The first scientific notion to have an impact on genetic selection was the discovery by Gregor Mendel of heredity through single gene effects on the phenotype of living organisms. Already before the start of 'industrial' selective breeding programmes in the 1940s, these principles were applied in poultry breeding: breeding for plumage colour used the same principles as noted by Mendel and selective breeding from superior parents to produce improved offspring was commonly applied by poultry breeders. At the same time reproductive technologies such as artificial incubation and hatching, lighting programmes to enable year round reproduction, and artificial insemination were being developed and introduced into poultry breeding programmes.
Another milestone in genetic selection was the development and application of the theory of quantitative genetics. This theory regards the animal as a black box with many genes contributing to the expression of all traits that can be measured. For every gene two copies are inherited from the parents, one from the mother and one from the father, and for the total genetic value this means that every offspring effectively samples fifty percent of its value from each of its parents.
Today's poultry breeding programmes all apply full pedigree-ing of all birds and exploit BLUP-breeding value estimations to obtain the best possible identification of superior breeding candidates. Obviously, the parents of the next generation have to be identified as early as possible (to minimise the generation interval) and genetic selection has to be devoted with the right emphasis to the right traits as demanded by the market.
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Article made possible through the contribution of ISA Hendrix Genetics.