限饲对断奶前湖羊母羊隐性乳房炎和部分血液生化指标的影响

Effects of restricted feeding on subclinical mastitis and some blood biochemical indices in ewes of pre-weaning Hu sheep

目的:通过断奶前限饲精料,探讨母羊营养和抗氧化等指标变化。方法:选择28只健康的2胎次哺乳期湖羊母羊,随机均分为Ⅰ和Ⅱ组,每只羊哺乳期饲喂精料0.8 kg/d。Ⅰ组羊自分娩第42天开始将每只羊精料降至0.26 kg/d;Ⅱ组羊在分娩第42~45天精料降至0.12 kg/d,第46天始,精料增加至0.26 kg/d。母羊断奶时间为第45天。分娩第41天精料调整前(d1)和第43天(d3)、第45天(d5)、第47天(d7)、第49天(d9),固定每组5只羊,颈静脉采血,抗凝离心和取样,置于-20℃保存,其中d5、d9全群羊空腹采血2 mL,抗凝置于4℃保存。d5收集乳房奶样置于-20℃保存。结果:相较于Ⅱ组,Ⅰ组白细胞总数高(P>0.05),d5的奶中体细胞数低(P>0.05),d7的结合珠蛋白含量高(P<0.05)。血浆Fe含量在组间无显著差异(P>0.05)。在所对应时间点,总蛋白、白蛋白、尿素氮和尿酸浓度,Ⅰ和Ⅱ组之间差异均不显著(P>0.05)。d1、d3和d52组葡萄糖、总胆固醇和甘油三酯指标均渐降低,尿素氮含量、总抗氧化能力呈增高趋势。Ⅱ组d5和d9的总抗氧化能力均低于Ⅰ组(P<0.01),Ⅱ组羊尿酸量持续增高。d92组甘油三酯量差异显著(P<0.05)。不同于Ⅰ组,Ⅱ组谷胱甘肽过氧化物酶活性递减。Ⅰ组d7和Ⅱ组d5的过氧化氢酶活性最高,其中Ⅱ组d5的酶活性高于Ⅰ组(P<0.05)。Ⅱ组d5丙二醛含量低于Ⅰ组(P<0.05)。结论:母羊在断奶前限饲精料未诱发临床乳房炎,相比过度限饲,精料降至0.26 kg/d的母羊在停止泌乳后的营养代谢能够避免高尿酸性抗氧化反应。

Objective:Ewes'impact on nutritional and antioxidant parameters was discussed by limiting concentrate feeding before weaning.Methods:A total of 28 healthy two-parity Hu sheep were randomly divided into groupⅠandⅡ.Before the experiment,the feeding conditions were consistent.Each sheep was fed with 0.8 kg/d concentrate feed and free consumption of roughage.During the experimental period,the daily concentrate feed of each sheep of group I was decreased to 0.26 kg/d on the 42nd day of delivery,that of group II was reduced to 0.12 kg/d on the 42nd to 45th day of delivery,and that was increased to 0.26 kg/d from the 46th.All ewes were weaned on the 45th day.On the 41st,43rd,45th,47th,49th day of delivery(d1,d3,d5,d7,d9),5 identical sheep in each group were used for jugular vein blood collection,anticoagulation,centrifugation,and the plasma was stored at-20℃.All sheep were collected 2 mL of fasting blood on d5 and d9.The plasma was stored at 4℃.The milk was collected at d5 and stored at-20℃.Results:The white blood cell count of groupⅠwas higher than that of groupⅡ,and the somatic cell count on d5 was lower than that of groupⅡ,Haptoglobin in groupⅠwas higher than that in groupⅡon d7(P<0.05).No significant difference was found in serum Fe between groupⅠandⅡ(P>0.05).The concentrations of total protein,albumin,urea nitrogen,and uric acid were not significantly different between groupⅠand groupⅡ,respectively,at the corresponding time points(P>0.05).On d1,d3,and d5,the indexes of glucose,total cholesterol,and triglyceride of sheep were gradually decreased.On the contrary,the urea nitrogen content and total antioxidant capacity were increased.The total antioxidant capacity on d5 and d9 of groupⅡwas lower than that in groupⅠ(P<0.01),and the uric acid in groupⅡwas gradually increased.In d9,the triglyceride levels of the two groups were significantly different(P<0.05).Different from groupⅠ,the glutathione peroxidase activity decreased in groupⅡ.The catalase activity on d5 in groupⅠandⅡwas the highest,and the enzyme activity of d9 in groupⅡwas higher than that in groupⅠ(P<0.05).The enzyme activity of d5 in malondialdehyde groupⅡwas lower than in groupⅠ(P<0.05).Conclusion:The reduction of concentrate feed before weaning did not induce clinical mastitis.The nutrient metabolism of ewe with concentrate decreased to 0.26 kg/d could avoided the high uric acid antioxidant reaction compared with over-restricted feeding after stopping lactation.