This study was conducted to investigate effects of farm, type of sow Landrace × Yorkshire, LY ； Yorkshire × Landrace, YL ； Yorkshire × Yorkshire, YY and multi-cross bred sow, MBS), parity, farrowing year, farrowing season and mating method on reproductive traits such as total number born per litter, number of born alive per litter, number of weaned per litter, number of mummified per litter, number of stillbirth. The Reproductive Records of 3,387 litters from January, 1999 to September, 2002 were obtained from four pig farms managed by Electronic Data Processing(EDP) system.
Reproductive performances for two types of F! Sows(YL and LY) were estimated as 11.34 ± 0.266 and 11.57 ± 0.263 heads for total number of bom alive per litter, and 10.05 ± 0.131 and 9.96 ± 0.153 heads for number of weaned per litter, respectively. These records are significantly higher(P＜0.05) than those of YY and MBS. However, number of mummified per litter, number of stillbom per litter, number of dead by diarrhea per litter, number of dead by other reasons during lactating period per litter and estrus interval did not show significant difference between types of sows. There were more total number of born per litter and number of weaned per litter in year 2001 than other year. As year passed, number of dead by crush per litter, number of dead by diarrhea per litter and number of dead by other reasons during lactating period per litter reduced from 0.18 ± 0.023 to 0.07 ± 0.022 head, 0.12 ± 0.21 to 0.02 ± 0.020 head and 0.43 ± 0.041 to 0.22 ±0.040 head, respectively and weaning rate increased from 0.94 ± 0.005％ to 0.97 ±0.005％. The total number of born per litter and number of born alive per litter were higher(P＜0.05) in the case of mating twice than mating once. The number of weaned per litter, number of mummified per litter and number of stillborn per litter were not significant(P＜0.05) between mating methods. Estrus interval was shorter on the occasion of twice artificial insemination(5.24 ± 0.153days) than twice natural mating(6.54 ± 0.466days).
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