【作者】 苏文伟；

【导师】 何宝祥；

【作者基本信息】 广西大学 ， 临床兽医学， 2008， 硕士

【摘要】 在使用高能量饲粮体制的奶牛场中,亚急性瘤胃酸中毒(SARA)发生较为普遍,导致了奶牛业的重大经济损失。本试验通过了解奶牛分娩前后乳酸等血液生化指标、牛奶成分等动态变化特征及动态相关性,揭示它们与奶牛SARA相关的变化规律,筛选出可供监测此病的指标,为建立经济实用的SARA监控体系奠定研究基础。本试验分两部分进行,试验一:随机挑选无明显临床差异的19头奶牛,在分娩前7天(-7天)、分娩当天(0天)、7天、14天、21天、28天、35天、42天、49天、56天,进行血浆乳酸、游离脂肪酸、钙磷镁钾的动态检测。试验二:随机挑选无明显临床差异的奶牛18头,于分娩前7天(-7天)、分娩当天(0天)、7天、14天、21天、28天、35天、42天、49夭、56天、63天测定血浆乳酸、内毒素、游离脂肪酸、血镁以及牛奶的乳脂、非脂乳固体、蛋白质含量。在上述试验中均将乳酸含量高且有SARA迹象的奶牛分配到患病组,其余的分配到对照组。试验结果表明:1.患病奶牛的血浆指标异常升高的时间段:乳酸在-7天～14天及35～49天,游离脂肪酸、内毒素在0天～14天,血钙在0天～7天;异常降低的时间段:血磷在7天～21天;血镁血钾在正常水平内波动。2.患病奶牛的牛奶成分含量异常降低的时间段:乳脂在14～28天;非脂乳固体、蛋白质在整个试验期没有异常的变化。3.患病奶牛的乳酸分别与游离脂肪酸、血钙有极高的正相关性,牛奶蛋白质与非脂乳固体存在着极显著的正相关,游离脂肪酸则与血磷存在显著的负相关性。4.患病奶牛乳酸、游离脂肪酸、乳脂异常变化的时间较长,瘤胃功能调节缓慢且不稳定。5.奶牛SARA大致发生在分娩前后一周内及分娩后5～7周内。乳酸、游离脂肪酸及乳脂是奶牛SARA监控的良好指标,血浆内毒素、钙磷镁钾以及牛奶非脂乳固体、蛋白质则有辅助奶牛SARA诊断的意义。更多还原

【Abstract】 The subacute rumen acidosis(SARA)have become a prevalent problem in the dairy herds exposed on a high amount of ruminally-available carbohydrate.This will result in the important economic loss associated with SARA in dairy herds.The objective of this study was(1)to understand the dynamic changes and correlations between blood lactic acid and other biochemical parameters and milk composition in dairy cows,(2)to demonstrate the regularity of the SARA development and(3)to choose reliable monitoring parameters which could conduce to the set up of the effective system of predicting and monitoring SARA in dairy herds.The study was divided into two parts:In the first part 19 dairy cows with non-clinical difference were randomly chosen;plasma lactic acid,non-esterified fatty acids, calcium,phosphonium,magnesium and potassium were dynamically determined,respectively at -7d(7d prepartum),0d(parturition day),7d,14d, 21d,28d,35d,42d,49d,56d postpartum.In the second part 18 dairy cows with non-clinical difference were randomly chosen,plasma lactic acid, endotoxin,non-esterified fatty acids and magnesium,and milk fat,milk solids-not-fat,protein content were determined at-7d(7d prepartum), 0d(parturition day),7d,14d,21d,28d,35d,42d,49d,56d,63d postpartum, respectively.In above two experiments the cows with high plasma level of lactic acid and relative signs of SARA were allocated to affected group,the remainder to control group.The following results were observed:1.The time for plasma parameters to increase to the abnormality in affected group:lactic acid in -7d～14d and 35d～49d,non-esterified fatty acids and endotoxin in 0d～ 14d,calcium in 0d～7d;the time for plasma parameters to decrease to the abnormality:phosphonium in 7d～21d.Normal fluctuations were observed in plasma magnesium and potassium.2.The time for milk composition content to decrease to the abnormality in affected group:milk fat in 14d～28d.The milk solids-not-fat and protein content abnormality were not observed during the experimental time.3.There were high positive correlations between plasma lactic acid and non-esterified fatty acids and between plasma lactic acid and calcium in affected group,respectively.Milk protein and milk solids-not-fat had positive correlation,but non-esterified fatty acids had negative correlation with phosphonium.4.The time for plasma lactic acid,non-esterified fatty acids and milk fat abnormality changing was longer,rumen function’s modulation was slow and a rapid fluctuation was observed in affected dairy cows.5. SARA in dairy cows occurs approximately within 1 week prepartum,and 1, 5～7 weeks postpartum.Plasma lactic acid,non-esterified fatty acids and milk fat could be considered to monitor SARA efficiently,but endotoxin, calcium,phosphonium,magnesium and potassium could serve as auxiliary diagnostic methods of SARA in dairy cows.更多还原