Impact of a postbiotic containing saponin, with or without vaccination, on the mitigation of colibacillosis in broilers challenged with avian pathogenic Escherichia coli serotype O78

      

Avian pathogenic Escherichia coli (APEC) cause colibacillosis in poultry operations resulting in significant flock health and economic burden, creating the need for additional solutions to promote resiliency against infection. This study evaluated a postbiotic feed additive containing a saponin ingredient (SCFP+; Dia-V™ PT_PLUS prototype, Diamond V, Cedar Rapids, IA), alone or in combination with vaccination, to ameliorate the severity of colibacillosis in broilers intratracheally challenged with APEC O78. Six hundred male broilers were randomly allocated across five treatment groups consisting of 4 pen replicates with 30 birds per pen. Birds were fed a basal diet and challenged birds fed the diet either supplemented with SCFP+ or not and administered a vaccine or not with challenge on Day 28. Necropsy, lesion scoring, and tissue samples were collected on Day 35 (n=5/pen) and remaining birds on Day 42. Tissues were analyzed for E. coli load with random isolate characterization by PCR. Data were analyzed in SAS v9.4 with Treatment as fixed effect and pen nested within block as a random effect. Day 35 mean lesions scores for perihepatitis, pericarditis and air sacculitis were numerically improved by all treatments. SCFP+ alone significantly reduced perihepatitis lesions over the challenged control (1.15 vs. 1.80; P=0.043) and approached significance for pericarditis (0.95 vs. 1.55; P< 0.10) with numerical improvement in air sacculitis (1.25 vs. 1.75). Vaccination alone numerically improved perihepatitis (1.35) and pericarditis (1.30) and approached significance for air sacculitis (1.20; P< 0.10). SCFP+ with vaccine numerically improved perihepatitis (1.25), pericarditis (0.90) and air sacculitis (1.20) scores all approaching significance (P< 0.10). Cumulative mean lesion scores were lowest for SCFP+ with and without vaccine both approaching significance. SCFP+ treatment resulted in lower mean APEC load in liver and lung tissue and % positive heart swabs. No treatment differences were observed in recovered birds at D42 and all treatments numerically improved livability over challenged control. These data suggest SCFP+, alone or in combination with vaccination, may be a viable, non-antibiotic solution to support reduction in the severity of colibacillosis in broilers.

Key Words: colibacillosis, postbiotic, saponin, broiler, vaccination.