News last update:6 Aug 2012

Fortifying feed with biodiesel co-products

Biofuel research isn't just a matter of finding the right type of biomass and converting it into fuel. Scientists must also find environmentally and economically sound uses for the by-products of biofuel production. Agricultural Research Service (ARS) scientists Brian Kerr and William Dozier have done just that.

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%.

It also contains small amounts of salt, methanol and free fatty acids. If glycerol is refined to 99% purity, it can be used in many products, including pharmaceuticals, foods, drinks, cosmetics and toiletries.

Glycerin in feed
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 equalled or exceeded the caloric energy available in corn grain.

Feeds containing up to 10% 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.

Safety levels for contaminants
Safe levels for salt, methanol and free fatty acids in crude glycerin consumed by non-ruminant 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.

ARS is the US Department of Agriculture's chief scientific research agency.

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