Interactions of coccidial vaccination status and protein sources in reduced-protein diets: impacts on immune responses and growth performance in broiler chickens

Authors: AJAO, ADELEYE - University Of Georgia; Shanmugasundaram, Revathi; OLUKOSI, OLUYINKA - US Department Of Agriculture (USDA); SELVARAJ, RAMESH - University Of Georgia; OLUKOSI, OLUYINKA - University Of Georgia

Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/28/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: n/a

Technical Abstract: This 42d study aimed to investigate the impact of partially substituting soybean meal (SBM) with canola meal (CM) or corn-DDGS (cDDGS) in reduced-protein (RP) diets on the growth and immune responses of vaccinated or unvaccinated broiler chickens. A total of 1296 Cobb 500 chicks were allocated in a 4×2 factorial arrangement (four diets × with or without vaccination) with 6 replicates/treatments. All chicks received a starter diet from d 0 to 7. Four diets were formulated for the grower (d 7–28) and finisher (d 29–42) phases, namely corn-soybean meal positive control with a 20% crude protein level (PC), the corn-SBM negative control (NC) with a 40 g/kg CP lower than the PC (NC-SBM), the NC diet where 80 g/kg CM replaced 60 g/kg SBM (NC-CM), and the NC diet where 100 g/kg cDDGS replaced 50 g/kg SBM (NC-cDDGS). On d 0, half of the chicks were vaccinated with Coccivac B52 (Merck Animal Health) using a vaccine spray cabinet. Samples for immunological responses were collected on days 7, 13, and 37. There was no significant diet × vaccine for growth performance on d 7, 28, and 42. However, birds fed the NC-SBM had lower (P < 0.05) weight gain and feed intake and a higher FCR than the PC diet on d 28. On day 7, vaccinated birds had higher (P < 0.05) bile anti-Eimeria IgA, macrophage nitric oxide (NO), cecal tonsil CD8+:CD4+ ratio, and IL-8 mRNA levels compared to unvaccinated groups. There were significant diet × vaccine interactions (P < 0.05) on d 13 for bile anti-Eimeria IgA concentrations and IL-1, INF', and LITAF mRNA levels in the cecal tonsils. For bile IgA, there were no treatment differences in the unvaccinated birds, but it was greater (P < 0.05) in PC than in all other treatments in the vaccinated birds. IL-1 mRNA was not different in unvaccinated birds, but NC-DDGS had the lowest (P < 0.05) IL-1 mRNA among the vaccinated birds. Macrophage NO was lower in vaccinated birds and greater (P < 0.05) in NC-SBM compared with NC-DDGS treatments. There were diet × vaccine interactions (P < 0.05) on d 37 for bile anti-Eimeria IgA, cecal tonsil IL-1, and spleen TGFß mRNA levels. Diet differences did not influence bile IgA in the unvaccinated group, but bile IgA was greater (P < 0.01) in PC and NC-SBM than in other diets among the vaccinated birds. In conclusion, although partly replacing SBM with CM or cDDGS in reduced-protein diets had modified immune response, the overall growth performance, especially FCR, was largely unaffected by treatments. Keywords: Reduced protein diets, canola meal, corn DDGS, vaccine, immunology