacity. In terms of nutrient cycling, these sites are major nutrient sinks in grazing landscapes. As stock are displaced and graze more heavily on the source sites in the landscape, overstocking can increase the rate of loss of nutrients via erosion and surface runoff. Quality of nutrients in the manure, as ingestion of more lignified, high phenolic compounds, can be found in the feces, slowing the rate of breakdown of organic matter and the nitrification process. This is a result of shifting species composition to lower palatable species which exhibit higher concentration of anti-quality compounds. In the most extreme situations, with high human populations such as in Thailand, so little land is available for grazing. Having livestock in the cropping system provides the opportunity to use techniques such as fallowing, with livestock serving as cash reserves; introduction of legumes (high quality fodder); and use of excess crop residues.

It may be good to introduce crops at periodic intervals to free up nutrients after being in derived pastures for several years. Trees act as nutrient pumps by taking up nutrients from deeper soil layers and depositing them with litter from canopy and roots (Vetaas 1992). This is particularly true in deep acidic sands where rapid leaching occurs.

Tanner et al. (1993) noted that cut-and-carry strategies in crop-livestock systems in Indonesia harvest excess of demand in order to create high-quality manure compost that includes feces and excess forage residues. They noted that feeding rates were adjusted to optimize production of cropping compost which was used in 90 percent of Java's agriculture. Livestock manure can be as an important trade item for crop residue among pastoralists divested of rangelands and village commons by cropping expansion.

2.3.2.1 Animal Versus Mechanical Power

See Section V-2.3.2.1.

2.3.2.3 Cropping Systems

See Section V-2.3.2.3.

2.4.0 Air Quality

2.4.1 Direct Indicators

See Section III-2.1.1.5.

2.4.1.1 Methane Emissions

Methane belongs to a class of trace gases that have been in the earth's atmosphere for millions of years (Khalil et al. 1994). Over the past 150,000 years, earth processes have produced stable concentrations of 600 to 700 ppbv during warm interglacial periods and about half as much during the major ice age (Stauffer et al. 1985). In recent times, however, rapid expansion of human populations has brought with it large increases in use of energy and expansion of agriculture land and livestock. Currently, global methane concentration is approximately 1700 ppbv, or more than double those levels recorded prior to human expansion, as measured from released air bubbles locked in polar ice. In the early 1980s increasing concentrations of atmospheric methane were reported (Khalil et al. 1994). The question is why is methane increasing? Either the sources are increasing emissions, the capacity of the atmosphere to remove methane is decreasing, and/or terrestrial systems are losing sink capacity. Consensus seems to have centered on increasing emissions rather than shrinking sinks. However, more attention is being paid to the possibility of decreasing sink, of which microorganism in aerobic soils are the greatest biological sink (Seiler and Conrad 1987). Steudler et al. (1989) indicated that elevated soil moisture and increased nitrogen input may lead to reduced soil-sink capacity under certain conditions.

Over the past ten years, well over eleven complete budgets of methane have been proposed, as reviewed by Johnson et al. (1994) and Khalil et al. (1994). As expected, estimates of methane sources and sink dynamics and resulting global balance is a difficult computation to calculate accurately. Many scientists have generally used a top-down inventory method in which sources and sinks are balanced, while taking into account the annual increase measured in the troposphere. Most inventories have focused on sources since there are few known sinks. Methane has a lifetime of eight to ten years. Atmospheric oxidation by the hydroxyl radical is the primary loss mechanism in the atmosphere (about 490 Tg/yr) coupled with removal by soils and chemical processes in the troposphere and stratosphere (20 to 50 Tg/yr). Khalil et al. (1994) estimated that the imbalance between sources and sinks is about 40 Tg/yr, representing an increasing atmospheric trend of approximately 1 percent per year. Because most of the increased methane is associated with land masses related to human activities, concentrations of methane are higher over continents and over the northern hemisphere in general.

Johnson et al. (1994) prepared a summary of methane emissions sources conducted by Cicerone and Oremland (1988), EPA (1989) and Gibbs et al. (1989). These analyses are presented in Table IV-6.

Table IV-6. Sources of methane emissions based on annual emissions of 540 Tg/yr

Source	Percent of Total
Natural wetlands	21
Wild animals and termites	7
Rice growing	20
Oil and gas drilling	8
Coal mining	6
Domestic animals	14
Animal waste	2
Biomass burning	10
Landfills	7
Oceans/lakes	2
Hydrates	1

The large sources, such as rice fields and cattle populations, are no longer increasing as quickly as in earlier post-World War II decades (Khalil et al. 1994). In fact, the role of cattle and rice growing in the global methane cycle is declining, reflecting a limit to expansion of available grazing land and flood-irrigated croplands.

Table IV-7. Estimates of global methane emission by animals and humans (adapted from Crutzen et al. [1986] and Lerner et al. [1988])

Species	Composition within a global fraction of 80.7 Tg/yr	Typical daily CH4 (l/hd)
Cattle, developed countries	41.0	210.0
Cattle, developing countries	30.0	134.0
Water buffalo	8.0	192.0
Sheep	9.0	19.0
Goats	3.0	19.0
Camels	1.0	223.0
Pigs	1.0	5.0
Horses and mules	2.0	74.0
Wild animals	5.0	variable
Humans	0.4	0.2

Global methane emissions from ruminant livestock is dominated by cattle (71 percent) followed by water buffalo, sheep, and goats. Because of lower body size, cattle from developing countries are assumed to emit 36 percent less methane per head each year.

Given the analysis of cattle, sheep, and goat populations by the four major agroecological zones (excluding Africa) defined in this document, methane emissions can be computed for each zone. Methane emissions (Tg/yr) are presented by agroecological zone in Table IV-8.

Table IV-8. Estimated methane emissions generated by cattle, sheep, and goats in the mixed-rainfed temperate (MRT), livestock grassland temperate (LGH), mixed-rainfed humid (MRH), and livestock grassland humid (LGH) agroecological zones, excluding Africa. The analysis represents emissions from an assumed total global emission of 540 Tg/yr with 57.2 Tg/yr for cattle, 6.9 Tg/yr for sheep and 2.3 Tg/yr for goats (values adapted from Crutzen et al. [1986] and livestock numbers reported in this document)

Agroecological zone	Cattle	Sheep	Goats	Total
	Tg/yr
Mixed-rainfed temperate	11.004	2.448	0.102	13.554
Livestock-grassland temperate	1.120	0.852	0.265	2.237
Mixed-rainfed humid	12.088	0.237	0.334	12.659
Livestock-grassland humid	12.877	0.408	0.142	13.427

Of the four agroecological zones discussed in this document, the livestock grassland temperate zone emit the lowest amount of livestock source methane (Table IV-8). Emissions were very similar across the other zones with the mixed-rainfed temperate yielding the highest levels. If water buffalo are added into the mixed-rainfed humid zone, there would be little difference between MRT, MRH, and LGH. Since cattle comprise the largest source of methane among the domestic ruminants, emissions followed the same trends as overall methane emissions. However, sheep were the greatest methane source in the MRT, while goats were the highest in the MRH.

The Blaxter and Clapperton (1965) relationship between feed intake, diet digestibility, and methane production has been used almost exclusively for predicting methane emissions:

% CH₄ = 1.3 + 0.112 D + L(2.37 - 0.05 D)

where
%CH₄ = methane, percent of diet energy
D = digestibility when fed at maintenance
L = multiple of maintenance feeding

Khalil et al. (1994) conducted an extensive analysis of the contribution of cattle to global warming between 1900 and 1985. According to their calculations, the warming due to methane increase over the last century is about 0.16⁰ C, and it is about 0.03 to 0.04⁰ C from the methane they emitted. The total warming from the increases of all gases (CO₂, N₂0, CH₄, CCl₃F, and CCl₂F₂) is about 0.65⁰ C. Up to the time of their study, cattle were estimated to have contributed only about 5 percent to the global warming over the past century from increases of all gases mentioned. Khalil et al. (1994) concluded that cattle did not appear to pose any future threat to global warming. They indicated that controlling methane emissions from grazing livestock are not an effective means of reducing future emissions, citing the increase of carbon dioxide as the single most important contributor to human-made global warming. To quote Khalil et al. (1994):

... controlling one of many sources of one of many gases is unlikely to have an effect on reducing global warming. It is therefore not surprising that the large increases of cattle populations appear to have an insignificant effect. Only in the context of a comprehensive plan to limit world-wide emissions from all man-made sources do the trace gases provide any leverage for reducing global warming. There are many possibilities of modest controls on CO₂ emissions that can reduce global warming more than very stringent controls on sources of trace gases. Whether controls on diffuse and variable sources such as cattle and rice agriculture are even possible, practical or even desirable on a global scale, are unanswered questions. Moreover, emphasis on reducing global warming through the methane cycle shifts the blame for global pollution from industrialized countries that have the largest role because of CO₂ emissions onto poorer nations that have most of the rice agriculture and cattle. This fact makes it unlikely that global controls on trace gases can be readily agreed upon or implemented.

2.5.1 Direct Indicators

2.5.1.1 Soil Fertility

An extensive review of impact of manure on soil fertility is provided in this series of documents by Brandjes et al. (1995). This section will focus on direct impact of manure in grazinglands conditions. The principal concern of manure application on soil fertility focuses on nutrient balance relative to amounts applied. Nutrients of particular concern are primarily nitrogen (N) and phosphorus (P), with secondary concern for potassium (K) and to a lesser degree copper (Cu) and zinc (Zc). Although not a nutrient per se, organic matter is another manure input into soils that can affect both soil fertility and physics.

Animal wastes are widely used as both crop and derived pasture fertilizer, but several characteristics must be considered when applied for example,

a) wide variability in water and nutrient content;
b) low plant-nutrient content as compared to commercial fertilizer;
c) high percent of carbon, which may be used by small animals, insects, and microorganisms;
d) storage and handling costs per unit of nutrient.

a) kind and class of animal supplying the manure;

b) nature of forage and concentrate feeds consumed by the animal, including extent of degradable nutrients;

c) housing, rearing, collection, processing, and storage techniques;

d) rate and method of application;

e) type of crops receiving the manure;

f) characteristics of soil (depth, cation exchange capacity, pH, current nutrient levels, organic matter, etc.);

g) other cultural inputs, such as irrigation and commercial fertilizer.

Phosphorus is excreted mainly in the feces with some partitioning to milk. Lesser amounts are partitioned to urine, scurf, and liveweight gain. The proportion of total phosphorus excreted as organic phosphorus is constant over a range of 0.1 to 0.4 percent in the feces while inorganic phosphorus increases. Therefore, the higher the phosphorus concentration of the diet, the greater the concentration of inorganic phosphorus in the feces and the higher its availability to plants (Wilkerson and Stuedemann 1992). Potassium excretion is mainly in the urine (50 to 90 percent). Sulfur excretion patterns in relation to sulfur concentration of ingested forage are similar to those of nitrogen. Copper is excreted primarily through the feces in a similar manner as phosphorus.

Given lower temperatures, higher stocking densities, and external-fed inputs associated with livestock grazing pastures in the mixed-rainfed temperate agroecological zone, issues of nutrient leaching are more of a concern in this zone. Given the high human populations associated with much of the mixed-rainfed humid zone, livestock manure is a scarce commodity, which requires integration with other soil fertility management strategies to adequately meet the fertility needs of crops. Derived pastures in the mixed-rainfed temperate and humid zones have a high capacity to take external nutrients from manure. Generally, the combined effects of animal offtake and harvesting of hay maintains nutrient loads in the soil below saturation levels. This is particularly true for the rainfed-mixed humid zone where temperatures are higher. Nutrient loading via livestock manure generally is in balance for the livestock-grassland temperate and livestock-grassland humid (native pastures) (Milchunas and Lauenroth 1993). However, evidence is growing that these systems can experience significant degradation once these ecosystems form erosion cells, accelerating nutrient and water loss from the system.

2.5.1.2 Methane Emissions

Very few studies are available related to methane emissions of livestock manure from grazingland conditions. However, Williams (1993) did measure methane production from manure pats defecated on grazinglands by forage-fed dairy cattle in Queensland, Australia. Methane emission rate was strongly influenced by the internal temperature of the pat. Emissions occur from 10 to 40⁰ C, increasing exponentially above 25⁰ C. The influence of temperature was similar to that found by Schutz et al. (1989) for methane emissions from rice patties. The reported rates were also consistent with those observed between temperature and methanogenesis from microorganisms in anoxic soil samples (Conrad et al. 1987). Overall, emissions from feces was found to be insignificant compared to those from the rumen.

Methane emissions are significant from swampy cesspit areas or runoff accumulation areas where high concentrations of livestock occur. Estimates by Williams (1993) estimated that methane from swampy accumulations of dairy wash water was equivalent to about 5 percent of that produced by the herd from fermentation in the rumen. See review of environmental impact of animal manure management in these series of documents (Brandjes et al. 1995).

2.8 Concentrate Feed Demand

2.8.1 Direct Indicators

Since landless impact of livestock is dealt with in another document in this series, this discussion will focus on grazingland interactions.

2.8.1.1 Soil Fertility

The primary effect of concentrate feeds on soil fertility occurs as nutrient return via the feces of fed animals. This effect is particularly apparent in highly concentrated livestock situations where desired high productivity requires external nutrient input. The agroecological zones with greatest external nutrient input is the mixed-rainfall temperate zone, representative of both high cropland development and livestock concentrations (see previous section in this document highlighting land cover and livestock populations).

In extensive rangeland conditions, animals tend to concentrate nutrients near watering points, holding pens, and thermal foci. When feeding winter supplemental feeds, nutrients tend to be concentrated in loafing areas due to animals' anticipating feeding activities. It has been well established that reducing feeding frequently forces animals to use a graze over larger areas, reducing nutrient concentration in feeding areas. There is little evidence that feeding of concentrate supplements on rangelands causes excessive nutrient loading on rangelands.

There is some concerns that nutrient loading due to feeding concentrate feeds to animals stocked at high densities on fertilized-derived pastures might lead to excessive nitrogen loading. Chalupa and Ferguson (1995) indicated that ration balancing with pasture quality offers opportunities to reduce the impact of feeding cows on the environment. Reducing nitrogen excretion must be evaluated in terms of meeting nutrient requirements in the rumen and at the tissue level of metabolism so that productivity, animal health, and profitability are not compromised.

The key to properly balancing nutrients is to devise more advanced analyses that partition carbohydrates and protein into differentially digested components and ascertain most limiting amino acids in the gut (Sniffen et al. 1992, Fox et al. 1995). It has been recognized that carbohydrates can be divided into soluble carbohydrates, rapidly fermentable fibrous carbohydrates, and slowly fermentable fibrous carbohydrates. Protein is divided into rumen-degradable, rumen-escape protein, and bound protein. To balance nutrients properly to optimize protein use by the animal requires an understanding of nutrient fractions in both the concentrate feed and the forage species. Laboratory techniques have been devised for concentrate feeds and simple derived-pasture species but are limited for more complex forage pastures. Stuth and Lyons (1995) have devised methodology to predict nutrient composition of diets via fecal scans with near-infrared reflectance spectroscopy of animals grazing forage resources. Blending improved wet chemistry analysis of concentrates with NIRS monitoring technology offers livestock owners a way to devise feeding programs that minimizes excess feeding of nitrogen.

3. Conclusions and Recommendations Relative to MRT-Environment

3.1 Appropriate Technologies and Mitigating Activities

3.1.1 The Great Leap in New Technology

A virtual revolution has taken place in livestock production and marketing techniques in much of the world during the past two decades. As a result, for example, the EEC has shifted from being a major beef-deficit region to a net exporter. Other countries, while continually increasing beef imports, have made great improvements in their production and marketing structure.

The United States provides a good example of the impact which can be derived quite quickly from technology development and an economic system which promotes its adoption. Beef production per head of cattle inventory increased from 55 kg in 1950, to 70 kg in 1960, to about 90 kg in 1989. The major reason has been increasing cattle weight. For example, steer calf-weaning rates increased from 207 kg in 1975, to 238 kg in 1989. Fed cattle (i.e., from feedlots) marketing weight increased from an average of 477 kg in 1975 to 505 kg in 1989. Average carcass weights increased from 263 kg in 1975 to 308 kg in 1989. The amount of beef produced per breeding cow increased from 145 kg in 1960 to 240 kg in 1989, a 66 percent increase in 30 years. The result is that 40 percent fewer cows in 1989 produced as much beef as the breeding-cow herd in 1960. The implications for developing countries are enormous. The strategy--focus on efficiency.

Changes during the past quarter century in the livestock industries of many countries have been spectacular, but they pale in light of potential developments during the next two decades. The purpose of this section is to summarize some of the innovations related to feed production and storage and changes in the ruminant animal system in particular. Many of the techniques discussed are now beginning to be applied; others are still in their most basic stages. Together these techniques represent a fascinating array of fruits from modern science. There will be opportunities for income improvement from some of the principal characteristics of future world animal agriculture.

History is most important for placing current and future animal agriculture in perspective. A fundamental approach is to organize agricultural change into eras as a means of "feeling" the dynamics taking place. The concept of eras also provides a means to understanding the why of processes rather than simply extrapolating from past trends. Developed countries are now in what Lu et al. (1979) term the era of "science power." Previous eras identified by them for the United States included the hand-power era, up until about the Civil War in the early 1860s, horsepower until about World War I, and mechanical power until about World War II (Figure 2). It is instructional that little increase in productivity took place until the era of science power.

All countries of the world have gone through, or are now engaged, in one or more of the eras shown in figure 2. The concept of eras is extended with the argument made that developed countries in particular are now entering what could be called the era of science and knowledge power. The reason is that knowledge, at all levels of an economy, acts as both a constraint and a resource in effective adoption of scientific advances in animal and crop agriculture. Furthermore, as will be shown, there is reason to believe the technology change curve will appear similar to the one in the recent past.

Technology, a human-made phenomenon that can be increased through research and development, has begun to be recognized as a resource because of the complementary relationship among various technologies. Imagination, time lag in adoption, and institutional constraints are becoming the principal limits to expanded animal productivity rather than the traditional three: land, labor, and capital. Technological changes related to livestock and meat production are occurring so rapidly that even scientists closely associated with each field of endeavor are finding it difficult to assess the implications for commercial application. The objective of the next several sections is to provide an understanding of the range and breadth of new technologies that have been recently developed or that can be expected to have commercial application within the next decade.

<???> Image Figure 2. United States agricultural productivity and growth- the era of science and knowledge power.

Source: adapted from Lu, Cline and Quance, 1979.

Numerous genetic-oriented technologies are being developed or have recently been made available. Examples are heat-period control to improve conception, embryo transfer to reduce time for genetic improvement and/or to obtain multiple calves, and embryo splitting to increase the number of embryos and to be used as a genetics-research device using multiple identical births. Great advances have also been made in sexing embryos and freezing them for long-term storage. In many parts of the world, this latter technique will revolutionize small ruminants and particularly the cattle industry.

Other genetic technologies include bovine growth hormone as a means to expand milk production from dairy cows, embryo infusion of human growth hormone genes to alter animal genetic makeup, and bred-in parasite resistance. Knowledge in the form of theory and application of genetic principles has led to more sophisticated sire evaluation programs, crossbreeding, and development of genetically superior calves.

Animal health improvements include recombinant DNA- (termed cDNA by molecular biologists and DNA by industry) developed vaccines, bovine interferon, electronic mastitis detection, implanted identification tags, use of invermectins for parasite control, and monoclonal antibodies. Recently there has been an explosive discovery of new hormones that regulate various physiological functions. The implications in this area are enormous. A host of new vaccines have either been developed or will be available over the next decade. The real problem is how to effectively utilize them, especially in developing countries. Indeed, animal health is one of the most rapidly expanding agribusiness areas. Overall, the products and techniques are much further advanced than is adoption or even producer knowledge of them.

The nutrition area encompasses a multitude of new products. Considerable improvement can be expected in current products such as anabolics (growth stimulants) and feed additives. Furthermore, producers have had, and will continue to have, a broad range of new practices and products--what may be called management tools--made available to them. Some recent advances are use of sodium bicarbonate to enhance feed conversion, magnesium to increase milk yield, and treatment of straw, hay and crops residues by ammonification and hydrogen peroxide to increase digestibility and energy value. Much research has been carried out on recycling of wastes from animals. One example is recyclable plastic pellets to provide roughage in animal feeds. This idea seems far fetched for LDCs, but the implications for a labor-abundant, feed-deficit area are large. Other nutritional advances include supplement selection procedures and rumen-regulating drugs (rumen metabolites).

3.1.3 Genetics, Biotechnology, and Genetic Engineering for Animals

Numerous genetic-oriented technologies are being developed or have recently been made available. Some of these, such as development of lean-type animals through crossbreeding of native and exotic breeds, are rather obvious. In addition, for large animals in particular, vast improvements are possible and will dramatically expand productivity. Much of the work in genetic improvement is simply application of known techniques and continued restructuring of the animal industry. However, many emerging techniques and technologies will help to speed up the genetic improvement process.

The term biotechnology refers to a wide array of techniques that use living organisms (or parts of organisms) to make or modify products, to improve plants or animals, or to develop microorganisms for specific uses. Although the term can be used quite broadly, its more general use is restricted to new technologies such as recombinant DNA (deoxyribonucleic acid) techniques (also called genetic engineering) and to cell culture and monoclonal antibody (hybridoma) methods. DNA is the molecular building block of genes and is the repository of genetic information in all organisms. Cell culture refers to the growth and maintenance of cells derived from multicellular organisms under controlled laboratory conditions. Monoclonal antibodies are identical antibodies (proteins produced by specific white blood cells in response to the presence of foreign antigens in the body) that recognize a simple, specific antigen and are produced by a clone of specialized cells. A clone is a group of genetically identical cells or organisms produced asexually from a common ancestor.

The term genetic engineering, used synonymously with recombinant DNA, includes a whole range of techniques involving the manipulation of the genetic material of organisms, including technologies by which genes are isolated from one organism and inserted into another organism. Scientists have developed the knowledge and ability to cut genetic code DNA and stitch it back together to produce the type of protein required. For example, using this technique, it is possible for dairy products to contain a range of proteins other than those typically found in milk. It will be possible for individual cows, as biofermenters, to become a source of potent new drugs against diseases. Furthermore, biotechnology is used to upgrade the quality of animals in a herd more quickly through improvement of genetic makeup and in rate of reproduction. It aids in increasing feed efficiency and milk production, and in development of animal vaccines and other pharmaceutical products.

Gene copying, a barrier to rapid development in genetics, has been improved by a technique in which cells are removed from embryos and mixed with an enzyme called polymerase. If the desired gene is present, the polymerase acts as a copying machine and allows the synthesis of a million or more copies of it. In this way sufficient copies can be made to detect the new gene. Previously, the problem was that when genetic DNA material was transferred into an egg, normal laboratory tests were unable to detect the DNA because of the very low levels. Since the embryos assayed with the polymerase enzyme cannot be subsequently implanted into a surrogate, it is necessary to make identical twins by splitting the embryo. One twin is tested for the inserted gene and, if present, the other twin is implanted. The main benefit is that the system saves time in reproduction, and thus genetic improvement can be made faster.

Another important breakthrough is the fluorescence-activated cell sorter which enables scientists to clearly separate a particular cell population from other cell populations. This equipment allows measurement of the DNA content of sperm, from which the sex of the sperm can be determined. That knowledge is used for in vitro (meaning outside the living organism and in an artificial environment such as a test tube) fertilization of animals. Some impacts of these genetically engineered embryos are leaner carcasses, increased milk yield, and more resistance to stress and disease.

Data management systems about genetic makeup of individuals have been developed in concert with the rapid expansion in personal computer capabilities. This enables manipulation of the millions of records on production traits of animals. These systems will have a major impact on speeding up genetic improvement in animals.

3.1.3.1 Reproduction, Artificial Insemination, and Embryo Transfer

Artificial insemination has been very successfully used for the past half-century, particularly in the dairy industry. Recent development of embryo transfer (ET) has led to speculation that this method will one day essentially replace artificial insemination. A virtual revolution in associated techniques, such as sexing embryos and sperm, embryo cloning, and estrus cycle regulation, promise great advances in reproduction and consequently point to greater productivity in the next few decades. Technologies are emerging at a bewildering rate. For example, it was only a few years ago that ultrasound was adopted for use in human reproduction. In this technique, now used to diagnosis pregnancy in cows, experienced technicians can determine sex at 55 to 60 days.

Embryo transfer (ET) is the process of retrieving one or more embryos from a pregnant donor animal and inserting them in a recipient (surrogate) which then carries the resulting fetus to term. The principal advantage is that multiple genetically superior animals can be obtained annually from a donor using a relatively low-grade, inexpensive recipient. Another advantage is that the genetic makeup of a herd can be expanded much more rapidly than through natural mating or artificial insemination. Additionally, it helps prevent disease transmission. Research over the past decade has led to a number of enhancements which will increase the use of ET. For example, implanting twin beef embryos into dairy cows after estrus synchronization has been shown to be physiologically and economically viable even though conception rates are lower and mortality rates higher than with routine artificial insemination.

Embryo transfer is a major business in dairy cattle and to a somewhat lesser extent in beef cattle. Over 100,000 transfers take place each year in the United States alone. Improvements in technique are being made almost daily. For example, ultrasonic scanning of donor cows prior to flushing has increased recovery rates from an average of four viable embryos per flush to six. Numerous other methods are also being developed to obtain and maintain viable embryos. One way is to place farm animal embryos into fertile poultry eggs as a transport medium. This is an alternative to freezing the embryos, which results in reduced pregnancy rates. Embryo transfer has been successfully used in goats on a research basis but not commercially since goats have a relatively low commercial value and ET cost is prohibitive. However, goats are useful for basic research on technologies like disease resistance. In basic research goat embryos have been bisected to produce monozygotic twins and they have been developed in vivo and in vitro.

3.1.3.2 Estrous Cycle Regulation

New light is being shed on the basic mechanisms controlling egg growth and function of the corpus luteum (the organ which produces hormones needed to maintain pregnancy). Perhaps the most important development is the discovery of the ovarian hormone inhibin (which decreases the ovulation rate), leading to the potential for producing transgenic animals in which the genes are repressed or deleted. Progress has been made in regulation of the estrous cycle of surrogate mothers. As a result, conception rates are greater leading to a higher proportion of animals born per mother annually. In addition, the number of viable embryos produced by each superovulation is expected to increase.

3.1.3.3 Embryo Splitting and Cloning

Embryos flushed from donor cows can be immediately transferred to a recipient whose reproductive cycle has been synchronized to accept the developing embryo or frozen for later transfer. The next step in sophistication, and one currently in use is physically splitting embryos to produce multiple copies. A problem is that if the embryo is divided more than twice, fewer offspring survive. Nevertheless, splitting is used widely in the cattle industry in many countries.

Nuclear transplantation is a more promising method than splitting to produce multiple copies of an embryo. This procedure, which has been successfully used, involves transfer of a nucleus from a donor embryo into an immature egg whose own nucleus has been removed. The recipient egg cell is activated by exposure to an electric pulse and allowed to develop into a multicelled embryo. This multicelled embryo is then used as a donor in subsequent nuclear transplantations to generate multiple clones.

3.1.3.4 In Vitro Fertilization

Artificial insemination of animals will be replaced in the next century by in vitro fertilization, i.e., obtaining embryos from artificially fertilized eggs. This technique will enable breeders to fertilize entire herds that have been artificially synchronized. China's first test-tube calf was born in 1989. In Japan a calf was born in 1991 from an in vitro embryo that had been preserved using noncrystallization freezing technology. Furthermore, at least two offspring have been bred by in vitro insemination of a cow that was herself bred by the same technique.

3.1.3.5 Embryo and Sperm Sexing

The ability to regulate the sex of an offspring is of major concern to animal producers. For example, commercial beef cattle producers generally would like male offspring as they command a higher price than females due to more rapid gain in weight. Dairy-cow owners, however, essentially prefer all females if the cows are inseminated with dairy-cattle semen. If replacements are not needed for the dairy operation, producers would prefer beef-type male calves, as male dairy cattle grade lower than beef-type cattle. Thus, the wide interest in sexing of embryos.

Sperm sexing is one way to control the sex of offspring. Several methods have been attempted, but the first effective one utilized cell-sorting techniques. Research is oriented toward improving the number of sperm sorted per hour and reduction in mortality of embryos produced by sorted sperm. Two other methods, neither of which has been adopted widely, are karyotyping (creating a picture of the number, size, and shape of the chromosomes contained in the embryonic cells) and use of antibodies to detect proteins (antigens) unique to male embryos. A fourth, a very rapid and accurate technique, is to match fragments of DNA that are contained only on Y (male) chromosomes with the same DNA fragments in the embryo.

3.1.3.6 Cloning

The cloning process is relatively simple in concept. A donor cow, for instance, is superovulated and then artificially inseminated, just as she would be in an ordinary embryo transfer procedure. Then, at 5.5 days, multiple embryos are nonsurgically flushed from the uterus of the donor. At that age, each of the 32 cells in every embryo is alike. Utilizing an intricate and highly complex microscope, the technician gently coaxes the cells apart and places them into the outer covering of an egg (oocyte) obtained from an ordinary cow which previously had its genetic material removed. The process is repeated with each of the other 31 cells until there are 32 new, 1-cell, 1-day-old embryos, each carrying the same genetic information. The embryos are then either incubated until they are 7 days of age--the optimal age for transfer to recipient cows--or they are incubated for 5.5 days and recloned. A biopsy is taken to determine the sex at the same time the embryo is closed.

Survival rate of cloned embryos is about 20 to 30 percent. With normal embryo transfer, about half of the transferred embryos result in births. In effect, about 3 to 5 births are expected out of each initial embryo cloned. By 1990, 9 Angus bulls had been produced from 1 embryo in Texas. As of the early 1990s numerous reports had been made on successes in Japan, the United States, and elsewhere.

3.1.3.7 Transgenic Animals

Transgenic animals are those containing foreign DNA in their germ lines. Production of these animals is possible only by first manipulating the embryo and transferring it to a recipient animal. Thus, the development of transgenic animals is a process of utilizing (a) new reproductive technologies of superovulation, in vitro egg maturation and fertilization, nuclear transplantation and embryo sexing; and (b) recombinant DNA technologies, i.e., identification, isolation, and transfer of selected genes. The objective is to genetically develop livestock with improved growth characteristics, milk yield, and resistance to disease and stress. Another purpose is for production of important pharmaceuticals for human use and as a way to model human diseases.

The process to make a transgenic organism is similar for plants and animals. The first step is to identify and purify the gene being transferred. Then appropriate mechanisms are used to transfer the gene into the recipient cell. Finally, applicable regulatory sequences must be included to ensure proper expression of the gene.

The most common way to produce transgenic animals is by microinjection, a method that involves direct injection of cloned DNA into a fertilized egg. Other direct transfer methods are electroporation (use of short electrical pulses) and chemicals, which make cell membranes permeable to the passage of large molecules such as DNA. Another possibility in its nascent stages is to use sperm. Another possible indirect means is to use vectors, i.e., viruses.

The first generated transgenic animals were mice, produced in 1980. Transgenic beef and dairy cattle, sheep, swine, poultry, and fish have since been produced almost exclusively by microinjection and viral vector methods. The drawback of microinjection is expense and low efficiency. One method to overcome the high expense of the methods described is to use stem cells derived from an embryo as a vector to introduce selected genes into a host embryo.

Targeted gene insertion using stem cells has a great advantage in livestock genetic improvement as it allows host (recipient) animal genes to be inactivated, or removed, and replaced with modified forms of genes. Inactivation of genes is a way to overcome some genetic characteristics which inhibit production of certain useful substances. For example, as described earlier, bovine somatostatin is a hormone that inhibits bovine somatotropin production. If this gene is inactivated there would be increased endogenous (i.e., by the host animal) somatotropin production, which would result in increased milk yield, growth rates, and feed efficiency. In effect, the need for exogenously administered somatotropin, such as bST, would be eliminated.

Research has shown that transgenic animals pass the genes on to their offspring thus making the procedure of great commercial interest. However, investigation on transgenic animals is expensive and consequently is restricted in scope. Production of transgenetic livestock with traits of economic importance is limited by the absence of embryo stem cell technology, lack of appropriate gene expression promotion, and inadequate knowledge about the physiological consequences of specific gene expressions. However, by 1992 significant advances had been made in genetic mapping, a major step to selection of males in a breeding program. The first patents for transgenic animals were granted on December 29, 1992.

3.1.3.8 Animal Health

Animal health care is expensive, both in terms of labor requirements and training of personnel for individual animal care, and at the national level for control or elimination of diseases. Biotechnology is opening the door to many ways of reducing cost and increasing productivity. One way, discussed at length in previous sections, is through genetic control of animals. For example, genes for the iron-binding glycoprotein have been built which will lead to a new range of probiotics. One discovery is the gene expressed in yeast, which creates lactoferrin, which can be used to bind iron in young animals. The binding ability of lactoferrin can be used to starve destructive microorganisms, such as Salmonella and coliforms, preventing them from growing in the animals' guts.

Biotechnology is also being used to create new vaccines (agents that stimulate an effective immune response without causing disease). One emerging technology is gene deletion or inactivation in a pathogen that causes the disease. This gene is then inserted into vector genes that cause an immune response to a pathogen. This vaccine is then given exogenously to the animal. Another approach is to synthesize some of the smaller peptides associated with white blood cells. They are then used in a manner similar to antibiotics. Genetically engineered vaccines have been developed to combat such diverse problems as Marek's disease in poultry and pseudorabies in swine. Work is proceeding on a vaccine against mastitis in dairy cows and on a recombinant vaccine to protect poultry from multiple diseases. It is expected that by the year 2000 vaccines will routinely be used in place of castration.

Work continues with monoclonal antibodies which can be used like drugs to provide passive immunity to disease-causing microorganisms. Another use of biotechnology is identification and replication of immunomodulators, hormone-like molecules that play a role in coordinating immune defenses to infectious agents, cancer, and autoimmune diseases. Also, considerable research is being focused on development of safe, accurate, rapid, easy-to-use, and inexpensive diagnostic procedures. Examples are tests for pregnancy and pathogenic organisms. Finally, bovine interferons, naturally occurring proteins of the immune system in cattle, are manufactured using DNA techniques for numerous broad applications, such as management of many viral related diseases like shipping fever (bovine respiratory disease).

3.1.4 Productivity Increases in Developed Countries

Agricultural biotechnology as well as other research advances described in earlier sections will have a major impact on animal productivity in the next several decades. The main recipients will be countries where information flows and industry structural changes are encouraged. Countries undergoing rapid change in rural policy which encourages development and adoption of new production and marketing technologies will advance quickly. Consequently, one guide to developing country's future level of productivity can be gained by evaluation of current levels of productivity in other countries and an assessment of the impact from the technological change process.

The 1992 report by the Office of Technology Assessment in the United States provides a good overview of 41 potentially available animal technologies, many of which have been described earlier in this study. Of the 41 animal-related technologies assessed by the OTA, 22 were estimated to be available by 1995 under the most likely scenario (Table IV-9). The main impact is on feed efficiency for all animals and reproductive efficiency for beef cattle.

Three technology adoption scenarios for the United States are presented in Table IV-9. They are (a less new technology, which means a relatively slow rate of adoption; b) the most likely adoption rate; and c) more new technology, a relatively rapid rate of technology development and adoption. The concept of three scenarios is very useful in understanding the many facets involved in technology adoption. This is because, apart from the research itself, there is the process of evaluation for product safety, market size, product positioning, and adoption time. The wide debate over use of anabolic growth promotants in Europe, and discussion about whether bGH (bovine growth hormone) is really needed in the United States, are cases in point. Many countries are pushing hard for new agricultural and livestock-production technology, but researchers and public officials are also quite cognizant of product safety and international controversies surrounding agricultural inputs. International experience demonstrates that as per capita incomes increase, producer, consumer, and official awareness of product safety, on the one hand, and efficiency, on the other, grow accordingly.

Feed efficiency in United States' livestock production under the most likely scenario will increase at an annual rate varying from 0.39 percent for dairy cattle, to 1.63 percent for swine (Table IV-10). In the case of dairy cattle this means that feed efficiency will increase just 4 percent, from 2.227 kg of milk produced per kg of feed in 1990, to 2.315 kg in 2000.

The most dramatic productivity increase in the past few decades has been milk yield in dairy cattle, which in the United States grew about 2.5 percent annually from 1960 to 1990. The OTA projects that milk yield will most likely grow at a compound annual rate of 3.06 percent from 1990 to 2000 (Table IV-10). A study by Simpson and van Blokland (1992) indicates that if milk yield in the United States were to increase just 2.0 percent annually in the decade of the 1990s, milk yield would grow from 6,440 kg in 1990 to 8,043 kg in 2000. The number of farms would decline from 182,000 in 1990 to between 108,000 and 123,000 in 2000, depending on assumptions about the number of cows per farm. In contrast, there were 269,000 dairy farms in 1985.

Table IV-9. Timing of commercial introduction of advancing animal technologies in the United States.

			Technology scenario
Technology			More new technology	Most likely technology	Less new technology
Somatotropins
	Bovine
		Dairy	1991	1991	1991
		Beef	1995	1997	2000
Beta-agonists			1991	1992	1995
Antibiotic growth promotants			1990	1990	1990
Steroid-like promotants
	Estrogen/androgen combinations		1990	1990	1990
	Control/sustained release		1990	1990	1990
Reproductive and embryo transfer
	Control of ovarian functions		1993	1995	1995
	Separation of X&Y bearing sperm		1992	1995	1995
	In vitro fertilization		1990	1990	1990
	Embryo sexing		1998	2000	>2000
	Cloning and nuclear transfer		1993	1995	1995
	Gene transfer		2000	>2000	>2000
Transgenic for ruminants
	Hormonally enhanced growth		2000	>2000	>2000
	Pharmaceutical production		2000	>2000	>2000
	Enhanced-disease resistance		2000	2000	>2000
Animal health
	rDNA technology		1991	1993	1995
	Gene deletion		1991	1995	1995
	Monoclonal antibodies		1991	1995	1995
	Peptides		1994	1996	>2000
	Immunomodulators		1994	1996	>2000

Source: U.S. Congress, OTA (1992).

		Beef Cattle		Dairy Cattle
Item		kg meat per kg feed	calves per 100 cows	kg milk per kg feed	kg milk per cow per year
1990		0.315	90.000	2.227	6.440
2000
	Less new technology	0.322	93.750	2.271	7,822
	Most likely technology	0.340	96.221	2.315	8,704
	More new technology	0.373	102.455	2.331	9,297
Annual rate of change, 1990 to 2000
	Less new technology	0.21	0.41	0.20	1.96
	Most likely technology	0.74	0.67	0.39	3.06
	More new technology	1.68	1.30	0.46	3.74

Source: U.S. Congress, OTA (1992).

The need for emphasis placed on feed efficiency in technological development has been well illustrated by Conrad and van Es (1983) who show, for example, that if daily weight gain of cattle is 0.25 kg per day, there is a 15 percent efficiency for gain. That means 85 percent of feed energy intake is used just for maintenance. But if the animal is gaining rapidly, say 1.5 kg per day, there is 65 percent efficiency for gain and only 35 percent is needed for maintenance.

Feed efficiency for beef has been stable in the U.S. for the past decade. But as shown in Table IV-10, new technologies are likely to increase feed efficiency. Under the most likely scenario feed efficiency will increase at a rate of 0.74 percent annually for beef and 1.63 percent annually for swine. If technology is adopted rapidly, annual growth rates in feed efficiency will be much higher, 1.68 percent and 2.44 percent for beef and swine, respectively. The adoption rates are for the United States. But the concept of differences among less likely, most likely, and more new technology hold true in any country, as they are a product of producer knowledge, industry structural change, and political and economic conditions.

Clearly, discussion about technology adoption rests heavily on producers themselves. Many of the technologies--and modern production practices in general--can only be adopted in both developing and in economically developed countries by producers with advanced management skills, producers whose continued interest is increased efficiency. Additionally, use of technology largely depends on the type of production subsector. Thus, industries or production subsectors with few producers and high control of production variables use a relatively high proportion of available technology. For example, it is estimated that in the United States breeding-level sheep and beef cattle producers, who face great difficulty in the control of production variables, often operate on a too small scale to have the basic infrastructure, knowledge, and management ability to adopt even well-known techniques such as growth promotants. They are estimated to apply only 40 to 60 percent of the latest technology. However, in beef and sheep feedlots, which have factory-type characteristics, about 85 to 90 percent of available technology is applied.

3.1.5 Implications of Technological Advances for Developing Country Animal Agriculture

An idea of the potential impact technological change will have on beef production in some countries can be obtained by review of the executive summary from a 1982 symposium titled "Future Agricultural Technology and Resource Conservation" (English 1983). The experts concluded that meat production per breeding cow will increase 25 percent in the United States by the year 2000 and 60 percent by 2030.

The conclusions, although directed at the United States, are relevant for even the poorest countries or regions of the world, as they provide targets or possibilities from which planning goals can be set. The conclusions also demonstrate that the human factor (management) rather than new technology development is the basic constraint to improving livestock product output. This conclusion is much different than for crops, where a much greater proportional emphasis is needed on both basic and applied research.

The brief summary of technologies either in the offing or that are in their early stages of adoption lead to a conclusion that the world is indeed entering an era in which knowledge, as shown in Figure 2, will be of paramount importance. In developing countries, as described in the section on education/extension, the human dimension is replacing capital as the critical factor. Rewards to both individuals and nations will come from imagination, proper planning, acceptable input/output price relationships, and a favorable political climate.

The impact adverse or distorted price relationships can have on introduction of livestock technologies is well documented by the case of cattle feedlots. This technology, which has helped to revolutionize the livestock industry in the United States and Canada has been tried in many developing countries, but seldom with success. Apart from managerial problems, governments have often set prices at levels which do not allow the lots to succeed. Even more difficult have been cooperative feedlots. Although feedlots are part of intensive production systems, they can be a vital component in changes of range-based ruminant animal systems.

It appears that the greatest advances at the national level in animal productivity and efficiency enhancement can be derived from determination of techniques and technologies that offer the greatest potential to meet national-level goals. Once those techniques are identified, a program must be developed which ensures all constraints to its adoption are overcome and that adequate support is provided to obtain the greatest synergistic effect. This concept might be called the technology-directed planning approach. At the risk of appearing redundant, it seems clear that with respect to the livestock industry, human capital development will provide the greatest synergism regardless of the technology chosen.

It can be predicted with great confidence that burdensome supplies of animal products will be the rule in developed areas in the foreseeable future as a result of relatively low population growth, changes in food tastes and preferences, and new technology. At the opposite extreme, hunger and famine will prevail in many regions due to uncontrolled population growth, political fragility, periodic adverse climatic conditions, and failure to invest in human capital. The problem is thus not one of inability at the global level to produce sufficient animal products to adequately feed a much larger world population than exists today. Rather, the difficulty is primarily lack of purchasing power, management capability, and inappropriate policies at both the individual person and national levels in certain regions.

Producers are and will be the key to realization of improvements in animal agriculture. Management--which means knowledge--is the weak link to improving the animal industry everywhere in the world. Technologies abound; the problem is to devise the means to accelerate their adoption. The rate in economically developed countries is already unbelievably fast due to entrepreneurship being properly utilized. The problem in low-income countries where adoption rates are less than satisfactory is to stimulate individual initiative. The key there, again, is to focus on the preliminary step, which is to determine client (government or private sector) problems and to work to provide compatible solutions.

The pace at which animal production and marketing technologies are being developed worldwide is astounding. Many of these technologies are transferred at a relatively sophisticated scientific level. Thus, one main criterion for developing countries is development of a scientific community with the resources to exploit the knowledge being created in economically developed countries (Vasil 1990).

Adoption of new technology is based on many factors ranging from producer adoption time to consumer acceptance based on perceptions of food safety. Some biotechnology products, such as improved vaccines, can be implemented fairly rapidly by companies producing the product and by producers. Others, such as recombinant somatotropins, have more difficult management and industry structural change requirements. Ultimately, adoption of technologies depends on their profitability and effectiveness compared to available technologies.

Much of the technology discussed in this section is sophisticated, yet relatively easy for even developing countries to implement. The very rapid introduction of artificial insemination in both developed and developing countries serves as an example of how quickly some apparently esoteric technologies such as embryo transfer can become established. Indeed, some developing countries have embarked on a major effort to introduce embryo transfer, primarily for the purpose of using embryos from abroad in place of importing live cattle. Finally, many of the constraints to health aspects, such as development and production of vaccines and therapeutics, take place at the manufacturing rather than the producer level and are thus not difficult to overcome.

Many of the world's livestock production systems are quite different from those in the United States. Nevertheless, review of the list in Table IV-9 does provide an indication of when many new technologies will potentially become available in them. The lag time in commercial adoption is a function of industry structural change, which, in turn, is mainly influenced by economic conditions. Adoption rate contains a synergistic effect since part of the technological change process involves growth in both size and scale of animal operations. As the number of production units is reduced, the remaining ones are generally the more efficient ones. In addition, as size of operation expands, the array of appropriate techniques and technologies also grows. Finally, as marginal producers leave animal agriculture and as mechanization replaces animal power, productivity of the remaining animals grows.

It is obvious that adoption of emerging technologies, as well as the multitude of technologies now available but not being used, will vary from region to region and even from farm to farm within a district. A salient point is that some producers will leap at opportunities and, through their early adoption, will benefit to a great extent. The slower adopters will eventually drop out. The concept of adoption applies to even the most mundane production techniques as well as sophisticated ones. Furthermore, several simple, yet unique, management practices are being developed in a wide variety of countries.

Also see Section II-3.1.

3.2 Education/Extension

See Section V-3.2.

3.3 Financial Stimulation

See Section III-3.4.

3.4 Land Tenure/Institutional Adjustments

See Section II-3.4.

3.5 Development Programs

See Section II-3.5.

3.6 Other Policies/Regulations

See Section II-3.7.

3.7 Research

See Section III-3.7.

4. MRT-Environmental Impact Case Study

4.1 Worldwide Experiences with Feedlots

Feedlots for cattle are a widely discussed strategy for substantial improvement of beef production. As such, the concept deserves mention in a paper on livestock strategies. The most important criteria for feeding grain to cattle is the beef-feed price ratio. In the United States and Canada, it has typically been about 10-12 to 1 for maize. The beef-feed price ratio is about 7-8 to 1 in EEC countries, about 4-5 to 1 in Australia and Argentina, and 2-3 to 1 in many of the African countries. Examination of the rations explains why feedlots have generally not been successful in countries outside the United States, except to a limited extent in the EEC.

A multitude of abandoned or little-used facilities attests to the failure of numerous attempts outside the United States and Canada to develop feedlots. In many countries, such as Australia, New Zealand, and the Central American countries, the decision to cease operation has usually been due to adverse world price movements--that is, a failure to predict future trends for lots based on export markets. Other main considerations, apart from economic relationships, are management and development of technical knowledge. Spring (1984) found that smallholder stall feeding in Malawi was successful, but incomes varied greatly depending on access to various management features and resources.

One way to overcome adverse grain cattle price ratios it to feed cattle by-products and crop residues (Jahanke 1982). There are numerous reports on feeding straw, coffee pulp, and animal wastes. Furthermore, there is considerable range of research methodologies being used to identify which by-products are suitable for animal feed and to evaluate their availability, nutritional characteristics, and potential for improvement through modification. It is apparent that despite important breakthroughs in improving the nutritive value of by-products, practical application of research results in existing animal feeding systems have been limited (Kiflewahid et al. 1983). As recently as ten years ago, the same was true for rice straw (Doyle et al. 1986).

It is becoming increasingly apparent that new feeding systems must be evaluated by means of careful comparison with methods currently in use. That means clear identification of clients and good ex-ante economic analyses to be sure the systems will be adopted. Perhaps most important is realization that effective by-product utilization does involve intensified production practices and that grain feeding, or silage use (which is a type of grain feeding), will often be required as a complementary feedstuff to by-products (Minish and Fox 1982, Perry, 1980).

An example of the importance that feedlots can play in range management improvement is China, where considerable small holder fattening of cattle takes place in the crop-growing areas. An ambitious project by FAO to improve beef production based on the use of crop residues has led to expansion of cattle feeding. Most of the effort, which proved quite successful, was based on treatment of rice straw, particularly with urea (Finlayson 1992, Mercier 1994). Directly related to this project in range improvements are results from an economic and feedstuffs use analysis carried out by Simpson and Ou (1995) which showed that shifting northern China rangeland use from one which includes both fattening and cow/calf to just calf raising is feasible. The study shows that net income to calf/cow producers expands greatly and that production cost per kg are less than in the grass fattening system. The analysis was also favorable for feedlots. In effect, producers in all parts of the production chain would benefit from the change.

Introduction of a specialized calf-raising system has considerable national or macro-level benefits. As China mechanizes the number of cattle used for work purposes is being reduced. At the same time there is an expanding demand for beef. The analysis indicates that if the cow/calf only system as well as improved management practices were introduced, the number of animals marketed from (excluding all breeding stock) would more than triple. Furthermore, on a feedstuffs-use basis, less than half as much metabolizable energy and crude protein would be required per kg of beef produced when a feedlot system is introduced. A critical factor is recognition that a country like China has a wide variety of feedstuffs available for fattening animals apart from the typical maize/soybean-based rations common to the developed countries.

4.2 Case Study--Mixed-Rainfed Temperate, U.S. Great Plains

Much contemporary livestock production in the U.S. Great Plains is based on rangeland intermixed with dryland farming and some irrigated areas. As early as the mid-1940s, ranchers began to incorporate improved pastures and complementary crops in native range livestock forage systems (Sims 1988). Sugar beet (Beta vulgaris L.) by-products, alfalfa (Medicago sativa), sorghums (Sorghum bicolor), corn (Zea mays L.), and small grains (Triticum and Secale sp.) grown on dryland areas were used to supplement cattle grazing native range. For the most part, these forage systems have provided a potential for dramatic change in land carrying capacities and range management without concomitant degradation of environmental variables.

In the Northern Plains of the U.S., crested wheatgrass (Agropyron desertorum), Russian wildrye (Psathyrostachys juncea), and western wheatgrass (Pascopyrum smithii) have been used to reclaim marginal farmland and complement native range. Lodge (1970) found that native range plus crested wheatgrass forage systems generally reduced land requirement per grazing animal by 25 to 30 percent, increased animal gains from 14 to 30 percent, and almost doubled average gain per ha. Consequently, grazing systems that utilized the cool-season improved pastures to complement the native sandhill prairie significantly increased total animal carrying capacity as compared to grazing native range alone. Grazing complementary forages at critical times provided rest for and improved the vigor of native prairie vegetation. In addition to improving animal gains, the reproductive performance of the cow herd was also enhanced. In a separate study, Adams et al. (1989) concluded that the primary benefits of seeded ranges in the Northern Great Plains are comparable to those documented for increased stocking rate and improved forage management; however, seeded ranges did not improve individual animal performance. These authors felt that native ranges in the Northern Great Plains that have not been abused through overstocking or other mismanagement are capable of producing forage that is difficult to improve on for individual animal performance.

Improved perennial grass species and summer and winter annual forages have been used to complement native range in the Southern High Plains (McIlvain 1976, Sims 1985). In studies at the Southern Plains Range Research Station, Woodward, Oklahoma, McIlvain (1976) found that 7 ha of native sandhill prairie was required for year-round grazing of spring calving cow-calf pairs and that this system would yield about 34 kg/ha of weaned calf (7 months old). With fall calving cows on about 4.5 ha of native range complemented with 0.4 ha of farmed forages per cow-calf unit (30 percent less land), weaned calf (10 months old) production was increased to about 70 kg/ha.

McIlvain (1976) also studied the use of native rangeland with complementary pastures and cropland utilizing Hereford steers about 8 months of age. The control treatment for the study approximated the best of the commonly used grazing practices in the area, i.e., continuous, yearlong stocking of native range at 3.56 hectares per steer. Studies had shown that this system produced more beef at a lower cost, while maintaining vigor and condition of the range, than any other.

One system studied by McIlvain consisted of 90 percent of the total land area native range and 10 percent weeping lovegrass (Eragrostis curvula). The average yearlong stocking rate per steer was 1.82 ha of native range plus 0.2 ha of lovegrass. Cattle were rotated to and from native range and within the lovegrass pastures as needed to optimize use each part of the system. Results of the system included an 82 percent increase in carrying capacity and 73 percent increase in beef per ha over the straight native range control (Table IV-11).

Table IV-11.

Hectares/Steer		Gain/Steer (kg)						Gain/Hectare
		NR			NR+Lovegrass
NR	NR+lovegrass	Win.	Sum.	Year	Win.	Sum.	Year	NR	NR+Lovegrass
3.8	2.1	45	143	188	45	131	176	20	35

Source: McIlvain, E.H. 1976. Seeded grasses and temporary pastures as a complement to native rangeland for beef cattle production. p. 20-31. In Proceedings for Symposium on Integration of Resources for Beef Cattle Production. Society for Range Management, 29th Annual Meeting, Denver, Colo.

The native range and wheat-sudan system increased carrying capacity 89 percent and beef per ha 100 percent over the native range control as an average of 6 years. Gain per steer was 17.3 kg more yearlong than on the native range system (Table IV-12).

Table IV-12.

Hectares/Steer		Gain/Steer (kg)						Gain/Hectare (kg)
		NR			NR+Wheat-Sudan
NR	NR+Wheat-Sudan	Win.	Sum.	Year	Win.	Sum.	Year	NR	NR+Wheat-Sud.
3.4	1.8	76	87	165	86	97	182	20	40

Source: McIlvain, E.H. 1976. Seeded grasses and temporary pastures as a complement to native rangeland for beef cattle production. p. 20-31. In Proceedings for Symposium on Integration of Resources for Beef Cattle Production. Society for Range Management, 29th Annual Meeting, Denver, Colo.

Table IV-13.

	Ha/Steer	Gain/Steer	Gain/Hectare		Returns/Hectare
System	(No.)	(kg.)	(kg.)	(%NR)	($U.S.)	(%NR)
NR	3.6	177	20	-	3.85	-
NR+Lovegrass	2.0	167	33	165	6.40	165
NR+Wheat-Sudan	1.8	191	42	211	10.00	260

Source: McIlvain, E.H. 1976. Seeded grasses and temporary pastures as a complement to native rangeland for beef cattle production. p. 20-31. In Proceedings for Symposium on Integration of Resources for Beef Cattle Production. Society for Range Management, 29th Annual Meeting, Denver, Colo.

More recently, Sims and Bailey (1995) reported that using a native mixed-grass community and complementary introduced forages reduced the land requirement of a Southern Great Plains cow-calf system from 8.1 ha per cow to 4.9 ha of mixed-grass prairie plus 0.6 ha of double-cropped farm forage. Although the land requirement was decreased by 30 percent, calf weaning weights of the native range-farm forage system were increased 37 percent for Angus-Hereford calves and 32 percent for Brahman-Hereford calves when compared to those of the native range only system. Fertilizer input was 68 kg of nitrogen per ha for the introduced cool-season annual grasses.

Summary and Interpretations

Rangelands of the Great Plains region of the U.S. have a long history of use by large ruminant herbivores. The kind of grazing animals, dynamics of grazing, and the quality of forage materials have been dramatically altered in recent decades with the advent of systems that include both high-producing introduced forage species and cropland used in conjunction with native range. The combination of increased land carrying capacity from native range-crested wheatgrass systems versus native range and increased animal gains has potential to nearly double the yield per land unit in the northern plains, meaning that the same land area would produce about twice the amount of beef as the traditional native rangeland system at an increase of only about 25 to 30 percent in stocking rate.

In the southern plains, studies have documented an 82 percent increase in land carrying capacity with the weeping lovegrass-native range combination and an 89 percent increase with the wheat-sudan-native range system compared to native range alone. These same systems increased gains per acre by 73 percent and 100 percent, respectively, compared to native range. Sims's (1985) work with steers at the same location produced 62 percent, 108 percent, 314 percent, and 348 percent increase in steer gains per ha for systems that included native range and weeping lovegrass; wheat-sudan or pearl millet; lovegrass, wheat-sudan or pearl millet, and Old World bluestems, respectively. Similar results were noted in studies involving cow-calf production systems (Sims and Bailey 1995).

While not all livestock producers in the Great Plains have mixed rain-fed farming potential, and many that do have the potential still use straight native range systems, the mixed crop-pasture-native range systems have provided an opportunity for substantial increases in total carrying capacity of the land and beef yield per unit of land over the past fifty years. The potential for still further increase in the total number of livestock in the ecozone is great, particularly as improved perennial and annual forage species are developed and additional producers integrate the use of complementary pastures with native range. However, while land carrying capacity and individual animal production has been greatly enhanced by such systems, climate and soils cause the area to remain primarily one of extensive rather than intensive use by livestock when compared to dairies or drylot operations. It must also be considered that the use of crops in forage systems in areas of less than 60 cm increases the risk of crop failure (an economic factor) and increases risk of vulnerability to soil erosion. Conversely, the use of improved perennial grasses involves no risk after initial land exposure during the process of stand establishment.

U.S. cattle population was estimated at about 0.082 billion at the turn of the century, reached a high of over 0.13 billion in the early 1970s, and declined to approximately 0.12 billion in 1984 (Khalil et al. 1994). Population trends of cows in the Great Plains of the U.S. have followed this national trend. Several of the most prominent cattle states, including Oklahoma, Texas, Nebraska, Kansas, and North and South Dakota all had less cattle in 1995 than in 1976 (USDA NASS 1994). These data indicate that although carrying capacity of the land area is being enhanced through the use of complementary pastures and cropland, the cattle available to contribute pollutants, such as methane and manure. This also indicates that there is improved opportunity for rangeland condition improvement in the general sense of lower cow numbers per unit of land area.

Coupled with less cattle numbers over the past twenty years, the flat to declining per capita consumption of beef in the U.S. does not lend to projections of a growing livestock feeding industry in the foreseeable future. Feeding facilities, and consequently point-source pollution risks from livestock production should remain relatively stable.

4.3 Case Study: Dairying in the U.S. with Specific Attention to the Northeast and Upper Midwest

4.3.1 Introduction

Institutional setting. In 1972 the U.S. Congress enacted the Clean Water Act (CWA) aimed at preventing the discharge of polluted water into streams, rivers, and lakes of the U.S. In 1987 the CWA was amended to control both point and nonpoint sources of pollution. Agricultural activities were generally treated as nonpoint sources; however, confined animal feeding operations (CAFOs) were designated to be point sources of water pollution. A CAFO is designated as a point source if the surface of the area where the livestock are confined cannot sustain vegetation and if they contain more than 1,000 animal units (700 dairy cows), or if there is a nonzero probability that they will discharge into waters of the U.S. (except in the event of a 24-hour, 25-year, or longer flood). If the CAFO is designated as a point source of pollution, it is required to obtain a National Pollution Discharge Elimination System (NPDES) permit which specifies structural guidelines for a CAFO waste management system. In addition to the general NPDES permit the Environmental Protection Agency (EPA) can require an individual permit which specifies sight specific management practices and facility requirements.

The federal agency, EPA, may delegate enforcement of the CWA to state agencies where the states have created standards deemed to be equivalent or more stringent than the CWA standards. Despite this similarity, there are significant differences in regulatory philosophy and enforcement standards from state to state. Some states do not have dairies that meet the 700 cow threshold size and, therefore, have chosen not to explicitly enforce dairy waste management regulations relating to CAFOs. Others are requiring permits of virtually every dairy farm regardless of size (Outlaw et al. 1993).

Recent structural trends. There are less than half the number of dairy farms in the U.S. today compared to 1978. However, dairy cows have only declined by about 10 percent since the average number of cows per dairy has increased from 33 to 61 during the period. Also, the percent of dairy farms with 50 or more cows climbed from 20 percent to 50 percent during the 1978-92 period, while the percent of the total dairy cows in herds of 50 or larger grew from 61 percent to 80 percent.

Regional shifts in production have also occurred during the last two decades. The western and southwestern U.S. have experienced dramatic increases in their percent of total U.S. milk production whereas the upper midwest and northeastern states have experienced significant declines. These trends are also seen in the changes in average cows per farm from 1978 to 1992 where the average number tripled for western and southwestern states but has not doubled for upper midwestern and northeastern farms (Outlaw et al. 1995).

Coincidental with these structural and locational shifts, the U.S. dairy industry was moving to increased use of confinement production technology to facilitate increases in efficiency through economies of size and labor specialization; and as environmental regulations became more stringent, economies of size in manure management became more important also (Purvis 1995). As a result, many of today’s large dairies in the west and southwestern U.S. are essentially "landless" animal production units with land (acres)/cow ratios of less than 1. These farms (milk factories) are clearly potential point sources of water pollution. In the Northeast and Upper Midwest, however, the trend to more cows per farm, while significant, has left the average dairy with a land (acres)/cow ratio of 3 to 3.5; still a land-based production system-- and still relying on land spreading of manure as the primary manure management practice (Outlaw et al. 1993).

4.3.2 The Problem

Increased livestock densities, elimination of nutrient deficiencies in many cropland soils and concerns about the environmental impacts of nutrient losses from farms has resulted in increased concern about excess nutrient balances on crop-livestock farms. Lanyon and Beegle (1989) indicate that nutrient management on crop-livestock farms is most challenging because of the cyclic patterns of activities related to both crop and animal enterprises and the need to account for nutrient requirements for crop production as well as assimilating and dissipating the nutrients in the manure from the animals.

Several studies have shown that increasing soil fertility is a significant problem for most dairies relying on land spreading for manure management (Purvis 1995). For example, tests in Pennsylvania showed that more than 37 percent of the soil test samples exhibited high to excessive phosphorus and potassium levels. In some counties over 70 percent of the tests showed high or excessive levels of P and K (Lanyon and Beegle 1989).

In brief, for every pound of nitrogen, phosphorus and potassium leaving a dairy farm as milk, livestock and crops sold, several pounds come on to the farm in the form of purchased feeds, minerals, fertilizers, detergents, etc. Even with 2 to 3 acres of cropland per cow, 10 to 30 percent of the nutrient inputs for the dairy herd may come in the form of purchased feedstuffs (Parker et al. 1992, Lanyon and Beegle 1989).

Although dairy farms with 2 to 3 acres of cropland per cow may not have immediate concerns of becoming nonpoint sources of pollution via soil nutrient buildup, they do have need to integrate careful soil nutrient management into their cropping practices. For example, since, on most farms, most of the manure is spread on land used for corn production, attention needs to be paid to zinc deficiencies if soil phosphorus levels are excessive due to manure or fertilizer applications. Similarly, forages produced on soils with high levels of potassium can result in magnesium deficiencies in cattle diets (Thomas 1994).

4.3.3 The Solution

Recent studies indicate that the increasingly stringent and costly, but highly uncertain, requirements for compliance with environmental regulations are causing many dairy operators to rethink the wisdom of their move to confinement production technology (Purvis 1995). There are increasing numbers of reports of dairy operators changing to grazing-based production systems. Research by Parker et al. (1992) showed that for a typical dairy farm in Pennsylvania, a grazing-based operation produced higher average annual net returns than a confinement system. These gains in the bottom line are achieved because both fixed and variable operating costs can be reduced sufficiently to offset the lower revenues which result from decreased milk yields per cow with the grazing-based systems. One of the primary limitations to wide adoption of the grazing-based technology is the climate induced variability in quantity and quality inherent in the production of grazed forages. In areas where probability of drought is significant, producers are unlikely to give up their confinement technology. However, if the cost and uncertainty of environmental compliance requirements for CAFOs continues to increase, a shift in share of milk production may occur back to the more humid areas (Midwest and Northeast) of the U.S. where grazing-based production is advantageous.

In addition, recent advances in understanding differential degradability of protein and optimum ratios of energy to protein are resulting in new nutrition models capable of managing nutrient inputs more efficiently. Improved nutrient ratio management reduces N and P loading of the system. Integrated feeding, lagoon management, and manure redistribution systems can potentially result in much reduced N and P from nonpoint sources.

4.4 Case Study: Using Grazing Animals to Control Noxious Weeds

4.4.1 Introduction

Undesirable plants, often referred to as weeds, are generally regarded as a problem because their presence reduces the usefulness or productivity of the land resource for agricultural production, causes loss of wildlife habitat, diminishes watershed protection, and can make protection of rare native plants difficult. The impact on agriculture and livestock production in loss of productivity may be measured in terms of increased costs or decreased revenues.

4.4.2 Introduction of Weedy Plant Species

In grazed environments, the introduction of weedy species is often associated with grazing animals. Both wild and domestic animals can be vectors for spread of weedy plant species. Native plants that are held in check through competition with other plant species in the community can also gain a competitive advantage if grazing animals reduce competition by selecting certain species as forage. Grazing, in effect, releases nonselected plants to enjoy a comparative advantage in terms of obtaining moisture and nutrients and completing physiological processes. Ecologically, introduction of weedy species often results from physical dispersal of seeds by animals, with the seeds either being carried and dispersed by the animals through physical adherence to hair and wool or passage of ingested seeds through the body and disposition of the seed in feces (Archer 1989). Human activities are often associated with the introduction of weeds to an area in which the weeds are not native (ship ballast, draft animal, vehicles, transfer in hay or seed).

A native plant community dominated by native perennials and in good ecological condition can generally withstand invasive weedy species. This is based on the assumption that all available nutrient and moisture niches are occupied and being captured by the native species. Most weeds that invade and become dominate do so on disturbed areas in which a seedbed suitable for plant establishment is available and the introduced weeds enjoy a competitive advantage over the resident native species (e.g., the native plants are preferred as forage plants by grazing animals, or early seral conditions have been created by human or natural activities that allow weeds to become established. This niche can be made available by reduction in cover and presence of native forage species through flooding, overgrazing, road building, cropping, etc.).

The most obvious example of creating early seral conditions is converting native rangeland sites to cultivated cropland. Although the purpose of cultivation is usually to produce food or cash crops or to improve forage productivity over native plant species by seeding introduced forage plants, these activities usually require the application of inputs to reduce competition from weedy species for the available moisture and nutrients. In drier environments, fallow cropping systems employing techniques for moisture conservation and preventing the establishment of weedy annuals through cultivation are often used to reduce competition of weeds with the agriculture crop. If improper farming techniques are employed or the land is too marginal to support long-term farming, leading to abandonment, weedy species usually dominate the abandoned fields for varying lengths of time depending on the associated environment.

Weed infestation has been and is a major problem in many different ecological zones. However, weeds appear to be more of a problem in "new world" agriculture and livestock production systems compared to "old world" agriculture systems. Most weeds that infest North America, Australia, and New Zealand are "old world" plants from Europe and Asia.

An example of the impact of weedy plant species on productivity of agriculture, livestock and native plant and animal habitat is illustrated as follows (adapted from table 12 of Radtke 1993).

Noxious Weed	Impact	Control Benefit
Common Grupina	1. Crowding of desirable species	1. Increased yield
Gorse	1. Crowding	1. Increased yield
	2. Limit animal access	2. Improve wildlife habitat
	3. Fire hazard	3. Reduce fire control costs
Leafy Spurge	1. Crowding of productive lands	1. Increased yields
		2. Lower alternative control costs
Rush Skeletonweed	1. Crowding and contamination	1. Increased crop yields
		2. Increased crop prices
		3. Lower alternative control costs
Tansy Ragwort	1. Direct loss of animals	1. Increased animal and crop yields
	2. Crowding	2. Increased crop price
	3. Contamination	3. Lower alternative control costs
Yellow Starthistle	1. Crowding	1. Increased yields
	2. Limit animal access	2. Increased wildlife habitat
	3. Damage to animals	3. Lower alternative control costs

4.4.3 General Weed Control

Weed control on infested lands requires a systematic and persistent effort that may take many years. Often it must be regarded as an ongoing land management activity that will need to be continued on a permanent basis. The degree of control possible depends on the size and density of the infestation, terrain, tools or equipment available, and planned use for the site. Costs of direct control such as using herbicides are often substantial compared to the improved productivity obtained in the short term.

Planning a control program requires making an initial decision about the aim of the program--eradicate, manage, or contain. Eradication is the elimination of the plant from the site and requires that all seed production is halted and the seed bank in the soil from previous years is depleted. This approach is not usually practical on large infestations but may be practical for small infestations to prevent the spread of the undesirable weed. Management focuses on reducing the weed to tolerable levels by decreasing plant densities, seed production, plant height, and canopy size, or by using it as a feed resource for ruminants. Containment is delineating boundaries around large infestations and concentrating control activities on the smaller patches that exist outside of the contained area to reduce the spread of the infestation.

Methods of weed control include mechanical (tillage, mowing and removal with hand tools), biological (insects, livestock grazing, and plant competition), fire, chemical, and prevention. The most effective control is usually obtained in conjunction with using two or more methods (Thomsen et al. 1994).

4.4.3.1 Mechanical Control

Mechanical control methods include cultivation whereby infested areas are cultivated at the proper time to reduce new growth and reduce seedbanks of specific weeds. A second mechanical method involves mowing at well timed and repeated intervals. Mowing is usually most effective if time of mowing is coordinated with plant development and availability of moisture. For example, mowing to control yellow star thistle (Centaurea solstitialis) is most effective when soil moisture is low and no irrigation or rainfall follows. However, research in California indicates that mowing at too early a time during plant growth can actually encourage growth of yellow star thistle. All mowing should be done just prior to seed formation in the plant (Thomsen et al. 1994).

4.4.3.2 Plant Competition

Efforts to control noxious or toxic weeds should include establishing competitive and adapted grasses and legumes in the stand. Seeding adapted and desirable forage species will limit opportunities for re-invasion by the controlled or other undesirable plant species in the advent that control of the target weed is achieved. Desirable plant species will be available to fill the niche vacated by the controlled weed species. Establishing adapted desirable plants is usually most effective if seeding is in conjunction with other control efforts such as application of herbicides. If seeded plants are to be competitive with the noxious weed, grazing by livestock must be managed to allow plant establishment and maintenance of desirable plant stands. Chemical herbicides are often used to control weed infestations but are costly to purchase and apply and are increasingly becoming perceptually and environmentally nonacceptable.

4.4.3.3 Grazing Management of Weed Infestations.

Controlled grazing has been demonstrated to be an effective method for managing large infestations of yellow star thistle in annual grasslands (Thomsen et al. 1994). Livestock will graze yellow star thistle before spines develop and it is an acceptable component of a ruminants diet. The beneficial impact of grazing is largely dependent on timing of grazing. Grazing during the bolt stage was most effective in reducing plant densities, height, and seed production and was most effective in enhancing native plant diversity. However, grazing during the rosette stage competitively favored yellow star thistle over other herbaceous vegetation because grazing impacts were equal for other plants. It was also necessary to graze at two- to three-week intervals. Another important consideration is selecting the proper grazing animal as invasive weedy plants may be toxic to some animals but not others.

Leafy spurge is a perennial weed of the spurge (Euphorbiaceae) family introduced to North America from Europe in the late nineteenth century. Since then it has been spreading rapidly in the north-central United States and southern Canada (Messersmith 1990). Al-Rowaily et al. (1995) found in a simulated defoliation and plant competition experiment that flowering and seed yield of leafy spurge were significantly lower. Over the three years of the study, observed reduction of flower and seed yields ranged from 90 percent to 50 percent for two clipping intensities.

Walker et al. (1995) conducted grazing trials with sheep and goats to determine if leafy spurge can be controlled through grazing by livestock. They found that goats had higher preference for leafy spurge compared to sheep. They also found that site influenced palatability of leafy spurge to both sheep and goats, although goats maintained a higher preference compared to sheep on both sites and that animals having previous experience consuming leafy spurge ingested greater amounts than animals that were naive.

Beck (1995) found in Colorado that herbicide application in the fall following grazing of leafy spurge infestations with sheep assisted the control of the weed with herbicide. Grazing and fall herbicide application (Picloram) was more effective than only applying herbicides in the spring or grazing alone.

Research in Montana examining control of leafy spurge with grazing by sheep indicated that leafy spurge is highly nutritious at early phenological stages and can be a preferred forage species of sheep trained to eat the weed. It took native sheep (without previous familiarity with the plant) three weeks to learn to eat the plant. As a result, persons with pastures infested with leafy spurge would pay a premium price for sheep already trained to eat leafy spurge. The most effective control of leafy spurge was obtained by sheep and goat grazing of the plant at the "yellow bract stage" (Olsen 1996).

Tansy ragwort (Senecio jacobaea), a noxious weed native to Europe and Asia, was introduced to western Oregon in the early twentieth century. Since that time, it has spread to rangeland in eastern Oregon and enjoyed the reputation of being the most important noxious weed in western Oregon, causing millions of dollars in animal losses from poisoning, agricultural losses from contamination, and costs associated with the control program. In 1974 the Oregon Department of Agriculture initiated a biological control program that identified, evaluated, and distributed biological agents. In 1993 the program cost approximately $240,000 per year to maintain (controlling distribution and eradication of tansy ragwort in eastern Oregon where conditions are less suited to plant establishment and monitoring of the biological control program in western Oregon. The net annual economic benefit of the program using insect grazers is estimated to be over $5,000,000.

4.4.4 Conclusion

Biological control involves the use of any biological organism such as insects, livestock grazing, and competitive plants. Animal grazers, both small (i.e., insects) and large (i.e., livestock), are included in the classification of biological control agents. Recent research and demonstrations has determined that grazing can be successfully used to control noxious weeds, such as Leafy Spurge and Yellow Starthistle. If the weed plant can be grazed by grazed by livestock, the weed can be converted from a pest species to a forage species. However, using livestock to control a weedy pest species requires greater dedication and management skills than other methods of weed control. Selecting the proper animal species and timing of grazing become important ecological and economical components of the weed control program.

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