When it’s time to choose a heifer bull, expected progeny difference for calving ease tops one beef producer’s list.
The birth weight expected progeny difference (EPD) is accurate but it’s simply an average, says Travis Olson of Ole Farms at Athabasca, Alta. For example, two bulls could have an average birth weight EPD of 75 lbs. But Bull A’s calves might consistently fall between 65 to 85 lbs., while Bull B’s calves could range between 55 to 95 lbs. Bull B’s average birth weight looks good, Olson concludes, but he has less consistent calving ease.
Olson and his family raise commercial and purebred Angus. Olson says that 15 years ago he paid more attention to birth weight but now he finds that calving ease is a better yardstick.
“It takes into account inconsistent bulls that have a good average but still sire occasional big calves,” he says.
A calving ease EPD is also more important than assessing a bull visually, he adds. “Some producers think a bull will work well on heifers if he has a narrow head and shoulders. There’s much more to it than that,” says Olson.
Olson says the breed associations have identified the genetics behind calving issues. A calving ease EPD takes into account multiple factors, he says, such as age and size of the cow, calf shape, gestation and the bell curve.
When buying an unproven bull at a sale, look at repeatability in the pedigree, Olson adds. “I get nervous when I see a bull whose calving ease numbers are acceptable but there are a few animals in his pedigree that weighed 95 lbs. at birth,” he says.
Olson looks for a few generations of high calving ease EPD when buying heifer bulls.
“If you have at least three generations of high calving ease EPDs stacked up, your rate of success will be far better. You don’t want a calf to throw back to a great-grandsire who happened to be a cow-killer, siring huge calves,” Olson says.
Selective breeding allows people to move away from undesirable traits like heavy birth weights, he adds, but these traits may still be lurking in the background. If certain genes line up, those undesirable traits can be expressed.
Importance of calving ease
The biggest factor that determines profit or loss in western Canadian beef herds is the percentage of calves weaned out of cows exposed to a bull, Olson points out.
“This takes into account the cows that didn’t get pregnant, cows that had calving problems and their calf was born dead, and calves that died out on pasture,” Olson adds.
A herd’s pregnancy rate may be high, but if some of the cows or heifers lose calves at birth, it cuts into profit, Olson adds. Labour costs drop if a producer doesn’t have to pull calves and if the calves are bouncing up at birth, getting colostrum, he says.
“They don’t have a swollen nose and they don’t have the stress from a difficult birth,” says Olson. “Their mothers are not overstressed from hard labour and they can get up and mother the calf. All these factors make calving ease extremely important.”
Olson says it’s also important to consider breed when selecting a heifer bull.
“Even though I feel there is more variation — especially in things like birth weight — within a breed than between breeds, some breeds do not have a reputation for calving ease,” he says.
Those breeds have other merits, he adds, and can provide great terminal crosses when bred to mature cows.
“It’s also important to be able to trust the information from the bull producer,” says Olson. “Not every seedstock breeder is always up front with accurate information.”
Over the years, Olson has noticed a few examples of this, such as the breeders whose catalogue lists every sale bull as having a birth weight of 76, 78 or 82 lbs.
“If you have 100 calves, there will be more range than that,” says Olson. Most of the calves in their own program are in the middle, but there are always a few outliers, he says. That includes a few light calves, and the mature old cow who goes long on gestation and births a 105-lb. calf with no problem, he says.
Another issue is that some seedstock producers breed for power, then use a heifer bull on their heifers. “They’ll state in the catalog that all those resulting offspring are good for heifers. But if a bull was 86 lbs. himself, out of a heifer, he’s not really going to be a heifer bull,” says Olson.
Olson adds that a heifer’s first calf is usually lighter than the calves she’ll have as a mature cow.
“I’d rather use an 80 lb. birth-weight bull on heifers if he was born out of a cow, than a 75-lb. bull born out of a heifer,” says Olson. Birth weight alone doesn’t give you the whole picture, he adds.
Which one is your best heifer bull?
While calving ease EPDs are crucial to Olson, he considers other factors, such as scrotal circumference and fertility.
Some people waffle on heifer bull traits and end up getting one with a little more growth and muscling, says Olson.
“This can get them into big trouble. I am prepared to sacrifice some muscle shape, etc., to get a bona fide heifer bull with true calving ease,” Olson says.
Others only use a bull on heifers for a year before moving him in with the mature cows.
“You don’t need to do that, and should also keep in mind that a good heifer bull is not always what you want in the cow herd,” says Olson. Typically, a good heifer bull is lighter-muscled, finer-boned, and won’t have as much growth as terminal bulls or powerful maternal bulls, he says, although there are exceptions.
Olson prefers to identify a good heifer bull and use him on heifers his entire life. A structurally correct heifer isn’t likely to be injured by a large bull, he says, and a talented bull will shift most of his weight to his hind legs.
As for the possibility of inbreeding, most breed associations have identified recessive genetic disorders and most progressive seedstock producers have purged them from their herds. Olson suggests keeping heifer bulls that have proven calving ease.
“You might have an inbred calf that is 20 lbs. lighter than the group average, but you (will) have a much higher percentage calf crop, and this will be more profitable than having dead calves,” he says.
Producers can often pick out a good heifer bull. But if, for example, a producer turned out three bulls with 70 heifers, it’s hard to know which bull sired the easy-born calves and which sired the calves that had to be pulled, Olson says.
“In that situation it’s wise to take DNA from those calves and see which bull was responsible,” says Olson.
“DNA testing is inexpensive, and all it takes is a sample from that 90-lb. dead calf or the calf you had to pull. You can cut off a piece of the ear and send it to the lab, along with a sample from each of those three bulls that were in that pasture,” Olson says.
If 10 out of 50 heifers had difficult births, that’s too many, says Olson. Some people cull the bull with the biggest head.
“In that situation, if you were using three bulls, you would be right about one in three times.”
DNA testing might reveal that the same bull sired eight of those calves, he says. It’s much cheaper than culling the wrong bull and having the same problem next year, he adds.
“Before the next breeding season you might decide to put that bull with the cows instead of heifers.”