本试验旨在探讨饲粮维生素D添加水平对生长獭兔生长性能、钙磷代谢、血液指标和抗氧化功能的影响。选取平均体重为（1.45±0.03） kg的3月龄獭兔200只，随机分成5组（每组40个重复，每个重复1只），分别饲喂维生素D添加水平为0（对照组）、500、1 000、2 000和4 000 IU/kg的试验饲粮，预试期7 d，正试期53 d。结果表明：饲粮维生素D添加水平对生长獭兔平均日增重、平均日采食量、料重比均无显著影响（P>0.05），平均日增重在维生素D添加水平为2 000 IU/kg时最高。饲粮维生素D添加水平对血清中钙、磷含量，粪中磷含量及胫骨中磷含量均无显著影响（P>0.05）。2 000 IU/kg组粪中钙含量显著低于0、500和4 000 IU/kg组（P<0.05），2 000 IU/kg组胫骨中钙含量极显著高于0、500和1 000 IU/kg组（P<0.01）。饲粮维生素D添加水平对钙、磷表观消化率无显著影响（P>0.05），但随维生素D添加水平的增加，钙、磷表观消化率呈先升高后降低趋势，以2 000 IU/kg组的值为最高。饲粮维生素D添加水平对血清碱性磷酸酶活性以及甘油三酯、胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇、甲状旁腺素含量均无显著影响（P>0.05）。血清总蛋白、白蛋白、降钙素和维生素D₃含量均以2 000 IU/kg组为最高，并显著高于对照组（P<0.05）。2 000 IU/kg组血清谷胱甘肽过氧化物酶活性极显著高于对照组和500 IU/kg组（P<0.01），1 000、2 000和4 000 IU/kg组血清总超氧化物歧化酶活性极显著高于对照组和500 IU/kg组（P<0.01），2 000 IU/kg组肝脏谷胱甘肽过氧化物酶活性极显著高于其他4组（P<0.01），2 000 IU/kg组肝脏总超氧化物歧化酶活性显著高于对照组（P<0.05）。饲粮维生素D添加水平对血清和肝脏丙二醛含量以及肝脏总抗氧化能力无显著影响（P>0.05）。综合考虑本试验所测指标，生长獭兔饲粮的适宜维生素D添加水平为2 000 IU/kg。

This experiment was conducted to study the effects of vitamin D supplemental level on growth performance, calcium (Ca) and phosphorus (P) metabolism, blood indices and antioxidant function of growing Rex rabbits. Two hundred 3-month-old Rex rabbits with an average body weight of (1.45±0.03) kg were randomly assigned to 5 groups with 40 replicates in each group and each replicate contained 1 rabbit. Rabbits in the 5 groups were fed experimental diets with the vitamin D supplemental levels of 0 (control group), 500, 1 000, 2 000 and 4 000 IU/kg, respectively. There was a pretrial period of 7 days followed by an experimental period of 53 days. The results showed as follows: vitamin D supplemental level did not significantly affect the average daily intake (ADI), average daily gain (ADG) and feed/gain (F/G) (P>0.05), and the highest ADG was found in 2 000 IU/kg group. Vitamin D supplemental level did not significantly affect serum Ca and P contents, fecal P content and shin P content (P>0.05). The fecal Ca content in 2 000 IU/kg group was significantly lower than that in 0, 500 and 4 000 IU/kg groups (P<0.05), and shin Ca content in 2 000 IU/kg group was significantly higher than that in 0, 500 and 1 000 IU/kg groups (P<0.01). Vitamin D supplemental level did not significantly affect the apparent digestibility of Ca and P (P>0.05), but with the increase of vitamin D supplemental level, the apparent digestibility of Ca and P showed a trend of first rise and then decrease, and the highest value was found in 2 000 IU/kg group. Vitamin D supplemental level did not significantly affect serum alkaline phosphatase (ALP) activity and the contents of triglyceride (TG), cholesterol (CHO), high density lipoprotein cholestorol (HDL-C), low density lipoprotein cholestorol (LDL-C) and parathyroid hormone (PTH) (P>0.05). Serum total protein (TP), albumin (ALB), calcitonin (CT) and vitamin D₃ contents in 2 000 IU/kg group were the highest and significantly higher than those in the control group (P<0.05). Serum glutathione peroxidase (GSH-Px) activity in 2 000 IU/kg group was significantly higher than that in control group and 500 IU/kg group (P<0.01), serum total superoxide dismutase (T-SOD) activity in 1 000, 2 000 and 4 000 IU/kg groups was significantly higher than that in control group and 500 IU/kg group (P<0.01), liver GSH-Px activity in 2 000 IU/kg group was significantly higher than that in other 4 groups (P<0.01), and liver T-SOD activity in 2 000 IU/kg group was significantly higher than that in control group (P<0.05). Vitamin D supplemental level did not significantly affect serum and liver malondialdehyde (MDA) content and liver total antioxidant capability (T-AOC) (P>0.05). Considering all measured indices of this experiment, the appropriate vitamin D supplemental level in the diet of growing Rex rabbits is 2 000 IU/kg.