Effects of dietary energy density on feed intake, body weight gain and carcass chemical composition of Omani growing lambs.

摘要

40 male Omani lambs were used in a feeding trial to study the effects of feeding diets containing various levels of metabolizable energy (ME) on growth and carcass composition. The trial was carried out on the months of July to October 1996 at the Agricultural Experiment Station, Sultan Qaboos University, Oman. Ten lambs were selected randomly and slaughtered at the start of the trial to provide information on initial carcass composition. 30 lambs were divided randomly into 3 groups and fed 3 dietsvarying in ME concentration (low, medium and high with ME 8.7, 9.95 and 11.22 MJ/kg DM respectively) from weaning (at average 76 days) until slaughter at the mean weight of 30 kg. Digestibility of dry matter (DM) was 66.9, 68.7 and 73.9% for low, mediumand high energy diets, respectively. Apparent gross energy digestibility was 66.8, 67.2 and 73.3% corresponding to dietary concentrations of 12.2, 12.6 and 13.9 MJ of DE/kg for low, medium and high energy diets, respectively. Daily DM intake ranged between 3.12 and 3.73% of body weight (BW) which was equivalent to 76.5-97.5 g/kg0.75 or 0.738-1.142 MJ ME/kg0.75. Daily BW gain increased (P<0.001) with increasing ME density with a maximum of 154 g/day observed in lambs on high energy diet during the last4 weeks of the experiment. Feed conversion ratio (FCR), i.e., kg feed/kg BW, improved with increasing ME density (P<0.001). Sheep fed high energy diet had heavier BW (P<0.01), empty BW weight (P<0.001), carcass weight (P<0.01), higher dressing percentage(P<0.05) but lower gut content (P<0.001) than lambs fed the low energy diet. Sheep slaughtered at the end of the trial had lower water, protein but higher carcass and non-carcass chemical fat than sheep slaughtered at the start of the experiment. It isconcluded that meat production from sheep in Oman will be improved in the form of higher BW gains and better carcass composition by increasing energy levels in the diet.