Effects of an all-natural feed additive on the intestinal integrity, mucosal immunity, and gut microbiome composition of Eimeria-infected broilers

M52 is a natural anticoccidial feed additive that has been shown to help prevent coccidiosis, maintain bird productivity, and has potential as an alternative to ionophores and chemical coccidiostats. This study further evaluated the effects of the product on host anti-Eimeria immunity, gut microbiome composition and intestinal integrity of broilers challenged with experimental coccidiosis. In this 28-d study, day-old Cobb broiler chicks were randomly assigned to 1 of 3 groups: (1) unchallenged control; (2) Eimeria-infected control; and (3) Eimeria-infected + M52 (70 g/MT feed). On d 14. chickens from treatments 2 and 3 were challenged with 100X Bio-Coccivet R Vaccine, a live polyvalent vaccine consisting of sporulated oocysts of 7 Eimeria spp. Peripheral blood mononuclear cell phenotype, ceca-cecal tonsil cytokine mRNA expression, duodenal/jejunum histopathology and gut microbiome of cecal content were examined. Eimeria challenge induced moderate to severe parasitic enteritis manifested with prominent villous hyperplasia, heterophil mucosal infiltration, and hemorrhagic or necrotic foci on d 19. The product markedly reduced these histopathological changes. On d 28, M52 significantly increased the abundance of CD4⁻TCRVβ1⁺, CD8⁻CD28⁺ and CD4⁻TCRVβ1⁺ subsets, which help uphold mucosal immune homeostasis and develop competent mucosal and systemic adaptive immunity when faced with pathogen insults. On d 19, M52 dampened Eimeria challenge-associated upregulation of cecal IL-10, whose immunosuppressive properties can also be exploited by pathogens to facilitate their own survival. Before Eimeria challenge, M52 enhanced the relative abundance of Blautia and L-Ruminococcus genera, 2 short-chain fatty acid producers, and further dampened the impairment on microbiota diversity associated with the subsequent Eimeria challenge. Collectively, M52 treatment promoted a well-balanced immune homeostasis, dampened intestinal damage, and preserved the microbiota diversity, which all contribute to an enhanced resilience to Eimeria spp. challenge.

Key Words: coccidiosis, anti-Eimeria immunity, IL-10, microbiome, intestinal integrity.

Presented at the 9th Symposium on Gut Health in Production of Food Animals, St. Louis, USA, 2021. For information on the next edition, click here.