85 The influence of supplementing isolated or intact structural fiber on the physicochemical properties of digesta and fecal consistency of nursery pigs

Abstract In human nutrition, functional fiber refers to isolated non-digestible carbohydrates with physiological roles, while structural fiber pertains to those that are intrinsic and intact in plants. Increasing dietary fiber in post-weaning pig diets has been shown to improve gastrointestinal health and alter fecal consistency. However, minimal research has been conducted on the role of supplementing isolated functional or structural fiber that are chemically insoluble in nursery diets. The experimental objective was to evaluate the effect of functional or structural insoluble fiber supplementation on the physicochemical properties of digesta and feces during the nursery period. A total of 256 newly weaned pigs were randomly assigned to one of four treatments across two replications with 4 pigs per pen and 16 pens per treatment for a 35-d study. The average initial pig body weight (BW) was 5.13 ± 0.65 kg and same sex pens were used and balanced across treatments. Dietary treatments consisted of a control nursery diet (PC), PC with 3% soy hulls (NC), PC with 2% isolated lignocellulose (ISO), and PC with 2% structural lignocellulose (STR). Treatments were fed across phase 1 (d 0-7) and phase 2 (d 7-21) diets, and a common diet was fed in phase 3 (d 21-35). On d 7, 14, 21, 28, and 35, fresh fecal samples were collected to determine water binding capacity (WBC), water swelling capacity (WSC), and fecal dry matter (DM). Fecal scores were also evaluated using a predefined scale (1 = solid; 4 = liquid). On d 21, one pig per pen closest to the mean BW was necropsied, and ileal, cecal, and colonic digesta were collected. Continuous data were analyzed as a linear mixed model (PROC MIXED) with treatment, sex, and period as fixed effects, replicate as a random effect, and initial BW as a covariate where appropriate. Fecal scores were analyzed using a multinomial model in PROC GENMOD and FREQ. Pigs fed ISO and STR tended to have greater fecal DM (24.1%, 24.6%, 25.4%, and 26.29% for PC, NC, ISO, and STR, respectively; P = 0.071). There was a greater proportion of solid and semi-solid feces in pigs fed ISO (P = 0.039). Fecal WBC was greatest in pigs fed PC, with NC and ISO performing intermediately, and STR having the least (2.66, 2.55, 2.50, and 2.39 mL/g of DM for PC, NC, ISO, and STR, respectively; P = 0.071). Fecal WSC increased with time (P < 0.001), but there was no impact of treatment (P = 0.983). Ileal digesta pH was decreased in NC and STR, relative to PC and ISO, (P = 0.007). There tended to be a similar response for cecal pH (P = 0.092). Pigs fed PC tended to have the greatest colonic WBC (P = 0.058). Collectively, supplementing isolated or structural lignocellulose can alter the physicochemical properties of nursery pig feces.