Distribution of α_S1-casein "welsh" variant in some Slovak and Czech sheep breeds

Abstract. Occurrence of the α_S1-casein D allele (formerly "welsh" variant) in sheep breeds Tsigai, Improved Valachian and Slovak Merino was investigated by means of isoelectric focusing in ultra thin polyacrylamide gel. This variant in herds of the above mentioned breeds was observed as follows: Improved Valachian 3.64%; Tsigai 5.57%; Slovak Merino 12.45%. In the last mentioned breed in a single animal α_S1-casein was not found at all (0.34% of the total). There is no mention of existence of null allele of sheep α_S1-casein in literature so far. In case of the Tsigai breed in one individual (0.24%) the "welsh" variant in homozygous form was observed.