Department of Population Medicine, University of Guelph, Ontario, Canada, N1G 2W1; Animal Welfare Program, University of British Columbia, BC, Canada, V6T 1Z4.
J Dairy Sci. 2011 Oct;94(10):4897-903. doi: 10.3168/jds.2010-4075.
The objective of this observational field study was to validate the relationship of serum concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and calcium with disease in early lactation across different management systems. Fifty-five Holstein freestall dairy herds located across the United States and Canada were selected and visited weekly for blood sample collection from 2,365 cows. Only diseases that were consistently recorded across herds and blood samples collected before the disease occurred were considered. Metabolite concentrations in serum in wk -1 relative to calving were considered as predictors of retained placenta (RP) and metritis, and metabolite concentrations in serum in wk -1 and wk +1 relative to calving were considered as predictors of displaced abomasum (DA). For each disease, each metabolite, and week of sampling in the case of DA, a critical threshold was calculated based on the highest combined sensitivity and specificity and used to categorize the serum concentrations into high and low risk categories. Multivariable logistic regression models were built for each disease of interest and week of sampling, considering cow as the experimental unit and herd as a random effect. Cows with precalving serum NEFA concentrations ≥ 0.3 mEq/L were more likely to develop RP [odds ratio (OR) = 1.8; 95% confidence interval (CI) = 1.3 to 2.6] and metritis (OR = 1.8; 95% CI = 1.5 to 2.9) after calving than cows with lower NEFA concentrations. Precalving NEFA ≥ 0.5 mEq/L (OR = 2.4; 95% CI = 1.5 to 3.7), postcalving NEFA ≥ 1.0 mEq/L (OR = 2.7; 95% CI = 1.7 to 4.4), and postcalving calcium ≤ 2.2 mmol/L (OR = 3.1; 95% CI = 1.9 to 5.0) were associated with subsequent risk of DA. In conclusion, elevated serum NEFA concentrations within 1 wk before calving were associated with increased risk of RP, metritis, and DA after calving. Serum NEFA and calcium concentrations in the 2 wk around calving in combination were associated with the risk of DA.
本观察性现场研究的目的是验证血清中非酯化脂肪酸（NEFA）、β-羟丁酸（BHBA）和钙浓度与不同管理体系下泌乳早期疾病的关系。从美国和加拿大各地选择了 55 个荷斯坦奶牛自由 stalls 牧场，并每周进行一次访问，以从 2365 头奶牛中采集血液样本。仅考虑在牧场中始终记录的疾病和在疾病发生之前采集的血液样本。将产犊前每周血清中的代谢物浓度作为预测胎衣不下（RP）和子宫炎的指标，将产犊前每周和产犊后每周血清中的代谢物浓度作为预测真胃移位（DA）的指标。对于每个疾病、每种代谢物和 DA 的采样周，根据最高的综合敏感性和特异性计算临界阈值，并将血清浓度分类为高风险和低风险类别。对于每个感兴趣的疾病和采样周，考虑到牛作为实验单位和牧场作为随机效应，建立了多变量逻辑回归模型。与血清 NEFA 浓度较低的奶牛相比，产前血清 NEFA 浓度≥0.3 mEq/L 的奶牛在产犊后更有可能发生 RP[比值比（OR）=1.8；95%置信区间（CI）=1.3 至 2.6]和子宫炎（OR=1.8；95%CI=1.5 至 2.9）。产前 NEFA≥0.5 mEq/L（OR=2.4；95%CI=1.5 至 3.7）、产后 NEFA≥1.0 mEq/L（OR=2.7；95%CI=1.7 至 4.4）和产后钙≤2.2mmol/L（OR=3.1；95%CI=1.9 至 5.0）与随后发生 DA 的风险相关。总之，产前 1 周内血清 NEFA 浓度升高与产犊后 RP、子宫炎和 DA 的风险增加有关。产犊前后 2 周内的血清 NEFA 和钙浓度与 DA 的风险有关。
