[Effects of feed restrictions during the growth of sows on their sexual maturity and subsequent reproduction].

Effects on reproduction of feed restriction during different periods of growth were investigated in 76 Large-White gilts given one of 3 treatments between 79 days of age (27.9 kg) and puberty. The control gilts (group 1) were fed ad libitum during the experimental period, and those in group 2 received 12% less feed from 61 kg of liveweight until puberty. The gilts in group 3 received 33% less feed before 61 kg and were then pair-fed with the gilts in group 1. All the gilts were mated at first estrus and received 2.4 kg of feed per day during pregnancy. They were laparotomized at 38 days after mating and slaughtered at 105 days of pregnancy to measure early and late embryonic mortality. Contrary to group 3 (age at puberty: 256 days), no difference was found in age at puberty between group 1 and 2 gilts (232 and 226 days, respectively). Early undernutrition delayed age at first estrus, even when followed by normal feeding after 61 kg of liveweight. The gilts in group 2 had less backfat (backfat depth 24 vs 31 mm) and weighed less at puberty than the others (111 kg vs 124 kg). Severe undernutrition tended to increase early embryonic mortality (21.1, 18.8 and 33% in groups 1, 2 and 3, respectively) but the reverse was observed thereafter so that there was no difference in total embryonic mortality at 105 days of gestation (32.6, 30.6 and 36.5% in groups 1, 2 and 3, respectively).