Abstract：
This study describes the association of non-esterified fatty acids (NEFA) and calcium concentrations at calving with early lactation disease, reproductive performance and culling in 646 dairy cows from 13 commercial grazing dairy herds in Uruguay. During one year, health events were recorded from calving to 30 days in milk (DIM). The first author visited each farm every 20 days. During each visit, body condition score (BCS) was recorded (scale 1-5), defining BCS < 3 as suboptimal and BCS > 3 as optimal, and a blood sample was taken from cows between 0 and 4 DIM for metabolite determination. To evaluate the association between health events (i.e., retained placenta-metritis and clinical mastitis) and risk factors (parity, BCS, high NEFA (> 0.6 mmol/L) and subclinical hypocalcemia (SCH) (< 2.10 mM)) data were analysed using multivariable logistic regression models. To evaluate the association of health events and risk factors with reproductive performance and culling, data were analysed using Cox proportional hazard regression models. A risk factor and an outcome of interest were assumed to be associated at P < 0.05 and a tendency to be associated was defined at P < 0.10. Overall, 47 % (n = 303) of the cows showed elevated NEFA concentration and 77 % (n = 499) had SCH. In addition, 21.5 % (n = 139) of the cows recorded at least one clinical disease. Cumulative incidence was 17 % (n = 109) for clinical mastitis, 4.2 % (n = 27) for retained placenta (RP)-metritis and 1.4 % (n = 7) for lameness. Clinical mastitis was associated with parity, with lower odds in primiparous (PP) cows (OR = 0.42, P < 0.01). Cows in an optimal BCS also tended to have lower odds (OR = 0.66, P = 0.07). Moreover, high NEFA and SCH cows had higher odds of CM (OR = 4.5, P = 0.01 and OR = 1.75, P = 0.04, respectively). Retained placenta-metritis tended to be associated with high NEFA concentration (OR = 2.2, P = 0.06). Primiparous cows with suboptimal BCS showed an increased first insemination rate (HR = 2.34; P < 0.01). The risk of culling was lower in PP cows (HR = 0.19; P < 0.01) and in cows with optimal BCS and low NEFA concentration (HR = 0.38; P = 0.03). Our data show that metabolic challenge (defined as peripartum suboptimal BCS, high NEFA or SCH) is associated with increased odds of clinical mastitis and RP-metritis, decreased probability of insemination and increased hazard of culling. Under grazing conditions, we suggest that farm management to improve the metabolic adaptation to lactation represents an opportunity to enhance cow performance in terms of health, fertility and longevity.
摘要：
这项研究描述了产卵时非酯化脂肪酸（NEFA）和钙浓度与早期泌乳疾病的关系。乌拉圭13个商业放牧奶牛群的646头奶牛的繁殖性能和扑杀。在一年中,记录了从产牛到牛奶（DIM）中30天的健康事件。第一作者每20天访问每个农场。每次访问期间,记录身体状况评分（BCS）（1-5级），将BCS<3定义为次优，将BCS>3定义为最优，并且从0和4个DIM之间的母牛采集血液样品用于代谢物测定。评估健康事件之间的关联(即，保留的胎盘子宫炎和临床乳腺炎)和危险因素(产次，BCS,使用多变量逻辑回归模型分析高NEFA(>0.6mmol/L)和亚临床低钙血症(SCH)(<2.10mM)数据.评估健康事件和危险因素与繁殖性能和扑杀的关系，数据采用Cox比例风险回归模型进行分析.在P<0.05时，假定风险因素和目标结果相关，在P<0.10时定义为相关趋势。总的来说,47%(n=303)的母牛表现出升高的NEFA浓度,77%(n=499)具有SCH。此外,21.5%(n=139)的奶牛记录至少一种临床疾病。临床乳腺炎的累积发病率为17%(n=109)，保留胎盘（RP）-子宫炎为4.2％（n=27），跛行为1.4％（n=7）。临床乳腺炎与产次有关，初产（PP）奶牛的几率较低（OR=0.42，P<0.01）。处于最佳BCS的奶牛也倾向于具有较低的几率(OR=0.66,P=0.07)。此外，高NEFA和SCH奶牛的CM几率较高（分别为OR=4.5，P=0.01和OR=1.75，P=0.04）。保留的胎盘子宫炎倾向于与高NEFA浓度相关（OR=2.2，P=0.06）。BCS次优的初产母牛的首次授精率增加（HR=2.34；P<0.01）。PP母牛（HR=0.19；P<0.01）和最佳BCS和低NEFA浓度的母牛（HR=0.38；P=0.03）的剔除风险较低。我们的数据表明，代谢挑战(定义为围产期次优BCS，高NEFA或SCH）与临床乳腺炎和RP-子宫炎的几率增加有关，授精概率降低，剔除风险增加。在放牧条件下,我们建议，农场管理，以提高代谢适应泌乳代表了一个机会，以提高奶牛的性能，在健康方面，生育和长寿。
