Genes controlling feathering and plumage colour

Feathers are probably the most complex derivatives of the integument to be found in any vertebrate and they are certainly one of the most striking anatomical features of birds. They are of great importance both to the poultry fancier and to the commercial poultryman. For the former much of the emphasis in breeding is to obtain a plumage pattern agreed upon by the ‘experts’ as the standard. For the commercial poultryman the feathers are important for two reasons: (i) since they are approximately 90% protein they represent a dietary protein input which will not be recovered at the end of the day as edible protein, (ii) they may also be a useful indicator of the growth rate and the sex of the bird. In this chapter both the structure and distribution of feathers are considered, and also the colours of the plumage. Although there has been quite a lot of research into the genes controlling feathering and plumage colour they are still, by general genetic standards of the 1990s, not well understood. There are are some instances where the genes controlling certain characters are well established, their alleles known, their dominance relations understood, and the genes in question have been mapped, but there are many other examples where it is not yet clear how many genes control a particular character and how they interact.