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RESEARCH ARTICLE (Open Access)

Supplementation of reduced protein diets with l-arginine and l-citrulline for broilers challenged with subclinical necrotic enteritis. 1. Growth, carcass yield, and intestinal lesion scores

Hiep Thi Dao https://orcid.org/0000-0002-3093-1207 A B , Nishchal K. Sharma A , Ali Daneshmand A , Alip Kumar A , Emma J. Bradbury C , Shu-Biao Wu https://orcid.org/0000-0002-1790-6015 A and Robert A. Swick https://orcid.org/0000-0003-3376-1677 A *
+ Author Affiliations
- Author Affiliations

A School of Environmental and Rural Science, Faculty of Science, Agriculture, Business and Law, University of New England, Armidale, NSW 2351, Australia.

B Faculty of Animal Science, Vietnam National University of Agriculture, Trau Quy Town, Gia Lam District, Hanoi 100000, Vietnam.

C Ridley AgriProducts, Melbourne, Vic. 3000, Australia.

* Correspondence to: rswick@une.edu.au

Handling Editor: Konstantinos Mountzouris

Animal Production Science 62(13) 1236-1249 https://doi.org/10.1071/AN21393
Submitted: 28 July 2021  Accepted: 6 February 2022   Published: 4 March 2022

© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context: Improving immune status through nutritional adjustments may be part of an effective strategy to reduce reliance on antibiotic growth promoters for controlling necrotic enteritis (NE) in broiler chickens.

Aims: This study examined the effect of dietary protein level and the replacement of crystalline l-arginine (Arg) with l-citrulline (Cit) in the reduced-protein diet on the performance of broilers challenged with subclinical NE.

Methods: Ross 308 cockerels (n = 720) were randomly allocated to six dietary treatments, with eight replicates of 15 birds per pen, during a 35-day feeding experiment. The treatments were as follows: standard protein without NE challenge (SP−); standard protein with NE challenge (SP+); reduced protein (two percentage points lower crude protein) without NE challenge (RP−); reduced protein with NE challenge (RP+); RP+ plus added Arg (103% of RP, RPA+) and RPC+ where supplemental Arg in RPA+ was replaced with Cit. The first four treatments were considered as a 2 × 2 factorial arrangement, with factors being NE (− or +) and protein level (SP or RP). Treatments SP+, RP+, RPA+, and RPC+ were analysed by one-way ANOVA.

Key results: Subclinical NE challenge reduced feed intake (FI), reduced body weight gain (BWG) and increased feed to gain ratio (FCR) from Day 0 to Day 35, increased intestinal lesion scores on Day 16, and reduced relative breast yield on Day 35 (P < 0.05). Feeding RP diets increased FI (P < 0.001), increased BWG (P < 0.01) and reduced FCR (P < 0.01) during the grower phase compared with SP diets when birds were challenged with NE. Birds in the RPC+ treatment had a lower overall FCR than did those in the SP+ treatment (P < 0.001). Birds in the RPA+ treatment had similar FI, BWG and FCR to those in the RP+ treatment (P > 0.05).

Conclusions: Collectively, the results showed protective effects of replacing the supplemental Arg with Cit against NE in RP diets, as indicated by higher performance during and after the challenge.

Implications: Feeding the RP diets supplemented with Cit may be part of an effective strategy to reduce reliance on antibiotic growth promoters for controlling NE in broiler chickens.

Keywords: arginine, carcass yield, citrulline, liver, low protein, meat chicken, necrotic enteritis, uric acid.


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