SDSU Research: Amino Acid Content of Distillers Grains

Brookings, South Dakota (July 6, 2007)--Amino acid balance may be a problem when including high rates of distillers grains in the diet, particularly in high-producing dairy cows, SDSU Extension Dairy Specialist Alvaro Garcia said.

The level of distillers grains in the diet is more of an issue when the diet is composed of corn and corn-derived feeds (for example, dry shelled or high moisture corn, and corn silage). If distillers grains constitute 20 percent of the diet, the total contribution of corn-derived feeds to the diet dry matter can be close to 50 percent.

A recent trial conducted by South Dakota State University evaluated the protein degradability in the rumen of soybean meal, dried distillers grains, and wet distillers grains. As expected, soybean meal had less rumen undegradable protein than either dried or wet distillers grains. Protein degradability in the rumen and intestinal protein digestibility varied among different sources of dried distillers grains. Soybean meal protein was more digestible in the intestine than either form of distillers grains, resulting in a greater overall protein digestibility.

In this experiment methionine was the first limiting amino acid in soybean meal, whereas lysine was the one in distillers grains. No differences were observed in the amino acid concentration among different dried distillers grains sources, although wet distillers grains had a higher milk protein score than dried distillers.

The milk protein score estimates the proportion of milk protein that a protein source can sustain until the first limiting amino acid is used up. This suggests wet distillers grains might be a more adequate rumen undegradable protein source.

The different nutrient profile also suggests that in high-producing dairy cows, the higher lysine concentration of soybean meal makes it an ideal complement to wet or dried distillers grains.

Contact:
Alvaro Garcia
605-688-5488