GENETIC IMPROVEMENT OF FARM LIVESTOCK

For over 10,000 years, since domestication began, the fortunes of the human race have been closely intertwined with the husbandry of livestock. During this time, whether wittingly or unwittingly, strains of livestock which are more docile and easier to tend, and whose products are better suited to human needs, have been identified and bred from.

By 2000 BC there were distinct breeds of dogs, cattle and sheep in Egypt. There were distinct livestock breeds in Northern Europe by Roman times. Breeds probably continued to evolve slowly, often with regional ties, until about 200 years ago.

The increase in the human population in the 18th century led to greater emphasis on ‘selective breeding’ (picking the best animals to be parents of the next generation) for increased production of meat, milk etc. Many modern livestock breeds originated then. Robert Bakewell, who is often credited as the pioneer of livestock improvement, practised ‘linebreeding’ (mating closely related animals) and measured and recorded the performance of his stock, to assist his selection decisions. Bakewell worked mainly with Leicester sheep and Longhorn cattle. His methods were widely followed by other breeders of the time.

In the 19th century Charles Darwin proposed that species evolved by natural selection, and that the key to this was variation between individuals. Darwin was influenced by the work of early livestock breeders like Bakewell, and his theory also helped us to understand the processes involved in ‘artificial selection’ - selection practised by breeders. Darwin’s work, and that of Gregor Mendel on the inheritance of flower colour, plant height, seed type etc., laid the foundations for the scientific development of livestock breeding.

In the 20th century scientific advances, especially in genetics, statistics and reproductive biology, helped us to understand and refine the process of selective breeding. Many of these scientific advances were made in Edinburgh, and research institutions here continue to have a major international role in innovation and in the application of science to livestock breeding.

Genetic improvement is permanent and cumulative, and when properly applied, a sustainable and highly cost-effective method of altering the performance of farm livestock. It is one of the most effective methods of enhancing the underlying efficiency and competitiveness of livestock industries, and of altering primary product quality.

One of the major current challenges is to harness new technologies to accelerate genetic improvement of farmed animals in a welfare-friendly and socially acceptable way.

Current research themes, in the UK and internationally, include:

•Developing ‘genome maps’ and DNA-based tests to identify animals with favourable genes for meat, milk or fibre production, product quality or disease resistance. ~

•Improving statistical and computing methods for analysing huge amounts of data (e.g. milk yields from all recorded animals in the UK or internationally).

•Broadening the aims of selective breeding to include animal health and welfare, as well as productivity and product quality.

•Ensuring that breeding programmes avoid excessive loss of genetic variation.

•Using advanced scanning equipment to measure leanness without harming animals.

By Professor Geoff Simm- Group Manager, Sustainable Livestock Systems-  The Scottish Agricultural College (SAC). Published in http://www.sac.ac.uk/ and not available anymore. This copy was saved by LC in June, 2004 and edited to be posted.