You lost one this spring. A first-calf heifer, up half the night, and by the time you got a chain on that calf it was too late for both of them. And the part that eats at you is that you did your homework. You bought a low birth-weight bull on purpose, for the heifers, because everybody says buy a low birth-weight bull for the heifers. His birth-weight number looked fine. You did the thing you were told and it still went wrong.
Here is what nobody made clear at the counter. Birth weight is not the number that tells you how easy a calf is born. It is one piece of it, and leaning on it alone is how a fine-looking number lets you down at two in the morning.
The number that actually says “born easy”
There is a number built for exactly this question, and it is not birth weight. It is CED, Calving Ease Direct.
CED is the American Angus Association’s prediction of how easily a bull’s own calves are born, without you having to pull them. It is reported as a difference against another Angus bull, like every EPD, and Expected Progeny Difference is what EPD stands for: a forecast about a bull’s future calves, not a measurement of the bull standing in front of you. With CED, higher is easier. A bull with a higher CED sires a higher share of calves that come on their own, unassisted. That is the whole trait, and that is the number you want when you are breeding heifers (angus.org EPD definitions).
Notice what CED does that birth weight cannot. Birth weight tells you how heavy the calf hits the ground. It says nothing about the shape of that calf, how it is put together, whether it comes easy for its size. CED folds all of that together and answers the real question directly: will this calf be born without a fight. Birth weight is one of the things that feeds into calving ease. CED is calving ease itself.
Why low birth weight alone fooled you
So why does the low birth-weight advice go wrong?
Because a light calf can still be a hard calf. Two calves can weigh the same and be born completely differently, depending on how they are built and how they are presented. Birth weight catches the weight and misses the rest. You can buy the lightest-birth-weight bull on the page and still land in trouble, because you picked the one number that only tells part of the story.
CED is the number that carries the rest of the story. That is why you lean on it, not on birth weight by itself. Read birth weight too, sure. It is real, and on heifers a lighter calf helps. But let it be one input, not the whole call. When the two disagree, the calving-ease number is the one built to answer your question (angus.org).
The cost of chasing birth weight to the floor
There is a second reason not to hang everything on driving birth weight down, and it costs you money long after calving season is over.
Birth weight is roped to growth. The same genes that make a light calf tend to make a slower-growing one. Darrh Bullock, an Extension specialist at the University of Kentucky, lays out the chain in his practical guide for using EPDs: higher growth usually brings heavier birth weights, and pulling hard the other way, chasing the lightest birth weight you can find, drags growth down with it. His word for the fix is balancing, not maxing and not minimizing.
So the man who buys nothing but the rock-bottom birth-weight bull, year after year, quietly gives up pounds at weaning. He solved calving season and lost the paycheck. CED lets you dodge that trap. A bull can carry a high CED, meaning his calves are born easy, without having the very lightest birth weight on the page, because CED is measuring the ease directly instead of forcing you to starve the birth weight to get there. You get the easy calving without paying for it in growth you did not have to give up.
CED is his calves. CEM is his daughters.
Now the part that trips up good cattlemen, because the page hands you two calving-ease numbers and they are not the same thing.
CED, again, is about the bull’s own calves being born easy. That is the number for right now, the one that gets a live calf on the ground out of the heifer you are breeding this year.
CEM, Calving Ease Maternal, is a different animal entirely. It is the Association’s prediction of how easily the bull’s daughters will calve when their turn comes, as first-calf heifers (angus.org). Higher is easier here too. But CEM is not about the calf in front of you. It is about the heifer calf you might keep, years down the road, having her own first calf without you up at two in the morning again.
Hold the two apart like this. CED is the calf being born now. CEM is the daughter calving later. One buys you an easy calving this season. The other builds a cow herd that calves easy on its own down the line.
Which one you lean on depends on what you are doing with the heifers. If you are breeding heifers and selling every calf, CED is your number. Get them born alive. If you are breeding heifers to raise your own replacements, the daughters you keep, then you want CED for this year’s calving and CEM for the kind of cow those daughters grow into. A replacement-minded man reads both. A man selling the whole calf crop leans on CED.
What to do at the sale book
Here is the short of it, the part to carry to the counter.
When you are buying a bull to turn out on heifers, find CED first and lean on it. Higher is easier. Read birth weight next to it, and favor a lighter calf on heifers, but do not let birth weight alone make the decision and do not chase it to the floor, because you will give up growth you cannot get back (Bullock). If you are keeping daughters, weigh CEM too, because that is the number that tells you whether those daughters will calve easy when it is their turn.
And the same line runs under all of it that runs under every number on the page. You do not compute any of these, and neither do we. The American Angus Association runs the whole evaluation across the breed every week and publishes CED, CEM, and birth weight ready to read. Deluisio Angus reads them and matches them to the job. Your part is to pick the right number for the right heifer, and now you know which one that is.
Related: Every Number on the Bull Page · Why You Cannot Push One Number Without Moving Another · What an EPD Is, in Plain English · back to the reading guides.
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