Supplementation of cows may have long-term impacts in future progeny
Feed expense is the highest cost, no matter what segment of the beef production business a producer is in. If a producer can decrease harvested feed costs, profitability can be improved, but how does this impact the cow and her future offspring?
Rick Funston, beef reproductive physiology specialist for the University of Nebraska, was one of a team of scientists studying pregnant beef cow nutrition and its lifetime effects on replacement heifer progeny.
The cows in the research project were all part of the same herd, same breeds and same genetics. During the three-year study, Funston looked at cows receiving supplementation while they were pregnant, comparing them to ones that didn’t receive supplementation.
The running age cows were supplemented during the winter and post-calving with one pound of 42 percent crude protein cake.
Analyzing the data, Funston saw no benefit in supplementing these cows as far as cow breed-back, but he did see more live calves weaned if that calf was from a supplemented cow.
Funston noted the cows with calves weaned in August were in better condition going into calving in April. Calves that were weaned in August or November and came from supplemented cows had weaning weights that were greater, Funston said.
“It made us think maybe we’re not just impacting that reproductive event, but also those progeny that weren’t even born yet,” he commented.
The calves from this project that were weaned in November, came from un-supplemented cows and fed to a finished weight and slaughtered lost nearly 100 pounds of live weight. Funston was surprised that something taking place before that calf was ever born could have this kind of impact.
“After analyzing all these systems, the most profitable was to wean the calves in November from supplemented cows,” he said. “If we take those calves clear to harvest, they will have an additional 100 pounds of live weight, which added 60 pounds to the carcass weight.”
On a side note, Funston also noticed that the calves from supplemented cows showed no difference from birth to weaning in the number of those that became sick compared to non-supplemented cows, but there was less post-weaning sickness in the calves that came from supplemented cows.
Replacement heifer considerations
Funston also looked at replacement heifer calf data and how supplements impacted weaning weights, adjusted 205-day weaning weights and weight at pregnancy checking.
These weights were all less if the heifer came from a cow that wasn’t supplemented, Funston said.
He then looked at age of puberty and percentage of heifers cycling, which are two of the most important things needed for reproduction to occur.
“There was no effect,” Funston said, “but when I looked at the percentage of heifers calving in the first 21 days, it was low. The final pregnancy rate was decreased in those heifers that came from cows that weren’t supplemented.”
Funston was also concerned how grazing cornfield residue was impacted.
In Nebraska, less than 10 percent of available corn acres are grazed, Funston said.
“If we are going to grow our cowherd, it’s not going to be with grass – not with those high feed costs. It is going to be with management systems that allow us to utilize more crop residue,” he commented.
This study looked at cows on winter range versus cows grazing corn residue. Both groups were fed a one pound, 32 percent cube that was primarily distiller’s grain.
They also had groups of cows on winter range and cornfield residue receiving no supplement.
For cows grazing cornfield residue, Funston saw no benefit of feeding a supplement. But for cows on winter range receiving no supplement that bred back and were pregnant, fewer calved within the first 21 days.
In the feedlot, the steers born to cows on winter range receiving no supplement were an average of nearly 70 pounds lighter.
At slaughter, it was noted that those calves didn’t marble as well, and it ultimately affected how well they would grade.
However, Funston did mention that the calves from non-supplemented cows were more efficient.
“Cows that are restricted and have heifer daughters that are restricted are more efficient and need less feed as pregnant heifers, which can potentially effect longevity. Animals are adapting to a lower nutrient environment over time by decreasing output, which is decreasing birth weight and weaning weight, and that is probably through the milk,” he said.
“The consequences of nutrient restriction need to be considered not only for the animal we think we are impacting but also to take into account how it may impact the fetus,” Funston added.