Genetic background of milk composition in rare African and European cattle breeds

Bovine milk is a fluid that contains a balance of many nutrients like fats, proteins, oligosaccharides and minerals which are essential for the development of the offspring. It has been shown in many studies that milk composition is partly affected by genetic factors. Most studies investigated the genetic background of (detailed) milk composition in the main dairy cattle breeds (e.g. Holstein and Jersey) and knowledge about genetic variation in milk composition of traditional cattle breeds is limited. Many traditional cattle breeds have not been selected intensely for milk production traits as e.g. the Holstein and Jersey but can cope better with environmental challenges, such as extreme climatic conditions and diseases. Beef cattle is not directly selected milk production but for maternal effects on weaning weight, which might be related to milk yield and composition. Consequently, long-term natural or artificial selection may have operated on genomic regions that control milk composition. Due to different selection strategies, traditional and other breeds might harbour unique genetic variants affecting milk composition which need to be conserved for the future. Thus, the objective of this research is to investigate genetic and phenotypic variation related to milk composition of different (native) cattle breeds, representing a wide geographical range and a divergent selective breeding history. For this purpose, whole genome sequence (WGS) data from the OPTIBOV project (including European and African traditional cattle breeds) and the 1000 Bull Genome Consortium will be used. Bioinformatic approaches will be used to investigate variation in genes related to milk composition. Genetic differences between sub species (Bos taurus vs Bos indicus vs Sanga), breeds selected for different purposes (dairy versus meat) and breeds in different countries/ecotype’s will be evaluated. In addition, milk samples of cows from the OPTIBOV project will be used to investigate how genetic variation is reflected in the detailed milk fat and protein composition.