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Commercial xylanase-products appear to be more efficient towards degredation of arabinoxylan in wheat than in rye
To study the effect of a combination of endo-xylanases from Trichoderma reesei and Bacillus subtilis on ileal viscosity, degradation of fiber and apparent ileal digestibility (AID) of nutrients in finely ground rye (FR), finely ground (FW) and coarsely ground wheat (CW) without (-) or with (+) enzyme, an experiment with 6 ileum-cannulated pigs (initial BW 33.6±0.5 kg) was performed using a 6x6 Latin Square design. The cereals were supplemented with vitamins, minerals, 500 FTU Phyzyme® XP/kg feed, dust-binder and chromic oxide (2 g/kg). Each pig was fed each diet 3 times daily for 1 week and ileal content collected for 8 h on day 5 and 7. For each pig per week samples were pooled and analyzed for viscosity, concentration and composition of solubilized high molecular weight (HMW) and low molecular weight (LMW) arabinoxylan, OM, crude protein, starch and marker. Data were analyzed as a Latin square design with a 2×3 factorial arrangement of treatment with enzyme, cereal source, and their interaction as sources of variation, and pig and period as random effects. For statistical analysis, viscosity data were subjected to logarithmic transformation and results reported as geometric means.
Enzyme addition reduced intestinal viscosity in the pigs from 2.1 to 1.5 mPa.s (P=0.012) when FW was fed, from 3.2 to 1.7 mPa.s for CW (P<0.0001), and from 9.7 to 7.6 mPa.s (P=0.04) for FR. Enzyme addition increased concentrations of soluble arabinoxylan from 5.7 mg/ml with FW- to 10.4 mg/ml with FW+ (P=0.0019) and from 8.5 mg/ml with CW- to 12.4 mg/ml with CW+ (P=0.0055), whereas no effect was seen for FR (10.8 mg/ml in FR- vs. 10.2 mg/ml in FR+, P=0.59). Concentrations of LMW-arabinoxylan increased from 0.2 to 2.9 mg/ml in FW (P=0.0002), from 0.4 to 5.7 mg/ml in CW (P<0.0001) and was 0.8 to 1.6 mg/ml in FR- and FR+, respectively (P=0.29). Enzyme addition overall increased AID of HMW-arabinoxylan (P<0.0001) with an increase in AID of FW from 14 to 29 % (P=0.0001), of CW from 18 to 31 % (P=0.0013), while it increased from 11 to 21 % in FR (P=0.0021). Enzyme addition did not affect AID of OM and crude protein, but overall increased AID of starch (P=0.031). However, by pairwise comparison this was only significant for FW (P=0.015). Collectively, the results suggest that the xylanase preparations were more efficient in degrading arabinoxylan from wheat than from rye.
Keywords:
viscosity, enzymes, nutrient digestibility