Written by: Dr. Jacquie Jacob, University of Kentucky
Brewers' grains are a by-product of beer making. Beer is the fifth most consumed drink in the world, surpassed only by tea, carbonate drinks, milk, and coffee. Brewers' grains should not be confused with distillers' grains, a by-product of ethanol production (ethanol is typically produced for inclusion in gasoline).
The nutritional content of brewers' grains varies depending on the grain used (barley, wheat, rice, or corn), the extent of the fermentation, and the type of fermentation process used. Brewers' grains are primarily fed to dairy cattle but have some nutritional value for poultry as well. The major problem limiting the use of dried brewers' grains in poultry rations is related to the grains' high fiber content.
It is difficult to compare research regarding the use of dried brewers' grains in poultry diets because of the different sources of the grains. For both broilers and layers, inclusion rates of 2% to 20% of the diet have been recommended. A few researchers have indicated that enzyme supplementation can improve the nutritive value of dried brewers' grains in poultry diets, particularly broiler starter diets. For turkey diets, reports indicate that when dried brewers' grains are used at more than 20% inclusion, supplemental lysine is required.
Producers can also use wet brewers' grains as a substrate for the growth of microorganisms for enzyme production. In order for microorganisms to grow in this medium, they produce a number of enzymes that aid in the breakdown of various nutrients. Aspergillus species (fungi) are used for industrial enzyme production, primarily to produce amylases and glucoamylases. The spent grains can also be used to grow Lactobacillus species (bacteria) for lactic acid production.