Digestible and metabolizable energy of crude glycerol for growing pigs

¹ Department of Animal Science, Iowa State University, Ames, IA 50011-3310
² USDA-ARS, Swine Odor and Manure Management Research Unit, Ames, IA 50011-3310
³ USDA-ARS Poultry Research Unit, Mississippi State, MS 39762-9665
⁴ Department of Poultry Science, Mississippi State University, Mississippi State, MS 39762-9665

^* To whom correspondence should be addressed. E-mail: brian.kerr{at}ars.usda.gov.

	Abstract

The apparent DE and ME values of crude glycerol for growing pigs were determined in 5 experiments using crude glycerol (86.95% glycerol) from a biodiesel production facility with soybean oil used as the initial feedstock. Dietary treatments were 0, 5, or 10% glycerol addition to basal diets in Exp. 1; 0, 5, 10, or 20% glycerol addition to basal diets in Exp. 2; and 0 and 10% crude glycerol addition to the basal diets in Exp. 3, 4, and 5. Each diet was fed twice daily to pigs in individual metabolism crates. After a 10-d adjustment period, a 5-d balance trial was conducted. During the collection period, feces and urine were collected separately after each meal and stored at 0°C until analyses. The GE of each dietary treatment and samples of urine and feces from each pig were determined by isoperibol bomb calorimetry. Digestible energy of the diet was calculated by subtracting fecal energy from the GE in the feed, while ME was calculated by subtracting the urinary energy from DE. The DE and ME values of crude glycerol were estimated as the slope of the linear relationship between either DE or ME intake from the experimental diet and feed intake. Among all experiments, the crude glycerol (86.95% glycerol) examined in this study was shown to have a DE of 3,344 ± 8 kcal/kg and a ME of 3,207 ± 10 kcal/kg, thereby providing a highly-available energy source for growing pigs.

Key Words: biofuels, crude glycerol, metabolizable energy, pigs