The inheritance of tibial dyschondroplasia in broilers.

A breeding programme to develop a line of chickens with a high incidence of tibial dyschondroplasia (TD) from Australian broiler stock is described. Despite the absence of a control flock, this programme has demonstrated that selection in a broiler population can rapidly increase the incidence of TD. There was consistent circumstantial evidence of the presence of a major sex-linked gene, the recessive allele of which is associated with an increased incidence of TD. The realised heritability estimates (obtained in the absence of a control flock) consistently exceeded 1.00, suggesting the presence of an environmental trend favourable to the onset of TD over the four generations of this investigation. There was a high maternal component or dominance genetic component, or both, for the inheritance of TD in the final generation, suggesting that environmental factors associated with the female parent line may influence the incidence of TD in broilers.