日粮锌缺乏继发的生长限制对肉仔鸡维生素A代谢影响的研究

以玉米淀粉和低锌豆粕为主要原料构成含锌4．67mg／kg的半纯合低锌基础日粮，将150只1日龄艾维茵肉仔鸡随机分为3个自由采食组与2个限制采食组。其中．自由采食组日粮是在低锌基础日粮中分别添加0、5、80mg／kg的锌，各组的VA添加水平均为3000 IU／kg日粮。2个限制采食组的日粮锌添加水平为80mg／kg，其它营养成分及采食量控制到与相应的低锌组一致的水平。结果表明，日粮锌水平低于9．67mg／kg时，可引起肉仔鸡血清VA浓度的明显下降。日粮锌含量为4．67mg／kg时，血清VA浓度的下降既与缺锌本身有关，又与因缺锌继发的采食量下降有关；日粮锌含量为9．67mg／kg时，血清VA浓度的下降主要是由缺锌继发的采食量下降引起的。限制采食也可引起肉仔鸡血清VA浓度的下降，但对血清锌浓摩无明显的影响。

Study of Effects of Growth Restriction Resulting from Zinc Deficiency in Diet on Vitamin A Metabolism in Broilers

150 one-day-old broilers were divided into five groups randomly which were composed of three groups ad lib. and two zinc-sufficient pair-fed groups. The three groups ad lib. were fed respectively the different experimental diets which were supplemented with three levels of dietary zinc (0, 5, 80 (mg/kg)) and (3 000)IU/kg of dietary vitamin A in the zinc-deficient semi-purified diet which contained 4.67 (mg/kg) zinc and was mainly made of corn starch and low zinc soybean meal. In addition, two zinc-sufficient pair-fed groups with the zinc-deficient groups were restricted to the average consumed by zinc-deficient groups in order to further explore the effects of feed intake and growth restriction as a result of zinc deficiency in diet on vitamin A metabolism in broilers. The results indicated that zinc deficiency would result in a significant depression of feed intake and growth and serum zinc and vitamin A concentrations in broilers. A significant decrease of serum vitamin A concentration was a result of feed intake and growth restriction resulting from zinc deficiency when dietary zinc level was 9.67 (mg/kg). However, significant decrease in serum vitamin A level was a result of not only zinc deficiency but feed intake restriction resulting from zinc deficiency when dietary zinc level was 4.67 (mg/kg). Feed intake restriction would result in an apparent decrease in serum vitamin A concentrations in broilers, but it had no effects on serum zinc concentrations.