围产期酮病奶牛血液生化指标特征分析

Analysis of blood biochemistry characteristics in dairy cows with ketosis during transition period

试验随机选取产前奶牛29头,跟踪采集产前2周、产前1周、分娩当天及产后3,7,14,21 d的血浆样品,检测血浆相关生化指标变化特征,并记录泌乳量。任意采集时间点血浆β-羟丁酸(BHBA)≥1.2 mmol/L则为酮病组, BHBA<1.2 mmol/L则为对照组。结果显示:随机选取的牛群中酮病发病率为58.6%,酮病主要发生在产后7～14 d;酮病组奶牛产前血液相关生化指标与对照组相比无显著性差异;与对照组相比,酮病组奶牛分娩当天血钾水平升高,血磷水平显著降低;产后3 d酮病组奶牛血浆甘油三酯、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)、BHBA、泌乳量显著高于对照组奶牛;产后7,14,21 d血浆BHBA、非脂化脂肪酸(ENFA)、TC、HDL-C、低密度脂蛋白胆固醇(LDL-C)水平极显著高于对照组奶牛,血糖水平显著低于对照组奶牛。二元Logistic回归分析显示:产后3 d血液TC、HDL-C、K、BHBA、泌乳量与奶牛酮病的发生显著相关。将显著性相关指标利用Logistic回归建模,最终建立了基于血液HDL-C、BHBA、泌乳量的奶牛酮病早期诊断模型,即y=17.95-9.81×HDL-C-2.71×BHBA-0.20×泌乳量,当y<0时存在发生酮病风险,模型早期预测奶牛酮病的准确率82.8%、灵敏度81.3%、特异性84.6%。

The objective of this study was to characterize and predict ketosis in dairy cows during the transition period using blood parameters.Twenty-nine antepartum cows were randomly selected,plasma samples were collected on antepartum week 2 and week 1,and 0,3,7,14 and 21 days postpartum,correlative blood biochemistry indexes were analyzed,and milk yield were recorded on 3,7,14 and 21 days postpartum.Diagnostic marker of ketosis was defined as a plasma hydroxybutyric acid(BHBA) concentration of ≥1.2 mmol/L.As the results,incidence of ketosis was 58.6%,and ketosis occurred mainly during 7 to 14 days postpartum.There was no significant difference in antepartum analyzed blood biochemistry.Compared with control group,dairy cow in ketosis group showed higher plasma kalium and significant lower plasma phosphorus concentrations at day of calving.The concentrations of plasma triglyceride,total cholesterol(TC),high density lipoprotein cholesferol(HDL-C),BHBA and milk yield on 3 day postpartum were significant higher in ketosis group dairy cow than in control group.Significant higher concentrations of plasma BHBA,non-esterified fatty acid(NEFA),TC,HDL-C and low density lipoprotein cholesferol(LDL-C) and lower glucose on 7,14 and 21 days postpartum were detected in ketosis group dairy cow than in control group.With binary logistic regression analysis,potential predictors of TC,HDL-C,plasma kalium,BHBA and milk yield on 3 day postpartum was selected for ketosis in dairy cow.The selected potential predictors were initially included in an overall history model.The results of a multiple logistic regression model showed that plasma concentrations of HDL-C,BHBA and milk yield were ideal predictors of postpartum ketosis in dairy cows,using the model equation:y=17.95-9.81×HDL-C-2.71×BHBA-0.20×milk yield,with a score of<0 considered as an risk for ketosis.The scoring rule had an accuracy of 82.8%,sensitivity of 81.3%and specificity of 84.6%.