Brian Kerr, research leader in Ames, Iowa, who works for the USDA Agricultural Research Service, says that crude glycerin was fed to laying hens and swine while their metabolisms were analysed. “Our goal was to use glycerin as an energy source for swine and poultry,” he said, adding that “you’ve got to have energy for animals and chickens to grow, as well as amino acids and other items, and (glycerin is) used for growth and productive purposes.”

Pakistan's The News, reports that although crude glycerin was determined to be a viable energy-creating feed, Kerr said the ever-fluctuating markets ultimately determine its use. “Corn would be cheaper,” he said, referring to the present situation. “When we started testing, glycerin was three cents a pound. Corn at that time was may be 6 cents a pound.”

However, now glycerin is 20 cents per pound. “At 20 cents a pound, it’s too expensive as an energy source,” he said. The testing consisted of energy-balance experiments that determined the effect of carefully applied dietary treatments, which ultimately rendered a metabolized energy number.

“We feed them a known quantity of feed or test ingredient, and then determine how much energy they have consumed from that diet and how much energy has been excreted in the feces or urine to come up with a metabolized energy number,” Kerr explained.