Effects of chromium yeast supplementation on productive and metabolic responses of laying hens fed diets containing different energy levels

ABSTRACT This study evaluated the effects of chromium yeast (Cr yeast) and two apparent metabolizable energy (AME) levels on productive performance, egg quality, and lipid and carbohydrate metabolism in laying hens. A total of 192 Bovans White laying hens at 47 weeks of age were randomly assigned to eight dietary treatments (six replicates each) in a 4 × 2 factorial arrangement: four levels of supplemental Cr (0, 0.2, 0.4, and 0.8 ppm as Cr yeast) and two AME levels (2,780 and 2,900 kcal AME kg−1). No significant effect of Cr yeast supplementation on feed intake, egg weight, egg production, intact eggs, egg mass, feed conversion ratio, or egg quality was observed. Egg quality parameters and Cr content in the yolk were not affected by dietary treatments. Plasma glucose and lipid levels were not influenced by either Cr yeast or AME levels used in this study. However, Cr yeast supplementation improved yolk percentage and hepatic glycogen content. The inclusion of Cr yeast at 0.2 and 0.4 ppm induced the highest hepatic glycogen content with the energy levels 2,900 and 2,780 kcal AME kg−1, respectively. Laying hens fed 2,900 kcal AME kg−1 showed the highest abdominal fat. The results observed in the present study support the hypothesis that the lack of positive effects of Cr yeast supplementation on production performance and egg quality may be related to good management practices, as the birds were not subjected to stressful conditions.

摘要 本试验评估了酵母铬（chromium yeast，Cr酵母）与2个表观代谢能（apparent metabolizable energy，AME）水平对产蛋鸡生产性能、蛋品质以及脂类与碳水化合物代谢的影响。选取192只47周龄的宝万斯白壳产蛋鸡，随机分为8个日粮处理组（每组6个重复），采用4×2因子试验设计：4个Cr酵母添加水平（0、0.2、0.4、0.8 ppm，以Cr酵母形式添加）与2个AME水平（2780和2900 kcal AME·kg⁻¹）。试验未观察到添加Cr酵母对采食量、蛋重、产蛋率、合格蛋数、蛋总重、料蛋比或蛋品质产生显著影响。日粮处理对蛋品质参数及蛋黄铬含量无显著作用。本试验所用的Cr酵母添加量与AME水平均未对血浆葡萄糖及脂类水平产生影响。但添加Cr酵母可提升蛋黄占比与肝糖原含量：当AME水平分别为2900 kcal·kg⁻¹与2780 kcal·kg⁻¹时，添加0.2 ppm与0.4 ppm的Cr酵母可分别获得最高的肝糖原含量。饲喂2900 kcal AME·kg⁻¹日粮的产蛋鸡腹脂沉积量最高。本试验结果印证了如下假说：由于试验鸡未处于应激状态，添加Cr酵母未对生产性能与蛋品质产生积极影响的原因可能与良好的饲养管理有关。