Bristol F
J Reprod Fertil Suppl. 1982;32:71-7.
A 6-year-old stallion was placed in a pasture for 9 days with 20 mares in which oestrus was synchronized with two treatments of PGF-2 alpha given 15 days apart. Breeding and observation began 3 days after the second treatment. Observations were carried out during the daylight hours (05:00 to 21:30 h). Eighteen mares showed oestrus and mated an average of 4.56 times each (range 1-12). There were 1.74 mounts per mating. The maximum number of matings by the stallion during 1 day was 16 on Day 2. The overall mean interval between matings was 72.8 min, ranging from 34.5 min on Day 1 to 128.7 on Day 6. The mares were mated at irregular intervals during oestrus but 16 of 18 (88.9%) mares mated at least once during the 3 days preceding the last day of oestrus. Only 5 mares mated on the last day of oestrus. Of the 20 mares, 17 (85%) were pregnant when examined 38 days after the end of the experiment. The results suggest that a stallion will indulge in significantly more mating activity at pasture than is currently expected with hand mating and still achieve a high first oestrus conception rate.
一匹6岁种马被放入牧场9天，与20匹母马在一起，这些母马通过间隔15天进行的两次前列腺素F2α处理使发情同步。在第二次处理后3天开始配种和观察。观察在白天（05:00至21:30）进行。18匹母马表现出发情，平均每匹交配4.56次（范围为1至12次）。每次交配的爬跨次数为1.74次。种马在第2天的1天内交配的最大次数为16次。交配之间的总体平均间隔为72.8分钟，范围从第1天的34.5分钟到第6天的128.7分钟。母马在发情期以不规则的间隔交配，但18匹母马中有16匹（88.9%）在发情期最后一天前的3天内至少交配了一次。只有5匹母马在发情期最后一天交配。在实验结束38天后检查时，20匹母马中有17匹（85%）怀孕。结果表明，与目前人工配种的预期相比，种马在牧场中的交配活动明显更多，并且仍然能达到较高的首次发情受孕率。
