In this case, you have a red-coated cow (RR) and a white-coated bull (WW). Since the alleles are codominant, the offspring will express a phenotype that reflects both alleles when they inherit one of each.
When you cross RR with WW, the F1 generation will all have the genotype RW. Because the alleles are codominant, the phenotype of the offspring will be a blend of the red and white coats, resulting in a pink coat.
Therefore, the expected phenotype of the offspring will be All pink coat.