Journal of Animal Science, Vol 73, Issue 6 1776-1783, Copyright © 1995 by American Society of Animal Science

JOURNAL ARTICLE

Plasma growth hormone, insulin-like growth factor I, and insulin-like growth factor binding proteins in pigs with divergent genetic merit for postweaning average daily gain

A. C. Clutter, L. J. Spicer, M. D. Woltmann, R. W. Grimes, J. M. Hammond and D. S. Buchanan
Department of Animal Science, Oklahoma State University, Stillwater 74078, USA.

Characteristics of growth hormone (GH), IGF-I, and IGF-binding proteins (IGFBP) were studied in gilts sampled from lines of pigs selected for either fast (line F, n = 14) or slow (line S, n = 14) postweaning ADG. Repeated blood samples were obtained from gilts (approximately 55 kg BW) during a period of feed deprivation and again during refeeding. Averaged across time, the difference in mean plasma GH concentrations of F and S gilts was not significant (7.7 vs 6.4 ng/mL; P > .20) during feed deprivation, and frequently, height, and amplitude of GH pulses did not differ (P > .25) for F and S pigs. Overall, F gilts had greater concentrations of plasma IGF-I than S gilts during feed deprivation (217.3 vs 145.1 ng/mL; P < .03). Across line, plasma IGF-I decreased (P < .01) during feed deprivation. Average GH did not differ (P > .40) for F and S gilts during the refeeding period. Average plasma IGF-I tended (P = .05) to be greater in F gilts than in S gilts during refeeding. Consistent with changes over time during feed deprivation, plasma IGF-I averaged across line increased (P < .01) in response to refeeding. Averaged across time (0 and 48 h refeeding), activity of IGFBP-2 (singlet band at 34 kDa) did not differ significantly (P = .17) in F and S gilts. However, there was a tendency (P = .13) for a line x time interaction.(ABSTRACT TRUNCATED AT 250 WORDS)