Genetic variation in bovine milk fat composition

In her thesis, Stoop shows that there is considerable genetic variation in milk fat composition, which opens opportunities to improve milk fat composition by selective breeding. Short and medium chain fatty acids had high heritabilities, whereas variation due to herd (mainly feed effects) was moderate. Long chain fatty acids had moderate heritabilities, whereas variation due to herd was high. Several genomic regions (QTL) with effect on short and medium chain, long chain, or both types of fatty acids were identified. Differences in results could be explained by the origin of the fatty acids; short and medium chain fatty acids are predominantly synthesized by the cow in the mammary gland, whereas long chain fatty acid are mainly of dietary origin. Results show that milk fat composition can be improved by selective breeding, which offers opportunities to meet consumers’ demands regarding health and technological aspects