Interactive effects among fiber and fat sources on energy and fat digestion in 53 to 74-kg pigs

Lay Summary Increasing dietary fiber reduces fat digestion, a reduction of which is affected more by feedstuffs with a high degree of insolubility (ie, dried distillers grains with solubles, DDGS or soybean hulls, SH) compared to those with a high degree of solubility (ie, sugar beet pulp, BP). In addition, the reduction in fat digestion due to fiber addition is impaired more if it is a saturated fat (e.g., tallow) compared to an unsaturated oil (e.g., soybean oil). Apparent total tract digestibility of energy was improved by supplementing tallow to the low fiber diet (a corn-soybean meal-based diet, CSBM), had little effect when added to the insoluble fiber diets (ie, DDGS or SH), but had a negative effect when supplemented to the soluble fiber diet (ie, BP). In contrast, the increase in apparent total tract digestibility of energy due to supplementing the CSBM-, DDGS-, and SH-based diets with soybean oil increased except for pigs fed BP, where the increase in energy digestibility was muted.