Current biodiesel supplies are often made from the triglycerides, or fat, found in soybean oil. But processing biodiesel from soybean oil also yields crude glycerin, also known as glycerol, which has a purity level of about 85 percent. It also contains small amounts of salt, methanol and free fatty acids. If glycerol is refined to 99 percent purity, it can be used in many products, including pharmaceuticals, foods, drinks, cosmetics and toiletries.

Kerr, Dozier and Iowa State University colleague Kristjan Bregendahl studied whether crude glycerin could be used to supplement the feed of laying hens, broilers and swine. They found that crude glycerin provided a supply of caloric energy that equaled or exceeded the caloric energy available in corn grain. Feeds containing up to 10 percent glycerin had little to no adverse effect on laying hen egg production or broiler body weight gain. Pig body weight gain, carcass composition and meat quality also showed little to no adverse change after equivalent levels of crude glycerin were added to their feed.

Safe levels for salt, methanol and free fatty acids in crude glycerin consumed by nonruminant livestock still need to be determined. But as corn grain ethanol production and conversion soar, corn grain supplies for livestock feed are decreasing. Using crude glycerin to supplement feed supplies could provide livestock producers with a readily available, inexpensive and energy- packed alternative to corn grain.