PSVI-12 - Ghrelin Plasm Concentrations Are Greater in High- vs Low-rfi Hampshire Male Lambs Within a Transient Surge of Secretion Just Before a Scheduled Meal Feeding

Abstract: The aim was to explore potential differences on ghrelin plasm concentrations between efficient and inefficient lambs within a transient surge of ghrelin secretion just before a scheduled meal feeding. Six high- (256±19 g) and six low-RFI (-242±19 g) Hampshire entire male lambs (Age=168±2 d and BW=63±5 kg) were taken out of 25 individuals in a 56-d GrowSafe SystemsÒ feeding trial. After a 10-d adaptation to a once-daily ad-libitum feed offering (0900 h), at d11 three lambs from each RFI group continued the once-daily feeding schedule (FED), whereas feed was witheld from the other three lambs (FAST) from each RFI group for 24-h (d11 to d12). Blood samples were collected via indwelling jugular catheter. In d11, ghrelin plasm concentrations were determined by ELISA in all animals at 0800, 0840, 0900, 1000 and 1100, and d12 at 0900, 1000 and 1100 in the FAST group. A linear model for repeated measures was adjusted with PROC MIXED of SAS. Plasm ghrelin levels began to increase at 0800, and RFI groups reached significant difference (P < 0.05) within both FED and FAST groups at 0840, with the greatest difference at peak concentartions at 0900 h (3.9±0.2 vs 2.4±0.2 and 3.9±0.2 vs 3.0±0.2 ng/ml for high vs low RFI, respectively). In the descendent phase of the curve for the FED group, one hour after feeding, ghrelin plasm concentration levels continued to be greater (P < 0.05) for high RFI vs low RFI animals and reached basal levels by 1100 h. For the FAST group, ghrelin concentrations continued to increase averaging maximum concentrations at the end of feed restriction, 0900 h of d12, being 4.9±0.2 ng/mL for the high RFI animals and 3.5±0.2 ng/mL for the low RFI ones. In conclusion, high RFI lambs show more pronounced transient surge of ghrelin secretion just before a scheduled meal feeding than low RFI lambs.