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

Shiva Greenhalgh, Bernard V. McInerney, Leon R. McQuade, Peter V. Chrystal, Ali Khoddami, Molly A. M. Zhuang, Sonia Y. Liu, Peter H. Selle

Research output: Contribution to journalArticle

2 Citations (Scopus)
11 Downloads (Pure)

Abstract

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; P = 0.009) in weight gain, by 3.10% (3,492 vs. 3,387; P = 0.019) in feed intake on the basis of pair-wise comparisons and numerically improved FCR by 4.04% (1.616 vs. 1.684). 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.

Original languageEnglish
Pages (from-to)168-178
Number of pages11
JournalAnimal nutrition
Volume6
Issue number2
DOIs
Publication statusPublished - Jun 2020

Bibliographical note

Copyright the Publisher 2020. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • Amino acid
  • Broiler chicken
  • Crude protein
  • Feathering
  • Starch:protein ratio
  • Wheat
  • Starch:protein ratios
  • Amino acids
  • Broiler chickens

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