ABSTRACT
The genetic selection of poultry has relied on the skills of pragmatic breeders throughout human history. During the past 100 years, this pragmatism has been guided by an increasing body of information describing the physiological systems that have been altered by selection for morphology and phenotype. During the past several years, information has been obtained about the physiological systems that control the passage of genetic information from one generation to the next. This information includes the reproductive biology and embryology of the bird, the cytological structure and organization of genetic information in birds, and the physiology of the systems that are controlled by the genetic code. This information has facilitated the development of many techniques to assist the breeder in the selection of genetic variants from either existing populations or from combinations of genetic material from other sources. This information is likely to reduce the constraints of sexual reproduction on the recombination of genetic material that directs physiological processes from which benefit can be derived.
