The reasons for keeping ruminants in developing countries are not always easily understood by the outsider. They are kept for a number of reasons, which change in priority depending on their location and owners including the following:—
for food (e.g. meat, milk and blood or any of these combinations) and also as a reliable food store for years of drought
as status symbols of wealth
as a means of accumulation of wealth to be cashed for a number of purposes (e.g. life threatening events; to meet marriage costs; to provide for pay-back etc.)
as an edge against inflation
for fuel (dung for sale or to provide for household cooking)
for fertiliser production (e.g. dung)
for religious purposes and/or entertainment (e.g. the fighting rams of Indonesia)
work purposes (ploughing, puddling of soil for rice etc.)
hides for leather
as investment by city business men to create a stake in agriculture which is often motivated by the possibility of tax relief
to make use of poor lands which would not otherwise be used for agricultural purposes.
The desire of the farmer to increase productivity of his animals, is highly dependent on the purpose for keeping the livestock. It is sometimes an advantage to maintain a low level of productivity. For example, if animal numbers are more important than production per animal, it is advantageous to have stunted, thin animals which require low management inputs.
In this presentation the target animals are the animals in the herds of small farmers where meat, milk, work, or any combination of these (meat/work, meat/milk, milk/work) are the major objectives as these are the major owners of livestock in developing countries and the target for many of the aid-sponsored projects.
Few developing countries have surplus tracts of land that can be regarded as fertile and therefore produce high quality fodder. In general, human population pressures and the primary need to supply human food ensures that livestock are restricted to:—
poor quality (often overgrazed) pasture lands, either infertile or with terrain that makes them impossible to utilise for crops or where erosion has made them unusable.
Table 2.1: Average meat production (kg) per animal of total population of cattle/buffaloes in Europe (representative of the concentrate/forage feeding systems) and in Asia/Pacific (1986)
standing crop residues or weeds following cropping when environmental conditions are poor for plant growth and a further crop in that year cannot be taken.
crop residues (cut and stored)
extensive pastures of poor quality and otherwise sparse (e.g. The Llanos of Colombia and Venezuela).
The net result is in general an extremely low rate of productivity with animals often at 5 years of age at maturity and productivity at 0.1–0.25 of that of ruminants in temperate countries grazing fertilised pastures or fed high quality feeds based on grain and immature pasture plants. A comparison of the levels of production of cattle between developed and developing countries is shown in Tables 2.1, 2.2 and 2.3.
Table 2.2: Average carcass weight (kg) per animal slaughtered (Jasiorowski, 1988) (1986 statistics)
Table 2.3: The change in the average milk yield per cow in industrialised and third world countries
|Percentage increase (%)|
|1976||1986||(1976 to 1986)|
Biotechnology research in industrialised countries is not generally aimed at low yielding animals. In addition to poor nutrition, adverse climate and disease, other stresses are also generally high, particularly in those countries situated in the tropics. These additional constraints are likely to affect and often remove any advantage of biotechnology transferred from developed countries.
The considerable differences in feed resources available in developing countries compared to developed countries (where most biotechnology research is presently centered) and the low cost of production systems employed in the developing world as compared with the industrialised world (where subsidies on agricultural production are often in excess of 40% of the value of the product) indicates that direct technology transfer is unlikely to be successful.
The feeds that are available to ruminants in developing countries are fibrous and relatively high in ligno-cellulose. They are usually of low digestibility and they are often deficient in critical nutrients, including protein, non-protein nitrogen and minerals.
As a generalisation, the forages consumed by ruminants in developing countries are almost always below 55% (usually 40–45%) digestibility and are often less than 8% crude protein and this protein level is more often around 3– 5%, e.g. cereal straws. The only exception to this is in the early growth phase of pasture and when stocking rates are extremely low and the animals are able to select for leaf material. The low levels of production per head and per acre of most grazing systems are indicated by the summary of data given by Walker (1987) (see Figure 2.1). Without supplements, these low levels of production lead to a highly inefficient use of the available feed, with a possibility that up to 30% of the feed consumed is dissipated as heat. This heat has at times great effects on feed intake particularly in the tropics (see Chapter 3).
It is necessary, therefore in discussing the nutrition of ruminants, to appreciate the digestion of forage based diets and the constraints to the utilisation of nutrients that arise largely from a fermentative digestion system, since this knowledge must considerably influence research priorities.
In the literature concerned with the nutritional value of forages, considerable emphasis is placed on the crude chemical composition of the forage. Although analyses that indicate cell solubles and cell wall materials are highly useful for studying the fermentative characteristics of a forage, they bear little relationship to its feeding value to the animal (see later). Considerable efforts is often put into feed analysis which is often totally unwarranted particularly in the developing countries. In this report the overriding effects of a balanced nutrient approach to feeding are emphasised. It is suggested that in most production systems for ruminants based on a poor quality forage, it is the balance of those nutrients providing the major building blocks for tissue synthesis and milk production, that should be the primary concern. With most forages and contrary to the assertations in the past that energy deficiency is the primary constraint to ruminant production on low quality feeds, the efficiency of feed utilisation is the major determinant of the production levels achieved. Therefore in reviewing the need for biotechnology research, this is the area for most consideration.
Recent evaluation of data from studies in tropical countries has indicated that medium to high levels of production at very high feed conversion efficiencies can be achieved by ruminants on poor quality forages adequately supplemented with critical nutrients (see Preston & Leng (1987) for review). Of more importance is that the efficiency of utilisation of the metabolizable energy of a straw based diet appropriately supplemented can be higher than that of grain based diets (Leng, 1989b). This suggests that the efficiency of utilisation of metabolisable energy of a forage can be markedly improved simply by supplementation (by up to 10 fold). It also discounts theories that the digestible nutrients from such feeds are less efficiently utilised than from grain based diets.
Figure 2.1: Cattle growth on pasture is a function of pasture type, fertiliser applications and legume content. Productivity per unit area is maximised for the different pastures at different stocking rates: 89 kg/ha for native pastures, 223 kg/ha for tropical grass with legume, 682 kg/ha for tropical grass with fertiliser and on temperate pasture (clover) 105 kg/ha. (Source: Walker 1987)