Glycerin/glycerol Use

Farmers are excited about the use of biodiesel as green fuel. Biodiesel is produced by reacting fats and oils with an alcohol (methanol is the usual choice) to produce a fatty acid methyl ester and a byproduct, glycerol. Glycerol, also known as glycerin, is a three-carbon sugar alcohol that has three hydrophilic alcoholic hydroxyl groups (-OH). Glycerin is widely used in soaps, cosmetics, foods and for many industrial uses.

One of the hot topics at the recent animal and dairy society meetings was the feed use of glycerin. Little research has been done on using glycerin in feeds. University of Arkansas researchers investigated the energy value of glycerin in typical U.S. broiler diets. They found in a preliminary study that up to ten percent glycerin could be fed chicks in battery brooders up to sixteen days. They then determined that the gross energy of the glycerin source used in these experiments was 1,631 kcal/lb, so they assigned a metabolizable energy value of 1,600 kcal/lb to the glycerin source. Diets were formulated using 0, 5 or 10 percent glycerin in a typical diet that met nutritional requirements used by the broiler industry. Each of the treatments was fed to eight pens of 60 male broilers during the 42-day experiment. Results indicated that including five percent glycerin in the diet had no effect on bodyweight, feed intake, feed conversion, mortality, dressing percentage or carcass measurements compared to the birds fed the control diet containing no glycerin. Feeding a diet containing ten percent glycerin resulted in reduced feed intake (4.735 vs. 4.886 kg), body weight at 42 days (2.706 vs. 2.871 kg), feed conversion (1.768 vs. 1.732) and dressing percentage (72.17 vs. 72.85%) compared to the control treatment. The researchers reported finding about 0.015 percent more potassium in the ten percent glycerin diet compared to the control, probably due to residue potassium remaining from biodiesel processing. These results indicate that glycerin can be used as an energy source in broiler diets. The research group indicated that additional research is needed to evaluate glycerin quality factors and effects on feed texture, pellet quality and other factors.

Cerrate, Sandro and co-workers. 2006. Glycerin useful energy source in broiler diets. Feedstuff, July 17. p14.