Hormonal response to dietary L-arginine supplementation in heat-stressed sows

The response of key metabolic hormones to dietary arginine supplementation in heat-stressed lactating sows was determined. Sixty-three sows were exposed to a thermoneutral (TN = 20 degrees C) or hot (HT = 29.4 degrees C) environmental temperature, and were fed diets containing 0.96% (control, Q, 1.34% (medium, ME) or 1.73% (high, HI) arginine. Blood samples were obtained 2 h postprandially on days 7, 14, and 21 of lactation and concentrations of insulin, glucose, growth hormone (GH) and prolactin were determined. Arginine supplementation increased insulin concentrations (P < 0.01) on day 14 of lactation, had no effect (P > 0.1) on glucose, and decreased (P < 0.05) GH with ME compared with C diets. There was a temperature x diet interaction (P < 0.05) for prolactin, with values being greater for the C compared with the ME and 111 diets at 29.4 degrees C, but being lower at 20 degrees C. There was no effect (P > 0.1) of temperature alone on any of the measured variables. Results indicate that arginine supplementation may mediate improvements in nutrient utilization by regulating the metabolism of both insulin and GH in lactating sows.