Cereal grains, such as corn and barley, are included as an energy source in rations for lactating dairy cows. Cereal grains contain high concentrations of starch, a component that is almost completely and uniformly digested in the gastrointestinal tract when processed adequately.
Among cereal grains, differences exist for ruminal starch disappearance rate. For instance, starch degradability in the rumen is greater for barley than for corn grains. As the ruminal starch fermentation rate of barley grains is greater than for corn grains, the National Research Council (NRC) established that the fiber requirements for dairy cows should be increased when feeding diets containing barley grains.
Hulless barley differs from traditional hulled barley in that the loose husk covering the caryopsis is removed during combine threshing and cleaning of the grain. Interest in growing hulless barley in the commonwealth of Virginia has increased for several reasons. From the perspective of the cash crop farmers, growing hulless barley instead of wheat allows small grain crops to be harvested two to three weeks earlier. This early harvest allows earlier planting of soybeans, therefore ensuring better growing conditions for the second crop. From the perspective of a dairy farmer, increasing interest has been observed for feeding hulless barley as an alternative to corn to high-producing dairy cows.
Our research team performed two trials at Kentland Farm feeding hulless barley to high-producing dairy cows. In the first study, we compared the production performance and the nutrient utilization of high-producing dairy cows when fed diets containing corn or hulless grains as energy sources. Overall, cows consuming diets with hulless barley grain performed as well as cows consuming diets with corn grain. In addition, and contrary to our expectations, we observed that feeding hulless barley did not decrease milkfat concentration.
In the second study, we evaluated the production performance and nutrient utilization of high-producing dairy cows when feeding hulled or hulless barley grains with different forage-to-concentrate ratios. Barley grains were ground and incorporated into concentrate pellets, which were further incorporated into a ration containing corn silage and alfalfa hay. Cows fed hulled or hulless barley-based diets with different forage-to-concentrate ratios resulted in similar lactation performances. As milk fatty acid composition was minimally affected by the diets, we concluded that a substantial or dramatic milkfat depression should not be expected when feeding diets containing 30 percent barley or less as the grain source.
In summary, the most important conclusion from our studies was that high-producing cows consuming hulless barley-based diets can perform as well as cows consuming corn-based diets. The second important conclusion was that milkfat depression should not be necessarily expected when feeding hulless barley to high-producing dairy cows. 
Gonzalo Ferreira is an extension dairy scientist at Virginia Tech. Email Gonzalo Ferreira.
—From Virginia Cooperative Extension's Dairy Pipeline
