Reproduction in the gilt 7. Exposure of young gilts to the same mature boar and relocation: effects on the attainment of puberty

Abstract

ABSTRACTTwenty-four Landrace × (Landrace × Large White) gilts were randomly allocated at a mean age of 70 days to each of two rearing treatments which were: (1) housing gilts with other gilts but in complete isolation from other pigs; or (2) housing gilts with fence-line contact with a mature boar. At 160 days of age all gilts were relocated, treatment 1 gilts being adjacent to a mature boar for the first time while treatment 2 gilts were adjacent to the same mature boar with which they had had contact during rearing. In addition, the gilts on each treatment were exposed to full contact with this boar for 30 min/day. There were no significant differences between the treatments in age (176 and 185 days) or weight at puberty (81·9 and 82·6 kg), in the interval from relocation and full boar contact to puberty (11 and 16 days) and in ovulation rate at the pubertal oestrus (11·6 and 11·5).In a second experiment, 72 gilts were reared with fence-line contact with a mature boar and at 160 days of age, half were relocated adjacent to a novel mature boar and the other half remained in the rearing house next to a novel boar with all gilts receiving full boar contact for 30 min/day. Significantly more relocated gilts reached puberty during the experimental period (25/32) than gilts which were only exposed to contact with a novel boar and not relocated (12/31) (P < 0·001) and those relocated gilts were significantly younger (187 v. 225 days; P < 0·001) and lighter (75·4 v. 93·9 kg; P < 0·001) at puberty and the induction interval was significantly shorter (20 v. 89 days; P < 0·001) compared with gilts on the second treatment.