Bacterial Chondronecrosis with Osteomyelitis in Broilers: Etiology and Selected Mitigation Measures

Abstract

Bacterial chondronecrosis with osteomyelitis (BCO) is the predominant cause of lameness in broiler chickens. It mainly impacts broiler production and animal welfare, causing substantial financial losses accounting for 1- 2% due to bird condemnations at the marketing age. Remediating BCO lameness disease demands investigating its causes using appropriate models and evaluating preventive measures, such as enhancing epithelial tissue health and tight junction integrity in the digestive and respiratory tract, strengthening immune functions, and improving bone strength. Therefore, the objectives of this dissertation were to 1) study predisposing factors for BCO lameness by investigating the effects of deoxynivalenol (DON) and fumonisin (FUM) mycotoxins contamination on BCO lameness by exposing broilers reared on wire (W) and litter flooring (L) to diets contaminated with mycotoxins (MTX), 2) determine the efficacy of adding different combinations of 1,25-Dihydroxyvitamin D3-glycoside (G-1,25(OH)2D3) and phytogenic antioxidants on improving bone and gut health and the immune system 3) investigate the optimal timing for adding Availa® ZMC to broiler diets to mitigate BCO lameness, reduce feed additive costs, and effectively protect against BCO lameness. As a result, the findings in this dissertation include three main significant areas. First, increasing the incidence of BCO lameness using mycotoxins due to increasing intestinal permeability supports a correlation between intestinal barrier integrity and BCO lameness and suggests that DON and FUM mycotoxins are predisposing factors for increasing BCO. Second, no significant difference in protection against BCO when supplementing 1.0 µg G-1,25(OH)2D3 individually or in conjunction with polyherbal mixtures or Thyme oil. In addition, increasing the G-1,25(OH)2D3 dosage from 1.0 µg/kg to 10 µg/kg did not yield a lower lameness incidence beyond the low dosage. Finally, incorporating 0.15% Availa® ZMC supplementation into the broiler diet during the initial 28 days is considered ideal for the 0.15% Availa® ZMC dose compared to adding 0.15% Availa® ZMC for the entire production cycle. In conclusion, this collection of studies provides valuable insights into understanding the etiology of BCO lameness and finding possible ways to prevent and remediate its occurrences.