Response of broiler chickens vaccinated against coccidiosis to diets containing varying amino acid density and a nucleotide-rich extract during the pre-starter and starter periods

Abstract

Growth depression is often associated with coccidial vaccinations used to suppress coccidiosis in broiler chickens. Dietary strategies such as amino acid (AA) modulation have shown promise in mitigating the negative impacts of coccidiosis. Additionally, nucleotide supplementation may support immune and digestive functions in young broilers, potentially enhancing their resilience to infections. The current study investigated the interactive effects of dietary AA density and nucleotide supplementation on growth response and processing yields of broilers vaccinated against coccidiosis. One thousand eight hundred male broiler chicks were assigned to 10 dietary treatments each with 9 replicate pens and 20 birds per pen. Eight dietary treatments contained two levels of AA density; “low” (1.20/1.15 %) or “high” (1.35/1.25 %) digestible Lys during the pre-starter and starter phases, respectively and included nucleotide supplementation in either, both, or neither phase. Two additional diets, containing low or high AA density without nucleotide supplementation were fed to unvaccinated chicks as positive controls. There was no interaction between AA density and nucleotide supplementation on growth or nitrogen digestibility under coccidia challenge. Broilers fed higher AA density had improved weight gain and FCR during the starter period. Nucleotide supplementation enhanced gut health by reducing intestinal lesions in birds receiving high AA diets. Higher AA density improved processing yield at d 41 but was associated with increased incidence of footpad lesions. Overall, our findings suggest that increased AA density supports growth and carcass traits in vaccinated broilers, but strategic use of nucleotide supplementation may help modulate gut health during periods of intestinal stress.