Capping dietary starch:protein ratios in moderately reduced crude protein,wheat-based diets showed promise but further reductions generated inferior growth performance in broiler chickens

• 作者: Ali Khoddami Bernard V.McInerney Leon R.McQuade Molly A.M.Zhuang Peter H.Selle Peter V.Chrystal Shiva Greenhalgh Sonia Y.Liu
• 来源期刊: 动物营养:英文版
• 学科: 农学
• 关键词: Amino acid Broiler chicken Crude protein Feathering Starch:protein ratio Wheat
• 年，卷（期）: 2020,（2）
• 页码范围: 168-178
• 页数: 11页
• 分类号: S831.5

摘要

The hypothesis that capping dietary starch:protein ratios would enhance the performance of broiler chickens offered reduced-crude protein(CP)diets was tested in this experiment.A total of 432 off-sex,male Ross 308 chicks were allocated to 7 dietary treatments from 7 to 35 d post-hatch.The experimental design consisted of a 3×2 factorial array of treatments with the seventh treatment serving as a positive control.Three levels of dietary CP(197.5,180.0 and 162.5 g/kg)with either uncapped or capped dietary starch:protein ratios constituted the factorial array of treatments,whilst the positive control diet contained 215.0 g/kg CP.The positive control diet had an analysed dietary starch:protein ratio of 1.50 as opposed to a ratio of 1.68 in the uncapped 197.5 g/kg CP diet and 1.41 in the corresponding capped diet and the capped 197.5 g/kg CP diet displayed promise.The growth performance this diet matched the positive control but outperformed the uncapped 197.5 g/kg CP diet by 10.4%(2,161 vs.1,958 g/bird;P=0.009)in weight gain,by 3.10%(3,492 vs.3,387 g/bird;P=0.019)in feed intake on the basis of pairwise comparisons and numerically improved FCR by 4.04%(1.616 vs.12684).However,the growth performance of birds offered the 180.0 and 162.5 g/kg CP dietary treatments was remarkably inferior,irrespective of dietary starch:protein ratios.This inferior growth performance was associated with poor feathering and even feather-pecking and significant linear relationships between feather scores and parameters of growth performance were observed.The amino acid profile of feathers was determined where cysteine,glutamic acid,glycine,proline and serine were dominant in a crude protein content of 931 g/kg.Presumably,the feathering issues observed were manifestations of amino acid inadequacies or imbalances in the more reduced-CP diets and consideration is given to the implications of these outcomes.