Feeding broiler chickens with arginine above recommended levels: effects on growth performance, metabolism, and intestinal microbiota

Abstract

Background: Arginine is an essential amino acid for chickens and feeding diets with arginine beyond the recommended levels has been shown to influence the growth performance of broiler chickens in a positive way. Nonetheless, further research is required to understand how arginine supplementation above the widely adopted dosages affects metabolism and intestinal health of broilers. Therefore, this study was designed to assess the effects of arginine supplementation (i.e., total arginine to total lysine ratio of 1.20 instead of 1.06-1.08 recommended by the breeding company) on growth performance of broiler chickens and to explore its impacts on the hepatic and blood metabolic profiles, as well as on the intestinal microbiota. For this purpose, 630 one-day-old male Ross 308 broiler chicks were assigned to 2 treatments (7 replicates each) fed a control diet or a crystalline L-arginine-supplemented diet for 49 d.

Results: Compared to control birds, those supplemented with arginine performed significantly better exhibiting greater final body weight at D49 (3778 vs. 3937 g; P < 0.001), higher growth rate (76.15 vs. 79.46 g of body weight gained daily; P < 0.001), and lower cumulative feed conversion ratio (1.808 vs. 1.732; P < 0.05). Plasma concentrations of arginine, betaine, histidine, and creatine were greater in supplemented birds than in their control counterparts, as were those of creatine, leucine and other essential amino acids at the hepatic level. In contrast, leucine concentration was lower in the caecal content of supplemented birds. Reduced alpha diversity and relative abundance of Firmicutes and Proteobacteria (specifically Escherichia coli), as well as increased abundance of Bacteroidetes and Lactobacillus salivarius were found in the caecal content of supplemented birds.

Conclusions: The improvement in growth performance corroborates the advantages of supplementing arginine in broiler nutrition. It can be hypothesized that the performance enhancement found in this study is associated with the increased availability of arginine, betaine, histidine, and creatine in plasma and the liver, as well as to the ability of extra dietary arginine to potentially ameliorate intestinal conditions and microbiota of supplemented birds. However, the latter promising property, along with other research questions raised by this study, deserve further investigations.

Keywords: Arginine; Broiler chicken; Growth performance; Metabolism; Microbiota.

Fig. 1

Final body weight (BW, A) and cumulative daily weight gain (DWG, B), daily feed intake (DFI, C), feed intake (FI, D), feed conversion ratio (FCR, E), and mortality (F) of CON and ARG birds in the entire trial (0–49 d). Means of 7 replicates/treatment are the white dots within the box plots or bar plots. ^*P < 0.05; ^***P < 0.001

Fig. 2

White striping (WS, A), woody breast (WB, B), and spaghetti meat (SM, C) incidence and severity in CON and ARG birds at D49. n = 292 and 288 breast fillets for CON and ARG, respectively. Score 0, normal; score 1, mild myopathy; score 2, severe myopathy. Count data were analyzed via Pearson’s Chi-squared test. ^*P < 0.05; ^***P < 0.001; NS, not significant

Fig. 3

Shannon index in the caecal content of CON and ARG birds at D49. Means of 14 birds/treatment are the white dots within the box plots