Genetic improvement in dairy cattle—an outsider’s perspective

Abstract

The author describes the improvement programmes that have normally been implemented for dairy cattle, and comments on these based on experience with other species. For the last half-century, most breeds have utilised two-stage schemes. Young sires have been given limited matings so that both future bulls and the majority of heifer replacements have been sired by older sires selected on progeny data for type, milk yield, and composition. Scientific methods of multiple trait selection have been only slowly accepted by commercial milk producers. The major genetic changes in Europe have, in any case, been brought in from other populations (North America). There are inevitable conflicts between the specific improvement goals of individual producers and those of the breeding organisations that control semen supplies. Numerically small populations should have different goals and should organise much simpler programmes based upon the widespread use of young sires. Inbreeding will become serious in all breeds unless current policies are modified.