Genetic improvement of cattle and sheep: putting science into practice

Genetic improvement is one of the most effective strategies available for altering the performance of farm animals. It is relatively slow compared to some other methods, such as improved feeding, but it is permanent and cumulative, and in most cases it is highly cost-effective and sustainable. Effective genetic improvement programmes contribute greatly to the efficiency and competitiveness of the livestock industries. Since the process of domestication began, whether knowingly or unknowingly, livestock have been changed genetically by subjective means. Some of the scientific foundations for more objective genetic improvement methods were laid over 100 years ago, and others followed from the 1900s to the 1930s. However, it is only over the past 50 years or so that these have been applied to any great extent in livestock improvement. At least until recently, these objective methods of genetic impovement have generally been used more effectively in pig and poultry breeding than in cattle and sheep breeding. The aim of this paper is to review briefly some of the recent advances in the application of science to the genetic improvement of dairy cattle, beef cattle and sheep. Over the last few years improved methods of predicting breeding value have become more widely used in Britain and elsewhere. This is especially important in the beef and sheep sectors where BLUP methods are relatively new. These methods produce more accurate EBVs for individual recorded traits. Also, in dairy cattle, beef cattle and sheep, the use of selection indexes by breeders and their clients is growing. These indexes augment the advantages of BLUP, by combining EBVs for individual traits to rank animals in order of the expected improvement they will make in overall economic merit. The continuing, and expanding, use of these selection tools will make a useful contribution to the efficiency and competitiveness of the British livestock industries.