what are expected from a mating a roan bull and a roan cow

The allele for black is B and the allele for white is B1. The heterozygous phenotype is known as erminette (black and white spotted). In shorthorncattle, when a red bull (R R) is crossed with a white cow (R 1 R 1), all the offspring are roan - a spotted, red and white or milky red color.