Effect of dietary energy level and docking on carcass characteristics of fat-tailed Kurdi sheep

Effects of partial docking on feedlot performance and body fat characteristics were studied in a fat-tailed sheep breed. Thirty-eight male lambs with an average weight of 4.44 ± 0.48 were randomly divided into two groups. The lambs in one group were partially docked at 3-4 h after birth, using rubber rings, and the lambs in another group remained intact (control). After weaning, 20 male lambs from each group were divided into two subgroups; one subgroup was fed with a normal dietary energy level   (2.45 Mcal/kg ME) and the other subgroup received a high-energy diet (2.73 Mcal/kg ME) for 84 days. The lambs were fed individually. At the end of the fattening period, the lambs were slaughtered for determination of carcass characteristics. Warm carcass weight (WCW) and fat depth at the12th rib was recorded. At 24 h postmortem, samples of omental fat (for chemical analysis), and caudal fat were taken from chilled (4°C) carcasses for the determination of fatty acid (FA) composition. No significant difference was observed for the weight gain between docked and control lambs during the suckling period. During the fattening period, docked lambs as well as lambs on high level of energy diet showed better weight gain (P < 0.05). No significant difference (P > 0.05) was observed for WCW and fat depth at the 12th rib between docked and control lambs, but WCW was significantly affected by the diet energy density (P < 0.05). Docked lambs produced leaner carcasses than did the intact lambs (P < 0.01). Docking did not influence feed consumption, but improved meat quality and amounts (by weight and percentage) of high price carcass cuts, and reduced total fat content as a percentage of the live weight. Dietary energy level affected the average daily gain and daily feed intake (P < 0.05). The most abundant FA in caudal and omental fat depots was oleic acid. Significant difference was observed in the percentage of all fatty acids between omental and caudal fat depots (P < 0.05). A negative correlation (-0.8465) was recorded between oleic and stearic acid concentrations (P < 0.001). In conclusion, docking of Kurdi lambs improved most feedlot characteristics (such as daily gain and feed efficiency) and may be recommended under industrial sheep production.