Aburto A, Britton W M
Department of Poultry Science, University of Georgia, Athens 30602-2772, USA.
Poult Sci. 1998 Apr;77(4):570-7. doi: 10.1093/ps/77.4.570.
Three experiments were conducted to determine the effects of high dietary levels of vitamins A and E on the utilization of cholecalciferol by broiler chicks. In Experiment 1, chicks were fed six levels of vitamin A (5,000, 10,000, 20,000, 40,000, 80,000, and 160,000 IU/kg). Cholecalciferol (vitamin D3) was not added to the basal diet but all birds were exposed to ultraviolet (UV) fluorescent light. Body weight was decreased only at levels of vitamin A of 80,000 IU/kg or above. In Experiment 2, birds were exposed to UV fluorescent light or no UV light, two levels of dietary vitamin A (1,500 and 45,000 IU/kg) and three levels of dietary vitamin D3 (0, 500, and 2,500 IU/kg) in a 2 x 2 x 3 factorial arrangement. The high level of vitamin A reduced (P < 0.001) bone ash but only at a marginal level of vitamin D3 (500 IU/kg) and when the birds were not exposed to UV light. In Experiment 3, birds were exposed to UV fluorescent light or no UV light, two levels of dietary vitamin E (10 and 10,000 IU/kg) and three levels of dietary vitamin D3 (0; 500 and 2,500 IU/ kg) in a 2 x 2 x 3 factorial arrangement. The high level of vitamin E significantly (P < 0.05) reduced body weight, bone ash, plasma calcium, and increased rickets but only at 500 IU/kg of vitamin D3. Feeding 2,500 IU/kg of vitamin D3 overcame the effects of the high level of vitamin E, causing a significant (P < 0.05) interaction. Ultraviolet light also prevented the detrimental effects of the high level of vitamin E. The results of these studies indicate that high dietary levels of vitamins A and E negatively affected the utilization of vitamin D3 only when D3 was present at a marginal level (500 IU/kg) in the diet but not when it was synthesized in the bird by exposure to UV light or supplemented at 2,500 IU/kg in the diet.
进行了三项试验以确定高剂量日粮维生素A和维生素E对肉仔鸡胆钙化醇利用率的影响。在试验1中，给雏鸡饲喂六种水平的维生素A（5,000、10,000、20,000、40,000、80,000和160,000 IU/kg）。基础日粮中未添加胆钙化醇（维生素D3），但所有鸡只均接受紫外线（UV）荧光照射。仅在维生素A水平达到80,000 IU/kg及以上时体重才下降。在试验2中，鸡只接受UV荧光照射或不接受UV照射，采用2×2×3析因设计，设置两种日粮维生素A水平（1,500和45,000 IU/kg）和三种日粮维生素D3水平（0、500和2,500 IU/kg）。高剂量维生素A降低了（P<0.001）骨灰含量，但仅在维生素D3处于临界水平（500 IU/kg）且鸡只未接受UV照射时。在试验3中，鸡只接受UV荧光照射或不接受UV照射，采用2×2×3析因设计，设置两种日粮维生素E水平（10和10,000 IU/kg）和三种日粮维生素D3水平（0、500和2,500 IU/kg）。高剂量维生素E显著（P<0.05）降低了体重、骨灰含量、血浆钙，并增加了佝偻病发病率，但仅在维生素D3为500 IU/kg时。饲喂2,500 IU/kg的维生素D3可克服高剂量维生素E的影响，产生显著（P<0.05）的交互作用。紫外线也可防止高剂量维生素E的有害影响。这些研究结果表明，仅当日粮中维生素D3处于临界水平（500 IU/kg）时，高剂量日粮维生素A和维生素E才会对维生素D3的利用率产生负面影响，而当维生素D3通过鸡只接受UV照射在体内合成或日粮中添加量为2,500 IU/kg时则不会产生负面影响。
