Dairy genetics and livestock breeding

Abstract

Background: The 21st century dairy cow is a very different animal from that of the past, even those being milked as little as 20 years ago. Since then, the production of dairy cows has substantially increased, whereas their somatic cell count has declined. Moreover, fertility has improved, foot, leg and udder conformation have seen changes for the better, and many other traits, including lameness, longevity and mastitis, are also moving in the right direction. This is as much a success story for genetics as it is for management and technology. It is impossible to apportion the exact part played by each factor – it will vary from trait to trait – but it is generally accepted that genetic gain has accounted for more than half of the improvement made in milk production over recent decades (Cassell 2001). Indeed, it is more important to continue to make these improvements than just identify the reasons for them, particularly in regards to traits affecting health, welfare and fertility. Genetic tools are playing an increasingly valuable role in this progress and should continue to do so in the future.Aim of the article: This article highlights the genetic tools and trait selection indexes that are currently available to the dairy sector in the UK, and the genetic progress that can be achieved by using them.