Selection of Animals on Milk Composition: The Opportunities of Genetics
Erik Mullaart - CRV BV
CRV is a large cattle-breeding organisation running different breeding programmes across the globe. CRV is, together with the Dutch Dairy Industry (NZO) and the Animal Sciences Group of Wageningen, a partner in the "Dutch Dairy Genomics" project since 2004. The results from this project have clearly indicated that there is a considerable variation in both fat composition (e.g., C14, C16, C18, unsaturated) and protein composition (e.g., kappa-casein and beta-lactoglobulin) of cow milk and that a considerable part of this variation is caused by genetics (moderate to high heritability). This clearly creates new opportunities to breed cows with a specific composition. At the same time, the recently developed Genomic Selection technique is causing a revolution in cattle breeding, by a huge increase in selection efficiency.
A few examples of selection of cattle for specific milk characteristics based on their genetics (genes) will be shown along with the potential effects of these genes on traits other than milk composition. For example, selection of cattle based on the B-variant of the beta-lactoglobulin gene results in milk with in a higher casein index. This higher index is an advantage for the cheese production as it results in more cheese. However, this B-variant has also some unfavourable effects on other traits hereby reducing the benefit for cheese production.
Ultimately some different scenarios for selection animals and breeding schemes will be discussed and compared with each other with respect to maximum genetic response. Using Genomic Selection our bulls are currently marketed for different segments such as "milk production" and "durability and health".
CRV can already select these B-variant female animals and has already some proven bulls available, which can be regarded "cheese"bulls. We foresee that based on this milk genomics project we will introduce some new segments such as "cheese" and "high unsaturated (CLA)".