Relationships between the bone pathologies, ash and mineral content of long bones in 35-day-old broiler chickens.

Histological examinations and estimations of the contents of ash, phosphorus and calcium were used to investigate the femora and tibiotarsi from lame and normal 35-day-old broilers from Holland, Northern Ireland and Scotland. The prevalence of different pathologies varied with the source of the broilers and there were correlations between histological and bone ash values. The most common condition causing lameness was bacterial infection within the physis and cartilaginous epiphysis (bacterial chondronecrosis) of the proximal tibiotarsus, and there was a possible link between rickets attributable to a relative phosphorus deficiency and this condition. There were wide variations between birds in the cortical bone quality as assessed histologically and by estimates of the bone ash content and phosphorus to calcium ratios. Theses variations may be related to different probabilities of bone fracture.