Bates Amy L, McGrath Shawn R, Robertson Susan M, Refshauge Gordon
School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
Gulbali Institute, Charles Sturt University, Wagga Wagga, NSW 2678, Australia.
Animals (Basel). 2022 Oct 24;12(21):2908. doi: 10.3390/ani12212908.
Sheep production in southern Australia may vary by breed, time of year, production output (wool, meat, or both), region and seasonal influence. Sheep producers with flocks of approximately 300-500 ewes ( = 58) were recruited across southern Australia to take part in a survey and mating variables were collected from over 30,000 ewes between October 2020 and August 2021. A Bayesian Network (BN) was developed to identify the interrelatedness and most influential variable on pregnancy and fetal number (of pregnant ewes) outcomes under different scenarios. The BN analysis indicated a low association between the variables explored, however, were breed dependent. In wool-based breeds a mating liveweight of 60-69.5 kg predicted the lowest non-pregnant and greatest number of fetuses, and in shedding ewes 70-79.5 kg predicted the lowest non-pregnant rate and 90-99.5 kg the greatest number of fetuses. Pregnancy rate and fetuses per ewe were optimized at ram percentages of 1.5% for Composite and Merino ewes and 2% for Maternal ewes. A mating BCS 4 resulted in greatest pregnancy rate and number of fetuses across all breeds. Curvilinear relationships between mating liveweight, BCS and ram percentage were observed with pregnancy rate and fetal number. Practically, reproductive potential is best managed on a breed basis and with consideration of all variables explored.
澳大利亚南部的养羊业可能因品种、年份、生产产出（羊毛、肉类或两者皆有）、地区和季节影响而有所不同。在澳大利亚南部招募了拥有约300 - 500只母羊（= 58只）的羊群生产者参与一项调查，并在2020年10月至2021年8月期间从30000多只母羊中收集了配种变量。构建了一个贝叶斯网络（BN），以确定不同情况下妊娠和胎儿数量（怀孕母羊的）结果之间的相互关联性和最具影响力的变量。贝叶斯网络分析表明，所探究的变量之间关联性较低，不过这取决于品种。在以产毛为主的品种中，配种时体重为60 - 69.5千克可预测最低的未怀孕率和最多的胎儿数量；在脱毛母羊中，70 - 79.5千克可预测最低的未怀孕率，90 - 99.5千克可预测最多的胎儿数量。对于复合品种和美利奴母羊，公羊比例为1.5%时，妊娠率和每只母羊的胎儿数量达到最佳；对于母本品种母羊，公羊比例为2%时达到最佳。配种时体况评分为4会使所有品种的妊娠率和胎儿数量最高。观察到配种体重、体况评分和公羊比例与妊娠率和胎儿数量之间存在曲线关系。实际上，繁殖潜力最好根据品种进行管理，并考虑所有探究的变量。
