RECONSTITUTION OF BODY RESERVES IN MULTIPAROUS SOWS DURING PREGNANCY - EFFECT OF ENERGY-INTAKE DURING PREGNANCY AND MOBILIZATION DURING THEPREVIOUS LACTATION

Multiparous Large White sows were used in two experiments to determine the effects of energy intake on the reconstitution of body reserves d uring pregnancy. In Exp. 1, 21 sows received one of three different en ergy levels during pregnancy: 7.4, 8.8, or 10.4 Meal DE/d. In Exp. 2, two energy levels (7.9 and 9.2 Meal DE/d) were fed to 36 sows that mob ilized low or high amounts of body reserves during the previous lactat ion (6 or 12 pigs per litter, respectively). Nitrogen balances were co nducted during five 7-d periods at 11, 32, 53, 82, and 104 d of gestat ion. All the experimental sows were slaughtered and dissected at the e nd of pregnancy; 24 control sows were similarly slaughtered at mating in order to estimate composition of BW gain, according to the comparat ive slaughter technique. In the two experiments, average nitrogen (N) retention increased linearly with energy supply from 9.9 to 14.5 g/d i n Exp. 1 (P < .001) and from 10.2 to 12.5 g/d in Exp. 2 (P < .05). Nit rogen retention was not affected by the extent of mobilization of body reserves during the previous lactation in Exp. 2. In both experiments , carcass weight(P < .001), muscle weight (P < .01), and dissectable f at weight (P < .001, Exp. 1; P < .01, Exp. 2) increased with energy su pply. We conclude that in high-producing modern multiparous sows, ener gy supply during gestation is a limiting factor for N retention and mu scle weight gain and should be approximately 8,500 kcal DE/d to ensure adequate restoration of body reserves.