The interaction between cereal and xylanase type was evident on iAX,tAX, iNSP and tNSP.
Coefficients of ileal digestibility of tAX and tNSP in pigs fed corn-based diets with xylanase B and E were similar but numerically superior to CAID in pigs fed wheat diets with xylanase C.
This observation can be ascribed to the fact that corn-based diets had a great composition of both insoluble and total NSP contents, available for hydrolysis. Conversely, pigs fed wheat diets with xylanase C had highest CIAD of iAX and iNSP compared with pigs fed other diets including corn-based diets with xylanase C.
The mechanism which led to the unexpected poor digestibility of iAX, iNSP and tNSP observed in pigs fed corn diets with xylanase C is unclear, but it suggests that there could be interactive factors other than the physicochemical nature of the cereal.
These observations augments the postulation that, even though xylanases could be from be the same microbe, substrate specificity plays the central role in enhancing xylanolytic activities, and consequently influence its requirement for accessory activities if maximum depolymerisation is to be achieved
This is supported by variations in digestibility of tAX and iNSP in both wheat- and corn-based diets in the present study, when xylanase E was used in the two rations.