Modified distillers grains lowers forage intake on native rangeland

Nov 22, 2013
by DTN

Feeding modified wet distillers grains (MDGS) to yearling heifers can replace some of the forage from native range grazing, a recent University of Nebraska-Lincoln (UNL) study found.

The study examined two aspects of feeding the MDGS: whether the MDGS could replace a portion of the forage required, as well as the method of delivering the MDGS on native ranges.

The feeding trial was one in a series of studies the UNL researchers have done to find practical applications for distillers grains on cow-calf operations, particularly those on native range situations such as those in Nebraska’s Sandhills region.

Distillers grain is very appealing for cow-calf operators because of its nutrient profile, according to Aaron Stalker, Beef Extension Specialist for the University of Nebraska West Central Research & Extension Center in North Platte, NE.

Protein is the first limiting nutrient in winter, he said. Of all the nutrients lacking in the animal’s diet, protein is the one lacking in the greatest amount relative to requirements.

There has been some debate among nutritionists as to which is first limiting: protein or energy.

“Nutritionists like to debate the issue,” he said. “But with distillers, the point is moot. Distillers grains are a good source of energy and protein, so it fixes both problems.”

The researchers first looked at calving cows, then calves and now yearlings. The studies have also been conducted using wet distillers grains, dry distillers grains and now modified distillers grains.

The issue with winter grazing on native forages that limit growth the most is protein, Stalker said.

“Even if you add energy, you don’t get as much of a response. The animal will still only be able to grow the amount that the protein will allow,” he said. “You can add minerals, vitamins, or other required nutrients, but protein is first limiting, it’s what’s holding them back the most. If you add protein, you get the biggest response.”

Stalker said another selling point for cow-calf operators is that the energy in distillers grains doesn’t disrupt forage digestion, or fermentation of cellulose, in the rumen that some energy sources such as starch do.

Another great benefit of distillers grain is its palatability.

“The palatability of distillers is great for calves,” he said. “Intake is a really important issue, especially around weaning. So the palatability of distillers makes it really appealing.”

Price is historically another reason to use DDG; however, in 2012 DDG prices spiked to record-high levels and priced it out of some rations. Despite those high prices, Stalker said that relative to the cost of grazed forage, DDG is still a less expensive source of energy.

Prices for grass/pasture rental to run cattle have been increasing for several years.

Except for 2012’s high prices, the energy in DDG costs less than the energy in renting grass for pasture. That was the idea behind the feed trial, Stalker said.

“Our idea was to replace grazed forage with DDG, thereby lowering the overall cost,” he said.

For the 120-day grazing experiment, 24 spayed yearling heifers were grazed on native summer range and randomly assigned to one of three dietary treatments:

  1. A control diet with no MDGS supplementation
  2. MDGS supplementation fed at 0.6 percent of body weight daily in a bunk.
  3. MDGS supplementation fed at 0.6 percent of body weight daily fed on the ground at different locations within the paddock each day.

After summer grazing, all heifers were fed five days at 1.8 percent of their body weight and weighed.

At the end of the trial, the supplemented cattle gained more (2.43 pounds a day versus 1.17 pounds a day) and had a greater ending body weight (880 pounds versus 726 pounds) than the control cattle.

Stalker pointed out that the cattle on the control diet were fed a protein supplement as well, just not distillers grains, and received the same amount of protein.

“We account for that so we could make sure our response wasn’t to the protein in the MDGS supplement,” he said. “It was the energy in the MDGS that gave us the additional gain.”

The researchers found that each pound of MDGS supplement fed replaced approximately 0.68 pounds of forage intake. In other words, the cattle fed MDGS consumed roughly 17 percent less forage.

Another advantage to supplementing MDGS is that the cattle receiving MDGS were placed in pasture at a higher stock rate.

“We allocated less grass per animal because we knew that distillers would displace some of the grass,” he said. “We had a 17 percent increase in stocking rate for the groups that were fed distillers.”

At the end of the grazing period, the researchers measured the residual forage in the pasture and saw no difference, he said.

In the end, the trial resulted in three important discoveries for producers, Stalker said.

“The additional gain from feed distillers is really a big economic benefit, and feeding modified distillers on the ground can be efficient,” he said. “Also, the displacement of forage and increased stocking rate is a credit, as well.

Cattle eat 0.5 to 0.7 pounds less grass for each pound of MDGS fed, which producers can account for when calculating their stocking rate.” — Cheryl Anderson, DTN