酵母铬和日粮蛋白水平对肥育羔羊生产性能和血液生化指标的影响

Effects of chromium yeast and dietary protein levels on performance and plasma metabolites in fattening lambs

研究了铬（Cr）和日粮蛋白水平（CP）对肥育羔羊的生产性能和血液生化指标的影响以及二者的互作效应。采用2×3完全随机试验设计，选择9周龄（（22．96±2．60）kg）的杜泊公羊与小尾寒羊母羊杂交的杂交一代雄性断奶羔羊48只，随机分为6个处理组，每个处理组8只，饲喂2阶段3种Cr水平（O（Cr0）、400（Crl）和800（Cr2）μg／kg（DM）酵母铬和2种CP水平（153和171g／（d·只），低蛋白日粮（LP）；189和209g／（d·只），高蛋白日粮（HP））日粮。饲养试验（60d）结束后，采集血液和胴体样品。结果表明：1）Crl、Cr2和HP均具有提高试验羔羊的平均日增重和体重的趋势（P〉0．05）。2）Crl和Cr2均具有增加胴体重、屠宰率、背最长肌面积、净肉重、净肉率和失水率，降低脂肪沉积和肌肉大理石花纹等级的趋势（P〉0．05），其中肌肉脂肪百分含量在Crl和Cr2处理与Cr0间差异显著（P〈0．05）。HP显著增加了羔羊的腹脂重（P〈0．05）、第10肋背膘厚（P〈0．05）、背最长肌面积（P〈0．01）和肌肉脂肪含量（P〈0．05），降低了净肉率（P〈0．01）。3）Crl具有降低血浆胰岛素含量和胰岛素水平与葡萄糖含量比值的趋势（P〉0．05）。Crl和Cr2均提高了血浆非酯化脂肪酸的含量，降低了甘油三脂的含量，并且这2项指标中各Cr处理之间差异均显著（P〈0．05）。Crl显著降低了血浆尿素氮含量（P〈0．05）。HP提高了血浆非酯化脂肪酸（P〈0．05）、尿素氮（P〈0．01）和血浆总蛋白的含量（P〈0．01）。在非酯化脂肪酸测定值中观察到了Cr与Cp的互作效应（P〈O．05）。试验结果说明：1）与CP相比，Cr（400或800μg／kg，DM）对羔羊生产性能和血液生化指标的影响不大；2）羔羊日粮添加铬0～800μg／kg（DM）可以改善胰岛素敏感性，并且调节能量与蛋白质代谢；3）Cr可以改善高脂肪沉积羔羊机体的能量代谢。

We studied the effects of chromium （Cr） and dietary crude protein （CP） levels and their interactions on perform- ance and plasma metabolites in lambs for 60d. Forty-eight, 9-week-old weaned healthy male lambs （Dorper, ♂ x Small-tail Han sheep, ♀, mean initial body weight = （22. 96 ＋ 2.60） kg） were used in a 2 x 3 factorial arrangement of two phases of diets consisting of three Cr levels from chromium yeast.- 0 （CrO）, 400 （Crl） and 800 （Cr2） g/kg（DM） and two CP levels （157 to 171 g/d per animal （LP） or 189 g/d to 209 g/d per animal （HP））. The results were as follows.- 1） The final weight and average daily gain increased in Crl, Cr2 and HP groups （P〉0. 05） ; 2） Carcass weight, dressing percentage, Iongissmus muscle area, net meat weight, net meat percentage and lost water percentage also increased, while lipid deposition and marbling grade decreased in both Crl and Cr2 groups （P〉0. 05）. Only the intramuscular fat rate was significantly different （P〈0.05） among Crl and Cr2 and CrO HP significantly increased the pelvic fat weight （P〈0.05）, fat thickness of the 10th rib （P〈0.05）, Iongissmus muscle area （P〈 0.01） and intramuscular fat rate （P〈0.05）, but decreased net meat percentage （P〈0.01）. 3） Insulin level and the ratio of insulin level to glucose content decreased in Crl （P〉0.05）. Both Crl and Cr2 had increased plasma nonesterified fatty acid, but decreased triglycerides content, and these two indexes in Cr groups were all significantly different （P〈0.05）. Crl decreased blood urea nitrogen content significantly （P〈0.05）. HP increased plasma nonesterified fatty acid （P〈0.05）, urea nitrogen （P〈0.01） and total protein content （P〈0.01）. In addi- tion, Cr x CP interaction （P〈0.05） was observed in nonesterified fatty acid. These results indicated that. 1） Cr had limited effects on performance and plasma metabolites of lambs than CP; 2） Under these dietary conditions, 0-800 g/kg （DM） Cr additive could improve insulin sensitivity and modulate the metabolism between energy and protein. 3） Cr could accelerate energy metabolism in fattening lambs with higher lipid deposition.