Bantamisation of traditional Dutch chicken breeds generated additional genetic diversity
17 april 2018
The traditional Dutch chicken breeds are of ornamental and cultural-historical importance. Population size of these breeds is small. In the last decades miniaturising of existing large chicken breeds has become popular.
The 60K SNP array was used to characterise the genetic diversity, demographic history, and level of inbreeding of Dutch heritage chicken breeds, and particularly of the bantam breeds. Results of the study were published in Heredity.
The study concluded that bantamisation has generated additional and identifiable genetic diversity. However, this diversity can only be preserved through structured breeding programmes. At the same time a high proportion of alleles was found to be shared between large fowls and neo-bantams, suggesting gene flow during neo-bantam development.
By mixing different breeds, hobby breeders have created bantam chickens showing the original large breed characteristics. The neo-bantam breeds are considered as new breeds, but with a high portion of shared alleles with the large breeds. The study also showed that the bantamisation trend has changed over time. In the early stages of bantamisation large fowls and true bantams were used. Later on, also the newly formed bantams were used. This is particularly evident in the Groninger Mew bantam, which shows genetic influences from the Groninger Mew and the Frisian Fowl bantam.
The prevalence of long runs of homozygosity (ROH) in the traditional breeds confirms recent inbreeding. A high diversity in management and breeding carried out in small breeding units explains the high heterogeneity in diversity and in ROH profile, displayed by traditional breeds compared to commercial lines. Results of this research highlight the importance of using DNA markers to inform breeding programmes on potentially harmful homozygosity and the potential loss of genetic diversity.
Further research has started in collaboration with the breeders, to evaluate their breeding results. The research is part of the EU Horizon 2020 funded IMAGE project.