In shorthorn cattle, the red color (E) does not completely dominate the white color (e) and the offspring is roan.

In shorthorn cattle, the red color (E) does not completely dominate the white color (e) and the offspring is roan. What color offspring should be expected from crossing a white cow with a roan bull?

1. What color should you expect from crossing a white cow with a roan bull?

Let E be the red color of the coat, then e the white coat.

Since the dominance in this case is incomplete, the heterozygotes – Ee – have a spotted color, that is, they are roan.

PP f ee (white) x m Ee (roan)

Let’s consider the possible combinations of gametes in genotypes.

m / f E ee Ee (roan) ee (white)
Analysis by phenotype:

50% – white,

50% are roans.

Genotype analysis:

50% are heterozygotes;

50% are homozygotes.

Answer: from crossing a spotted (roan) bull and a white cow, calves can be either white or roan.

2. When will a farmer receive a three-color herd of cows?

To achieve this goal, you need to take a roan bull and roan cows as producers. Let us prove this by the crossing scheme.

RR f Ee (roan) x m Ee (roan)

m / f E e E EE (red) Her (roan) e Her (roan) ee (white)

Analysis by phenotype:

25% are red;

50% – roan;

25% are white.

Analysis by phenotype:

50% are homozygotes (25% for the dominant trait, 25% for the recessive trait);

50% are heterozygotes.

Answer: to get a tricolor herd, roans must be taken as broodstock.