Poultry Mineral Nutrition Laboratory, College of Animal Science and Technology, Yangzhou University, Yangzhou 225000, China.
Mineral Nutrition Research Division, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
J Anim Sci. 2022 Apr 1;100(4). doi: 10.1093/jas/skac092.
The current dietary Ca recommendation of broilers is primarily based on the previous studies carried out more than 30 yr ago. However, the modern commercial broilers are quite different from those more than 30 yr ago. The present experiment was conducted to evaluate an optimal dietary Ca level by bone characteristics and Ca metabolism-related gene expression of broilers fed a corn-soybean meal diet from 22 to 42 d of age. A total of 252 22-d-old Arbor Acres male broilers were randomly assigned to 1 of 7 treatments with 6 replicate cages of 6 birds per cage for each treatment. Broilers were fed the corn-soybean meal diets containing 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, 1.00%, or 1.10% Ca for 21 d, and each diet contained 0.31% non-phytate P. The results showed that the mineral contents in tibia and middle toe bone, mineral density in tibia and middle toe bone, middle toe ash percentage, middle toe ash Ca percentage, and tibia alkaline phosphatase mRNA expression level of broilers were influenced (P < 0.04) by dietary Ca level and increased quadratically (P < 0.05) as dietary Ca level increased. The estimates of optimal dietary Ca levels were 0.55%, 0.60%, 0.70%, 0.72%, 0.63%, 0.66%, and 0.70%, respectively, based on the best fitted broken-line, quadratic, or asymptotic models (P < 0.02) of the above sensitive indices. These results indicate that the optimal dietary Ca level would be 0.72% to support all of the Ca metabolism and bone development of broilers fed the corn-soybean meal diet from 22 to 42 d of age.
当前肉鸡的膳食钙推荐量主要基于 30 多年前进行的先前研究。然而，现代商业肉鸡与 30 多年前的肉鸡有很大的不同。本试验旨在评估从 22 至 42 日龄饲喂玉米-豆粕日粮的肉鸡的最佳饲粮钙水平，通过骨特性和钙代谢相关基因表达来评估。将 252 只 22 日龄的 Arbor Acres 雄性肉鸡随机分配到 7 个处理组中的 1 个，每个处理组有 6 个重复笼，每个重复笼有 6 只鸡。肉鸡饲喂含有 0.50%、0.60%、0.70%、0.80%、0.90%、1.00%或 1.10%钙的玉米-豆粕日粮 21 d，每种日粮含有 0.31%非植酸磷。结果表明，日粮钙水平影响胫骨和中趾骨的矿物质含量、胫骨和中趾骨的矿物质密度、中趾灰分百分比、中趾灰分钙百分比以及胫骨碱性磷酸酶 mRNA 表达水平（P<0.04），且随饲粮钙水平的增加呈二次曲线增加（P<0.05）。基于上述敏感指标的最佳拟合折线、二次或渐近模型，估计最佳饲粮钙水平分别为 0.55%、0.60%、0.70%、0.72%、0.63%、0.66%和 0.70%（P<0.02）。这些结果表明，从 22 至 42 日龄饲喂玉米-豆粕日粮的肉鸡，最佳饲粮钙水平为 0.72%，以支持所有的钙代谢和骨骼发育。
