Over the past decade, fiber has evolved into an increasingly important topic in swine nutrition. Prior to 2008, there was little interest in fiber because most commonly used ingredients contained very low levels. When ethanol production emerged as a major market for corn, the pork industry was forced to use the fermentation byproduct — distillers dried grains and distillers dried grains with solubles. Suddenly the neutral detergent fiber content of typical pig diets increased from 5% to 15% or even 20%.