Supplementing pregnant cows with protein on winter pasture leads to better calf performance, says a professor at the University of Nebraska-Lincoln.
A cow’s diet while pregnant affects her calf after birth and in some cases right to slaughter, Dr. Rick Funston told producers at a recent Rancher’s Research Update at Johnstone Auction Mart in Moose Jaw.
Funston said he and his colleagues and students have run several research projects looking at how cows and their offspring respond when the pregnant cow is supplemented with protein. The university’s herd runs on the Nebraska sandhills, and the cows are naturally serviced Red Angus and Simmental crosses which calve in the spring.
“These cattle are all the same genetics. But how we manage that cow is influencing the expression of (the calves’) genes, even before they’re born.”
Benefits steers in feedlot
Pregnant cows were supplemented with protein cubes for 90 to 100 days. Funston said they focused on correcting the first limiting nutrient.
“Yeah, they’re deficient in energy (while grazing winter grass). But protein is what corrects that first limiting nutrient, which is crude protein deficiency, and it allows animals to digest the feed they eat better, and it also allows those animals to eat more, which corrects that energy issue, too.”
Calves born to non-supplemented cows were lighter at weaning than the supplemented group, Funston said.
In one study, researchers examined how supplementing winter range cows with protein affected their steers. Steers out of non-supplemented cows were lighter through the feedlot.
“We took off nearly a hundred pounds of live weight on these calves if we didn’t supplement their mother during late gestation,” Funston said. “Something that happened before this calf was ever born impacted its live weight and subsequent carcass weight.”
Steers from supplemented cows also had better carcass quality grades, and supplementing cows during pregnancy also affected steer health in the feedlot.
“They didn’t have any difference in sickness from calving to weaning, but from weaning to slaughter, we had more sick calves if they came from cows that weren’t supplemented during gestation.”
In a three-year study, Funston and his colleagues also found supplementing pregnant cows affected their heifers. Three times a week they fed one herd protein cubes, which were 42 per cent protein. The control group received no supplement. After calving, all the calves ran together.
Pregnancy rates were higher in heifers from supplemented cows.
“Not only have we influenced steer carcass weight,” he said. “Now we show we influence heifer fertility based on how we manage those cows.”
Heifers from non-supplemented cows hit puberty later and were lighter. They were more feed-efficient than heifers born to supplemented mothers, but Funston doesn’t know if they remained more feed-efficient after they were evaluated. He said the savings from feed efficiency were offset by other benefits, such as better fertility in heifers and better steer carcass weight and quality.
“In all cases, it has been more profitable to supplement, especially if you take those animals clear to harvest,” he said.
Protein supplementation benefits cows
Researchers also looked at whether cows grazing corn residue benefited from protein supplementation. One group grazing combined corn received protein supplement, while another did not. Researchers also compared supplemented cows on winter range to non-supplemented cows. Supplementation was a distiller’s grain cube that was about 30 per cent protein. Cows were kept on the same treatment for three years.
Grazing corn residue increased cow body condition and body weight. Supplemented cows on corn residue didn’t gain any more weight than the unsupplemented cows on corn residue.
But cows on winter range had better body condition if they were supplemented. Supplemented winter range cows also calved earlier and had heavier calves at weaning.
Cows on winter range that weren’t supplemented became pregnant later than their supplemented counterparts.
“We’re starting to erode reproduction by keeping those cows on the same treatment (grazing winter grass without supplementation) for three consecutive years as a producer might do (if this was his management strategy.)” †