Effect Of Different Energy Levels On Growth Performance, Fur Quality And Expression Of IGF-Ⅰ、IGF-ⅠR And KAP6.1Gene In Rex Rabbits

The experiment was conducted to study the effect of different energy levels on growthperformance、fur quality and expression of IFG-Ⅰ、IGF-Ⅰ R and KAP6.1gene in skin tissueof weaned rex rabbits. One hundred and sixty rabbits were divided into four groups with fortyreplicates every group. Rabbits were offered diets with energy of9.7(groupⅠ)、10.5(groupⅡ)、11.3(group Ⅲ) and12.1(group Ⅳ) MJ/kg, respectively. The formalexperiment lasted two months. Feed intake was recorded every day. Live weight and furindicators were measured each month. In order to explore the effect of energy on the wholeprocess of growth, experiment was conducted in continuous two months. Samples werecollected in the ages of2.5months and3.5months. Six rabbits were randomly selected, heartblood collection and slaughtered. One square centimeter skin tissue was collected in centre ofback. Total RNA was extracted and reverse transcription. The relative expression of IGF-Ⅰ、IGF-ⅠR and KAP6.1gene was detected with fluorescence quantitative PCR method. Theresults were as follows:1. Average daily gain(ADG) increased with the rising of energy levels in certain range.ADG was greater in energy levels of11.3MJ/kg than9.7MJ/kg (P<0.05). ADG greater inenergy levels of10.5MJ/kg than9.7MJ/kg(P<0.05). Energy levels significantly affected theratio of feed and gain(F/G). The group of energy level9.7MJ/kg, F/G was bigger than othergroups.2. Energy significantly affected total cholesterol levels (P<0.05), total cholesterol contentincreased with increasing of energy levels. Total serum protein and globulin contents rase atfirst, then decreased; group of11.3MJ/kg had the greatest content (P<0.05). The ratio ofalbumin and globulin (A/G) was contrary. Urea, uric acid and creatinine contents were nosignificant difference. Mineral elements,with increasing of energy level, P contents increasedfirst and decreased. And the contents of Na and Cl rase.3. Energy levels significantly affected body length of rex rabbits, body length in group of11.3MJ/kg was significant bigger than other groups (P<0.05). But it had no significant effect on fur area. Chest in Group of9.7MJ/kg was significant less than other groups (P<0.05).Wool length was significantly longer in group of10.5MJ/kg than9.7MJ/kg (P<0.05). Wooldensity was greatest in four groups when energy level was10.5MJ/kg.4. With the rising of energy levels, relative expression of IFG-Ⅰ、IGF-ⅠR and KAP6.1gene increasing at first, then reduced in the age of1.5to2.5months. Expression ofIFG-Ⅰ and IGF-Ⅰ R gene was significantly higher in group of11.3MJ/kg than9.7MJ/kg inthe age of2.5months. And expression of IFG-Ⅰ a nd IGF-Ⅰ R gene was highest in group of11.3MJ/kg in the age of3.5months, but no significant difference than other groups. Relativeexpression of KAP6.1gene was different in the two months. Expression of KAP6.1gene rasewith increasing of energy level in the age of2.5months. While its expression increased firstand then decreased in the age of3.5months.In conclusion, energy levels affected growth performance and fur quality, and regulatedgene expression of skin tissue. When energy level was11.3MJ/kg, rex rabbits grew fasted,and their fur quality was good, and expression level of IFG-Ⅰ, IGF-ⅠR and KAP6.1genewas highest. Therefore, the optimum energy level was11.3MJ/kg in the age of1.5to3.5months of rex rabbits.