Abstract：
We retrospectively analyzed the effects of dry period length (DPL) on milk yield and postpartum health using 152 commercial dairy farm data, including 46,228 dairy cows in Hokkaido, Japan, and examined the optimal DPL. The DPL was divided into eight categories: ≤25, 26-35, 36-45, 46-55, 56-65 (reference), 66-75, 76-85, and ≥86 d. The total milk yields (the sum of milk yield during the 55 d before and the 305 d milk yield after calving) of cows with DPL of ≤55 d did not differ from the reference group. Cows with DPL of ≤55 d had lower odds ratios (OR) of a displaced abomasum (DA), ketosis, milk fever (MF), and abnormal milk fat-to-protein ratio but had higher puerperal fever (PF) and stillbirth ORs than the reference group. Cows with a DPL of 46-55 d had the lowest PF and stillbirth ORs among the short DPL categories. The extremely short (≤25 d) and long (≥86 d) DPL increased the ORs of mastitis and abnormal liner score of somatic cell counts (SCCs) compared with the reference group. We conclude that shortening DPL can reduce postpartum health problems without reducing milk yield and that the optimal DPL is 46-55 d.
摘要：
我们使用152个商业奶牛场数据回顾性分析了干旱期长度（DPL）对牛奶产量和产后健康的影响，包括北海道46,228头奶牛,Japan,并检查了最佳DPL。DPL分为八类：≤25、26-35、36-45、46-55、56-65（参考），66-75、76-85和≥86d。DPL≤55d的奶牛的总产奶量（产奶前55d期间的产奶量和产奶后305d的产奶量之和）与参考组没有差异。DPL≤55d的奶牛移位皱胃（DA）的比值比（OR）较低，酮症,牛奶热（MF），乳脂蛋白比异常，但产褥热（PF）和死胎ORs高于参照组。在短DPL类别中，DPL为46-55d的奶牛的PF和死胎OR最低。与参考组相比，极短（≤25d）和长（≥86d）的DPL增加了乳腺炎的OR和体细胞计数（SCC）的异常衬里评分。我们得出的结论是，缩短DPL可以在不降低产奶量的情况下减少产后健康问题，并且最佳DPL为46-55d。
