There’s a quick way to improve certain characteristics in a commercial cattle herd: switch up the bull breed.
“The main advantage of crossbreeding is that it is a really quick and cost effective way of improving some really economically important traits that are virtually impossible to improve by genetic selection,” said Dr. Reynold Bergen, science director for the Beef Cattle Research Council.
Advancements in genetic testing allow cattle producers to select for various traits affecting growth, carcass and feed efficiency, among others. Influencing low heritability traits is much harder, and that’s where using a different breed of bull enters the picture.
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“Crossbreeding is a really quick and cost effective way of improving performance for those low heritability traits, like reproduction and fertility and longevity,” said Bergen.
Animals of the same breed, assuming they are purebred, have common relatives somewhere in the family tree, and that means there is some degree of inbreeding.
“Where inbreeding depression hits is on those low heritability traits,” said Bergen.
The opposite of that depression, of course, is hybrid vigour. By crossbreeding, the thousands of genes that influence various traits essentially “shuffle the deck” and provide an opportunity for genetics to overcome inbreeding depression.
The positive effects of crossbreeding and the resulting hybrid vigour are well known among cattle producers, and an early research example in Alberta dates back to the 1950s.
At the Onefour research station, Agriculture Canada scientists imported three Brahman bulls and mated them to Hereford cows. Then they compared straight-bred Hereford females with the resulting Brahman-Hereford cross females.
“They just kept them around as long as they kept having calves,” said Bergen.
Any cow that failed to calve two years in a row was culled.
“After 16 years they had fewer than 20 percent of the straight-bred cows left but over 60 percent of those crossbred cows were still around. They were not babied, those cows. It was ranch conditions … but those crossbred cows lived a lot longer, produced more calves than the straight breds, so that’s a pretty clear example.”
It’s not an example recommending the Brahman breed for use on the Prairies, Bergen added. Some of the crossbreds died because they couldn’t handle harsh winters.
It is, however, an illustration of the value in adding new genetics to a herd.
Though Herefords were once the most popular and common breed in prairie cattle herds, that crown has shifted to Angus. Commercial producers who have stuck with Angus bulls over the years should consider changing it up, said Bergen.
“I suspect there’s probably people that have been using Angus bulls for the last four or five times they’ve switched out their bull battery. If they’ve been buying the same breed every time, whether it’s Angus or anything, they might have started out with crossbreeds to begin with but if you’ve bred back to the same breed for the last six generations, you’re virtually purebred.”
That means any hybrid vigour is long gone.
Though some people maintain breed loyalties, Bergen said it probably isn’t a huge problem on the commercial side because of one major factor: economics.
“I think one of the things that most cow-calf producers hold most dear to their hearts, though, is the returns per cow per year and their production costs.”
He said Alberta Agriculture researchers calculated that cows with a high degree of hybrid vigour returned an average of $161 more per year than those without it.
Most of that is likely due to fertility and longevity, two traits that are difficult to select for through genetic testing.
Of course, it’s not enough to switch bull breeds just for the sake of change, Bergen notes. Selecting sires with good genetics is always the first step.
