Irikura N, Uematsu M, Kitahara G, Osawa T, Sasaki Y
Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
Miyazaki Agricultural Mutual Aid Association, Miyazaki, Japan.
Reprod Domest Anim. 2018 Feb;53(1):34-39. doi: 10.1111/rda.13049. Epub 2017 Aug 12.
The conception rate (CR) of Japanese Black cattle has been decreasing since 1990. The objectives of this study were to compare CR by artificial insemination (AI) number, and to assess the interaction between AI number and possible factors related to CR in Japanese Black cattle. Records of 11,182 AI records for 6,741 heifers and 61,302 AI records for 13,139 cows on 977 farms were analysed. The average CR of heifers was 47.0%, and CR at the first, second and third AI was higher than at the fourth or subsequent AI (p < 0.05). The average CR of cows was 47.8%, and their CR at first and second AI was higher than the fourth or subsequent AI (p < 0.05). Data analysis with CR as the dependent variable revealed significant interactions of AI number with interval from calving to first AI and AI season. Cows first serviced at ≤48 days post-partum had lower CR than those at ≥90 days at first AI (p < 0.05), but the interval from calving to first AI did not affect CR at second AI. Cows serviced in the autumn had a higher CR at first AI than those serviced in the spring and winter (p < 0.05); however, there was no seasonal difference in CR at the second AI. In summary, CR began to decrease from the fourth AI in heifers and the third AI in cows. The AI season and the interval from calving to first AI significantly affected CR only at the first AI.
自1990年以来，日本黑牛的受孕率（CR）一直在下降。本研究的目的是比较人工授精（AI）次数对受孕率的影响，并评估AI次数与日本黑牛受孕率相关潜在因素之间的相互作用。分析了977个农场中6741头小母牛的11182条AI记录以及13139头母牛的61302条AI记录。小母牛的平均受孕率为47.0%，第一次、第二次和第三次AI时的受孕率高于第四次及以后AI时的受孕率（p<0.05）。母牛的平均受孕率为47.8%，第一次和第二次AI时的受孕率高于第四次及以后AI时的受孕率（p<0.05）。以受孕率为因变量的数据分析显示，AI次数与产犊至首次AI的间隔时间以及AI季节之间存在显著交互作用。产后≤48天首次接受人工授精的母牛受孕率低于产后≥90天首次接受人工授精的母牛（p<0.05），但产犊至首次AI的间隔时间对第二次AI时的受孕率没有影响。秋季接受人工授精的母牛首次AI时的受孕率高于春季和冬季接受人工授精的母牛（p<0.05）；然而，第二次AI时的受孕率没有季节性差异。总之，小母牛在第四次AI、母牛在第三次AI后受孕率开始下降。AI季节和产犊至首次AI的间隔时间仅在首次AI时对受孕率有显著影响。
