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

Abstract

Bacterial chondronecrosis with osteomyelitis (BCO) is a septic necrosis of the skeletal system of unknown origin and an important cause of lameness in broiler chickens. Epithelial inflammation has been proposed as an avenue for bacterial translocation leading to BCO. We evaluated the effect of subclinical necrotic enteritis (SNE), an intestinal inflammatory event, with the development of BCO. In each of two experiments, chickens were divided into three treatments: 1) SNE challenge, including both dietary (wheat- and fish-based diet) and intestinal pathogenic challenges (Eimeria maxima and Clostridium perfringens), 2) dietary challenge only, and 3) control diet (corn- and soy-based diet). Floor ramps were introduced as part of an established method for increasing the frequency of BCO. The efficacy of the SNE challenge was corroborated by necropsy evaluation of a representative sample of the population. At the end of each experiment, all birds were evaluated for BCO. A high incidence of BCO was found, even in birds with no external signs of lameness. However, the incidence of BCO was not correlated with the intestinal challenge. Conclusions: under the conditions used in these studies, a treatment that is associated with severe damage to the intestinal mucosa does not change the incidence of BCO in broiler chickens.

Keywords: Bacterial chondronecrosis with osteomyelitis (BCO); enteritis model; femoral head necrosis; necrotic enteritis; skeletal stress model.

Figure 1

Bacterial chondronecrosis with osteomyelitis classification: (a) transitional femoral head chondronecrosis; (b) complete femoral head chondronecrosis; (c) proximal tibial head chondronecrosis.

Figure 2

Incidence of subclinical necrotic enteritis (SNE) during Experiments 1 and 2. Randomly selected birds from each treatment group were necropsied at 31 days of age (Experiment 1, 9 birds/group; Experiment 2, 5 birds/group). Asterisks (*) denote statistically significant differences (p < 0.05) in the incidence of SNE between the Challenge Diet + Infected and Challenge Diet groups.

Figure 3

Incidence of bacterial chondronecrosis with osteomyelitis (BCO) for Experiments 1 (day 50) and 2 (day 59). For both experiments, there was no significant effect of treatment on the incidence of BCO.