Schüller L-K, Burfeind O, Heuwieser W
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
Clinic for Animal Reproduction, Faculty of Veterinary Medicine, Freie Universität Berlin, Koenigsweg 65, 14163 Berlin, Germany.
J Dairy Sci. 2016 Apr;99(4):2996-3002. doi: 10.3168/jds.2015-10080. Epub 2016 Jan 29.
The objectives of this retrospective study were to examine the effect of heat stress on natural service and artificial insemination (AI) breeding methods. We investigated the influence of short- and long-term heat stress on the conception risk (CR) of dairy cows bred by natural service or by AI with frozen-thawed or fresh semen. In addition, the relationship between breeding method and parity was determined. Cows bred by AI with frozen-thawed semen exposed to long-term heat stress (mean temperature-humidity index ≥73 in the period 21d before breeding) were 63% less likely to get pregnant compared with cows not exposed to heat stress. Cows bred by AI with fresh semen were 80% less likely to get pregnant during periods of short-term heat stress than during periods without heat stress. Furthermore, multiparous cows bred by AI with frozen-thawed or fresh semen were 22 and 67% less likely to get pregnant, respectively, than primiparous cows. No influence of heat stress or parity was noted on the CR of cows bred by natural service. The present study indicates that the likelihood of dairy cows becoming pregnant is reduced by short- and long-term heat stress depending on the type of semen employed. In particular, CR of cows inseminated with fresh semen is negatively affected by short-term heat stress and CR of cows inseminated with frozen-thawed semen is negatively affected by long-term heat stress.
这项回顾性研究的目的是检验热应激对自然配种和人工授精（AI）繁殖方式的影响。我们调查了短期和长期热应激对通过自然配种或使用冻融精液或新鲜精液进行人工授精的奶牛受孕风险（CR）的影响。此外，还确定了繁殖方式与胎次之间的关系。与未受热应激影响的奶牛相比，在配种前21天期间平均温湿度指数≥73的长期热应激环境下，使用冻融精液进行人工授精的奶牛受孕几率降低了63%。在短期热应激期间，使用新鲜精液进行人工授精的奶牛受孕几率比无热应激期间降低了80%。此外，与初产奶牛相比，使用冻融精液或新鲜精液进行人工授精的经产奶牛受孕几率分别降低了22%和67%。未发现热应激或胎次对自然配种奶牛的受孕风险有影响。本研究表明，根据所用精液类型，短期和长期热应激会降低奶牛受孕的可能性。特别是，短期热应激会对使用新鲜精液授精的奶牛受孕风险产生负面影响，长期热应激会对使用冻融精液授精的奶牛受孕风险产生负面影响。
