Hereford producers have always prided themselves on the mothering ability of their cows. Now they have a way to measure and predict how much of that trait will be passed on by a particular bull.
Scientists at Agriculture Canada’s Lethbridge Research Centre have developed a maternal productivity index, or MPI, that combines into a single measurement of fertility, productive herd life, maintenance costs and genetic potential for growth.
“We’re going to provide purebred Hereford breeders and their commercial bull customers with a relatively simple tool to increase the genetic potential of their cattle to wean heavy calves over a sustained herd life with minimized input costs,” said lead researcher Denny Crews.
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Canadian Hereford Association consultant Sean McGrath said that until now, bull buyers have had to consider a dizzying array of genetic factors when looking for a bull that will produce good mothers.
“At some point for guys it gets a little confusing,” he said.
That will change this spring when the MPI is made available to producers who participate in the association’s breed improvement program.
“If I see a bull with an MPI of 125 and a bull with an MPI of 115, I know that 125 is going to produce heifers that are going to stay around longer and be better producing females,” McGrath said.
“It’s a tool to simplify selection for guys. It takes a lot of the guesswork out and it makes it fairly straightforward.”
Until now, most measurements of genetic traits have focused on production improvement in offspring, such as growth rates and carcass quality.
“In terms of the maternal side, this is a huge first step in the industry,” McGrath said.
The complicated MPI calculation incorporates weaning weight, cow weight and “stayability.”
Weaning weight provides information on calf growth and a cow’s milk production. Cow weight is an indicator of cow maintenance costs. Stayability measures the probability of a cow weaning at least three calves during its lifetime.
McGrath said the MPI was developed as a flexible index that can incorporate other traits over time if deemed appropriate. But according to two pilot projects, the MPI is working fine as is.
“By and large the response has been, ‘this reflects my cows better than any number I’ve seen,’ ” McGrath said. “That’s our target and our goal.”
McGrath said the measurement will become a standard part of genetic evaluations done each fall before the bull buying season. But it will be only one of many factors a buyer has to consider when purchasing a sire.
“He’s still got to have four legs, he’s still got to pass the semen test, he’s still got to have libido and he’s got to be structurally what you’re looking for – the whole gamut.”
