Enzymes: the difference between malt and feed barley

Barley has been cultivated as a food source for many thousands of years. During the 20th century, considerable knowledge was gained on producing barley varieties with quality attributes that were more suited to a specific end-use, namely alcoholic beverages. Most countries that produce barley have malt and feed classifications. Typically, barley classified as feed is comprised of either varieties that are not suited biochemically for malting or have failed to meet malting industry delivery specifications. In several countries, including Australia, more barley is used for feeding cattle than in beer production. Anecdotal evidence suggests that malt varieties are best for feeding cattle, but insufficient data has been available to support this generalization. We have undertaken a study comparing detailed malt quality traits with feed quality traits on more than 30 varieties to ascertain a scientific basis to this theory. Results indicate that most of the resting grain components are required at similar levels for each end-use, i.e., high levels of starch, low levels of fiber (thin husk) and nonstarch polysaccharides, and moderate levels of protein. The most significant area of difference is the need for malt varieties to produce moderate to high levels of hydrolytic enzymes that break down endosperm components during malting and mashing. Varieties that performed especially well in both end-uses, i.e., good malt quality and improved animal performance, were current malting varieties. These results demonstrate that barley breeding programs can effectively select breeding lines for both malt and feed quality by focusing on malt quality and selecting lines with high levels of enzymes.