Effects of mixed volatile fatty acid sodium salt on insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-3 (IGFBP-3) in plasma and rumen tissue, and rumen epithelium development in lambs

Abstract

Fifteen cross-bred male lambs (Dorset × Small Tail Han), aged 7 weeks, with average liveweight of 13.8±0.8 kg, were used to study effects of feeding mixed volatile fatty acid (VFA) sodium salt on insulin-like growth factor-I (IGF-I), insulin-like growth factor-binding protein-3 (IGFBP-3) in plasma and rumen tissue and rumen epithelium development. The lambs were randomly divided into 5 groups with 3 lambs in each group. Graded levels of mixed VFA sodium salt (the molar proportion of acetate, propionate, and butyrate was 65:25:10), i.e. 0, 5, 15, 30 and 60g/d was added into milk replacer as experimental treatments I, II, III, IV and V, respectively. The trial lasted 24 days. No differences were found in plasma IGF-I and IGFBP-3 between different treatments (P>0.05), or in IGF-I and IGFBP-3 in rumen dorsal sac and in IGF-I in ventral sac between different treatments (P>0.05), while IGFBP- 3 of treatments IV and V was higher than other treatments in ventral sac (P 0.05). It was concluded that feeding mixed VFA sodium salt up to 60 g/d per lamb in milk replacer had no significant effect on development of rumen epithelium. Key words: volatile fatty acid sodium salt; insulin-like growth factor-I (IGF-I); insulin-like growth factor-binding protein-3 (IGFBP-3); rumen epithelium; lambs.