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Published online by Cambridge University Press: 02 September 2010
Attainment of puberty and the ovulation rates for the first three oestrous cycles were studied in gilts reared to 160 days alongside contemporary castrate or entire males before introducing them to mature boars.
Gilts which were introduced to the boars at 160 days of age reached puberty at younger ages and lighter weights than isolated gilts. Rearing treatment did not affect the age of puberty. Gilts which were isolated from boars after 160 days of age reached puberty earlier if they had been reared with entire rather than castrate contemporary males. The interval from introduction of the boars to first oestrus was related to age and weight at the time of introduction.
Ovulation rate at the pubertal oestrus was the same in both isolated groups, and higher in both these groups than for gilts induced into early puberty by boars. Ovulation rate increased at the second and third oestrous cycle and groups differed only at the first oestrus. In a second experiment, the reproductive performance of gilts approximately 218 days of age experiencing either their first, second or third oestrus was studied. No differences were found among the groups and the conclusion is that in gilts of similar age and weight the oestrous cycle at which mating takes place does not affect reproductive performance.