Milk genomic: Unsaturation of milk fat

Last summer, the Milk Genomics Initiative revealed the presence of large genetic variation in fat composition of bovine milk.

The Milk Genomics Initiative studies the genetic background of detailed milk composition and is a collaborative project between Animal Breeding and Genomics Centre (ABGC) of Wageningen UR (WUR) and the Dairy Science and Technology Group of WUR, funded by WUR, HG, NZO and STW.

The DGAT1 gene was shown to be a major gene involved in the variation in milk-fat composition. Recent study shows that also stearoyl-CoA desaturase 1 (SCD1) plays a significant role.

Animals are capable of desaturating saturated fatty acids to unsaturated fatty acids by the SCD1 enzyme, which catalyzes the insertion of a double bond between carbon atoms 9 and 10 of a fatty acid.

An alanine (A) to valine (V) mutation in SCD1 was genotyped in almost 2000 first-lactation Holstein Friesian cows, which were also phenotyped for milk-fat composition.

The V allele was associated with lower levels of unsaturated C10, C12 and C14 fatty acids, as compared to the saturated counterparts, but with higher levels of unsaturated C16 and C18, as compared to the saturated ones.

From a human health perspective, the V allele is the favourite allele because of its association with less saturated C16 (the most important ‘bad guy’), and more unsaturated C18 fatty acids (the ‘good guys’).

The results are described in a paper accepted by the Journal of Dairy Science.