Laboratory of Theriogenology, Department of Veterinary Medicine, Faculty of Agriculture, Yamaguchi University, Yamaguchi, Japan.
Theriogenology. 2010 Jan 15;73(2):180-9. doi: 10.1016/j.theriogenology.2009.08.011.
The objectives of this study were to derive a useful case definition of delayed resumption of ovarian activity, based on factors associated with reduced fertility, and to assess its impact on subsequent reproductive performance in Holstein cows (Bos taurus). Milk samples were collected twice weekly from 219 cows from four commercial herds, and whole-milk progesterone concentrations were determined with an enzyme-linked immunosorbent assay. Ovulation was considered to have occurred 5 d before the first rise of milk progesterone concentration above the basal level. Survival analysis was used to derive a case definition of delayed resumption of ovarian activity postpartum based on factors that were predictive of reduced pregnancy rate. First postpartum ovulation occurring beyond 35 d postpartum was associated with a reduced pregnancy rate (hazard ratio [HR]=0.50; P<0.001) and was defined as delayed resumption of ovarian activity; overall, 75 (34.9%) cows were in this category. These cows were more likely not to conceive on first artificial insemination (odds ratio [OR]=2.85; P=0.01) and more likely not to become pregnant within 100 d (OR=3.30; P=0.001) and 210 d (OR=3.20; P<0.001) postpartum compared with cows with normal resumption of ovarian activity. Furthermore, 13 (6%) cows that ovulated within 35 d postpartum had a prolonged (> or =14 d) interval between either first and second or second and third luteal phases postpartum. A prolonged interluteal interval was also associated with a reduced pregnancy rate (HR=0.35; P=0.02). Days open (mean +/- SEM) were greater (P=0.0002) in cows with delayed resumption of ovarian activity (213+/-13 d) and in cows with prolonged interluteal interval (220+/-37 d) than in cows with normal resumption of ovarian activity (152+/-9 d). In conclusion, first ovulation occurring beyond 35 d postpartum was defined as delayed resumption of ovarian activity, and the first ovulation occurring within 35 d postpartum but the absence of luteal activity > or =14 d between two consecutive luteal phases was defined as a prolonged interluteal interval; both abnormalities adversely affected the subsequent reproductive performance of Holstein cows.
本研究的目的是基于与生育力降低相关的因素，推导出一个有用的卵巢活动延迟恢复的病例定义，并评估其对荷斯坦奶牛（Bos taurus）随后繁殖性能的影响。从四个商业牛群中采集了 219 头奶牛的每周两次奶样，并使用酶联免疫吸附测定法测定全乳孕酮浓度。排卵被认为发生在第一次牛奶孕酮浓度高于基础水平的前 5 天。生存分析用于根据预测妊娠率降低的因素，推导出产后卵巢活动延迟恢复的病例定义。产后第 35 天以后发生的首次产后排卵与妊娠率降低相关（风险比[HR]=0.50；P<0.001），被定义为卵巢活动延迟恢复；总体而言，有 75 头（34.9%）奶牛属于这一类。这些奶牛首次人工授精时更有可能不怀孕（优势比[OR]=2.85；P=0.01），在产后 100 天（OR=3.30；P=0.001）和 210 天（OR=3.20；P<0.001）内怀孕的可能性也较小，与卵巢活动正常恢复的奶牛相比。此外，有 13 头（6%）在产后 35 天内排卵的奶牛，产后第一次和第二次或第二次和第三次黄体期之间的黄体期间隔延长（>或=14 天）。黄体期间隔延长也与妊娠率降低相关（HR=0.35；P=0.02）。卵巢活动延迟恢复的奶牛（213+/-13 d）和黄体期间隔延长的奶牛（220+/-37 d）的开放天数（平均值+/-SEM）更大（P=0.0002），而卵巢活动正常恢复的奶牛（152+/-9 d）。总之，产后第 35 天以后发生的第一次排卵被定义为卵巢活动延迟恢复，产后第 35 天以内发生的第一次排卵，但两次连续黄体期之间黄体活动>或=14 天的缺失被定义为黄体期间隔延长；这两种异常都对荷斯坦奶牛随后的繁殖性能产生不利影响。
