Breeds of cattle have differentiated gene pools. Differentiation was under the effects of selection (for example for the high milk yield), random genetic drift and environmental selection (natural selection). Nowadays, tracking the genes which are known to be associated with the properties of the milk one can identify the status of the breed in relation to the property under consideration. The DGAT1 gene is located in the centromeric end of chromosome 14 in cattle, otherwise known as the acetyl-CoA: diacylglycerol acyltransferase 1(DGAT1), and has been recently identified as a strong candidate gene for milk production traits. This monographph describe various aspect of bovine DGA T1 gene.