Growth performance and immune response during active Eimeria infection are modified by dietary inclusion of canola meal or corn-DDGS in reduced-protein corn-soybean meal diets

Authors: Shanmugasundaram, Revathi; ADELEYE, AJAO - University Of Georgia; FATHIMA, SHANA - University Of Georgia; OLADEINDE, ADELUMOLA - US Department Of Agriculture (USDA); SELVARAJ, RAMESH - University Of Georgia; APPLEGATE, TODD - University Of Georgia; OLUKOSI, OLUYINKA - University Of Georgia

Submitted to: Animal Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2024
Publication Date: 8/7/2024
Citation: Shanmugasundaram, R., Adeleye, A.M., Fathima, S., Oladeinde, A., Selvaraj, R., Applegate, T.J., Olukosi, O.A. 2024. Growth performance and immune response during active Eimeria infection are modified by dietary inclusion of canola meal or corn-DDGS in reduced-protein corn-soybean meal diets.. Animal Nutrition. (19); 1-15. https://doi.org/10.1016/j.aninu.2024.05.007.
DOI: https://doi.org/10.1016/j.aninu.2024.05.007

Interpretive Summary: Coccidiosis causes financial losses to the poultry industry. Higher levels of dietary crude protein can worsen the severity of coccidiosis in broiler chickens. Conversely, using diets with reduced crude protein (RP) can enhance the immune responses of these chickens. The choice of plant protein source, such as soybean meal (SBM), canola meal (CM), or corn-distillers dried grains with solubles (cDDGS), also plays a significant role in this context. The study aimed to compare the effects of including these protein sources in RP diets for broiler chickens challenged with coccidiosis. The results revealed a significant interaction between the diet and coccidia challenge on various immune parameters. Specifically, reducing the crude protein content of the grower diet by 4% (from 20% to 16%), achieved by reducing the SBM content of the diet, did not negatively impact the host immune response to the Eimeria challenge. While reducing crude protein content in the diet appeared to enhance the IgA response, further reductions in SBM and supplementation with CM and cDDGS may have adverse effects on antibody production. However, the production of IFN-', a critical factor in combating coccidial infections, was not compromised by the dietary changes. This underscores the importance of careful dietary formulation to optimize immune responses in poultry facing coccidial challenges. However, partial replacement of SBM with CM and cDDGS was found to impair the host immune response in the study. These findings emphasize the intricate relationship between dietary factors, immune responses, and the metabolic demands of the immune system during infections.

Technical Abstract: High dietary crude protein concentrations increase coccidiosis severity, and reduced-crude protein (RP) diets can improve the broiler’s immune responses, which may depend on the plant protein source. The objective of this study was to compare the effects of soybean meal (SBM), canola meal (CM), or corn-DDGS (cDDGS) inclusion in RP diets for Eimeria-challenged broilers. A total of 1120 broiler chicks were distributed in a 4 × 2 (four diets × with or without challenge) factorial arrangement in seven replications. The four dietary treatments, fed between 7 and 28d, were (i) a standard diet with 20% crude protein (SP); (ii) RP (16%) corn-SBM (RP-SBM); (iii) a RP diet in which 8% CM replaced 6% SBM (RP-CM); and (iv) a RP diet in which 10% cDDGS replaced 5% SBM (RP-cDDGS). On d15, birds were challenged with mixed Eimeria (+E) oocysts. Samples were collected on d21, and the data were analyzed by a two-way ANOVA. There was a significant diet × Eimeria challenge interaction (P < 0.05) on bile anti-Eimeria IgG concentrations, splenocyte proliferation, macrophage nitric oxide (NO) production, and cecal tonsil IL-17 mRNA amounts. Birds in the RP-SBM +E group had higher (P < 0.05) bile anti-Eimeria IgG concentrations compared to the SP +E group. Within the E+ group, birds in the RP-SBM +E group had higher (P < 0.05) macrophage NO than the other groups. Birds in the RP-SBM +E group had higher (P < 0.05) IL-17 mRNA amounts in the spleen and cecal tonsils compared to the other treatment groups. Birds in the RP-cDDGS +E group had a lower (P < 0.05) CD8+:CD4+ ratio compared to the RP-SBM+E group. It can be concluded that reducing the crude protein content of the grower diet by 4% (from 20% to 16%), achieved by reducing the SBM content of the diet, did not impair the host immune response to the Eimeria challenge. However, partial replacement of SBM with CM and cDDGS impaired the host immune response.