Young L G, King G J
J Anim Sci. 1981 Jul;53(1):19-25. doi: 10.2527/jas1981.53119x.
Reproductive performance of gilts initially bred on first observed estrus was compared with that of gilts bred on third observed estrus. One-hundred and twelve Yorkshire gilts were used and 106 conceived. Conception rate to initial breeding was lower among gilts bred on first versus third observed estrus (69.6 vs 77.4%). Estrus was observed in some gilts between 140 and 149 days of age; the mean age at estrus for all gilts that were bred was 177.8 days. The mean weight at puberty was 91.7 kilograms. There was a tendency toward increased litter size at birth and weaning when breeding was delayed to third estrus, but the difference was not statistically significant. Live weight of piglets was increased in litters from sows bred initially on third estrus. The weaning-to-estrus or conception interval was not influenced by initial breeding on first or third estrus. Maintaining gilts until third observed estrus required feed and accommodation for approximately 44 additional days before breeding and resulted in 1.4 additional pigs per sow over three parities.
将首次观察到发情时初次配种的后备母猪的繁殖性能与第三次观察到发情时配种的后备母猪的繁殖性能进行了比较。使用了112头约克夏后备母猪，其中106头受孕。首次观察到发情时配种的后备母猪与第三次观察到发情时配种的后备母猪相比，初次配种的受孕率较低（69.6%对77.4%）。在一些140至149日龄的后备母猪中观察到发情；所有配种后备母猪的发情平均年龄为177.8天。初情期的平均体重为91.7千克。当配种推迟到第三次发情时，出生时和断奶时的产仔数有增加的趋势，但差异无统计学意义。最初在第三次发情时配种的母猪所产仔猪的断奶体重有所增加。断奶至发情或受孕间隔不受首次或第三次发情时初次配种的影响。将后备母猪饲养到第三次观察到发情需要在配种前额外提供约44天的饲料和圈舍，并且在三个胎次中每头母猪多产1.4头仔猪。
