Hybrid Vigor

Cows can be bred within their breed or with a different breed (cross breeding).

Hybrid vigor (technically heterosis) is the superiority in performance of the crossbred animal compared to the average of the straightbred parents. Cattle producers are increasingly using this as a way to get healthier, bigger, and easier calving animals.

Heterosis is calculated using the formula:
% Heterosis = [(crossbred average – straightbred average) ÷ straightbred average ] x 100.

From Scott P. Greiner, Extension Animal Scientist, at Virginia Tech:

“If the average weaning weight of the straightbred calves was 470 pounds for Breed A and 530 pounds for Breed B, the average of the straightbred parents would be 500 pounds. If Breed A and Breed B were crossed and the resulting calves had an average weaning weight of 520 pounds, heterosis would be calculated as: [(520 – 500) ÷ 500] x 100 = 4 %. This 4% increase, or 20 pounds in this example, is defined as heterosis or hybrid vigor.

“Perhaps the most important advantage for crossbreeding is realized in the crossbred cow. The advantage of the crossbred calf is two-fold: an increase in calf livability coupled with an increase in growth rate. Maternal heterosis results in improvements in cow fertility, calf livability, calf weaning weight, and cow longevity. Collectively, these improvements result in a significant advantage in pounds of calf weaned per cow exposed, and superior lifetime production for crossbred females.

“The other important advantage to crossbreeding is the ability to take advantage of the strengths of two or more breeds to produce offspring that have optimum levels of performance in several traits. As an example, British breeds generally excel in marbling potential whereas Continental breeds typically are superior for red meat yield (cutability). Combining the breed types results in offspring that have desirable levels of both quality grade (marbling) and retail yield (yield grade). Similarly, milk production and growth rate may be most effectively optimized by crossing two or more breeds.

“It is important to realize that the crossbred offspring will not excel both of the parent breeds for all traits. In the example given previously, straightbred calves of Breed B would have had heavier weaning weights (530 pounds) than the Breed A x Breed B crossbreds (520 pounds). However, Breed B females may be larger in mature size and have higher milk production potential resulting in increased nutitional requirements and higher production costs. Limited feed resources coupled with very high milk production may result in lower reproductive performance.

Therefore, the cumulative effect of crossbreeding when several traits are considered is more important than the effect on any one particular trait.”

(Thanks to Blair Hunewill for the picture)