URBANA, Ill. — Given greater oil-extraction efficiencies at corn-ethanol plants, resulting co-products have reduced fat — such as distiller’s dried grains with solubles. That means less energy for pigs and other livestock consuming them as part of their diet.
Fat contains more energy than all other nutrients. So if there is less fat, we would expect energy to be decreased, Hans Stein, University of Illinois professor of animal science, said in an Extension news release.
In one experiment, researchers fed dried grains with solubles in corn-based diets to 72 barrows averaging 18 kilograms at the start of the two-week experiment. By analyzing feces and urine from the animals, researchers quantified how much energy was absorbed and retained in the animals.
Compared to a corn-based diet without dried grains with solubles, there was less metabolizable energy in all eight sources of reduced-oil dried grains with solubles.
The researchers didn’t see a lot of variability among the eight sources, which was a little surprising, Stein said. There were only two sources that were significantly different from each other in terms of energy. But most importantly all had less energy than corn. Corn and dried grains with solubles were in the past considered to have the same amount of energy.
Producers may need to add additional sources of fat in pig diets if using reduced-oil dried grains with solubles. But according to a separate experiment reported in the study, the ingredient still has value.
In the second experiment, researchers analyzed amino-acid digestibility in seven reduced-oil sources of dried grains with solubles. Partially digested material was extracted from the ileum of 24 pigs after a week on the experimental diets.
The digestibility of amino acids in those reduced-fat diets is a little greater than we have seen in the past. We think the industry is doing a better job of heating or drying dried grains with solubles. If they dry the material too much, amino acids are damaged. It appears they are doing a better job of avoiding that, which results in greater amino-acid digestibility.
With the combination of reduced energy and greater protein in new reduced-oil dried grains with solubles, researchers are not recommending a change to the standard ratio — of dried grains with solubles to corn — in diets for growing pigs.
Stein has said for at least 10 years that a producer can give 30% dried grains with solubles in the diet to growing pigs and sows. After determining the feeding value for reduced-oil dried grains with solubles, he said university researchers have decided not to change the recommendation.
But if diets are formulated to a specific dietary-energy concentration, it may be necessary to add a little extra fat to the diets if reduced-oil dried grains with solubles are used.