Holm D E, Thompson P N, Irons P C
Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
Theriogenology. 2008 Dec;70(9):1507-15. doi: 10.1016/j.theriogenology.2008.06.098. Epub 2008 Aug 8.
We estimated the effect of estrus synchronization on reproduction, production and economic outcomes in 272 beef heifers randomly allocated to a synchronized Test group or an unsynchronized Control group. The Test group received AI upon estrus detection for 6 days followed by PGF2 treatment of heifers that had not shown estrus by day 6 (PGF/6). In both groups AI was continued for 50 days, followed by a 42-day bull breeding period. Heifers were followed through their second breeding season and until they had weaned their first calves. Synchronization resulted in a reduction in median days to first insemination (8 vs. 11 in the Test and Control groups, respectively, P<0.01) and median days to calving of calves born to AI (14 vs. 20, P=0.04). There was no significant difference in pregnancy rate to the AI period (60.0% vs. 51.8%, P=0.18), final pregnancy rate (82.2% vs. 83.2%, P=0.87) or pregnancy rate to the subsequent breeding season (96.0% vs. 95.0%, P=1.00). Although mean calf weaning mass was not significantly different (207.0 kg vs. 201.4 kg, P=0.32), the total mass of calves weaned in this study was 14,843 kg vs. 13,060 kg and the benefit: cost ratio for synchronization was 2.8. It was therefore concluded that a PGF/6 protocol may affect the total mass of calves weaned by changing days to calving, weaning rate, the ratio of male: female calves born and/or the birth mass of calves.
我们将272头肉用小母牛随机分为同步化处理的试验组和非同步化处理的对照组，评估发情同步化对繁殖、生产和经济产出的影响。试验组在检测到发情后进行6天的人工授精，随后对到第6天仍未发情的小母牛进行PGF2处理（PGF/6）。两组的人工授精均持续50天，随后是42天的公牛配种期。跟踪小母牛至其第二个繁殖季节，直至它们断奶产下第一头小牛。同步化处理使首次人工授精的中位天数减少（试验组和对照组分别为8天和11天，P<0.01），人工授精所产犊牛的产犊中位天数减少（分别为14天和20天，P=0.04）。人工授精期的妊娠率（60.0%对51.8%，P=0.18）、最终妊娠率（82.2%对83.2%，P=0.87）或随后繁殖季节的妊娠率（96.0%对95.0%，P=1.00）无显著差异。虽然犊牛平均断奶体重无显著差异（207.0千克对201.4千克，P=0.32），但本研究中断奶犊牛的总重量为14843千克对13060千克，同步化处理的效益成本比为2.8。因此得出结论，PGF/6方案可能通过改变产犊天数、断奶率、出生公母犊牛比例和/或犊牛出生体重来影响断奶犊牛的总重量。
