Stein said this research has opened new doors for swine nutrition.

"We knew the concentration of fat in the diet affects the value that is determined for apparent digestibility," Stein said. "However, by correcting these values for the endogenous losses, we can calculate the true digestibility of fat fed to pigs."

Results of the research indicate that more information on fat digestibility is needed to ensure diets are formulated economically.

"We now know that fat digestibility should be determined as ileal digestibility rather than total tract digestibility to avoid the influence of the microbes in the hindgut of pigs," he said. "We also know that for practical feed formulation, it is more accurate to use values for true ileal digestibility than for apparent ileal digestibility because these values are not influenced by the level of fat in the diet."

However, Stein said we still don't know many of the factors that influence fat digestibility in different feed ingredients and we do not have good data for the true ileal digestibility of fat in most of our feed ingredients. A better understanding of how fat is utilized by the pig after absorption is also needed. Stein believes follow-up research should focus on addressing these questions and determining the energy value of the different sources of fat used in swine diets.

"Effect of the form of dietary fat and the concentration of dietary neutral detergent fiber on ileal and total tract endogenous losses and apparent and true digestibility of fat by growing pigs," was recently published in the Journal of Animal Science. Researchers include D.Y. Kil, T.E. Sauber, D.B. Jones, and H.H. Stein.