Disclosed herein is a method for screening for the allele associated with a desired SCS phenotype, which comprises: obtaining a DNA sample from a bull to be tested for the desired SCS phenotype; and detecting the presence of an adenine at position 11 in a gene encoding a bovine beta2-adrenoreceptor. Also disclosed is a milling attribute PCR-RFLP kit containing a pair of primers which flank the 11.sup.th nucleotide position of the bovine beta2-adrenoreceptor gene, and a restriction enzyme specific for the CCCGGG site, which can be SmaI.