Arginine Requirements for WOD188 Broilers on a Low-Protein Diet: Insights from Growth Performance and Intestine...

The efficacy of low-protein diets, an effective approach to the high-quality protein feed shortage, relies on precisely meeting the amino acid requirements of broilers.

This study aimed to determine the arginine requirement of WOD188 broilers fed low-protein diets and to assess the effects of arginine on growth performance, intestinal function, and nitrogen metabolism.

Experiment 1: WOD188 broilers (29-d-old, male, n = 300) were randomly assigned to a normal-protein diet or 4 low-protein diets with standardized ileal digestible arginine-to-lysine ratios (SID Arg:Lys) of 96%, 107%, 118%, and 128% (6 cages/treatment, 10 broilers/cage). After 13 d, growth performance was recorded and regarded as the primary outcome for evaluating the arginine requirement. Samples of blood, breast muscle, intestine, and chyme were collected for the analysis of serum parameters, meat quality, intestinal morphology, gene/protein expression, and intestinal microbiota. Experiment 2: A total of 90 broilers (35-37-d-old) were fed the same 5 diets and collected excreta to measure nitrogen content. Data were analyzed by one-way ANOVA and regression modeling.

A dynamic requirement model for SID arginine intake (Y) was established as Y = 1.703 × BW^0.70 + 0.750 × body weight gain (BWG). The optimal growth performance and peak nitrogen utilization efficiency were achieved at SID Arg:Lys 107%-115%. Low-protein diets with arginine supplementation decreased meat pH, fecal nitrogen content, serum total protein (TP) and blood urea nitrogen (BUN) concentrations (P < 0.05), while increasing intestinal villus height and NO concentrations (P < 0.05). It also upregulated intestinal CAT-2 mRNA expression, barrier-related protein (ZO-1/ Occludin) expression, and decreased interleukin 10 inflammatory factor concentrations (P < 0.05). The low-protein diet significantly reduced bacterial α-diversity (ACE and Chao1 index, P < 0.05), linear discriminant analysis (LDA) effect size analysis further identified Lactobacillus as key biomarkers LDA score > 2.0, false discovery rate (FDR)-adjusted P < 0.05).

This study established the dynamic arginine requirement model of WOD188 broilers fed the low-protein diet. Dietary arginine enhanced growth performance, carcass traits, and meat quality, while improving intestinal microbiota composition, barrier, and transport function, ultimately elevating nitrogen utilization efficiency.