Abstract: The experiment was conducted to study the effects of different amounts of dietary lysine on production performance,serum insulin-like growth factor-Ⅰ (IGF-Ⅰ) concentration and IGF-Ⅰ mRNA expression of growing rabbits. One hundred of 70 days New Zealand rabbits were allocated to individual cages and randomly divided into five groups. Five diets containing 0.55%,0.65%,0.75%,0.85% and 0.95% lysine respectively, were formulated as experimental treatments. The results suggested there was no significant difference in daily weight gain,feed/gain ratio(P＞0.05) with the increasing dietary lysine, however serum GH, IGF-Ⅰ and insulin(Ins) content increased significantly (P＜0.05) and reached the largest value under the lysine adding content of 0.85%,0.75% or 0.95% respectively. The IGF-Ⅰ relative expression level in the liver and muscle was up-regulated accompanying with the dietary lysine level increased. The present study suggested that the dietary lysine levels have significant effect in the IGF-Ⅰ expression and serum content.

Key words: lysine; growing rabbits; IGF-Ⅰ; growth performance