Comparison Among Protein Levels and Sources on Performance and Carcass Traits of Assaf Lambs

Discussion Committee: 
Prof. Jamal abu Omar
prof.Adnan Shqueir - External
Dr.Maen Samara - Internal
Prof. Jamal abu Omar
Omar Khalil Ibrahim Naser
Twenty male Assaf lambs were used,in this experiment, to investigate the effects of feeding sunflower meal (SFM) as a substitute for soybean meal (SBM) in rations at two crude protein (CP) levels (14 and 18% as fresh basis) on the feedlot performance, (average daily gain, feed conversion ratio, visceral organs, some carcass merits and digestibility), of fattening Assaf lambs. Lamb's average initial body weight was 29.04 kg (S.D. = 4.69 kg). Lambs were randomly divided into four groups of five lambs in each group. Lambs were fed in morning and evening individually with total mixed rations (TMR), and was considered as replicate. Lambs in groups 1 and 2 were fed fattening rations where soybean meal is the source of protein at two CP levels, 14 and 18%. However, lambs in groups 3 and 4 were fed fattening ration similar to the first two groups except that sun flower meal was the protein source. Lambs were weighted on a weekly basis. Body weight change, feed intake, average daily gain and different carcass traits were determined. In addition, visceral organ mass as well as dressing percentage and carcass cuts were also measured. Major nutrients digestibility was determined through conduction of a digestion trial. From the first week until the eighth week of the trial, the lambs fed with  the 18% CP SBM ration recorded the highest (P<0.05) weight (48.79 kg) compared to lambs fed with  the 18%CP SFM ration which showed the lowest weights (43.45 kg). The mean weight gain in lambs fed with the14% CP SFM was similar to that of lambs fed with both crude protein levels of SBM. The weight change tends to decline as SFM level increased after 4 weeks compared to other treatments. Furthermore, the highest average feed intake was observed in the 14% CP SFM and the lowest was with 18% CP SBM. Digestibility of DM and, CP were similar among all treatment rations, but level of protein and source had no effect on EE and OM digestibility. There were no significant differences in the average final body weight (FBW), average daily gain (ADG) and average feed conversion ratios (FCR) among the treatments. Results also showed that source and level of protein had a significant effect on average leg and shoulder weights. Lambs fed with 18% CP SFM had the highest weight loss during carcass chilling at 3◦C for 24 hr., while the 14% CP SFM had the lowest weight loss value. However, there were significant differences (P<0.05) between hot and cold carcass weights. Level of SBM had a significant effect on lung average weights. However, liver average weights were significantly by protein source (14% CP of SBM vs. 18% CP SFM). Heart average weights were not affected by type or level of protein. In general, this study further confirmed that SFM could replace SBM as a protein source; also increasing protein level will not result in any improvement in lamb performance.
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