Dietary Fiber Source and Stage of Gestation Impact Water Balance and Fecal Physicochemical Properties of Sows

Thomas A Crome, Kyle Vahlenkamp, Mark A Giesemann, Amy L Petry

Providing soluble fiber in sow diets is known to increase satiety, reduce incidences of constipation, and decrease the rate of assisted farrowings due to its physicochemical properties. However, fiber sources commonly used in U.S. sow diets have negligible solubility and water holding capacity, but carbohydrases may improve these characteristics. The objective of this experiment was to evaluate the impact of soluble fiber from sugar beet pulp, insoluble fiber from corn DDGS, and carbohydrase supplementation on water balance and fecal physicochemical properties of sows at mid- and late-gestation. A total of 36 confirmed gestating sows (186 ± 4.6 kg BW) were blocked by parity and randomly assigned to a 2×2 factorial arrangement of treatments on d 28 of gestation (n = 8) with factors of fiber type [insoluble (IF; 355 g/d) or soluble fiber (SF; 98 g/d)] and enzyme supplementation (Rovabio Advance P10; Adisseo, Antony, France). Diets were fed from d 28 to 109 of gestation at a feeding level of 2.1 kg (SID-Lys 11 g/d and 4.5 NE-Mcal/d). Two 8-d periods of metabolism collections took place on d 50-59 (mid-) and 99-108 (late-) of gestation. Fresh fecal samples were taken from each sow on d 1 of each collection period and water balance was measured from d 4-7. Daily water allowance was set at 80 mL/kg of BW per day. Data were analyzed as repeated records using a linear mixed model with block as a random effect, and fiber type, enzyme supplementation, and period and their interactions as fixed effects. Daily water allowance was used as a covariate where appropriate. No interactions were observed among the main effects (P > 0.63), and there was no effect of enzyme supplementation on water balance or fecal physicochemical properties measured (P > 0.13). Sows fed SF had an increase ratio of grams of water excreted per gram of fecal DM (1.73 vs 1.96 g/g; Fiber P = 0.002) and had 76.6% greater fecal water binding capacity than those fed IF (5.18 vs. 9.15; Fiber P = 0.044). Irrespective of diet, sows in late gestation excreted 14.9% more water per g of DM in their feces (Period P < 0.001) and had increased fecal water binding capacity (5.02 vs 9.67%: Period P = 0.035). In late gestation, urine output increased by 30.5% (1182 vs 1543 mL/d; Period P=0.028) and estimated fecal moisture output increased by 12.3% (367 vs 412 mL/d; Period P = 0.015). Urine specific gravity increased by 0.6% in late gestation (1.00 vs 1.01 g/ml; Period P = 0.047). Sows fed SF had 22.3% less urine output (P = 0.045) but 21.8% more estimated fecal moisture output (P = 0.048). With decreased urine output and increased fecal moisture, these data suggest that there is a repartitioning of water, with greater water retention in the gastrointestinal tract of sows fed SF and during late gestation.