Farmer jones has a herd of cows. brown coat is dominant over white coat in cows and his cows are all brown. farmer jones likes brown cows and wants to keep his herd brown by selling off any heterozygous cows. heterozygous cows are brown but have the recessive gene for white coat. suppose farmer jones wants to do a test cross of his cows to see what type of genotypes are carried for coat color throughout his herd. what is the genotype of the control bulls he should use to test for the heterozygous genotype?