The Role of Dietary Supplementation of Yeast Cell Walls in Response to aInoculation in Broiler Chickens.

Abstract

Controllingduring broiler production is a topic of interest from a public health standpoint, as colonized birds can contaminate poultry products during processing and sicken humans if not properly cooked or handled before consumption. The aim of this study was to evaluate dietary yeast cell wall (YCW) as a potential alternative to antibiotic growth promoters with or without achallenge. A total of 2240 day-old Ross 708 males were randomly assigned within 8 experimental groups with a 4 × 2 factorial design, with 4 diets (negative control [CTL-], positive control [CTL+, bacitracin, 50 g/ ton], YCW constant dose [400 g/ton], and YCW step-down dose [SD, 800, 400, and 200 g/ton in the starter, grower, and finisher periods, respectively]) and with or without a Day-16oral gavage challenge at a 10-colony-forming-units (CFU)/ml dose. Body weights and feed consumption were measured on Days 0, 14, 28, and 41 to determine broiler performance. Ileum tissue samples were collected from 24 birds per treatment on Days 17 and 24 (1 and 8 days postinoculation [PI]) for relative gene expression (RGE) analysis. Cecal content samples were collected from 24 birds per treatment on Days 24, 34, and 42 forenumeration and prevalence calculation. A total of 80 birds per treatment were processed to determine carcass yield on Day 44, and on Day 45, 16 carcass rinsates per treatment were collected forenumeration and prevalence calculation. The interaction between diet and inoculation did not influence growth performance (> 0.05). However, a diet effect was observed in the starter period where birds fed SD diet had a lower feed conversion ratio than birds fed CTL- diet (= 0.0165). Additionally, the treatment of birds inoculated withfed with SD had a trend to a lower feed conversion ratio during the grower period (= 0.0550). The RGE of interleukin 1β and interleukin 10 was similar in all treatments 1 and 8 days PI. The RGE of avian beta defensin 10 was similar in all treatments on Day 1 PI, but different on Day 8 PI (= 0.0476). All birds inoculated withhad similar CFU per milliliter counts in the cecal contents at Days 24, 34, and 42 (> 0.05), and all birds inoculated with phosphate-buffered saline were negative forafter prevalence testing. After processing 1) carcass yield was similar in all treatments (> 0.05); 2)-inoculated birds fed CTL- had lower CFU per milliliter counts than birds provided CTL+ and constant-dose diets (= 0.0383); and 3) all birds inoculated with PBS were negative for. Overall, under the conditions of this study, the addition of YCW during achallenge did not have an impact on growth performance, innate immune response, cecal colonization, carcass yield, or carcass colonization after processing.