The conventional wisdom is that early weaning of calves allows their dams to gain condition, resulting in feed savings and better rebreeding rates. Preliminary results of new research at the University of Nebraska-Lincoln (UNL), however, seem to contradict that.

“It’s just one year’s worth of data, but the preliminary indication is that there may be no advantage to early weaning as a way to save feed. We’ll see how it plays out over the next few years,” says Terry Klopfenstein, UNL professor of ruminant nutrition.

Klopfenstein’s research is part of cow-efficiency work being conducted at UNL, Texas A&M University  and Oklahoma State University under a $2-million endowment from the Dr. Kenneth and Caroline McDonald Eng Foundation. Klopfenstein’s work and that of other researchers from the three institutions will be detailed at a symposium set for Sept. 12-13 in the Johnny Carson Center on the UNL campus. (Learn more about the symposium here.)

Confinement scenario

What sets Klopfenstein’s cow-calf research apart is that it’s conducted in a confinement situation, which allows a level of control and analysis not allowed in a pasture situation.

“I’ve been at this (cow-efficiency research) for 50 years and we haven’t yet figured out how to measure how much a cow eats in a grazing situation. We can talk about saved forage, but it’s an estimated value. In a feedlot, you can measure the feed every day and totally control the diet,” he says.

UNL’s cow confinement research consists of 84 cows split evenly between two facilities at opposite ends of the state. One group is located at UNL’s research facility near Mead, 35 miles north of Lincoln. The second group is based in the more arid environment of UNL’s Panhandle Research and Extension Center near Scottsbluff.

Klopfenstein and his UNL colleagues’ first year of research focused on evaluating in a total confinement production system the impact of early weaning at 90 days, vs. normal weaning at 205 days. The researchers also studied cow reproduction and performance, calf growth and health, and the energy efficiency of producing a weaned calf to 205 days of age. A second objective was to compare the efficiencies between range and confinement-based cow-calf production systems.

After calving last summer, the cows and calves remained together until half of the calves were weaned at 90 days, with the rest weaned at 205 days. Researchers wanted to study whether it’s more efficient to feed the cow to produce the milk for the calf, or to wean the calf and feed it directly.

A diet of 60% wet distillers grains and 40% crop residue was fed to all cows, with cows whose calves were weaned at 90 days limited to 15 lbs. of dry matter. “It was probably half of what those cows would have eaten free-choice,” Klopfenstein says, but it was sufficient for the cows “to maintain their weight and gain a little bit.”

The calves weaned at 90 days received the same diet. “So all we had to do was measure the amount fed to each group to see which was more efficient. I don’t think anyone has tried to do it this way before, but we think it’s a valid way to try to answer the question. And our first year’s data indicates it’s just as efficient to leave the calf on the cow, as it is to wean the calf and feed it,” he says.

Meanwhile, ultrasound for pregnancy was conducted in early March on both groups of cows, and no statistical difference in settling rate was found. “A higher percentage of cows were determined bred among the early-weaned group, but it wasn’t statistically significant. Again, this is only one year’s data.”

Klopfenstein says one of the project’s surprises was the health of the calves. Calving was conducted last summer in the feedlot, and researchers used individual pens to mimic the progression of calving pastures used in the Sandhills Calving System. Thus, groups of close-up cows move through a succession of pens in order to maximize a clean calving environment.

“Calf health was one of our concerns, but we had no cases of scours among the calves. Of course, sunshine is a great sterilizer,” he says.

Because summer 2012 was extremely hot, Klopfenstein was concerned about cows calving in 100° heat. “The cows did fine. Calves, however, should have a bit of shade while in confinement.”

Klopfenstein says he sees the potential in Nebraska for confining and calving cows in the summer, followed by grazing cornstalks in fall and winter months.

“Cornstalks are a tremendous resource and the feeding economics are very favorable. I could perceive a system with calving in the feedlot in June or July, a turn-out on cornstalks in October, natural breeding on cornstalks, with the calves left on the cows and weaned in February or March when the pairs come off of cornstalks. We would then just drylot the cows until the following October.”

Klopfenstein says what makes such a system feasible is Nebraska’s abundance of corn residue, which is a seriously underutilized feed resource for cattle. “It isn’t very well utilized from a grazing standpoint; what we’re short on in Nebraska is green grass in the summer. Thus putting the cows in drylot in summer makes some sense to me,” he says.