The number of breeds of domesticated animals, especially livestock, have declined rapidly. The proximate causes and processes involved in loss of breeds are outlined. Also the path-dependent effect and Swanson’s dominance-effect are discussed in relation to lock-in of breed selection. While these effects help to explain genetic erosion, they need to be supplemented to provide further explanation of biodiversity loss. In the respect, it is shown that the extension of markets and economic globalisation have contributed significantly to the loss of breeds. In addition, the decoupling of animal husbandry from surrounding natural environmental conditions, particularly industrialised intensive animal husbandry, is further eroding the stock of genetic resources. Recent trends in animal husbandry raise serious sustainability issues, apart from animal welfare concerns.