Effect of birth weight and litter size on the performance of landrace gilts until puberty

Background: The selection for larger litter size has resulted in reduction of average birth weight and in increase of withinlitter birth weight variation in pigs. Birth weight is one of the most important factors affecting the survival and performanceof piglets until weaning. The aim of this study was to evaluate the effect of litter size into which gilts were born and theirindividual birth weight on mortality and culling rate until the time of selection, as well as on puberty onset.Materials, Methods & Results: Female Landrace piglets (n = 1525) were identifi ed and weighed within 18 h after birth.They were also weighed at weaning (n = 1379), and at the end of the nursery (n = 1198) and rearing phases (n = 940).Three classes of litter size were created: Small LS (7-11 piglets), Intermediate LS (12-13 piglets) and Large LS (14-19piglets). Gilts were also separated in three classes according to their birth weight: Low BW (530-1200 g), IntermediateBW (1205-1600 g) and High BW (1605-2535 g). When compared to High BW gilts, the risk of death until weaning wasgreater (P < 0.05) in Low BW gilts from Intermediate LS and Large LS litters, but not in Low BW gilts from Small LSlitters. Within the Low BW class, the risk of mortality until weaning was greater or tended to be greater if gilts were bornin Intermediate LS (P < 0.05) or Large LS (P = 0.079) litters compared to those from Small LS litters. Average dailyweight gain (ADWG), and weights at 22, 75 and 155 days of age, increased according to the increase in birth weight(P < 0.05). There was no effect of birth weight or litter size on mortality and culling rate, during nursery and rearing phases,and on percentages of gilts in anoestrous until 30 days after boar stimulation (P > 0.05). The risk of not being selected forbreeding was greater (P < 0.09) in Light BW gilts than in High BW gilts in all litter size classes. Low BW gilts were olderat the beginning...(AU)

Effect of birth weight and litter size on the performance of landrace gilts until puberty

Background: The selection for larger litter size has resulted in reduction of average birth weight and in increase of withinlitter birth weight variation in pigs. Birth weight is one of the most important factors affecting the survival and performanceof piglets until weaning. The aim of this study was to evaluate the effect of litter size into which gilts were born and theirindividual birth weight on mortality and culling rate until the time of selection, as well as on puberty onset.Materials, Methods & Results: Female Landrace piglets (n = 1525) were identifi ed and weighed within 18 h after birth.They were also weighed at weaning (n = 1379), and at the end of the nursery (n = 1198) and rearing phases (n = 940).Three classes of litter size were created: Small LS (7-11 piglets), Intermediate LS (12-13 piglets) and Large LS (14-19piglets). Gilts were also separated in three classes according to their birth weight: Low BW (530-1200 g), IntermediateBW (1205-1600 g) and High BW (1605-2535 g). When compared to High BW gilts, the risk of death until weaning wasgreater (P 0.05). The risk of not being selected forbreeding was greater (P < 0.09) in Light BW gilts than in High BW gilts in all litter size classes. Low BW gilts were olderat the beginning...