INFLUENCE OF FEED RESTRICTION IN PRIMIPAROUS LACTATING SOWS ON BODY CONDITION AND METABOLIC PARAMETERS

Twenty-four primiparous sows were allocated at farrowing to a high (H: 5.5-6 kg feed/day) or a low (L: 2.5-3 kg/day) level of feeding. Litte rs (8-10 piglets) were weaned at 28 +/- 2 days. Serial blood samples w ere collected 1 day before weaning (W-1), in the hours following weani ng (W) and 1 day after (W + 1). L sows lost significantly more weight (38 versus 15 kg) and backfat (5.3 versus 2.3 mm) during lactation tha n H sows. On day W-1, L sows had higher mean concentrations of NEFA (P < 0.01) and GH (P < 0.1) and lower concentrations of insulin and IGF- I (P < 0.05) than H sows. Mean concentrations of glucose and cortisol did not differ between groups of sows. On day W + 1, these parameters were not different between treatments, except IGF-I concentrations whi ch remained lower in L than in H sows (P < 0.05). We conclude that lac tating primiparous sows alter secretion of metabolic hormones to favou r mobilization of body reserves to support milk production. Low insuli n and IGF-I may be involved in reduced ovarian activity at and after w eaning, through LH-dependent and independent pathways. (C) Inra/Elsevi er, Paris.