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New Reproductive EPDs

 

By Lance Bauer, Director of Breed Improvement

Beefmaster Breeders United (BBU) is releasing new reproductive Expected Progeny Differences (EPDs).

Beefmasters are known for being a maternal breed and these new EPD tools will help us to select for more maternal animals. The first new Beefmaster EPD is Age at First Calf and the second new EPD is Stayability. Age at First Calf (AFC) is for heifers and Stayability (STAY) is a lifetime measurement.

Age at First Calf is defined as the difference between a heifer’s birthdate and the birthdate of her first calf. When looking at this number, a lower number is more favorable indicating that a heifer is having her calf at a younger age. Contemporary groups for this are broken by utilizing yearling weight groups and the service type with a 120-day calving window. This helps to separate animals that are bred to calve at 24 months from those bred to calve at 30 months. Since AFC is a reproductive trait, the heritability is low, but statistically significant from zero. This means that the trait can be selected for but is going to take more time to change than traits with higher heritability, such as growth and carcass traits.

Stayability is defined as the probability that a female would be reported as calving in the herd at age five or greater. For STAY, a higher number is more favorable because this indicates that a female has a higher probability of remaining in the herd past five years of age. To calculate this, animals enrolled in Whole Herd Reporting (WHR) were used and the use of disposal codes were used to determine if an animal was in the herd and had a calf at the age of five. The age of five is used for this calculation because this is an industry standard and research suggests that animals have paid for themselves by the age of five, on average. Again, the heritability of this trait is low, but improvements can be made with selection.

These two new EPDs are tools that can be used to help select more maternal animals and they will eventually be incorporated into $M as we work to prove ourselves as the most maternal breed in the industry. When using these tools for selection try to select for animals with a lower AFC and a higher STAY, but do not forget or neglect other traits. Another trait that would be beneficial for the maternal selection would be a mature cow weight, these can be collected along with a Body Condition Score when calves are weaned. As a breed we are continuing to move forward with proving our value as the source for maternal genetics.

 

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