Once a heifer drops her first calf…is she one of the cows?
According to University of Missouri Extension beef nutritionist Justin Sexton, it's important to remember the nutritional needs of heifers differ from those of the mature cows in the herd. Sexton said conventional wisdom holds that a heifer that's never been bred needs to be 65 percent of her mature weight at breeding, although there's some debate about whether 55 percent will suffice. "Whatever that number is," said Sexton, "it's less than 100 percent. So then, a first-calf heifer, when she calves, we target her to be about 85 percent of her mature weight when she drops that first calf."
That means the heifer will gain the remaining 15 percent of her mature weight between ages two and five, most of it in that initial year. The first-calf heifer also will not necessarily be at the same level of milk production as the mature cow. Sexton said, "The key is to get an acceptable level of milk production—but more importantly, get that heifer to breed back or be cycling 80 days from calving—she is going to need a higher level of energy. We hope that she calved at a body condition score of 6, so that she is carrying some amount of stored energy in the form of fat on her back that she can access as needed. That way, he said, she can still head into the breeding season at a body condition score of a 5."
Whether the animal is a first-calf heifer or a mature cow, Sexton said it's extremely difficult for producers to feed a cow so that she will gain condition while she's lactating. That means the opportunity to add condition to a cow lies in the 90 days prior to calving. "The thing I recommend to producers," he said, "is they go into their herd at weaning time, or 90 days prior to calving—when the next breeding season starts, maybe earlier if they get the chance—and body condition score those cows, and be willing to sort them." A pregnancy check at that time is also important, he said, "because those open cows don't need to be taking feed away from the productive group."
Sexton said the cows with a body condition score of 6 can be sorted into one group with adequate condition for calving; first- and second-calf heifers, and cows that came through the summer thin might not have achieved that body condition score and would need to be managed differently. The important thing here is to provide good forage, and the key to that, said Sexton, is forage testing. "One of the things I tell producers is," he said, "Feed cost isn't high enough, if we're not willing to take a $20 forage test to determine what 85 to 95 percent of (the cows') feed intake is going to be from a fiber, energy and protein value." Whether a supplement is needed, he said, may depend on whether "we did a good job of making hay in the summertime—which was a challenge this year, due to the rain."
And here's where the actual vs. desired condition score comes into play. Each number on the score is the equivalent of 80-100 lbs. of body weight. "If we need to add 100 lbs. of body weight in 90-100 days," Sexton said, "we're talking gains in excess of 2 lbs/day, so there's certainly a higher percent of energy that's going to be required in the form of concentrates; forages aren't going to supply enough energy."
Sexton said the most important aspect of separating heifers from cows is the ability to direct nutrients to the cattle that need it. He said, "One example I like to use is, let's say we're going to feed 3 lbs/head/day—that's a random number—of some concentrate. If I've body condition scored my cows and I know that my cows are acceptable but my heifers need a little more feed, every two head I'm going to feed 6 lbs. I'm better off to feed 4 lbs to the heifers and 2 lbs to the cows; my feed bill hasn't changed, but I've directed the nutrients more toward the group of animals that need it."
