Chondronecrosis with osteomyelitis in broilers: Further defining a bacterial challenge model using the wire flooring model

Abstract

Lameness in broiler chickens is a significant animal welfare and financial issue. Bacterial chondronecrosis with osteomyelitis (BCO) leading to lameness can be enhanced by rearing young broilers on wire flooring. Using the wire floor system, we identified Staphylococcus agnetis as the predominant isolate in BCO of the proximal tibiae and femora, and blood of lame broilers. Administration of S. agnetis isolates in water can induce lameness. We now report that the wire floor system increases bacterial translocation into the blood stream. We have also determined that approximately 10 CFU/mL is the minimum effective dose in the drinking water and that challenge at 10, 20, or 30 days of age produces similar incidences of lameness. BCO isolates of S. agnetis are much more effective than other Staphylococcus species and can overwhelm the protective effects of some commercial probiotics. Finally, we also demonstrated that the BCO lameness induced by administration of S. agnetis in the drinking water is transmissible to unchallenged broilers in the same pen.

A Review of Current Knowledge on Staphylococcus agnetis in Poultry

“…Basic media for staphylococcal samples are 5% blood agar (bovine or ovine blood), Müller–Hinton, or Trypticase Soy agar supplemented with blood [ 3 , 41 , 49 , 56 ]. In some cases, CHROMagar Orientation (DRG International, Union County, NJ, USA) has been used as a medium to initially differentiate cultured colonies [ 40 , 59 ].…”

“…S. agnetis has been primarily associated with bovine mastitis [ 49 , 51 , 52 , 53 , 54 , 55 , 57 ]. Since 2015 it has been identified as an etiological factor responsible for bacterial chondronecrosis with osteomyelitis (BCO) [ 40 , 59 ], endocarditis and septicemia in broiler chickens ( Gallus gallus domesticus ) [ 41 ] ( Table 3 ).…”

“…In those cases, bacteria were not cultured from blood samples, which indicated that bacteria in the bone did not originate from a generalized (systemic) infection [ 40 ]. One isolate out of 81 was designated as S. agnetis strain 908 and chosen by Al-Rubaye et al [ 40 ] for detailed analyses and further studies [ 59 ].…”

“…It was confirmed that administration of live S. agnetis (strain 908) into drinking water induces high incidences of lameness (>50%) in broilers when combined with the wire flooring model [ 40 , 59 ]. Even though inoculation with S. agnetis happened early in the chicks’ lives, the first lame birds became identifiable only from day 35, which means that BCO lameness can be induced by exposing birds to S. agnetis at an early age [ 59 ].…”

Incidence of Bacterial Chondronecrosis with Osteomyelitis (Femoral Head Necrosis) Induced by a Model of Skeletal Stress and its Correlation with Subclinical Necrotic Enteritis

“…Oral inoculation with E. cecorum leads to a greater incidence of vertebral BCO in broilers, as compared to air sac or intravenous exposure routes [12], although this effect may be dose-dependent. Administration of S. agnetis in the drinking water increases the incidence of BCO in birds subjected to a "wire floor" gait instability model [13]. Moreover, administration of oral probiotics reduces the incidence of BCO [10].…”