Soterios Economides
Agricultural Research Institute
Nicosia, Cyprus
Summary
Introduction
Materials and methods
Results and discussion
References
Research work on crop residues and agro-industrial byproducts included surveys to evaluate and determine the quality and seasonality of production, quantity in relation to animal numbers and location, chemical composition of each byproduct, nutritive value, and the response of animals to diets containing various proportions of byproducts.
Experiments were carried out with dehydrated or ensiled citrus pulp, grape marc and poultry litter. Dehydration maintains the quality of byproducts high in moisture and sterilizes poultry litter. Ensiling was used as an alternative-method because of the high cost of fossil fuel for dehydration. Ensiling killed pathogens present in poultry litter and silages made of citrus pulp and poultry litter or grape marc and poultry litter were used to replace part of the concentrate mixture of the basic diets of growing heifers and dairy cows.
Cereal straw is an important source of roughage but its nutritive value is very low. Straw intake and quality were improved when straw diets were supplemented with nitrogen and energy sources (soybean, or urea and barley grain). Alkali treatment using NaOH, Ca(OH)2 in combination with urea also improved the quality of straw. However, the most promising method of improving the quality of straw seems to be ammoniation using a urea solution.
In Cyprus, as in many other Middle East countries, low roughage production is the main constraint in ruminant production (Economides, 1985). As a result, large quantities of concentrate feeds are imported to meet the increasing demand of an expanding livestock industry. The use of locally produced feedstuffs, crop residues and agro-industrial byproducts (e.g., cereal straw, citrus pulp, grape marc and poultry litter) to replace these concentrate feeds is of great importance and was studied in our programme as a matter of high priority.
The objectives of this study were:
* To identify, quantify and describe the seasonal availability and alternative uses of all locally available ruminant feedstuffs;* To determine the nutritive value and voluntary intake of these feedstuffs and to evaluate their use in ruminant diets;
* To identify where byproducts are produced and to relate this information to the numbers and types of animals.
The following is a brief description of a series of experiments:
1. Experiments with dehydrated citrus pulp, grape marc and poultry litter
Dehydrated citrus pulp or grape marc were used in two separate trials to replace 20% of barley grain on an equal weight basis in dairy rations (Economides, 1974).
The use of poultry litter as a ruminant feedstuff has been studied extensively (Bhattacharya and Taylor, 1975). It can be used as a ruminant feedstuff provided it contains no pathogens, drugs or other medicants. Furthermore, high levels of minerals such as Cu should be withdrawn from poultry rations if the waste is to be used as ruminant feed. Early work in Cyprus on the use of dehydrated poultry litter in ruminant diets has been reviewed (Hadjipanayiotou, 1984). Poultry litter has been used in experiments with growing heifers, lactating goats and ewes, fattening kids and fattening calves to replace up to 30% of conventional concentrate mixtures.
2. Experiments with ensiled poultry litter, citrus pulp and grape marc
In view of the high cost of sterlizing poultry litter with the dry heat processing method, Harmon et al (1975) proposed the ensiling process in order to destroy existing pathogens.
Poultry litter was screened, using a 20 mm metal grid to remove caked material, and was ground in a hammer mill before being ensiled, alone, or in a mixture with straw, weeds and grapefruit peels, in small silos for laboratory investigations.
The effect of ensiled poultry litter with either grape marc (PLGM) or citrus pulp (PLCP) was studied in four experiments (Economides and Hadjipanayiotou, unpublished) with growing heifers and lactating cows (1 kg of a conventional concentrate mixture was replaced by 2 kg of PLGN or 4 kg of PLCP). The silages were prepared in earthen pits and the ingredients were added layer after layer.
One part of poultry litter (approx. 75% DM) was used for every four parts of citrus pulp (18.3% DM) or two parts of grape marc (50% DM). Some characteristics of the silages are presented in Table 1.
Table 1. Composition, acid content and pH of silages prepared from poultry litter mixed with either grape marc (PLGM) or citrus pulp (PLCP).
|
|
PLGM |
PLCP |
|
Dry matter (%) |
49.8 |
23.4 |
|
Crude protein (%) |
18.9 |
14.2 |
|
Ash (%) |
10.2 |
8.3 |
|
pH |
5.04 |
3.73 |
|
Free acetic acid (%) |
0.32 |
0.91 |
|
Bound acetic acid (%) |
3.50 |
3.35 |
|
Lactic acid (%) |
0.72 |
1.72 |
|
Butyric acid (%) |
Nil |
Nil |
3. Experiments with cereal straw
The most important byproduct in Cyprus, cereal straw, constitues 75% of the presently utilized byproducts for ruminant feeding (Economides, 1984). Cereal straw in the long (baled) or chopped form is used extensively in all ruminant diets and all production systems in varying proportions with concentrates. The nutritive value of straw, however, is low, with low nitrogen content being the major factor limiting its intake (Elliot and Topps, 1963; Fick et al, 1973).
4. Supplementation of straw with nitrogen and energy
The importance of adequate nitrogen intake in relation to energy intake on the performance of sheep has been extensively studied (Orskov, 1977; Kempton and Leng, 1980). Studies were carried out to determine the effect on the feed intake and performance of fattening lambs of a basal diet of oaten chaff, glucose and urea, supplemented with fishmeal and/or an infusion of glucose in the abomasum. Furthermore, the effect of supplementing straw with soybean meal (150 g/head/day) or a molasses-urea mixture (0.3-0.5 kg/head/day) was studied. Supplementing straw with nitrogen source and/or energy (Economides et al, 1981) significantly increased straw intake by mature Chios ewes (Table 2). Dry matter intake was increased by 19, 22 and 31% when straw was fed ad libitum in conjunction with barley grain alone (250 g/day), urea and barley grain (10 g urea and 240 g barley grain) and soybean meal (80 g) and barley grain (170 g), compared to the unsupplemented straw. Digestibility coefficients for DM, OM and CP of the total diet were significantly lower for the unsupplemented straw diet (Table 2). Barley grain alone, and urea and soybean supplementation increased the daily energy intake of the unsupplemented straw diet by 111, 144 and 152%, respectively.
Sheep fed the urea or soybean meal supplemented diets consumed adequate nitrogen to meet maintenance requirements whereas nitrogen intake was inadequate on the other two diets. Supplementing straw with barley grain only, increased straw intake and improved the energy balance of sheep, but nitrogen intake was very small.
Table 2. Effect of straw supplementation with nitrogen and energy on the performance of Chios sheep.
|
|
Diets |
||||
|
Straw |
Straw + soya + barley grain |
Straw + urea + barley grain |
Straw + barley grain |
||
|
Intake (kg DM) |
0.68 |
1.12 |
1.03 |
1.05 |
|
|
Digestibility (%) |
|
|
|
|
|
|
|
Organic matter |
42 |
57 |
53 |
53 |
|
|
Gross energy |
37 |
54 |
55 |
49 |
|
|
Crude protein |
0 |
47 |
52 |
13 |
|
Energy intake (MJ/day) |
3.75 |
9.45 |
9.20 |
7.90 |
|
|
Protein intake |
0 |
51 |
53 |
7 |
|
|
Cost of supplementation |
|
|
|
|
|
|
|
US $/day |
- |
0.041 |
0.030 |
0.026 |
5. Experiments with urea treated straw
Treatment of low quality roughages with NH3 has been recommended (Sundstol et al, 1979). The merit of NH3 over NaOH is possibly that it is safer, although more unpleasant, to handle and also adds non-protein nitrogen to the straw. However, treatment of straw with urea to generate NH3 has been proposed (Jackson 1978). Urea is more pleasant than NH3, is less hazardous to handle and requires no pressure tanks for storage and transportation. The effect of ammoniation using urea on the intake and nutritive value of chopped barley straw was studied in two separate trials (Hadjipanayiotou, 1982). The straw was treated with a 10% urea solution at the rate of 400 l/t straw and stored in sealed containers for 1, 15, 30, 45 and 60 days.
As shown in Table 1, neither milk yield nor liveweight changes were affected by feeding-20% citrus pulp when the diets were isonitrogenous. However, cows fed grape marc produced less milk and gained less liveweight, indicating a lower energy value of grape marc compared with barley grain.
The in vitro digestible organic matter in the dry matter ("D" value) was 0.39, 0.43, 0.47 and 0.74 for poultry litter, straw, weeds and grapefruit peels respectively. The calculated digestible energy content of poultry litter, straw, weeds and grapefruit peel was 7.2, 7.9, 7.8 and 14.60 MJ/kg DM respectively. Addition of poultry litter at ensiling resulted in significant increases in nitrogen and ash content of the original material. All initial mixtures were positive for the pathogen Protaus but it was destroyed after ensiling.
The rate of growth of heifers fed PLCP silage was similar to that of heifers on the control diet (36 vs 33 kg). Dairy cows fed the PLCP silage (with calculated energy content of 11.6 MJ/kg DM) or the control diet produced similar milk yields. milk fat content and liveweight changes.
Heifers fed PLGM silage (calculated energy content 7.1 MJ/kg DM) gained less liveweight (30 vs 39 kg) than heifers on the control diet. Dairy cows fed the PLGM silage or the control diet produced similar milk yields but cows fed PLGM produced milk with higher fat content (3.39 vs 2.52%) and lost 3 kg, while cows on the control diet gained 24 kg.
No pathogens were isolated in the poultry litter. Crude fibre content in both silages was high because poultry litter had been collected from a broiler house with sawdust bedding.
Voluntary intake, digestibility and intakes of energy and protein were considerably lower with straw compared with either barley or lucerne hays (Table 3). Intake of dry matter was respectively 12.9 and 31% higher for lucerne and barley hays than for straw. Crude protein content and the digestibilities of protein and organic matter were highest for lucerne hay and lowest for cereal straw (Economides et al, 1981). Its energy content was 5.5 MJ ME/kg DM and the intake of ME by sheep was 3.75 MJ/day, less than half the energy requirements of a 60 kg sheep (Economides, 1981) and zero protein intake.
Table 3. Protein content, intake and digestibility of straw, barley hay and lucerne hay.
|
|
Barley straw |
Barley hay |
Lucerne hay |
|
Crude protein (%) |
3.6 |
11 |
24.3 |
|
Dry matter intake (kg/ewe/day) |
0.68 |
0.89 |
1.55 |
|
Digestible protein intake |
|
|
|
|
(g/ewe/day) |
0 |
45 |
320 |
|
Digestibility (%) |
|
|
|
|
Organic matter |
42 |
60 |
67 |
|
Crude protein |
0 |
46 |
35 |
In vitro digestibility reached maximum 45 days (Table 4) post-treatment, though the change in digestibility from 30 to 45 days was not significant. The overall increase in digestibility of treated straw over the untreated was 11 percentage units. of the originally added N. 44% was retained in the straw and free NH3-N accounted for 31% of the retained N. NH3-N increased as the total N decreased with ensiling time.
Table 4. In vitro digestibility of DM, D- value, total N and NH3 -N concentration in the dry matter of treated and untreated straw.
|
|
Untreated straw |
Ensiling period (days) |
||||
|
1 |
15 |
30 |
45 |
60 |
||
|
DM digestibility |
0.46 |
0.46 |
0.50 |
0.56 |
0.58 |
0.58 |
|
D-value |
0.42 |
0.42 |
0.45 |
0.51 |
0.54 |
0.54 |
|
Total N (g/kg DM) |
5.0 |
23.0 |
20.0 |
14.0 |
14.3 |
12.3 |
|
NH3-N (g/kg DM) |
0.5 |
1.0 |
2.0 |
4.0 |
4.7 |
4.5 |
The voluntary intake and in vivo crude fibre and dry matter digestibilities of urea treated straw, fed alone, increased by 47, 40 and 20% respectively, compared with untreated straw (Table 5). The digestibility of the total diets was similar when either treated or untreated straw formed 20% of the diets. The digestible energy value of treated straw increased by 20%.
Table 5. Voluntary intake, digestibility, digestible energy concentration, crude protein retention and absorption, ruminal NH3 -N concentration and pH of the four straw diets.
|
|
Diets |
||||
|
US |
TS |
US+C |
TS+C |
||
|
Voluntary straw intake (kg DM) |
0.45 |
0.80 |
- |
- |
|
|
Digestibility (%) |
|
|
|
|
|
|
|
Dry matter |
42 |
53 |
73 |
74 |
|
|
Organic matter |
44 |
55 |
74 |
76 |
|
|
Crude fibre |
52 |
73 |
49 |
59 |
|
|
Crude protein |
0 |
34 |
73 |
73 |
|
|
Gross energy |
40 |
48 |
74 |
76 |
|
Digestible energy (MJ/kg DM) |
7.34 |
8.80 |
14.76 |
15.08 |
|
|
Crude protein (g/day) |
|
|
|
|
|
|
|
absorbed |
negative |
20.3 |
106.0 |
115.0 |
|
|
retained |
negative |
negative |
47.0 |
44.0 |
Bhattacharya A N and Taylor J C, 1975. Recycling animal waste as a feedstuff: a review. Journal of Animal Science 41: 1438-1457.
Economides S. 1974. The effect of dried citrus pulp and grape marc on milk yield and milk composition of dairy cows. Technical Paper 7. Agricultural Research Institute, Nicosia.
Economides S. 1981. The energy requirements of the Chios sheep. 1:- Requirements for maintenance and late pregnancy. Technical Bulletin 40. Agricultural Research Institute, Nicosia.
Economides S. 1984. Inventory of crop residues and agro-industrial by-products in Cyprus, 1984. Miscellaneous Reports 15. Agricultural Research Institute, Nicosia.
Economides S. 1985. The roughage situation in Cyprus in relation to Animal health and productivity. Miscellaneous Reports 18. Agricultural Research Institute, Nicosia.
Economides S. Hadjipanayiotou and Georghiades E. 1981. The nutritive value of straw and barley and lucerne hay and the effect of nitrogen supplementation on the nutritive value of straw to sheep. Technical Bulletin 39. Agricultural Research Institute, Nicosia.
Elliot R C and Topps J H. 1963. Voluntary intake of low protein diets by sheep. Animal Production 5: 262-276.
Fick K R. Ammerman C B. McCowan C N. Loggins P E and Cornell J A, 1973. Influence of supplemental energy and biuret nitrogen on the utilization of low quality roughages by sheep. Journal of Animal Science 137-143.
Hadjipanayiotou M, 1982. The effect of ammoniation using urea on the intake and nutritive value of chopped barley straw. Grass and Forage Science 37:89-93.
Hadjipanayiotou M, 1984. The use of poultry litter as ruminant feed in Cyprus. World Animal Review 49:32-38.
Harmon C W. Fontenot J P and Webb K E Jr. 1975. Ensiled broiler litter and corn forage. I: Fermentation characteristics. Journal of Animal Science 40:144-155.
Jackson M G. 1978. Treating straw for animal feeding. FAO Animal Production and Health Paper No. 10.
Kempton T J and Leng R A, 1990. Protein nutrition of growing lambs. 1: Responses in growth and rumen function to supplementation of a low protein cellulosic diet with either urea casein or formaldehyde treated casein. British Journal of Nutrition 42:289-302.
Orskov E R. 1977. Proceedings of the second international symposium on protein metabolism and nutrition. The Netherlands. Flerohof.
Sundstol F. Coxworth E and Mowat D N. 1978. Improving the nutritive value of straw and other low quality roughages by treatment with ammonia. World Animal Review 26:13-21.
