Milk Genomics Initiative: Cow’s DNA determines composition of milk

The DNA of a cow can play an important role in determining the composition (fat, protein) of her milk. The Milk Genomics Initiative (MGI) of Wageningen UR studies which genes contribute to milk that is suitable for the production of cheese or milk with a favourable fatty acid composition. The programme thus makes an important contribution to innovations at dairy farming organisations and the dairy industry.

Cow milk rich in casein is extremely suitable for the production of cheese. By studying which genes are responsible for the production of casein, cows may be selected based on their natural tendency to produce casein-rich milk, or whether or not their milk is rich in unsaturated fatty acids which is better for consumers’ health.

Fat content is hereditary
Wageningen UR’s Milk Genomics Initiative studies the relationship between the hereditary traits of cows, and the quality of the milk these cows produce. The researchers have discovered major differences in the composition of milk fat among different cows. A substantial part of these differences may be explained by the cows’ genetic predisposition. The researchers have also tracked down several of the genes which contribute to this genetic variation. Genetic variation is the reason that one cow will naturally produce milk with a high protein content, while another cow will produce milk rich in fat.

Dairy industry
Knowledge on these natural differences is valuable to the dairy industry. Having this knowledge on the genetic background of the differences in milk composition makes it possible to breed cows which will produce milk of an even higher quality. A database has now been created which contains information on approximately 2000 cows from some 400 dairy farms, making it the first database of its kind worldwide.

Breeding programmes
MGI is a collaborative effort between the breeding and Genetics chair group and the Product Design and Quality Management chair group at Wageningen University. The goal is to develop breeding programmes which make optimum use of natural genetic variation to improve existing dairy products or to develop innovative dairy products. This research will allow the dairy industry to better meet changing needs among consumers who, for health reasons, want products with more unsaturated fatty acids.

Milk composition
Besides, DNA is not the only factor that plays a role in the milk composition. Approximately half of the differences are determined by the cow’s genes. Nutrition also has an impact on the milk composition. For example, a diet rich in linseed will cause the cow to produce milk with high level of unsaturated fatty acids.