Evaluation of these traits in terms of their heritability, ease of measurement and genetic correlation with health, reproduction and condition will be paramount to ensure their future implementation in breeding programmes.
It is well known that traditional selection of Holstein-Friesian dairy cows for increased milk production has inadvertently resulted in a decline in the health and fertility of such cows. In recent years, there has been increased emphasis on the inclusion of functional traits in breeding goals in an attempt to improve reproduction and health, while simultaneously reducing involuntary culling of animals. The measurement of such traits is however often difficult and extremely subjective, with many of them having low heritability and therefore little potential to ultimately improve health and fertility.
Locomotion is a trait that describes the quality of a cow’s gait and has a role in determining lameness, which is a major concern on dairy farms with severe consequences on milk yield, reproductive performance, and welfare. Diseases of the legs and feet are also highly prevalent among dairy farms, causing significant economic losses due to involuntary culling of chronically lame animals. Body condition score is a trait that measures body tissue reserves and can be used to predict the fertility, health, and welfare of cows. Body condition score is thought to have high genetic variability and is strongly correlated with breed and other conformation traits, making it ideal for use in selection indices. Overall, locomotion and body condition score are among the main traits with links to fertility and health, hence the interest to include them in breeding programme criteria.