The evidence for the benefits of the latter remain subject to considerable debate, with the data produced to date failing to show any clear advantage of such multi-NSP-enzyme dosing (i.e. multiple activities within the same enzyme class) over a well-targeted single-enzyme xylanase product. Potential conflicts between similar modes of action, such as breakdown of the beneficial end products of xylanase action, as well as difficulties achieving equal levels of thermostability and efficacy in the bird, appear the most likely reasons.