Assessing the Impact of Spraying an Enterococcus faecium-Based Probiotic on Day-Old Broiler Chicks at Hatch on the Incidence of Bacterial Chondronecrosis with Osteomyelitis Lameness Using a Staphylococcus Challenge Model

Bacterial chondronecrosis with osteomyelitis (BCO) lameness is a bone disease characterized by the translocation of bacteria from the gastrointestinal tract, which colonize microfractures in broiler leg bones caused by rapid animal growth rate and weight gain, resulting in lameness. As such, BCO lameness represents a significant challenge for the poultry industry. This study aims to evaluate the effect of spraying broiler chicks on d0 at hatch with an Enterococcus faecium probiotic on the incidence of BCO-induced lameness, utilizing a Staphylococcus aureus challenge model. There were four treatments: (1) negative control (no probiotic + no challenge, NC); (2) positive control (no probiotic + challenge, PC); (3) low dosage (4.0 × 108 CFU/chick + challenge, LOW); and (4) high dosage (2.0 × 109 CFU/chick + challenge, HIGH). On d5, groups two through four were challenged with Staphylococcus aureus through the drinking water at a concentration of 1.0 × 105 CFU/mL. Cumulative lameness incidence was determined through daily evaluations and necropsies conducted on lame birds starting from d22. Data were subjected to a binomial general regression analysis (significant p < 0.05). On d56, the PC group exhibited the highest cumulative lameness incidence (58.0%; p < 0.05), followed by LOW (36.0%), HIGH (28.7%), and NC groups (25.3%), respectively. These results suggest early probiotic application at day-of-hatch successfully reduced the incidence of lameness in challenged birds, thus contributing to understanding of efficient and sustainable broiler production.

Deoxynivalenol and fumonisin predispose broilers to bacterial chondronecrosis with osteomyelitis lameness

Bacterial chondronecrosis with osteomyelitis (BCO) lameness is the most critical animal health and welfare issue facing the broiler industry worldwide. It is estimated that 1 to 2% of bird condemnation at marketing age is caused by BCO lameness, resulting in tens of millions of dollars in annual losses. Fast-growing broilers are prone to mechanical stress that triggers bacterial translocation across epithelial barriers into the bloodstream, followed by bacterial colonization in the growth plate of long bones, and eventually, bone necrosis and lameness. Mycotoxins (MTX) are secondary metabolites produced naturally by microfungi, of which deoxynivalenol (DON), fumonisin (FUM), and zearalenone are the most prevalent in corn and soybean-meal-based diets. The presence of these mycotoxins in feed has been proven to reduce the barrier strength of the intestinal tracts and trigger immunosuppressive effects. In this study, we investigated the effects of the DON and FUM-contaminated feeds on the incidence of BCO lameness in broilers reared in both wire- and litter-floors. 720 one-day-old broiler chicks were assigned to the 2 × 2 factorial design: 2 MTX diets containing DON and FUM on wire flooring (MTX-W) and litter flooring (MTX-L), and 2 diets without MTX contamination on control wire flooring (CW) and control litter flooring (CL). Throughout the trial, the cumulative incidence of lameness per treatment was assessed by necropsying the lame birds. Birds in the MTX-W group had a higher incidence of lameness compared to those in CW (73.3% vs. 62.0%) (P < 0.05), and birds in the MTX-L group had a higher incidence of lameness compared to birds in CL (54.0% vs. 34.0%) (P < 0.05). MTX elicited net increases in BCO to a greater degree on litter (+20%) than on wire flooring (+12%). The increased incidence of BCO lameness in the MTX-W coincided with increased intestinal permeability supporting a correlation between intestinal barrier integrity and BCO lameness. To conclude, DON and FUM are predisposing factors for increasing BCO. However, no significant interaction exists between the diet and floor types in inducing lameness in broilers.

Inducing experimental bacterial chondronecrosis with osteomyelitis lameness in broiler chickens using aerosol transmission model

Lameness disease attributed to bacterial chondronecrosis with osteomyelitis in broilers affects production, animal welfare, and food safety in the poultry industry. The disease is characterized by necrotic degeneration of the rapidly growing femora and tibiae due to bacterial translocation from the respiratory or gastrointestinal tracts into the blood circulation, eventually colonizing the growth plate of the long bones. To investigate the etiology, pathogenesis, and intervention measures for BCO, developing an experimental model that reliably induces BCO lameness is of the utmost importance. In the past, we have employed a wire-flooring model and a litter-flooring model administered with a bacterial challenge to investigate strategies for mitigating BCO. However, multiple issues on labor-intensive barn setup and cleanout efforts for the wire-flooring system and concern of direct pathogenic exposure to the broilers for the litter-flooring models rendered these research models less effective. Thus, we investigated a new approach to induce experimental BCO lameness using an aerosol transmission model employing a group of birds reared on wire-flooring pens as a BCO infection source, and the disease is further disseminated through the airborne transmission to other birds reared on litter flooring in the same housing environment. The effectiveness of the aerosol transmission model in inducing BCO lameness was concluded from 4 independent experiments. The cumulative lameness generated from the BCO source group on the wire floors versus negative control treatments on the litter floors from Experiments 1, 2, 3, and 4 were 84% vs. 69.33%, P = 0.09; 54.55% vs. 60%, P = 0.56; 78% vs. 73.50%, P = 0.64; 81% vs. 74.50%, P = 0.11. Overall, the cumulative lameness generated from the wire floors was successfully transmitted to the birds on litter floors without significant statistical differences (P > 0.05). The effectiveness of the aerosol transmission model for experimentally triggering BCO lameness provides a reliable system for evaluating practical intervention strategies for BCO lameness in broilers.