The nutritional status of the gestating cow and heifer has far-reaching implications, not only for her future fertility but, potentially, for the health and performance of her calves (including the fertility of her heifer offspring), and ultimately, a producer’s bottom line. To optimize long-term herd performance — and keep production costs down — it’s crucial to supplement those females in a strategic way.
Because reproduction rates and feed costs are two of the most critical factors for any beef system’s success, balancing reproduction and nutritional needs remains a hot area of research. “Reproductive traits, as we are able to measure them today, are very lowly heritable,” says Rick Funston, an associate professor and beef reproductive physiology specialist at the University of Nebraska. “Therefore, we use the other component of what influences those traits, which is management. Largely through nutrition, we manage reproduction by the timing of and the need for supplementation when nutrient availability doesn’t meet requirements.”
The question boils down to this: How can producers maximize reproduction without overspending on feed? “We’re always trying to find that optimal level,” says Scott Lake, associate professor and beef specialist at the University of Wyoming Extension. “Maximizing reproduction and optimizing reproduction, from an economic standpoint, might not be the same thing. You want to find that fine line.”
Complicating matters is the fact that there’s no one-size-fits-all answer. “That’s something producers are going to have to pencil out,” Lake says. “Generally speaking, if you’re getting 98 to 100 percent conception, you’re overfeeding probably 85 to 90 percent of the herd. If you get 90 percent conception rate and let that bottom 10 percent fall out, I think economically you’re better off, but exactly what that number is will depend on your resources and your feed costs.” Also complicating the equation: what we’re now learning about fetal programming and the ways nutritional levels impact progeny performance.
When supplementation matters
At the University of Nebraska, they’ve looked at supplementation for cows grazing on winter range, as well as early weaning as a management tool to provide extra body condition going into winter grazing, Funston says. The results: no significant payoff for either practice. “In a spring-calving herd, it largely hasn’t benefitted the cow to either supplement or early wean, provided they’re on an increasing plane of nutrition going from calving to breeding,” he says. That last point turns out to be key — environmental conditions provided the cows with what they needed, at the time they needed it most.