Effect of reduced-crude protein diets on ileal amino acid digestibility and relative nutrient transporter gene expression in broiler chickens during coccidial challenge.

Authors: YOON, JUNE HYEOK - University Of Georgia; AJAO, ADELEYE - University Of Georgia; Shanmugasundaram, Revathi; Oladeinde, Adelumola; OLUKOSI, OLUYINKA - University Of Georgia

Submitted to: International Poultry Scientific Forum
Publication Type: Abstract Only
Publication Acceptance Date: 11/27/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: N/A

Technical Abstract: The objective of the study was to investigate the effect of reduced-crude protein (RCP) diets with soybean meal (SBM), canola meal (CM), or corn-dried distiller’s grains with solubles (cDDGS) on growth-phase-related ileal amino acid (AA) digestibility and relative gene expression of protein synthesis and degradation in pectoralis major of broiler chickens under coccidiosis vaccination. A total of 1,296 male chicks were allocated in a 4 × 2 factorial arrangement (diet × vaccination) with 6 replicates. All birds were fed a starter diet from d 0 to 7. Four experimental diets were formulated for the grower (d 7-28) and finisher (d 28-42) phases, namely positive control (PC) corn-SBM-based diet, with 200 or 180 g/kg CP for the grower and finisher phases, respectively, corn-SBM negative control (NC) with 40 g/kg CP lower than PC (NC-SBM), an NC diet where 80 g/kg CM replaced 60 g/kg SBM (NC-CM), and an NC diet where 100 g/kg cDDGS replaced 50 g/kg SBM (NC-cDDGS). All diets were isocaloric and formulated to have similar digestible AA concentrations. On d 0, half of the birds were vaccinated with Coccivac B52. Ileal digesta were collected from 2 birds per pen and pooled to generate 6 independent digesta samples for the non-vaccinated and vaccinated groups on d 7. Ileal digesta on d 15 and 23 were collected from 5 birds per pen. Jejunal tissue and pectoralis major muscle were collected on d 23 for relative gene expression of nutrient transporter and protein synthesis and degradation, respectively. On d 7, vaccination numerically decreased the ileal AA digestibility. The ileal digestibility of N, His, Ile, Lys, Phe, and Val in NC-cDDGS was lower (P < 0.05) compared to the PC diet on d 15. There was no interaction effect on ileal AA digestibility on d 23; the ileal digestibility of N, His, Ile, Lys, and Phe in NC-CM and NC-cDDGS was lower (P < 0.05) than in the PC diet. There were no treatment differences in the relative gene expression of jejunal peptide and AA transporter, however, protein synthesis gene (EIF4EBP1) expression was lower (P < 0.05) in the vaccinated group compared to the non-vaccinated group. on d 23. In conclusion, reduced-CP diets with CM and cDDGS may lead to lower ileal AA digestibility compared to the standard-protein diet. However, protein synthesis and degradation genes in the pectoralis were not affected by the dietary treatments, irrespective of the coccidiosis vaccination. Keywords: Reduced Protein, Digestibility, Vaccination, Coccidiosis, Broiler