Glucose tolerance, luteinizing hormone release, and reproductive performance of first-litter sows fed two levels of energy during gestation.

This experiment was conducted to determine the effects of gestational energy intake on glucose tolerance, LH profiles, and reproductive performance of first-litter sows. Sixteen pregnant gilts were assigned to either high energy (11 Mcal of ME/d; H) or normal energy (6.5 Mcal of ME/d; N) diets during gestation. They did not receive the treatment diets until 35 d of gestation and had free access to the same commonly used diet during lactation. A glucose tolerance test (1 g glucose per kg BW) was conducted after 18 h of feed deprivation on 110 d of gestation and 15 d of lactation. Blood samples were collected at -10, -5, 0 (immediately before glucose infusion), 2, 4, 6, 8, 10, 15, 20, 25, 30, 40, 50, 60, 80, 100, 120, 150, and 180 min for assay of glucose and insulin concentrations. Blood samples were also taken on d 7, 14, and 21 of lactation and on 1 d postweaning for 6 h with 10-min intervals for LH characteristics. Sows in Group H had greater gain of BW and backfat during gestation (P < .001) and had less feed intake and greater weight loss during lactation (P < .002) than those in Group N. Sows in Group H (8.0 d) showed 1.6 d longer (P = .07) weaning-to-estrus intervals than those in Group N (6.4 d). After glucose infusion, insulin levels in Group H were higher (P < .05) than those in Group N. Lower LH concentrations on 1 d postweaning were found (P < .05) in sows in Group H than in Group N. This study indicates that energy intake during gestation is negatively related to feed intake during lactation. Reduced feed intake during lactation of sows having high gestational energy impairs glucose tolerance, suggesting that interaction of insulin with LH secretion may influence weaning-to-estrus intervals.