Value of Heterosis.qxp_Layout 1 7/13/22 2:56 PM Page 2
The Value of Heterosis by Lane Giess, director of Commercial & Nontraditional Data Programs The adage “Our breed can do it all” has — and may continue to be — pressed by some breed association representatives and certainly some seedstock producers. This concept alone is false and in some small way can be attributed to holding back the beef industry and more importantly the commercial cattle producers. Not a single breed by itself can capture heterosis. The economic stability of commercial producers is of great importance, and continuing to push singular breed usage is a detriment to farm and ranch longevity at all levels. The value of heterosis is a reduction of production
A cross of two strains of maize (left and right) yields a hybrid (center) bigger than both parents. Credit: David Cavagnaro with assistance from Lois Girton and Marianne Smith.
costs, an increase in animal performance and efficiency, an increase in the value of the products sold, and often simpler breeding programs. So what is heterosis? Heterosis, also known as hybrid vigor, is the superiority of a crossbred animal relative to the average performance of its straightbred parents. Research has shown time and time again that crossbreeding results in calves that are far superior to their straightbred counterparts. There are two reasons for the resulting boost in performance from crossbreeding: 1) Increasing the level of heterozygosity across the genome lessens the effect of gene dominance for diminished performance (i.e., hybrid vigor), and 2) an increased use of breed complementarity of parent breeds (i.e., maternal line and terminal line). In the beef industry, the effect of direct heterosis on calf performance has been documented. An example of this is if you mate a straightbred parent where the average weaning weight is 550 to another straightbred parent where the average weaning weight is 500. The average weaning performance of those calves is 546. That is 21 pounds heavier than the average of the parent performance. It’s clear the benefit of heterosis results in improved performance across an array of economically relevant traits, but perhaps even more important is the compounded production advantage through crossbred females. The largest economic impact crossbreeding yields is through maternal heterosis and crossbred females. Would you find it valuable to have females produce 600 pounds more weaning weight and last over a year longer on average than straightbred females? Crossbred females make more money. Period.
Table 1: Various traits relating to performance and the unit increase attributed to heterosis.*
Trait
Units: Direct Units: Maternal
Units: Direct
Bos taurus x Bos taurus
Bos taurus x Bos indicus
Calving Rate, % 3.2 Calving Assistance Rate, % Calf Survival, % Survival to Weaning, % 1.4 Weaning Rate, % Birth Weight, lb 1.7 Weaning Weight, lb 16.3 Yearling Weight, lb 29.1 Average Daily Gain, lb/d 0.08 Longevity, years Number of calves Cumulative Weaning Weight, lb
34
Register / July/August 2022
3.5
Units: Maternal
4.3 4.9 -1.4
15.4 -6.6 8.2
1.8 11.4 78.5
20.8 -2.4 3.2
0.8 1.6 18 1.36 1.36 0.97 600