Kawashima Chiho, Kaneko Etsushi, Amaya Montoya Carlos, Matsui Motozumi, Yamagishi Norio, Matsunaga Nobuyoshi, Ishii Mitsuo, Kida Katsuya, Miyake Yoh-Ichi, Miyamoto Akio
Graduate School of Animal and Food Hygiene, Obihiro University of Agriculture and Veterinary Medicine, Japan.
J Reprod Dev. 2006 Aug;52(4):479-86. doi: 10.1262/jrd.18003. Epub 2006 Apr 21.
The aim of this study was to investigate the relationship between the first ovulation within 3 weeks postpartum and subsequent ovarian cycles and fertility in high producing dairy cattle in Hokkaido, Japan. In Experiment 1, 110 cows (44 primiparous and 66 multiparous) were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent ovarian cycles. Milk samples were collected twice weekly from 7 to 100 days postpartum. The first ovulation was identified by an increase in milk progesterone (P4) to more than 1 ng/ml within 3 weeks postpartum. The numbers of cows showing ovulation and anovulation within 3 weeks postpartum were 31 (70.5%) and 13 (29.5%) in the primiparous cows and 35 (53.0%) and 31 (47.0%) in the multiparous cows, respectively. The patterns of ovarian resumption after calving were classified into two types (normal ovarian cycles and abnormal ovarian cycles) on the basis of milk P4 concentrations. Initiation of normal ovarian function in cows ovulated within 3 weeks postpartum occurred earlier than in anovulated cows regardless of the number of calvings (primiparous, 27.8 days vs. 44.4 days; multiparous, 30.6 days vs. 55.7 days; P<0.01). Out of the multiparous cows that ovulated within 3 weeks postpartum, initiation of normal ovarian function followed by a normal luteal phase was earlier than when it was followed by an abnormal luteal phase (25.5 days vs. 40.4 days; P<0.05). Milk P4 concentrations after the first ovulation were lower than those after the second ovulation in both the primiparous and multiparous cows (P<0.05). In Experiment 2, 22 multiparous cows were used to determine the effects of the first ovulation within 3 weeks postpartum on subsequent fertility. Blood samples were collected once a week from 0 to 3 weeks postpartum. The interval from parturition to first service in ovulated cows was shorter than in anovulated cows (68.4 days vs. 94.8 days; P<0.05). The conception rate by 100 days after calving tended to be higher in ovulated cows than in anovulated cows (50.0% vs. 16.7%, P=0.09). In conclusion, our data strongly suggests that ovulation within 3 weeks postpartum is a crucial phenomenon for subsequent resumption of ovarian function and conception, and thus it can be used as an index of subsequent reproductive performance.
本研究旨在调查日本北海道高产奶牛产后3周内首次排卵与随后的卵巢周期及繁殖力之间的关系。在实验1中，使用110头奶牛（44头初产牛和66头经产牛）来确定产后3周内首次排卵对随后卵巢周期的影响。在产后7至100天，每周采集两次牛奶样本。首次排卵通过产后3周内牛奶孕酮（P4）升高至超过1 ng/ml来确定。初产牛产后3周内排卵和不排卵的奶牛数量分别为31头（70.5%）和13头（29.5%），经产牛分别为35头（53.0%）和31头（47.0%）。根据牛奶P4浓度，产犊后卵巢恢复模式分为两种类型（正常卵巢周期和异常卵巢周期）。产后3周内排卵的奶牛正常卵巢功能的起始时间早于未排卵的奶牛，无论产犊次数如何（初产牛，27.8天对44.4天；经产牛，30.6天对55.7天；P<0.01）。在产后3周内排卵的经产牛中，正常卵巢功能起始后接着正常黄体期的时间早于接着异常黄体期的时间（25.5天对40.4天；P<0.05）。初产牛和经产牛首次排卵后的牛奶P4浓度均低于第二次排卵后的浓度（P<0.05）。在实验2中，使用22头经产牛来确定产后3周内首次排卵对随后繁殖力的影响。在产后0至3周，每周采集一次血样。排卵奶牛从分娩到首次配种的间隔短于未排卵奶牛（68.4天对94.8天；P<0.05）。产犊后100天的受孕率排卵奶牛倾向于高于未排卵奶牛（50.0%对16.7%，P=0.09）。总之，我们的数据强烈表明，产后3周内排卵是随后卵巢功能恢复和受孕的关键现象，因此它可作为随后繁殖性能的一个指标。
