1315
Effects of dietary supplementation of β-mannanase on ileal digestibility of fiber and viscosity of jejunal digesta in nursery pigs fed corn and soybean meal-based diets
This study is to determine the effects of β-mannanase (CTCZYME, CTCBIO Inc, Seoul, Korea) on ileal digestibility of nutrients and viscosity of jejunal digesta in nursery pigs fed corn and soybean meal-based diets. Forty eight barrows at 6 wk of age (initial BW: 15.7 ± 1.1 kg) were assigned to 4 dietary treatments with different levels of β-mannanase (0, 200, 400, and 600 Unit/kg feed). Experimental diets contained 56.4% corn, 30.0% soybean meal, 10.0% DDGS, and 3.7% others. Pigs were housed individually in metabolism crates and received experimental diets at a fixed amount based on BW of pigs (daily feed allowance = 0.09 x BW0.75 kg) for 11 d. Chromium oxide (0.3%) in experimental diets as an indigestible marker was provided from d 8 to 11. Actual feed intake, any feed refusals, and BW were measured on d 7 and 12 to monitor growth. On d 12 after 8 h of last meal, pigs were euthanized to collect digesta from jejunum and ileum. Digesta from jejunum were used to measure viscosity with a viscometer (DV‖+, Brookfield Engineering Laboratories, Inc., MA). Digesta from ileum were used to measure apparent ileal digestibility of energy, NDF, and ADF. Tissues from jejunum were fixed for morphological evaluation. The data were analyzed using Proc Mixed of SAS based on randomized complete block design. Morphology of jejunum was not affected by dietary supplementation of β-mannanase. Viscosity of digesta in jejunum tended to decrease linearly (P = 0.076, 5.2 to 3.8 mPa·s) with increasing supplementation of β-mannanase. Dietary β-mannanase also tended to increase (P = 0.093, 53.4 to 64.7%) apparent ileal digestibility of energy in a quadratic manner at the highest digestibility at 600 Unit of β-mannanase per kg feed. There was no change in ileal digestibility of NDF and ADF by supplemental β-mannanase indicating that the increase in energy digestibility is not due to the release of monosaccharides from mannans by β-mannanase. Collectively, dietary supplementation of β-mannanase enhanced energy utilization in nursery pigs by reducing viscosity of digesta potentially enhancing digestibility of nutrients.
Keywords: ADF, β-mannanase, energy utilization, NDF, pigs, viscosity