Abstract:
ObjectiveThis study investigated the effects of ovariectomy on growth hormone(GH) levels, fattening per-formance and meat quality of grazing Zabuye goats, in order to provide technical support for short -term fattening of Zabuye goat in pastoral areas of northern Tibet. MethodNinety two-year-old female Zabuye goats of similar weight were selected and devided into control group and ovariectomy test group randomly. During the test, local free grazing habits were practiced and no supplement feeding at night were provided for the goats. The goats were weighed with empty stomach and jugular vein blood were sampled at 9:30 am on 0,7,14,21,28,35,42,49 and 56 d after ovariectomy, then serum GH level variation was recorded. After day 56, ten goats from each group were randomly selected and slaughtered, their slaughter performances(carcass weight, dressing percentage, net meat weight and net meat percentage) and meat quality(shear force,pH value,cooking loss, color and fat, protein content, water content, fatty acid content,amino acid content, vitamin content, cholesterol content and six elements) were analyzed. ResultSerum GH levels of goat in test group were signifi-cantly higher than that of control group(P<0.01, the same below) from day 7 after ovariectomy to the end of the trial. In the first seven days after ovariectomy, the weight of the goats declined, then increased steadily afterwards. Until the end of the trial, average weight reached 32.93 kg/goat, which was significantly higher than that of control(29.41 kg/goat). In test group, carcass weight(14.29 kg/goat), dressing percentage(43.38%), net meat weight(10.48 kg/goat) and net meat per-centage(131.82%) were significantly higher than those of control group. Shear force, water loss rate and cooking loss rate of longissimus dorsi muscle significantly decreased compared to those of control, meat redness a* also declined(P<0.05, the same below). Compared with control group, fat content significantly increased, water content significantly decreased. In longissimus dorsi muscle, saturated fatty acid(ΣSFA) was significantly lower than that of control, yet monounsaturated fat-ty acid(ΣMUFA) was significantly higher; essential amino acid(EAA) and total amino acid(TAA) were significantly lower than those in the control group, but lysine and cysteine contents increased, and reached significant difference level com-pared with the control group. Compared with control group, vitamin E in longissimus dorsi muscle significantly reduced,but changes in other vitamin contents were not significant; selenium content increased significantly, and contents of iron and magnesium increased significantly, yet zinc decreased slightly. ConclusionOvariectomy on two-year-old female Zabuye goats can raise serum GH levels, promote rapid growth of muscle tissue. Dressing percentage, net meat weight and net meat percentage improve after short term fattening especially, and meat quality is optimized obviously.