How does the red factor work in the Dutch Belted breed? | Bestyet A.I Sires | Grazing Genetics from Dutch Belted and Milking Shorthorns

Revised from the April 2017 Dutch Belted Bulletin

Some of you have asked how the red factor works. How can a black cow have a red calf, sometimes even sired by a black bull? How can a red cow have a black calf?

While Dutch Belted cattle are generally black with a white belt, the recessive red factor has always been present to some extent in the population, so some red animals do occur. Some may also be brown or brindled (streaked). For our purposes here we will equate all non-black coat colors as “red” even though there are other variations.  Known red factor sires are often designated with RC in their stud listing.

Sir Upson’s Red Legacy, a Dutch Belt who is the brown variation of red.

Using Punnett squares for red factor inheritance

A very simplistic model for determining the likelihood of red (or brown) offspring is the Punnett square, representing genetic inheritance of red and black color as determined primarily by two color genes.  Each individual has two color genes and will transmit one of these (completely at random) at each mating. Black (B) is dominant, while red (r) is recessive. 

In the Punnett squares below, BB is a black animal with no red factor, Br is a black animal that is a red carrier, and rr is a red animal.  The single letters across the top represent the genes that can be contributed by one parent, and those along the left edge the contributions of the other parent.  You combine the elements from row and column where they intersect to find all the possible results of that mating.  The likelihood of the result in any square is 1:4 or 25%. 

So, you can see how a black cow can have a red calf if she’s a red carrier and bred to a red carrier black bull (25% chance). And a red cow can have a black calf if she’s bred to a black bull (100% chance if the bull is not a red carrier, 50% chance if he is a red carrier).

Note:  As mentioned above, there are actually variations of red that can occur. See for complete explanation and availability of genetic testing for these factors.

The Punnett squares showing the results from different matings of red and black animals.
BB = black animal carrying no red gene
Br = black animal carrying the red gene
rr = a red animal