van Straten M, Friger M, Shpigel N Y
Hachaklait, Mutual Society for Veterinary Services, Caesarea Industrial Park, Israel.
J Dairy Sci. 2009 Sep;92(9):4386-94. doi: 10.3168/jds.2009-2204.
The objective of this study was to determine associations between body weight (BW) and body condition score (BCS) variables indicating a more severe negative energy balance in early lactation and events of somatic cell counts (SCC) >250,000 cells/mL and SCC >400,000 cells/mL in dairy cows. We studied lactations from 634 primiparous and 1,086 multiparous Israeli Holstein dairy cows originating from 7 commercial dairy farms. Generalized mixed models with a random herd effect were used to quantify the effects of BW and BCS variables in early lactation on events of elevated SCC. Data were analyzed using 2 different approaches. In the first approach, only first events in a lactation were taken into account, whereas in the second approach, all events in a lactation were analyzed and repeated events from the same cow were accounted for. Although no associations were found between the different BW and BCS variables and first events of elevated SCC, associations were present between these variables and events of elevated SCC when all events were analyzed. The cumulative incidence of a lactation with multiple events of SCC >250,000 cells/mL was 8.8 and 27.7% for primiparous and multiparous cows, respectively. The odds of an event of SCC >250,000 cells/mL were 25% greater for cows belonging to the upper quartile in relative BW loss from calving to nadir BW (loss >12.3, 15.0, and 15.7% for first-, second-, and third- parity and greater cows, respectively) compared with cows losing less relative BW. Odds of an event were 44% greater for cows with ketosis when compared with cows without. The cumulative incidence of a lactation with multiple events of SCC >400,000 cells/mL was 4.1 and 14.3% for primiparous and multiparous cows, respectively. The odds of an event of SCC >400,000 cells/mL were 43% greater for cows belonging to the upper quartile in relative BW loss from calving to nadir BW compared with cows losing less relative BW. Odds of an event were 33% greater for cows with ketosis when compared with cows without. Assuming that extreme BW loss and ketosis in early lactation indicate a more severe negative energy balance, our findings support the hypothesis that greater negative energy balance in early lactation predisposes dairy cows to udder inflammation. Considering the fact that many of the events were recurring, we stress the importance of including all events in the analysis and postulate the possibility of long-term detrimental effects of negative energy balance on udder health.
本研究的目的是确定体重（BW）和体况评分（BCS）变量之间的关联，这些变量表明早期泌乳期能量负平衡更为严重，以及奶牛体细胞计数（SCC）>250,000个细胞/毫升和SCC>400,000个细胞/毫升的情况。我们研究了来自7个商业奶牛场的634头初产和1086头经产以色列荷斯坦奶牛的泌乳情况。采用具有随机牛群效应的广义混合模型来量化早期泌乳期BW和BCS变量对SCC升高情况的影响。数据使用两种不同方法进行分析。在第一种方法中，仅考虑泌乳期的首次事件，而在第二种方法中，分析泌乳期的所有事件并考虑同一头牛的重复事件。虽然在不同的BW和BCS变量与SCC升高的首次事件之间未发现关联，但在分析所有事件时，这些变量与SCC升高的事件之间存在关联。初产和经产奶牛中，SCC>250,000个细胞/毫升的多个事件的泌乳累积发生率分别为8.8%和27.7%。与相对BW损失较少的奶牛相比，从产犊到最低BW相对BW损失处于上四分位数的奶牛（初产、二胎和三胎及以上奶牛的损失分别>12.3%、15.0%和15.7%），SCC>250,000个细胞/毫升事件的发生几率高25%。与没有酮病的奶牛相比，患有酮病的奶牛事件发生几率高44%。初产和经产奶牛中，SCC>400,000个细胞/毫升的多个事件的泌乳累积发生率分别为4.1%和14.3%。与相对BW损失较少的奶牛相比，从产犊到最低BW相对BW损失处于上四分位数的奶牛，SCC>400,000个细胞/毫升事件的发生几率高43%。与没有酮病的奶牛相比，患有酮病的奶牛事件发生几率高33%。假设早期泌乳期的极端BW损失和酮病表明能量负平衡更为严重，我们的研究结果支持以下假设：早期泌乳期更大的能量负平衡使奶牛易患乳房炎。考虑到许多事件是反复发生的，我们强调在分析中纳入所有事件的重要性，并推测能量负平衡对乳房健康可能存在长期有害影响。
