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

J Anim Sci. 2002 Jan;80(1):84-93. doi: 10.2527/2002.80184x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adipose Tissue / anatomy & histology
  • Age Factors
  • Anabolic Agents / administration & dosage
  • Anabolic Agents / pharmacology*
  • Animals
  • Blood Glucose / analysis
  • Drug Combinations
  • Drug Implants
  • Energy Intake
  • Estradiol / administration & dosage
  • Estradiol / pharmacology*
  • Food Deprivation / physiology
  • Insulin-Like Growth Factor Binding Protein 3 / blood*
  • Insulin-Like Growth Factor I / metabolism*
  • Male
  • Meat / standards*
  • Random Allocation
  • Swine / blood
  • Swine / growth & development*
  • Trenbolone Acetate / administration & dosage
  • Trenbolone Acetate / analogs & derivatives*
  • Trenbolone Acetate / pharmacology*


  • Anabolic Agents
  • Blood Glucose
  • Drug Combinations
  • Drug Implants
  • Insulin-Like Growth Factor Binding Protein 3
  • Revalor
  • Estradiol
  • Insulin-Like Growth Factor I
  • Trenbolone Acetate