Genetic History and Genome Structure of the Brahman Breed

Two subspecies of cattle are used in modern agriculture. Bos taurus taurus cattle were domesticated in West Asia and spread into Europe, Africa, and East Asia. Bos taurus indicus cattle were domesticated in the Indus Valley in South Asia from a more tropically adapted wild ancestor, have spread into South East Asia and parts of China and form the basis of commercial cattle populations in tropical regions of Australia, the USA, South America and Asia. Indicine cattle have lower fertility and slower growth than taurine cattle, perhaps due to adaptation to tropical environments. Composite, mixed indicne and taurine, cattle usually have better adaptability and productivity in tropical environments than either of the parental breeds, possibly due to the retention of favorable genes from both subspecies. To achieve a more productive but adapted beef cattle herd it is important that we understand genetic structure of both sub species. A DNA resource of approximately 200 sires in the Brahman breed, dating from the 1950s, has been collected and the most influential sires sequenced. Analysis of the pedigree revealed that the 50 sires sequenced represent approximately 7% of the genetic diversity of the current generation of Brahman cattle. Sequencing a subset of key founders revealed that sections of the taurine genome have preferentially been retained from the time when, early in breed formation, taurine animals were used to expand the numbers of Brahman cattle. The information will allow more informed selection decisions on economically important traits such as fertility, growth and carcass traits.