Calving Ease and Growth in Angus EPDs: How to Weigh the Tradeoff

Every bull buyer faces the same tension. Calves that grow fast are worth more per head, but the same genetics that build growth can also build birth weight, and a hard-pulled calf costs time, money and sometimes a cow. Seedstock producers face the tension from the other side, because they must breed bulls that satisfy both camps. We do not claim to know exactly how seedstock herds across the country rank these traits, since we could not verify a survey with a trustworthy figure. What we can do is explain how the traits interact and how to decide for your own herd.

The traits on the sheet

The American Angus Association publishes a set of EPDs that cover this ground. Calving ease direct (CED, shown as a percentage) predicts the ease with which a sire's calves are born to heifers. Birth weight (BW, in pounds) predicts calf size at birth. Calving ease maternal (CEM) describes how easily a bull's daughters' calves are born when those daughters become cows. Weaning weight (WW) and yearling weight (YW) cover growth, and milk describes a daughter's contribution to her calf's weaning weight (American Angus Association data descriptions).

Higher CED is generally favored, and lower BW is generally favored when calving ease is the priority. Higher WW and YW are favored for growth. Expect these to move in opposite directions often, because heavier calves at weaning are frequently heavier at birth.

Why they correlate, and why they do not have to

Birth weight and growth are positively related genetically, so selecting hard for growth tends to raise birth weight. But the relationship is not perfect. Some sires combine moderate birth weights with strong growth, and that combination is exactly what buyers hunt for. It is also why calving ease is not simply the inverse of birth weight: CED reflects calf size and other factors, such as shape and gestation length, that affect delivery.

Decide by the group of females you are breeding

Heifers

First-calf heifers are smaller and have less room, so calving ease should lead. Pick bulls with strong CED and moderate BW, with accuracy high enough that you trust the numbers. A heifer that calves without help rebreeds more readily, which protects the next year's calf crop as well.

Mature cows

Mature cows can usually handle a bit more birth weight, so you can lean toward growth. Even so, a difficult calving costs you in labor, vet bills and risk, so setting a ceiling on BW is sensible.

Replacement females

If you plan to keep daughters, look at CEM and milk too. Daughters of a calving-ease sire will pass along his genes for calving ease to their own calves, and excess milk in a limited-forage environment can cost you condition.

Think about your market

Where calves go also affects the balance. If you sell calves at weaning by weight, growth carries more value. If you retain ownership, carcass traits and feed efficiency join the picture. A guide to the dollar indexes appears in the Association's descriptions, and tools such as $W (weaned calf value) and $B (beef value) combine traits into a single figure, so you do not have to balance each EPD by hand. The tradeoff is that an index embeds assumptions about prices and management that may not match yours.

A simple method that works

1. Set a calving ease floor and a birth weight ceiling for each group of females.
2. Remove any bull that fails the screen, regardless of how good his growth looks.
3. Among the remaining bulls, choose for growth and carcass traits relevant to your market.
4. Check accuracy, and when it is low, treat the number as less certain.

This keeps the decision simple, because the traits that cause the biggest losses, calving problems, are handled first. Our guide to reading an EPD sheet explains accuracy and percentile ranks, and the replacement heifer guide picks up from there.

Management still matters

EPDs predict genetics, not weather or nutrition. Heifers overfed before calving may have larger fetuses and fat-restricted pelvic areas, and heifers that are underdeveloped will struggle even with easy-calving sires. Heifer condition, pelvic measurements where used, and a good calving-season watch routine all reduce the risk. The University of Nebraska beef program at beef.unl.edu carries practical material on calving management.

Buyer takeaways

Consumers rarely see these traits, but they feel the result in supply. Herds that avoid calving losses raise more calves at lower cost, and good carcass genetics reach the plate through programs such as Certified Angus Beef. For a general overview of how bull selection affects the herd, see farm.fm's page on understanding bulls, and use the agriculture directory to find seedstock producers.

Trait definitions, scales and index weights change from time to time, so check current American Angus Association documentation before purchasing. This site is independent and not affiliated with the Association or Certified Angus Beef.