EPD index for Herefords developed

Scientists at the Agriculture and Agri-Food Canada Lethbridge Research Centre, in collaboration with the Canadian Hereford Association, have developed the first Expected Progeny Difference (EPD) index for maternal traits in Hereford cattle.
“Selection for the maternal productivity index should improve the genetic potential of Herefords to consistently wean heavy calves over a sustained herd life, without correspondingly increasing cost of production,” said Dr. Denny Crews, a quantitative geneticist with AAFC.
The Canadian Hereford Association is expected to make the EPD index available to breeders this spring.
EPDs are broadly accepted production tools, backed by beef breeding organizations. The indexes enable selection for a wide variety of economically important traits in beef production.
Until now, however, no index-based EPD of this type has been available for cow efficiency.
In general, beef cattle selection indexes focus on production improvements in offspring for certain traits. Typical examples are growth rate and carcass quality.
However, these EPDs generally don’t adequately acknowledge other factors, such as cost associated with these improvements.
The maternal productivity index is different in that it focuses on the capability of the parent animal to produce improved offspring in a consistent, sustainable, and cost-efficient manner.
Maternal productivity is a composite trait—that is, a trait composed of several elements. Compared to other traits, composite traits are complex and more difficult to evaluate.
To decode the components of maternal productivity, Dr. Crews used data from the Hereford herd at the Onefour research substation.
“We found weaning weight, cow survival, and cow weight at weaning to be determining factors for maternal productivity,” he said.
Weaning weight provides information on both calf growth and milk production of the cow, noted Dr. Crews. The cow survival rate, defined as the probability of a cow weaning at least three calves over her herd life, represents lasting productivity.
The weight of a cow when she weans her calf is an indicator of cow maintenance costs.
Once the trait components were determined, performance records of the Canadian Hereford Association database were evaluated to create the maternal productivity index.
“The EPD was established by weighing the relative economic value of each of the selected traits by their respective breeding value,” said Dr. Crews.
“We found we were able to increase both growth performance and survival characteristics while moderating any increase in cow size,” he added.
That can be a significant improvement in practical economical terms for the beef industry.
EPDs have proven to be practical breeding tools adding direct benefits to beef cattle producers, and the new maternal productivity index is another option.
These practical breeding tools, complemented by the many molecular research developments on the horizon, can help build a truly economically-sustainable beef industry.

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