10/15/2026
It seems like a great time to talk about the Heifer Pregnancy (HP) EPD
We've been talking about the maternal traits that help us make more informed decisions on our future cow herd. Here's another one to discuss and consider whether it applies to your situation.
First of all, what is the HP EPD meant to predict? Let's get the official definitions from a few breeds for you.
🐂 Angus defines HP as a selection tool to increase the probability or chance of a sire's daughters becoming pregnant as heifers during a normal breeding season. Higher values are more favorable.
🐂 ASA/IGS defines HP as the difference in the percentage of daughters that will conceive and subsequently calve at two years of age. Higher values are more favorable.
So...let's go break that down a bit more ⬇️
If I'm keeping replacement heifers out of a bull, HP helps me compare the genetic differences in the likelihood of those daughters becoming pregnant during their first breeding season.
Let's say we're comparing two bulls within the same breed:
Bull A = +10 HP
Bull B = +5 HP
That's a five-percentage-point difference. If we developed and bred 100 comparable daughters from each bull under similar conditions, we'd expect approximately five more successful pregnancies from Bull A's daughters, on average.
😎 Here's where HP gets interesting.
Heifer pregnancy is traditionally considered a lowly heritable trait. In other words, genetics play a role, but environment and management can have a substantial influence on whether a heifer becomes pregnant. Nutrition, development, breeding management and other factors all contribute to the outcome.
You'll also notice that HP EPD accuracies can be relatively low, especially on younger animals without daughter records.
‼️ Heritability and EPD accuracy ARE NOT the same thing, but both are worth trying to understand a bit better.
Okay seedstock breeders...where does the HP EPD get its information from? This section is for you.
Back to our favorite subject...complete reporting!
Reporting requirements vary by association, but here's information worth capturing and submitting where applicable:
✅ Complete exposure records of heifers entering the breeding herd, including AI and pasture in/out dates.
✅ Pregnancy outcomes, including the heifers that come up open.
✅ Assigning appropriate calf removal or disposal codes for heifers that leave the herd prior to being exposed (especially important in Associations where they rely on dam enrollment information to collect heifer pregnancy data).
Why does this matter ❓
If we're only reporting the heifers that successfully calve, we're missing at least a part of the story. The evaluation needs information about both successful and unsuccessful breeding outcomes to better identify genetic differences in fertility between sires. Open heifers being reported is important to the full picture. Records across groups of genetically related heifers give us a better opportunity to understand whether genetics may be contributing to that outcome.
🤠 Commercial producers...what does this EPD mean for you?
If you're buying bulls to produce replacement females, HP is another maternal EPD worth considering for your decisions. I'd recommend starting by finding the percentile ranking within the breed population and identifying a range that fits your breeding objectives. If you’re using HP, I would encourage you to look at the accuracy of the EPD and take that into account as well. This is a trait we would recommend using as a supporting selection criterion alongside the other maternal traits you’re trying to balance.
As a reminder, fertility isn't determined or evaluated by a single EPD.
🔑 Key Takeaways:
✅ HP helps predict differences in the likelihood of a sire's daughters becoming pregnant as heifers.
✅ Use percentile rankings to understand where a bull falls within his breed population, and consider the accuracy of the prediction.
✅ Recommended to use HP alongside other maternal selection criteria, not in isolation.
Genomics and precision mating strategies can provide additional information when we're trying to build a more complete picture of the females we're creating and evaluate the potential of what can be inherited. Make sure to ask our team about RightMate, especially if you AI.
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