卵巢摘除对放牧扎布耶盐山羊GH水平、育肥性能及羊肉品质的影响

Effects of ovariectomy on growth hormone(GH) levels,fattening performance and meat quality of grazing Zabuye goat

【目的】研究卵巢摘除对放牧育肥布耶盐山羊生长激素(GH)水平、育肥性能及羊肉品质的影响,为在我国藏北牧区开展扎布耶盐山羊短期育肥提供技术支持。【方法】选择90只体重相近的2岁龄扎布耶盐母山羊,随机分为空白对照组和卵巢摘除试验组,试验期间两处理组母羊均按当地牧民习惯自由放牧,夜间不予补饲。在卵巢摘除后第0、7、14、21、28、35、42、49和56 d上午9:30空腹称重并颈静脉采血,分析血清GH水平变化情况;饲养56 d后,每组随机屠宰10只母羊,测定其屠宰性能(胴体重、屠宰率、净肉重、净肉率)及羊肉品质(剪切力、pH、蒸煮损失、色度及脂肪、蛋白质、水分、脂肪酸、氨基酸、维生素、胆固醇及6种元素的含量变化)。【结果】从卵巢摘除后第7 d开始至试验结束,母羊血清GH水平较对照组极显著升高(P<0.01,下同);卵巢摘除后前7 d,母羊体重略有下降,此后体重增重稳定增长,至试验结束时平均体重为32.93 kg/只,极显著高于对照组(29.41 kg/只)。卵巢摘除扎布耶盐母山羊的胴体重(14.29kg/只)、屠宰率(43.38%)、净肉重(10.48 kg/只)和净肉率(131.82%)均极显著高于对照组;背最长肌的剪切力、失水率和蒸煮损失较对照组极显著降低,羊肉红度a*显著降低(P<0.05,下同);羊肉脂肪含量较对照组显著提高、水分含量显著降低;背最长肌饱和脂肪酸(ΣSFA)显著低于对照组、单不饱和脂肪酸(ΣMUFA)显著高于对照组;必需氨基酸(EAA)和总氨基酸(TAA)均极显著低于对照组,但赖氨酸和胱氨酸含量极显著高于对照组;背最长肌中维生素E较对照组显著降低,其他维生素含量则无明显变化;背最长肌硒含量较对照组极显著提高,铁和镁含量较对照组显著提高,锌含量较对照组略有下降。【结论】摘除2岁龄扎布耶盐母山羊的卵巢能有效提高其血清GH水平,促进肌肉组织生长发育,尤其是经短期育肥后,扎布耶盐山羊的屠宰率、净肉重和净肉率提高,羊肉品质明显改善。

【Objective】This study investigated the effects of ovariectomy on growth hormone（GH） levels, fattening performance 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. 【Method】Ninety 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. 【Result】Serum GH levels of goat in test group were significantly 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 percentage（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 fatty 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 compared 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. 【Conclusion】Ovariectomy 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.