Genetics of skeletal integrity in meat type chickens

Abstract

Genetic selection in meat-type chickens has led to an impressive improvement of important traits such as growth rate, feed efficiency and meat yield. Unfortunately, this improvement in production performance has led to the increased incidence of metabolic disorders such as leg problems. Furthermore, it has been indicated that the optimal growth and development of the skeleton have been compromised. Leg problems and low quality bones impact negatively the economy of the meat-type chicken industry and also affect the welfare of the birds. Although those skeletal issues have been directly associated with improvement of growth rate, the genetic association among leg problems, bone quality traits and growth rate has not been conclusively evidenced. In order to devise practical breeding strategies it is necessary to ascertain adequately the nature of that genetic relationship. We carried out different analyses to study the genetic basis of leg problems such as tibial dychondroplasia (TD) and varus-valgus deformities (VVD), and several bone quality traits, and studied the genetic association among leg problems, bone quality traits and growth rate. The leg problems and the bone quality traits that we studied have an additive genetic component. It was found that the genetic associations of TD and VVD with growth rate and bone quality traits were weak. The results suggested that genetic selection for growth rate impact negatively some traits that are related with the integrity of leg bones.