Utilization of agricultural residues as animal feeds for fattening sheep in Saudi Arabia

Abstract

Due to diversified agricultural activities in Al Khalidiah Farm, SA (2500 hectares), more than 7000 ton/year of different agricultural residues (AGR) are produced annually. The study consisted of two trials; the first one aimed to evaluate the chemical composition and nutritive value of some selected AGR to be used as animal feeds and to evaluate the effect of dehydration treatments on their chemical and microbiological analysis. The second trial was conducted to investigate the impact of feeding combinations of five feed ingredients made from the tested agriculture residues on the performance of fattened sheep lambs. During the first trial, seven types of AGR (one ton each) were collected namely: 1- Landscape mowing grasses (LMG), 2- Mixed ornamental plants residues (MOPR), 3- Olive trees pruning (OTP), 4- Citrus tree pruning (CTP), 5- Date trees pruning(DTP), 6- Horse stable grasses residues (HSGR) and 7- Green houses by-products (GHBP). These AGR were air-dried, ground and tested for preliminary chemical composition and nutritive value. Five tons from each of new AGR materials were air -dried, ground then heated in a drying drum at 90°C for 15 minutes. Five samples were taken, randomly, from each air- dried material and after being heated to evaluate the impact of heating on the chemical analyses and microbiological parameters of the tested materials. During the second trial, five rations from the tested AGR ingredients were formulated and offered to fifty weaned lambs (2 month- old and averaged 17.0 ± 0.73 Kg body weight) divided randomly in five groups (10 lambs each) in a group feeding system for a 9-week fattening period. The rations were offered ad libitum and consisted of: 1- LMG, 2- MOPR, 3- HSGR, 4- A mixture of olive tree pruning mixed with orange fruits by-products (OTPOF) for the four groups: R1, R2, R3, R4, respectively while the control group (R5) was offered Alfalfa hay. All groups were offered the Concentrate Feed Mixtures (CFM) at 60% of the total ration while roughages were offered at 40%. Animals were weighed at the beginning of the experiment and biweekly. Feeding allowances were adjusted biweekly according to body weight changes. Voluntary feed intake, feed conversion and feeding costs were determined. Representative samples of the feed ingredients were tested for chemical, pathogens and microbiological analysis. Results of the first trial indicated that all AGR feed ingredients appeared to be nutritious since they contained enough concentration of nutrients to cover animal nutritional requirements. Crude protein content varied among the feed ingredients and ranged from 6.53% (CTP) to 19.77% (LMG). Heating treatment, generally, did not affect (P>0.05) all nutrients concentration nor microbiological parameters of all tested feed ingredients. Results of the second trial showed that animals fed R2 followed by R1 recorded the highest average daily gain of 283 and 280 g/day, respectively as a reflection of their high feed intakes. Feed costs of rations R1 and R2 were comparable and showed the lowest feed costs per one kilogram gain (SR 1.35 and 1.36, respectively) while the control ration (R5) recorded the highest feed cost (SR 2.23). It is shown that lambs of R3 were more efficient in feed conversion (3.52 gm DM/gm gain) than the other tested rations. It could be concluded that using AGR in feeding animals is economic and has a positive impact on productive performance feeding costs of fattened lambs. © 2010 WIT Press.