摘要
This paper presents data on fertility and litter size obtained with artificial insemination with frozen semen in five breeds of Norwegian sheep. The study is based on cervical inseminations reported by the technicians/veterinarians for the period 1984–1988. During this period 3000–3600 elite ewes were inseminated each year with semen from genetically superior rams. In addition, lambing data from sheep recording was used in this study.
The non-return rate (NR%), defined as percent ewes not returned to service within minimum 20 days, was estimated to be about 60%. This variate was affected significantly by technician/veterinarian, flock-year, ram, age of ewe, number of inseminations per heat, date and time of insemination. The analysis indicates a reduction in litter size at birth of about 0.2–0.4 lambs when elite ewes were artificially inseminated rather than naturally mated. The optimal insemination time was found to be 15–20 hours from heat detection. It is also shown that technicians obtaining high NR% also obtain lower reductions in litter size from AI.
摘要译文
本文介绍了五种挪威绵羊用冷冻精液进行人工授精获得的育性和产仔数。该研究基于1984 - 1988年期间技术人员/兽医报告的宫颈授精。在此期间，每年有3000-3600名精英母羊用来自遗传优良公羊的精液进行授精。此外，本研究使用来自绵羊记录的产羔数据。非返回率（NR％），定义为在最短20天内未返回服务的母羊百分比，估计约为60％。这种变化受到技术人员/兽医，鸡群年，公羊，母羊年龄，每热量授精次数，授精日期和时间的显着影响。分析表明，当精英母羊人工授精而不是自然交配时，出生时窝产仔数减少约0.2-0.4只。从热检测发现最佳授精时间为15-20小时。还显示获得高NR％的技术人员也从AI获得较低的产仔数减少。
IngridOlesen;. Effects of cervical insemination with frozen semen on fertility and litter size of Norwegian sheep[J]. Livestock Production Science, 1993,37(1-2): 169-184