Journal of Animal Science, Vol 80, Issue 1 84-93, Copyright © 2002 by American Society of Animal Science

JOURNAL ARTICLE

Effects of restricted feeding, low-energy diet, and implantation of trenbolone acetate plus estradiol on growth, carcass traits, and circulating concentrations of insulin-like growth factor (IGF)-I and IGF-binding protein-3 in finishing barrows

C. Y. Lee, H. P. Lee, J. H. Jeong, K. H. Baik, S. K. Jin, J. H. Lee and S. H. Sohnt
Department of International Livestock Industry, Chinju National University, South Korea. cylee@cjcc.chinju.ac.kr

Effects of restricted feeding (80% ad libitum), feeding a low-energy diet containing 84% DE (2.95 Mcal/kg) of the control diet, and implantation of Revalor H (140 mg trenbolone acetate plus 14 mg estradiol-17beta) on growth, carcass traits, and serum concentrations of insulin-like growth factor (IGF)-I and IGFbinding protein-3 (IGFBP-3) were studied in crossbred finishing barrows beginning from 59 +/- 0.9 kg of body weight. Blood samples were taken every 3 wk and the animals were slaughtered at approximately 105 kg body weight. Restricted feeding caused a decrease (P < 0.01) in ADG; feeding the low-energy diet was effective in reducing backfat thickness but decreased gain:feed; the implantation caused a decrease in ADG, feed intake, and backfat thickness and increased gain:feed. Overall pork quality based on pH, drip loss, and the lightness in color of longissimus muscle was not affected by any of the treatments. Serum IGF-I concentration increased following the implantation but did not change (P > 0.05) due to other treatments. Immunoreactive IGFBP-3 concentration was not changed by any of the treatments. Overall ADG was positively correlated with early-stage (d 21) IGF-I and IGFBP-3 concentrations only in unimplanted barrows, whereas backfat thickness was negatively correlated with d-42 IGF-I concentration in all but unimplanted barrows with ad libitum intake. A strong positive correlation (P < 0.01) between IGF-I and IGFBP-3 concentrations was apparent with increasing age of the animals. Results suggest that growth rate and backfat thickness are decreased by a moderate restriction of feed or energy intake with no accompanying changes in circulating IGF-I and IGFBP-3 concentrations and that the beneficial effect of Revalor H implantation on feed efficiency may be mediated, in part, by IGF-I. Moreover, both IGF-I and IGFBP-3 concentrations may be useful as growth indices in pigs.

This article has been cited by other articles:

				T. F. Oresanya, A. D. Beaulieu, and J. F. Patience Investigations of energy metabolism in weanling barrows: The interaction of dietary energy concentration and daily feed (energy) intake J Anim Sci, February 1, 2008; 86(2): 348 - 363. [Abstract] [Full Text] [PDF]

				C K Hilleson-Gayne and J A Clapper Effects of decreased estradiol-17{beta} on the serum and anterior pituitary IGF-I system in pigs J. Endocrinol., December 1, 2005; 187(3): 369 - 378. [Abstract] [Full Text] [PDF]

				C. Farmer, D. Petitclerc, M. T. Sorensen, M. Vignola, and J. Y. Dourmad Impacts of dietary protein level and feed restriction during prepuberty on mammogenesis in gilts J Anim Sci, August 1, 2004; 82(8): 2343 - 2351. [Abstract] [Full Text] [PDF]