U.S. soybean farmers have redefined the measure of feed ingredient quality and value based on content of essential amino acids (EAAs).

Calculating the sum of the five most critical amino acids (lysine, cysteine, methionine, threonine and tryptophan) provides a numerical Critical Amino Acids Value (CAAV).

These five amino acids are required for overall health, fetal development, muscle growth, and production of meat, milk and eggs in monogastric livestock, poultry and farm raised fish. When these five EAAs are not present in sufficient quantities in feed ingredients, nutritionists must supplement with synthetic amino acids, increasing production costs and often resulting in “hot” rations which potentially lead to excess nitrogen excretion and negative environmental consequences.

Whole soybeans and meal have historically been valued largely on crude protein quantity; an estimate based on its nitrogen content. A higher crude protein (CP) content does not necessarily equate to higher protein quality or better nutritional value in feeding monogastric animals. True protein quality is based on the presence and balance of essential amino acids. Current ingredient purchasing decisions based largely on higher crude protein will not necessarily provide the best value feed ingredient.

Climate Impacts Soybean Quality

Soybeans grown in cooler climates, such as in the northern region of the U.S., have been shown to have higher CAAV than soybeans with higher crude protein levels from warmer regions in the south.


While cooler weather limits nitrogen fixing in the soybean plant, resulting in lower crude protein content, it has the opposite effect on CAAV.

Research(1) shows northern-grown soybeans that have lower crude protein levels have higher CAAV than soybeans with higher CP scores. In northern grown soybeans this increased level of CAAV occurs naturally and thus limits feeders needing to add synthetic amino acids to feed rations.

To help soybean and soybean meal customers better take advantage of this benefit, the soybean checkoff boards of North Dakota, South Dakota and Minnesota developed the CAAV to measure essential amino acids and evaluate soybean quality.

Iowa Soybean Association | https://www.iasoybeans.com/programs/soybean-meal/

Buying and feeding protein based feed ingredients on crude protein estimate is inefficient and may be costly. CAAV measurements deliver more value to producers, buyers and nutritionists by providing a more accurate picture of soybean protein quality.

Purchasing and feeding protein sources based on EAAs is more efficient, cost-effective and potentially less polluting than buying based on crude protein alone. That’s because crude protein is only an approximate estimate of protein and does not provide information about EAA content or balance.

The CAAV measurement delivers greater value to producers by providing a more complete and accurate profile of soybean protein quality, especially for northern-grown soybeans that often have lower total crude protein but higher CAAV.

(1)Research has been conducted by:

  • University of Minnesota
  • Iowa State University
  • United Soybean Board
  • American Soybean Association
  • U.S. Soybean Export Council
  • Eastern Cereal and Oilseed Research Centre in Canada
  • Australian Oilseeds Federal