Reproduction in the gilt 1. The influence of age and weight at puberty on ovulation rate and embryo survival in the gilt

Abstract

SUMMARYFifty-three Landrace × (Landrace × Large White) young female pigs (gilts) were fed ad libitum from selection at 20 kg live weight until mating at the second oestrous period. All gilts were subjected to a change of environment at 55 kg live weight, and the male was introduced daily from 64 kg live weight. Gilts were mated twice at second heat, and slaughtered on the 20th day of gestation. There was a range in age at puberty from 135 to 235 days (mean 178·9 ± 3·4 days), and in weight at puberty from 70 to 125 kg (mean 90·5 ±2·3 kg), indicating that there is a potential in some animals, at least, to attain sexual maturity at a very young age. Neither gilt age norweight at puberty significantly affected ovulation rate at second oestrus, conception rate or embryo survival during the first 20 days of gestation.Gilts sired by one boar reached puberty significantly earlier (P < 0·05) than did the offspring of three other boars.