DNA-based identification of novel ovine milk protein gene variants

•All main milk protein genes sequenced in 170 animals.•8 breeds including 7 local Swiss breeds.•Local Swiss breeds have only scarcely been analysed to date.•Three new protein variants detected for ovine αs2-casein and α-lactalbumin.•Polymorphisms found to exist in a previously unobserved haplotype context.

The high variability of the six main milk proteins is known to influence milk production traits, cheese processing properties as well as the nutritive value of milk and has been intensively analysed especially in cattle. In sheep, a remarkable variability of the milk proteins has been described on protein level, too. However, the knowledge about its genetic background remains scarce. Within the current study we directly sequenced the DNA of the milk protein encoding genes CSN1S1, CSN2, CSN1S2, CSN3, LAA and LGB in up to 170 sheep belonging to eight Swiss and French sheep breeds. Thereby, we identified three new variants of αS2-casein and α-lactalbumin (herein denoted as CSN1S2*H, LAA*C and LAA*D) and detected 18 of 28 already known variants. Furthermore, previously unknown combinations of already known polymorphisms of CSN1S2 were observed and integrated into the existing nomenclature.