Veterinary Medicine Teaching and Research Center, 18830 Road 112, Tulare, CA 93274.
INRA, Université Clermont Auvergne, VetAgro Sup, UMR1213 Herbivores, F-63122 Saint-Genes-Champanelle, France.
J Dairy Sci. 2019 Sep;102(9):8367-8375. doi: 10.3168/jds.2018-16180. Epub 2019 Jul 10.
The objective of our study was to identify cow-level factors associated with subclinical hypocalcemia at calving (SCH) in multiparous Jersey cows. A total of 598 Jersey and 218 Jersey × Holstein crossbreed cows from 2 commercial dairy herds were enrolled in a retrospective cohort study. Blood samples to determine total Ca concentration were collected from the coccygeal vessels at 3 h 19 min (±2 h 33 min) after calving. We used 2 serum Ca concentration thresholds to define SCH: <2.00 mmol/L (SCH-2.00) and <2.12 mmol/L (SCH-2.12). We evaluated the association of cow-level factors with SCH with multivariable Poisson regression models. Variables evaluated for association with SCH were herd; parity (2, 3, and ≥4); breed; previous lactation length and 305-d mature-equivalent milk yield; previous lactation first test milk yield and last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; calving ease; and calf sex for singletons. We categorized continuous variables into quartiles (≤25th percentile, interquartile range and ≥75th percentile). The prevalence of SCH among Jersey cows was 40 (SCH-2.00) and 64% (SCH-2.12). Jersey cows of higher parity had greater risk of SCH-2.00 and SCH-2.12. The risk of SCH-2.12 was higher after birthing male calves. We also found a tendency for previous lactation length and previous lactation 305-d mature-equivalent milk yield effect to affect risk of SCH-2.12. The risk of SCH-2.12 was lower for cows that had a previous lactation length shorter than the 25th percentile compared with cows that had a previous lactation length within the interquartile range. The risk of SCH-2.12 was higher for cows that had a previous lactation 305-d mature-equivalent milk yield below the 25th percentile compared with cows that had a previous lactation 305-d mature-equivalent milk yield above the 75th percentile. Also, Jersey × Holstein crossbreed was associated with increased risk of SCH-2.00. In the multivariable analysis, we observed no association between SCH and previous lactation first test milk yield; last test somatic cell count; lengths of calving interval, gestation, dry, and close-up periods; body condition and locomotion scores at calving; and calving ease. Our study identified parity, breed, calf sex, previous lactation length, and previous lactation 305-d mature-equivalent milk yield as cow-level factors associated with SCH in multiparous Jersey cows.
我们的研究目的是确定与经产荷斯坦奶牛亚临床低钙血症（SCH）相关的奶牛水平因素。共有来自 2 个商业奶牛场的 598 头荷斯坦奶牛和 218 头荷斯坦奶牛杂交牛被纳入回顾性队列研究。在产后 3 小时 19 分钟（±2 小时 33 分钟）时，从尾骨血管采集血液样本以确定总钙浓度。我们使用 2 个血清钙浓度阈值来定义 SCH：<2.00mmol/L（SCH-2.00）和<2.12mmol/L（SCH-2.12）。我们使用多变量泊松回归模型评估与 SCH 相关的奶牛水平因素。评估与 SCH 相关的因素有：牛群；胎次（2、3 和≥4）；品种；上一个泌乳期长度和 305 天成熟当量产奶量；上一个泌乳期第一次产奶量和最后一次体细胞计数；产犊间隔、妊娠、干奶和围产期长度；产犊时的体况和运动评分；产犊难易程度；单胎产仔的性别。我们将连续变量分为四分位数（<=第 25 百分位数、四分位间距和>=第 75 百分位数）。荷斯坦奶牛 SCH 的患病率为 40%（SCH-2.00）和 64%（SCH-2.12）。较高胎次的荷斯坦奶牛发生 SCH-2.00 和 SCH-2.12 的风险更大。产公犊后发生 SCH-2.12 的风险更高。我们还发现上一个泌乳期长度和上一个泌乳期 305 天成熟当量产奶量的趋势对影响 SCH-2.12 的风险有影响。与上一个泌乳期处于四分位间距内的奶牛相比，上一个泌乳期长度低于第 25 百分位数的奶牛发生 SCH-2.12 的风险较低。与上一个泌乳期 305 天成熟当量产奶量高于第 75 百分位数的奶牛相比，上一个泌乳期 305 天成熟当量产奶量低于第 25 百分位数的奶牛发生 SCH-2.12 的风险更高。此外，荷斯坦奶牛杂交种与 SCH-2.00 风险增加有关。在多变量分析中，我们没有观察到 SCH 与上一个泌乳期第一次产奶量、最后一次体细胞计数、产犊间隔、妊娠、干奶和围产期长度、产犊时的体况和运动评分以及产犊难易程度之间存在关联。我们的研究确定了胎次、品种、犊牛性别、上一个泌乳期长度和上一个泌乳期 305 天成熟当量产奶量是与经产荷斯坦奶牛 SCH 相关的奶牛水平因素。
