Abstract
Postnatal maternal environments were compared for their effects on the reproductive performance of female swine. Crossfostering was used to establish postnatal environments of small (six pigs) and large (14 pigs) litters. These litter sizes were formed by reallotting pigs between two dams within 24 hr of parturition. Standardized litters from 46 pairs provided a total of 270 females for mating. Failure of females to exhibit estrus or to conceive was essentially equal for those raised in small and large litters. Individual weights diverged (P<.01) by 14 days between females raised in small and large litters. This divergence (.49 kg) increased to 4.49 kg at weaning (8 weeks). The difference in weights was only slightly greater at 140 days. Age at onset of first estrus was not significantly different between treatment groups. Advantages for females reared in small litters were noted in all replications for both corpora lutea and embryo number. Overall advantages of 1.01 for corpora lutea (P<.05) and 1.18 for embryo number (P<.10) were found. While not as consistent among replications, overall advantages for total number born and number born alive were .88 and 1.18 (P<.10), respectively. Due to the limited data, statistical tests of litter size differences were not very sensitive. However, the consistent advantages in corpora lutea, embryo number and litter size of females reared in litters of six pigs indicate that postnatal maternal environment may have an important effect on reproductive traits. Copyright © 1976. American Society of Animal Science. Copyright 1976 by American Society of Animal Science.