Relationship of various measures of performance with ovulation rate and number of embryos 30 days after breeding in gilts.

Abstract

This study involved the records of 241 purebred Duroc, Hampshire and Yorkshire gilts and 103 two-breed cross gilts resulting from all possible crosses among the purebreds. In purebred gilts, the number of corpora lutea was correlated (P< .05) with average daily gain (r = 0.15), age at 100 kg (r = –.17), breeding weight (r = 0.23) and days from 100 kg to breeding (r = 0.20). In two-breed cross gilts, the number of corpora lutea was correlated (P< .05) with birth weight (r = 0.25), weaning weight (r = 0.28), average daily gain (r = 0.20), age at 100 kg (r = –.20) and breeding weight (r = 0.46). The size of the litter the gilt was born or weaned in, her birth weight, average daily gain, age at 100 kg, and backfat probe were not significantly correlated with the number of embryos she had 30-days postbreeding regardless of the type of breeding of the embryo. The correlation between the gilt's weaning weight and number of embryos was significant (P< .05) for gilts with three-breed cross embryos but not for gilts with purebred or two-breed cross embryos (r = 0.35, 0.02 and 0.11, respectively). Breeding age and days from 100 kg to breeding were correlated (P< .05) with the number of embryos for gilts with two-breed cross embryos (r = 0.17 and 0.15, respectively) but these correlations were not significant for gilts with purebred embryos (r = –.13 and –.05, respectively) or for gilts with three-breed cross embryos (r = –.05 and 0.14, respectively). The correlation between breeding weight and number of embryos was significant for gilts with two-breed cross and three-breed cross embryos (r = 0.15 and 0.41, respectively) but not for gilts with purebred embryos (r = –.03). Ovulation rate accounted for 13.7, 5.8 and 23.0% of the variation in the number of purebred, two-breed cross and three-breed cross embryos, respectively (P< .05).