The future of molecular genetics in poultry breeding

Effectively, poultry breeding started when the chicken was domesticated thousands of years ago. Through human intervention many different breeds evolved over the centuries, but breeders began to use scientifically based selection methods less than a century ago. Mendel discovered the working of single genes and the chicken was one of the first species in which this basic concept was applied, e.g. in the selection methods for plumage colour. Industrial poultry breeding for production traits, however, is mostly based on quantitative genetics theory, which was largely developed for selective breeding of large farm animals such as cattle and pigs. Nevertheless, poultry breeding always led in the exploitation of knowledge of single genes such as those for plumage colour and for sex linked traits that can be used for sexing of day old chicks. Quantitative genetic methods effectively regard the animal as a black box with many genes contributing to the expression of all traits under selection. Molecular genetics is now opening this black box by elucidating the effect of single genes on the phenotypic expression of traits. As breeding deals with identifying and exploiting the genetic basis of phenotypes, there is no doubt whatsoever that the use in breeding of knowledge of molecular genetics , i.e. molecular breeding, will totally change our current practices of selective breeding in poultry breeding. In addition, it is likely to also affect the role of the poultry breeding industry in poultry production. The only relevant qualification of this prediction is on the time scale. We predict that methods of assessing genetic variability at the genome level (DNA) rather than at the phenotypic level (measuring traits in animals) will be the basis of selective breeding within ten years. This will affect the structure of breeding programmes and also impact the integration of breeding in the poultry production system. The new knowledge of the molecular basis of poultry phenotypes that is generated along the way will be used to engineer and re-design the poultry genome with novel technologies, and genetically engineered poultry breeds will be marketed within twenty years from today. ___________________________________________________________________________