EFFECTS OF A SHORT-TERM FEED RESTRICTION ON GROWTH PERFORMANCE, BLOOD METABOLITESAND HEPATIC IGF-1 LEVELS IN GROWING RABBITS

A total of 144 weaned hybrid HYLA rabbits (40-day-old) were randomly divided into 4 groups, to investigate the effects of the intensity of one week's feed restriction on short- and medium-term growth performance, blood metabolites and hepatic IGF-1 in growing rabbits. Restricted groups were fed with 30% (Group L30), 50% (Group L50) 70% (Group L70) of ad libitum feeding for 1 wk and then fed ad libitum until the end of the experiment (75 d of age). The control group (Group AL) was fed ad libitum throughout the experiment. Total feed intake (-15.8%) and feed conversion ratio (-13.2%) were lower in the L50 than in the AL group (P<0.05), but no difference was found between the L30, L70 and AL groups (P>0.05) for these parameters. Total weight gain did not significantly differ among the 4 experimental groups (38.5 g/d; P>0.05). At the end of the feed restriction period, the total serum protein level (P=0.01) was higher in restricted rabbits than AL rabbits (P<0.01), while the hepatic IGF-1 level was lower in L30 and L50 groups than in the 2 other groups (P<0.001). However, no difference remained between groups at the end of the experiment. In contrast, calcium, triglycerides, alkaline phosphatase, urea nitrogen and total cholesterol levels were similar between groups (P>0.05) throughout the experiment. In conclusion, a short-term feed restriction improves feed conversion ratio in a lasting way, transiently alters serum protein and IFG-1 levels and leads to compensatory growth in growing rabbits.