Fortifying feed with biodiesel co-products

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.