中文摘要：

本试验旨在研究饲粮中添加25羟基维生素D3（25-OH-D3）和1α羟基维生素D3（1α-OH-D3）代替维生素D3对42～63日龄黄羽肉鸡生长性能、血清生化指标、胫骨发育和养分消化率的影响。试验选用42日龄黄羽肉公鸡2 400只,随机分成8个处理,每个处理5个重复,每个重复60只鸡。处理1（正常钙磷饲粮对照组）的维生素D3、钙、磷含量分别为2 780 IU/kg、0.8%、0.55%;处理2（低钙磷饲粮对照组）～8的维生素D3、钙、磷含量分别为0 IU/kg、0.7%、0.45%;处理3～5中25-OH-D3的添加水平分别为50、70、90μg/kg,处理6～8中1α-OH-D3的添加水平分别为2.5、5.0、10.0μg/kg。试验期21 d。结果表明：1）与低钙磷饲粮对照组相比,除添加50μg/kg 25-OH-D3未使黄羽肉鸡平均日采食量（ADFI）有显著变化（P〉0.05）外,添加不同水平的25-OH-D3或10.0μg/kg 1α-OH-D3均可显著提高黄羽肉鸡生长性能（P〈0.05）,添加70、90μg/kg 25-OH-D3或2.5、5.0、10.0μg/kg 1α-OH-D3均可显著提高钙表观消化率和真消化率（P〈0.05）,添加5.0、10.0μg/kg 1α-OH-D3可显著提高磷表观消化率和真消化率（P〈0.05）;添加50、70、90μg/kg 25-OH-D3或10.0μg/kg 1α-OH-D3均可显著提高血清磷含量和显著降低血清钙磷比（P〈0.05）,添加90μg/kg 25-OH-D3或10.0μg/kg 1α-OH-D3还可显著降低血清抗酒石酸酸性磷酸酶（TRAP）活性（P〈0.05）,但各处理血清碱性磷酸酶（ALP）活性差异不显著（P〉0.05）;添加90μg/kg 25-OH-D3或10.0μg/kg 1α-OH-D3可显著提高胫骨粗灰分重、钙磷比、鲜重、脱脂重、脱脂重指数、长度、折断力和骨密度（P〈0.05）,但对胫骨粗灰分率、钙含量和鲜重指数均没有显著影响（P〉0.05）。2）与正常钙磷饲粮对照组相比,添加70、90μg/kg 25-OH-D3或2.5、5.0、10.0μg/kg 1α-OH-D3均可显著提高钙表观消化率（P〈0.05）,添加10.0μg/kg 1α-OH-D3可显著提高磷表观消化率和真消化率（P〈0.05?

英文摘要：

This study was conducted to investigate the effects of 25-OH-D3 and 1 ct-OH-D3 replacing vitamin D3 on growth performance, serum biochemical indices, tibia development and nutrient digestibility of yellow-feathered broilers aged from 42 to 63 days. A total of 2 400 male yellow-feathered broilers aged 42 days were randomly divided into 8 groups with 5 replicates per group and 60 chickens in each replicate. Treatment 1 （control group ） was fed a basal diet, in which the contents of vitamin D3, calcium, phosphorus were 2 780 IU/kg, 0.8%, and 0. 55%, respectively. For treatments 2 （low phosphorus and calcium control group） to 8, the contents of vitamin Da, calcium, phosphorus were 0 IU/kg, 0.7%, 0.45%, respectively. For treatments 3 to 5, the contents of 25-OH-Da were 50, 70 and 90 μg/kg, respectively. For treatments 6 to 8, the contents of 1a-OH-Da were 2.5, 5.0 and 10.0 μg/kg, respectively. The experiment lasted for 21 days. The results showed as follows： 1 ） compared with low calcium and phosphorus control group, except that 50 μg/kg 25-OH-D3 did not affect average daily feed intake （ P 〉 0.05 ）, the supplementation of different levels of 25-OH-D3 or 10.0 μg/kg 1 a-OH-D3 significantly improved the growth performance of yellow-feath- ered broilers （P 〈 0.05） ; the supplementation of 70 and 90 μg/kg 25-OH-Da or 2.5, 5.0 and 10.0 μg/kg 1 a-OH-Da significantly improved calcium apparent and true digestibility （ P 〈 0.05 ）, and the supplementation of 5.0 and 10.0μg/kg 1a-OH-D3 significantly improved phosphorus apparent and true digestibility （P 〈 0.05 ） ; the supplementation of 50, 70 and 90 μg/kg 25-OH-D3 or 10.0 μg/kg 1a-OH-D3 significantly im- proved serum phosphorus content and decreased serum the ratio of calcium to phosphorus （Ca/P） （ P 〈 0.05 ）, and the supplementation of 90 μg/kg 25-OH-Da or 10.0 μg/kg 1a-OH-D3 significantly decreased ser- um tartrate resistant acid phosphatase （TRAP） activity （P 〈0.05）, while there was no significant difference