The scoop on soybean meal

Editor's note: The following article was written by PORK Network Editor JoAnn Alumbaugh.

It was originally published in the

April issue of

PORK Network.

Corn and soybean prices are comparatively low now, which helps lower your cost of production. It also provides an opportunity to look at the percentage of these inputs in your pigs' diets to see if higher levels of soybean meal, for example, make good economic sense.

The level of soybean meal fed to pigs typically depends on a variety of factors such as its cost, price, availability of alternative proteins, production practices and performance expectations. The trend is to feed higher levels to younger pigs but performance concerns have existed.

"In 1929, approximately 10,000 soybean varieties were imported from China for U.S. researchers to study, which laid the foundation for the rapid ascension of the United States as a world leader in soybean production," says Gary Cromwell, Emeritus Professor in the Animal and Food Sciences Department at the University of Kentucky.

Crushing of soybeans for production began on a small scale in 1918, Cromwell says. In the past, greater variability in soybean meal quality existed, due to where it was sourced, the number of ways it could be processed and the effectiveness of that processing. Feeding higher levels of a SBM that hasn't been processed properly and having higher levels of trypsin inhibitor and urease can lead to performance lag.

Improved testing and processing procedures have minimized some of those concerns.

Cromwell says, "The digestible amino acid profile of soybean protein more closely matches the amino acids requirements of pigs and poultry than any other oilseed meal."

More about Amino Acids
The requirements for amino acids by pigs are expressed as grams or percentages of digestible amino acids in the diets, calculated by multiplying the concentration of amino acids in feed ingredients by the digestibility of that amino acid. Soybean meal is the primary source of digestible amino acids in diets fed to pigs because the concentration of digestible amino acids in soybean meal is greater than in other protein sources.

Researchers at Hubbard Feeds have looked at increasing the levels of soybean meal in pigs' diets. They report that the quality of soybean meal is often determined by urease activity, which detects under-heating. The level of urease activity is correlated to the level of trypsin inhibitors and other anti-nutritional factors. If properly heat treated, the value should be 0 to 0.2. Trypson inhibitor levels can also be tested and values should fall within the range of 1 to 4 mgTI/g of SBM. Potassium hydroxide (KOH) solubility is used to detect overheating of soybeans during processing. The level of KOH solubility determines the nitrogen solubility and levels below 80% could indicate overheating and decreased amino acid availability.

Research Continues
Soybean growers are investing through the United Soybean Board to enhance soybean oil and meal composition. The research priorities for improving soybean meal include increasing levels of certain essential amino acids, improving soy protein's amino acid balance and digestibility, reducing selected carbohydrates, improving phosphorus availability and improving overall utilization. The research targets will enhance soybean meal's feeding value and also have a positive environmental impact by reducing nutrient levels in livestock and poultry waste.

The Soybean Meal Info Center says primary targeted traits include increasing the methionine and cystine by 50%; reducing phytate bound phosphorus by 50%; and increasing the metabolizable energy by about 10%. Secondary traits include increasing the digestibility of soybean protein by 5% and increasing the level of lysine, threonine and tryptophan by more than 20%. These traits would reduce synthetic amino acid, dical phosphate and fat supplementation needed for many livestock and poultry diets.

Part of the research challenge will be to make sure that the new soybean cultivars are high yielding and competitive with other varieties available to soybean growers. Since some of the traits have limited economical value by themselves, it will be important to stack the traits in new varieties to increase their economic value. Soybean growers are interested in expanding public and private research that will achieve these goals to improve soybean composition and make soy protein even more valuable to the meal user.