Department of Animal Science, College of Agriculture and Life Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 2010 Feb;93(2):546-54. doi: 10.3168/jds.2009-2277.
The objectives of this study were to 1) establish cow-level critical thresholds for serum concentrations of nonesterified fatty acids (NEFA) and beta-hydroxybutyrate (BHBA) to predict periparturient diseases [displaced abomasa (DA), clinical ketosis (CK), metritis and retained placenta, or any of these three], and 2) investigate the magnitude of the metabolites' association with these diseases within 30 d in milk. In a prospective cohort study of 100 freestall, total mixed ration-fed herds in the northeastern United States, blood samples were collected from approximately 15 prepartum and 15 different postpartum transition animals in each herd, for a total of 2,758 samples. Serum NEFA concentrations were measured in the prepartum group, and both NEFA and BHBA were measured in the postpartum group. The critical thresholds for NEFA or BHBA were evaluated with receiver operator characteristic analysis for all diseases in both cohorts. The risk ratios (RR) of a disease outcome given NEFA or BHBA concentrations and other covariates were modeled with multivariable regression techniques, accounting for clustering of cows within herds. The NEFA critical threshold that predicted any of the 3 diseases in the prepartum cohort was 0.29mEq/L and in the postpartum cohort was 0.57mEq/L. The critical threshold for serum BHBA in the postpartum cohort was 10mg/dL, which predicted any of the 3 diseases. All RR with NEFA as a predictor of disease were >1.8; however, RR were greatest in animals sampled postpartum (e.g., RR for DA=9.7; 95% CI=4.2 to 22.4. All RR with BHBA as the predictor of disease were >2.3 (e.g., RR for DA=6.9; 95% CI=3.7 to 12.9). Although prepartum NEFA and postpartum BHBA were both significantly associated with development of clinical disease, postpartum serum NEFA concentration was most associated with the risk of developing DA, CK, metritis, or retained placenta during the first 30 d in milk.
1）确定奶牛血清非酯化脂肪酸（NEFA）和β-羟丁酸（BHBA）浓度的临界阈值，以预测围产期疾病（瘤胃酸中毒、酮病、子宫内膜炎和胎衣不下，或其中三种疾病）；2）调查产后 30 天内这些代谢物与这些疾病的关联程度。在美国东北部的一个前瞻性队列研究中，选择了 100 个自由卧床，全混合日粮喂养的牛群，每个牛群采集了大约 15 头产前和 15 头不同的产后过渡期动物的血液样本，总共采集了 2758 个样本。在产前组测量血清 NEFA 浓度，在产后组测量 NEFA 和 BHBA 浓度。用受试者工作特征（ROC）分析评价两个队列中所有疾病的 NEFA 或 BHBA 临界阈值。利用多变量回归技术，考虑到牛在牛群中的聚类，对疾病结局的风险比（RR）进行建模，以 NEFA 或 BHBA 浓度和其他协变量为自变量。在产前组中，预测任何 3 种疾病的 NEFA 临界阈值为 0.29mEq/L；在产后组中，预测任何 3 种疾病的 NEFA 临界阈值为 0.57mEq/L。在产后组中，预测任何 3 种疾病的血清 BHBA 临界阈值为 10mg/dL。所有以 NEFA 为预测疾病指标的 RR 均大于 1.8；然而，在产后采样的动物中 RR 最大（例如，DA 的 RR=9.7；95%置信区间为 4.2 至 22.4）。所有以 BHBA 为预测疾病指标的 RR 均大于 2.3（例如，DA 的 RR=6.9；95%置信区间为 3.7 至 12.9）。虽然产前 NEFA 和产后 BHBA 均与临床疾病的发生显著相关，但产后血清 NEFA 浓度与产后 30 天内发生瘤胃酸中毒、酮病、子宫内膜炎和胎衣不下的风险最相关。
