饲喂高精料日粮对泌乳期山羊泌乳性能及抗氧化能力的影响

Effects of feeding high concentrate diets on lactation indicators and antioxidant levels in the mammary glands of lactating goats

为了研究长期饲喂高精料日粮对泌乳期山羊泌乳性能和乳腺组织抗氧化能力的影响,实验选用12只健康经产泌乳中期关中奶山羊,随机分为两组,分别饲喂精粗比为35∶65(低精料组,LC,n=6)和65∶35(高精料组,HC,n=6)的日粮。实验期共10周,实验期间采集羊奶与血液;实验结束后采用静脉注射的方法对山羊进行安乐死,随后采集乳腺组织并迅速置于液氮中速冻后保存于-70℃待测。结果显示,HC组山羊乳产量显著高于LC组(P<0.01),同时乳中乳糖,乳蛋白的比例随着泌乳时间的增加而显著升高。与LC组山羊比较,HC组山羊乳腺组织中SREBP1和GLUT1 mRNA表达显著下降(P<0.05);磷酸化AKT1蛋白表达呈下降趋势(P=0.08);除此之外,HC组山羊乳腺组织的总抗氧化能力T-AOC(P=0.06)和GSH酶活均呈下降趋势(P=0.08)。这些结果表明,长期饲喂高精料日粮可降低乳腺组织的抗氧化能力,同时可降低乳中乳脂率以及乳腺组织中SREBP-1和P-AKT的表达。

The effect of feeding high concentrate diets for extended periods on lactation indicators and antioxidant potential in the mammary glands of lactating goats,12 health multiparous guanzhong goats in mid lactation were randomly allocated to two groups; one group receiving diets with low concentrate（concentrate∶ roughage 35∶65） as the LC group（n=6）,and another receiving high concentrate diet（concentrate∶roughage 65∶35） as the HC group（n=6）.The experimental lasted for 12 weeks.At the end of the experiment,goats were slaughtered after overnight fasting.All goats were killed with neck vein injections of xylazine and pentobarbital.Mammary glands and other tissues were sampled and quickly placed in liquid nitrogen and stored at-70 ℃ for gene and protein expressions analysis.The results showed that milk production was significantly increased by feeding a high-concentrate diet and the percentage of milk lactose,protein and fat was significantly increased with lactation time.The expression of sterol regulatory element-binding protein1（SREBP1） and Glucose transport 1（GLUT1） m RNA was significantly decreased（P〈0.05）,and AKT1 protein levels tended to be lower（P=0.08） in the HC group compared to the LC group.The HC diet moderately reduced the activity of T-AOC the enzyme（P=0.06） and GSH（P=0.08）.These results suggest that feeding high concentrate diets reduced the antioxidant ability and significantly decreased the percentage of milk fat as well as down-regulated SREBP1 and p-AKT expression in the mammary glands.