EFFECT OF FEEDING LEVEL IN THE GILT DURING PREGNANCY ON VOLUNTARY FEED-INTAKE DURING LACTATION AND CHANGES IN BODY-COMPOSITION DURING GESTATION AND LACTATION

Forty-eight Large White gilts were divided at mating into three feeding groups: low (L), medium (M) and high (H). The gilts of groups L, M and H were fed 1.8, 2.25 and 2.7 kg/day during pregnancy of a diet containing 17% protein, respectively. They were given the same diet ad libitum during lactation. Reproductive performances during gestation and lactation were similar in the three groups. Net weight gain during pregnancy and backfat depth gain increased linearly with feeding level: 37.1 kg and 4.2 mm, 53.3 kg and 8 mm and, 64.3 kg and 11.4 mm in groups L, M and H, respectively. Feed intake during lactation was significantly affected by pregnancy treatment, especially during the first week. A negative relationship was established between backfat depth at farrowing and lactation feed intake: -63 g day-1 mm-1 during the whole lactation and -95 day-1 mm-1 during the first week. A positive relationship was also found between body weight gain during pregnancy and weight loss during lactation. The results show that predicted muscle weight loss during lactation increased with pregnancy feeding level whereas predicted fat weight loss was affected only by level of feed intake during lactation. Weight gain from mating to weaning was positive in all treatments: + 24.9, + 33.6 and + 39.7 kg for groups L, M and H, respectively, whereas backfat depth decreased by 4.1, 2.2 and 0 mm for groups L, M and H, respectively. This shows the limits of a feeding strategy based only on the target of weight gain.