PS7-21. Interaction Between Growth Stage of Pigs and Soluble Dietary Fiber-to-insoluble Dietary Fiber Ratio for Ileal Digestibility and Hindgut Disappearance of Energy and Nutrients.

Abstract

Nursery pigs have relatively underdeveloped digestive and absorptive capacities. As pigs grow, the hindgut continues to develop and fiber fermentation occurs mostly in the hindgut. Fibers are partitioned into soluble and insoluble portions. Soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) differ in physicochemical properties and digestibility in the gastrointestinal tract of pigs. The objective of the present experiment was to test interactive effect of growth stage of pigs and SDF-to-IDF ratio on apparent ileal digestibility (AID), apparent total tract digestibility (ATTD), and hindgut disappearance of energy and nutrients. Two experimental diets with SDF:IDF of 0.08 and 0.32 were provided to nursery pigs and growing pigs in a 2 × 2 factorial arrangement. Six nursery barrows with an initial body weight of 14.8 kg (standard deviation = 1.4) and 6 growing barrows with an initial body weight of 59.7 kg (standard deviation = 2.5) were employed. Animals were surgically fitted with a T-cannula at the distal ileum and individually housed in pens. A low SDF:IDF diet contained 1.8% SDF and 23.1% IDF and consisted of 60.6% corn, 20.5% soybean meal, and 15.0% corn cobs (SDF 2.3% and IDF 84.1%) whereas a high SDF:IDF diet contained 5.9% SDF and 18.4% IDF and consisted of 58.0% corn, 18.0% soybean meal, and 20.5% sugar beet pulp (SDF 20.0% and IDF 47.6%). Both experimental diets were formulated to contain 25.0% total dietary fiber. In both growth stages, the pigs were assigned to 2 dietary treatments in a crossover design with 2 periods to obtain 6 observations for each simple effect. Each experimental period consisted of 5 days of adaptation, 1 day of fecal collection, and 2 to 3 days of ileal digesta collection. The high SDF:IDF diet caused less (P < 0.05) AID of energy, dry matter, and organic matter in growing pigs whereas the SDF:IDF did not affect the AID of energy and nutrients in nursery pigs (interaction P < 0.01). The high SDF:IDF diet caused greater hindgut disappearance of energy, dry matter, and organic matter with greater magnitude of increment in growing pigs compared with nursery pigs (interaction P < 0.05). The ATTD of energy, dry matter, and organic matter in pigs fed the high SDF:IDF diet was greater (P < 0.001) than those fed the low SDF:IDF diet regardless of growth stages of animals. Taken together, hindgut disappearance of energy and nutrients was affected by SDF-to-IDF ratio, more dramatically in growing pigs compared with nursery pigs.