EPD Selection for Maternal Sires

With AI season and bull sales right around the corner, it might be time to consider what EPDs (Expected Progeny Differences) would best fit your operation. This article will discuss the Angus EPDs and the four most critical maternal traits that allow you to build a better cow herd.

The number one trait is docility. Docility is one of the most heritable traits. Breeding to a bull with high docility will not only result in calmer calves but will give you better average daily gains (ADG). Calves with high docility will consume less energy running about the pen. According to the Penn State Extension study, a 2009 daily rate of gain study examined the feeding of 13,000 head of Angus calves. The study was conducted by dividing calves into three groups based on their docility. The three groups were docile, restless, and aggressive. According to the study, the average daily gain of the docile calves was 0.26 pounds per day higher. The docile calves in the study also had a lower mortality rate, along with a higher percentage of prime and choice quality grades.

The number two trait to consider is maternal dollars ($M). Maternal dollars is an EPD comprised of nine different traits. The traits included in $M are calving ease direct (CED), maternal calving ease (CEM), weaning weight (WW), milk, heifer pregnancy (HP), docility (DOC), milk weight (MW), and foot score EPDs – both foot angle (Angle) and claw set (Claw). When selecting a bull for maternal traits, $M is an important one. In theory, a high milk EPD should result in a higher weaning weight since the cow is producing more milk. However, if you are only selecting for a higher milk EPD, you will end up with a higher maintenance cow. Therefore, $M is a better selection tool because it considers multiple traits. Claw and angle scores are also critical. The better these scores are, the longer your cattle should hold up. Therefore, they remain in your herd longer.

Calving EPD is the number three trait to examine. These include calving ease direct (CED), maternal calving ease (CEM), and birth weight (BW). CED and CEM are calculated by the percentage of unassisted births. The higher the number, the fewer assisted births. CED predicts the average in which sires’ calves will be born unassisted in contrast to other sires when bred to first-calf heifers. CEM predicts how the daughters of a particular sire should calve without any assistance. Although both are heritable traits, birth weight is still the number one factor in calving difficulties. Many factors, including feed, environmental temperature, and exercise, can influence BW. On a 1-9 scale body condition score, anything above a six is more likely to need calving assistance. This is because excess fat stored in the pelvic region causes a smaller birth canal. Environmental temperature is also an important BW factor. When the temperature is cold for an extended period, cattle shunt blood from their extremities to their internal organs. The uterus of a pregnant cow has a lot of blood flow. Thus, if blood is instead directed towards internal organs, BW will be higher.

The number four trait we are discussing is heifer pregnancy (HP). Although HP is not one of the most heritable traits, it is still a necessary trait to review. HP examines the likelihood  that a sire’s daughters will become pregnant in their first breeding season. HP is not only important for breeding efficiency but also in weaning a bigger calf. When a heifer breeds on her first cycle, she will have more time for the uterus to heal and breed back for the next season.

In conclusion, producers selecting for maternal traits will retain better-producing females. If you would like to get more in-depth on EPDs, please contact one of your Sioux Nation representatives.