Genetic selection for extensive conditions

Humans have selected animals which are more suited for food production or other purposes, since the process of domestication of livestock began, whether this selection was done knowingly or unknowingly. The deliberate selection of improved breeds and strains has been a particularly important feature of agriculture in the last couple of centuries, especially in the industrialised countries. For most of this period, selection has been based on subjective assessment of the merits of animals, but objective tools for selection (e.g. performance recording and statistical methods for evaluation of genetic merit) have become widely used in the last few decades. These tools have been used to a large extent in pig, poultry and dairy cattle breeding, but to a much lesser extent in the beef cattle and sheep breeds common in extensive production systems, However, these extensive systems themselves have changed to a much lesser extent than those in which pigs and poultry are kept, Hence there have been opportunities for natural selection for traits conferring better adaptation to these environments. Additionally there has been some subjective selection for traits thought to confer better adaptation. There is considerable scope for wider uptake of existing objective methods of genetic improvement in the harsher areas of the UK, and elsewhere, However, these methods are likely to be more effective if the genetics of traits conferring adaptation to harsh environments are better understood, and if the most important of these traits are included in the breeding goal, Traits conferring better adaptation may include physical attributes such as litter size, fleece type and the ability to store body fat, some aspects of behaviour, especially maternal and grazing behaviour, and disease resistance, A better understanding of the relationships between production traits and these adaptation traits will also be critical for the development of appropriate, sustainable breeding programmes, This approach should reduce the risk of there being detrimental correlated effects of selection, and may provide opportunities to improve animal welfare.