home → articles → Genetics & Performance | Email to a Friend

Crossbreeding Revisited

published: May 3rd 2010
by: Jeff Jaderborg
source: University of Minnesota

Many are just finishing their calving season and will soon be changing over to breeding season mode looking to answer that question of what sire to breed my cows to this year. Well, this year I ask you to consider what heterosis could do for your operation.

Heterosis defines how much superior a crossbred animal is above the average of a straight bred animal. The amount of heterosis expressed for a given trait is related inversely to its heritability. Heritability is the proportion of the measurable difference observed between animals that is due to additive genetic differences and passes from one generation to the next.

Because reproductive and maternal traits have low heritabilities, their responses to selection will be slower; however, producers can make significant improvement in those traits through crossbreeding programs that maximize heterosis. With growth traits, which are moderate for heritability and heterosis, progress is possible through both selection and crossbreeding.

Crossbreeding allows you to take advantage of two very different genetic pools, which would not be possible if you were to us one breed only. Many purebred breed lines today have been bred within multiples of the same pedigrees for three to four generations.

A common way to eliminating this and to increase heterosis of the offspring is using crossbreeding. This practice showed many benefits starting back in the mid 1900s. In 1968, Turner found that there was a 9.2 percent increase in calf-crop production traits with a crossbred over straight bred cows.

A very common term that many might have been heard of with crossbreeding is the F1 cow to produce an F2 calf. When you hear this, they are discussing the first and second generations. The F1 cross will always produce the highest degree of heterosis of all crosses.

One of those that you may see today would be the Hereford and Angus cross making a F1 black baldy commercial cow. Having that F1 commercial female crossed to a third breed such as Charolais, to increase heterosis of the F2 calf; thereby, getting the full potential of traits from three breeds using heterosis.

A producer selling his calves at weaning isn't the only one that can benefit from heterosis, which can be seen in Table 1. Producers who retain ownership will see benefits such as heifer reaching puberty sooner, and longevity of brood cows increasing. You as a producer can calculate heterosis percentage that you could gain using a simple equation as seen in Figure 1.

An example of this is if the average weaning weight of the straightbred calves of breed A was 475 lbs., and 425 lbs. for breed B calves, the average of the straightbred would be 450 lbs. If the average weaning weight of the crossbred calves was 470 lbs., the percent heterosis would be estimated as: [(470 - 450)/450] x 100 = 4.4%

A saying that I have heard multiple times through the years in the crossbreeding world is that heterosis may be the only free lunch in cattle breeding. If you crossbreed, you can get and use heterosis. But not all free lunches from heterosis are equal. Do crossbreeding rightly and the free lunch can be a steak sandwich; do crossbreeding wrongly and the sandwich can be a hot dog. As cattle producers, we continue to work to increase our profits with use of new technologies and genetics, but the old tool of crossbreeding to gain heterosis should still be in our operations tool box to maximize those profits.