The effects of arginine and branched-chain amino acid supplementation to reduced-protein diet on intestinal health, cecal short-chain fatty acid profiles, and immune response in broiler chickens challenged with Eimeria spp.

Authors: LIU, GUANCHEN - University Of Georgia; AJAO, ADELEYE - University Of Georgia; Shanmugasundaram, Revathi; TAYLOR, JAMES - Agri-Food And Biosciences Institute; BALL, ELIZABETH - Queens University - United Kingdom; APPLEGATE, TODD - University Of Georgia; SELVARAJ, RAMESH - University Of Georgia; KYRIAZAKIS, ILIAS - Agri-Food And Biosciences Institute; OLUKOSI, OLUYINKA - University Of Georgia; KIM, WOO - University Of Georgia

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2023
Publication Date: 5/9/2023
Citation: Liu, G., Ajao, A.M., Shanmugasundaram, R., Taylor, J., Ball, E., Applegate, T.J., Selvaraj, R., Kyriazakis, I., Olukosi, O.A., Kim, W.K. 2023. The effects of arginine and branched-chain amino acid supplementation to reduced-protein diet on intestinal health, cecal short-chain fatty acid profiles, and immune response in broiler chickens challenged with Eimeria spp.. Poultry Science. 102 (7): 1-17. https://doi.org/10.1016/j.psj.2023.102773.
DOI: https://doi.org/10.1016/j.psj.2023.102773

Interpretive Summary: Coccidiosis causes financial losses to the poultry industry. Anticoccidial drugs can be used to prevent coccidiosis. However, consumer preference for antimicrobial-free-poultry production necessitates identification of alternative to antimicrobials. One promising solution is through nutritional interventions, such as amino acids. Amino acids can minimize intestinal damage and facilitate recovery during coccidial infection. Arginine is an essential amino acid, is important for the growth and development of broiler chickens and plays an important role in stimulating immune system. Leucine, isoleucine, and valine are also essential amino acids. Leucine, isoleucine, and valine stimulate immune response and intestinal health. Lowering the protein content in broiler diets saves cost because of protein is the most expensive component of poultry diet. But lowering protein content will lead to amino acid imbalance and can increase the severity of coccidial infection. This study hypothesized that supplementations of arginine, leucine, isoleucine, and valine in reduced-protein diets could improve intestinal integrity and immune responses of broilers during coccidial infection. Our findings identified that feeding a reduced-protein diet to infected birds increased intestinal damage and therefore, increased the severity of coccidiosis. However, arginine, leucine, isoleucine, and valine supplementation partially reversed the negative effects of low protein diet. Arginine, leucine, isoleucine, and valine supplementation exerted beneficial effects on the immune response of broilers.

Technical Abstract: We investigated the effects of supplementing arginine and branched-chain amino acids (BCAA) in broilers fed reduced-protein diets and challenged with Eimeria spp. All birds were fed the same starter diet meeting Cobb 500 nutrient specifications from d1-9. Four grower diets: positive control (PC) with 18.5% crude protein (CP); reduced-protein negative control (NC) with 16.5% CP; or NC supplemented with arginine or BCAA at 50% above recommendations (ARG or BCAA) were fed to the birds from d9-28. Birds were allocated in a 2 × 4 factorial arrangement (4 diets, each with or without challenge), with 8 replicates per treatment. On d14, the challenge groups were orally gavaged with mixed Eimeria spp. Intestinal permeability was higher (P < 0.05) in NC than PC, whereas the permeability of ARG and BCAA groups did not differ significantly from PC. On d28, a significant interaction (P < 0.01) was observed in CD8+: CD4+ ratios in cecal tonsils (CT), Eimeria challenge increased the ratios in all groups except for the ARG group. On d21, a significant interaction was found for CD4+CD25+ percentages in CT (P < 0.01) that Eimeria challenge increased the percentages only in PC and NC groups. On d21 and 28, significant interactions (P < 0.01) were found for macrophage nitric oxide (NO) production. In non-challenged birds, NO was higher in the ARG group than other groups, but in challenged birds, NO was higher in both ARG and BCAA groups. On d21, a significant interaction was found for bile anti-coccidial IgA concentrations (P < 0.05) that Eimeria challenge increased IgA only in NC and ARG groups. The results suggest that a reduced-protein diet exacerbates the impact of the Eimeria challenge on intestinal integrity, but this could be mitigated by arginine and BCAA supplementations. Arginine and BCAA supplementations in reduced-protein diets could be beneficial for broilers against Eimeria infection by enhancing the immune responses. The beneficial effects of arginine supplementation tended to be more pronounced compared to BCAA supplementation.