The growth hormone receptor (GHR) is associated with animal growth and development. To investigate such effects on GHR gene expression, a total of 102 Hu lambs were randomly allocated to one of three groups (Group 1: starter diet from 7 d of age, weaning at 56 d of age; Group 2: starter diet from 42 d of age, weaning at 56 d of age; Group 3: starter diet from 7 d of age; weaning at 28 d of age). Six lambs from each group were sacrificed every 14 d to investigate the effects of starter feeding and weaning age on GHR mRNA expression in the liver and rumen. The results revealed that GHR mRNA expression was significantly higher in the liver and rumen (p < 0.05) than in other tissues. Early starter feeding up-regulated hepatic GHR mRNA expression on days 14, 28, 42 and 56 and ruminal GHR mRNA expression on days 28, 42, 70, and 84 (p < 0.05). Early weaning up-regulated hepatic GHR mRNA expression on days 56, 70 and 84 and ruminal GHR mRNA expression on days 42, 56, 70 and 84 (p < 0.05). Dietary and weaning regimes and age affected the hepatic and ruminal GHR mRNA expression.
Keywords: Feeding programs; gene expression; growth hormone; lambs; receptors; weaning.