临床型乳房炎对泌乳高峰期奶牛生产性能、体况评分和血清生化指标的影响

Effect of Clinical Mastitis on Productive Performance, Body Condition Score Variation and Serum Biochemical Indexes in Cows at Peak Lactation

本试验旨在研究临床型乳房炎对泌乳高峰期奶牛生产性能、体况评分和血液生化指标的影响。选用来自同一牛场的1~3胎、产后57d、患有临床型乳房炎的8头荷斯坦牛作为研究对象,以另外8头健康奶牛作为对照,记录每天采食量和产奶量,每周进行2次体况评分和乳成分分析,分析其产后9~11周内生产性能和体况变化,于产后第77天晨饲前采集颈静脉血样,检测血清白蛋白、葡萄糖、25-羟基维生素D_3、总钙和β-羟丁酸水平。结果表明,临床型乳房炎患牛产奶量呈线性下降(R^2=0.96),体况评分呈线性升高(R^2=0.88);患病牛干物质采食量、饲料转化率、产奶量、4%乳脂肪校正乳产量、能量校正乳产量、牛奶乳酸含量和冰点显著降低(P<0.05);乳蛋白率、牛奶酪蛋白和游离脂肪酸含量、牛奶体细胞计数显著升高(P<0.05);患病牛血清白蛋白和25-羟基维生素D_3的水平低于生理正常值范围,血清葡萄糖含量超出生理正常值范围;血清葡萄糖水平显著升高(P<0.05),血清白蛋白含量显著降低(P<0.05);患病牛血清β-羟丁酸含量有高于对照组的趋势(P=0.08);两组间其他乳成分含量及产量、总钙的水平无显著差异(P>0.05)。试验结果提示,临床型乳房炎可降低泌乳高峰期奶牛采食量、产奶量、饲料转化率和牛奶品质,提高奶牛体况评分,使血清相关生化指标出现异常。

This study evaluated the effects of clinical mastitis（CM） on productive performance, body condition score（BCS） and serum nutrition metabolism related biochemical indexes of cows at peak lactation. Eight Holstein cows without mastitis and another eight diagnosed with CM were used in this study. All cows were from the same farm and with the same days in milk（57 DIM） and similar parities（1~3）. Dry matter intake and milk yield were recorded daily, BCS and milk compositions were analyzed twice weekly. On 77 DIM, serum was obtained via jugular vein before morning feeding for the analysis of albumin, glucose, 25 hydroxyvitamine D_3 [25（OH）D_3], total calcium and beta hydroxybutyric acid（BHBA） content. The result showed that in cows with CM, BCS increased（R2=0.88） and milk yield decreased（R^2=0.96） linearly by DIM. Dry matter intake, milk yield, 4.0% fat corrected milk yield, energy corrected milk yield, feed conversion rate, milk lactose composition and freezing point depression decreased in cows with CM（P〈0.05）. Composition of milk protein and free fatty acid increased in cows suffered from CM（P〈0.05）. In serum, concentration of albumin and 25（OH）D_3 were below the normal physiological ranges, while composition of glucose was over the physiological limit in cows with CM. Albumin composition was lower and glucose level was higher in serum of cows with CM（P〈0.05）; serum BHBA level tended to be higher in cows suffered from CM（P=0.08）. Significant differences were not observed in other milk profiles and level of total calcium and 25（OH）D_3 between both groups（P〉0.05）. In conclusion, milk quantity and quality were depressed, BCS increased and composition of some serum metabolism related biochemical indexes varied in cows suffered from clinical mastitis at peak lactation.