Research conducted at Uppsala University, Sweden, The Livestock Conservancy and Virginia Tech in the USA have used genomics to study breed formation and the roots of modern meat chickens.
The mid-19th century was an era of revolution for poultry breeders. The newly imported chickens from Asia were crosses with American landrace chickens and various European breeds in order to establish new breeds and varieties that were standardised by the American Poultry Association founded in the early 1870s.
Since 1957 there has been two classifications for farmed poultry; high weight selection (HWS) and low weight selection (LWS). Both lines are considered representative of the White Plymouth Rock breed since the mid-20th century in the USA.
After sequencing the DNA from HWS, LWS and other breeds that are believed to have contributed to the development of the White Plymouth Rock breed.
The result of this research showed that an old American breed, the Dominique, was a major contributor to the White Plymouth Rock. Dominique, Black Java and Cochin breeds contributed to the maternal ancestry, while contributions on the male ancestry include Black Java, Cochin, Langshan, Light Brahman, and Black Minorca.
The proportional contribution of each of the founders is consistent with the records from the time. Differences in the overall ancestral contributions to the HWS and LWS lines were minor, despite more than 60 years of selection. The livestock and poultry breed of today are the result of foundation, isolation and selection.
“Genomic analysis has proven to be a good tool for understanding genetic contributions to breed development. Through additional study of founder contribution to chromosomes and genes, such analyses may also reveal more about the importance of drift and selection in closed populations. Such work also highlights the importance of conserving pure breeds and selected lines of chickens, “says Örjan Carlborg, Professor at the Department of Medical Biochemistry and Microbiology, Uppsala University, and lead author of the study.