Early Calvers Are Set Up for Success
Easy calvers are the kind of heifers and cows every rancher wants. But here’s another one that’s just about as important – early calvers.
Whenever your calving season starts, you want your cows to be front-loaded and drop healthy, vigorous calves in the first 21 days. That means a cow got bred and conceived in her first cycle after bull turnout.
About two thirds of matings result in conception, says Brad White, Kansas State University associate professor of production in the College of Veterinary Medicine. If your herd is doing well and front-loaded, you will get about two thirds of your calves in that first 21-day calving cycle.
The problem is those other cows – the ones that calve late. Sometimes, you’ll catch them up next year, but more often you don’t. The reason is that most cows have an anestrous season (noncycling) averaging 50 days after calving. “Some cows take 60 to 80 days to cycle,” says White. “For heifers, it can be as much as 100 days after their first calf before they cycle.”
If you do the math on that, it’s easy to see why it is so hard to get a late-calving cow or heifer caught up the next year. When it’s time to turn the bull out again, the only cows actually cycling are the ones that calved early. Cows that calved late are almost assured of breeding late again, maybe by two cycles.
On the other hand, cows that calve early tend to stay early. White calls this the annual calving momentum of your herd’s reproductive profile.
“You’re either moving it forward with higher and higher percentages of early calvers, or you’re moving the other direction with more delayed calves. It’s good momentum, or it can be bad,” he says.
Studies show that if a heifer has her second calf in the first 21 days of that calving season, she is very likely to stay in the herd for a long and productive life. When lots of them are doing so, that’s White’s definition of positive momentum.
“We have demonstrated that cows that calve early with their first and second calves wean heavier calves through their sixth calf,” notes White. “It really carries over. In fact, an early calver can produce the weight equivalent of a whole additional calf over the cow’s lifetime. If I can get more than two thirds of my cows to calve in the first 21 days, it’s that many extra calves.
“Late calving is almost worse than having an open cow. If she’s open, I see her and sell her. Late calvers are just lost productivity that I probably didn’t see,” he says.
If you know your reproductive momentum is bad with too many late calvers, one solution is to replace the late calvers with some purchased repl acement heifers that are front-loaded to calve early.
In your own heifer development program, because of the potential for prolonged anestrous of heifers, you should strongly consider breeding heifers to calve before your mature cows. That would help ensure they make it into the first 21 days the following calving season.
If you retain and develop heifers from your own herd, White says it’s really important that you select your biggest and most mature heifers as replacements. “You want heifers that breed early, and the three most significant influencers of puberty are age, weight, and breed,” he says. “I like to use a combination of age and weight when selecting heifers, and I like them to be about 65% of their mature weight at first breeding.”
White says you should consider a program to develop more heifers than you actually need for your herd. You can keep the ones that breed and conceive early and that will help you build front-loaded momentum in your calving season. Others that end up not fitting your calving season may fit someone else’s, and you can sell them.