Whole Raw Soybean a Competitive Protein Supplement for Cows and Calves

By Aaron Berger

Current market conditions for raw, whole soybean are making them price competitive in parts of Nebraska with other protein sources, such as distillers grains and alfalfa hay, to be used as a protein supplement for cows, as well as weaned calves.

The following are some principles to remember when feeding raw, whole soybean to cattle.

Soybean is approximately 40% crude protein and 20% fat and should be introduced gradually into the diet. Because high fat levels in cattle diets can negatively impact fiber digestion, they should not be fed at a level higher than needed to meet protein requirements in the diet. 

In growing calves, limit soybeans to 7% of the diet or less, and 5% or less in finishing diets. 

Raw soybean contains a trypsin-inhibiting enzyme important for protein digestion in non-ruminant and monogastric animals. Because of this enzyme, raw soybean should not be fed to nursing calves and calves less than 300 pounds. 

Raw soybeas also should not be fed to animals receiving a diet containing urea. Soybeans contain the enzyme urease, which breaks down urea into ammonia at a very rapid rate. Toxicity occurs when the rate of ammonia entering the bloodstream overrides the liver’s capacity to filter it out.

The protein in soybean is approximately 70% rumen degradable and 30% rumen undegradable. Growing calves being fed corn silage and other feeds that are low in rumen undegradable protein show improved average daily gain performance when protein sources such as distillers grains that are high in rumen undegradable protein are utilized to meet protein needs. Feeding raw whole soybean in place of distiller’s grains to meet protein needs in a diet that is predominantly corn silage would result in decreased animal performance.