No evidence yet to justify use of multi-enzyme product

The statement was made in a paper recently published in the Asian-Australasian Journal of Animal Science (AJAS) reviewing the mechanisms by which fibre-degrading feed enzymes can improve animal performance when added to monogastric diets. The problems associated with the fibrous NSPs in plant-based feed ingredients – increased digesta viscosity, wet litter, reduced nutrient utilisation – are widely known, but the optimum strategy for tackling them is less well understood.

“The challenge is that the literature advocating multi-enzyme dosing is based on studies which are incomplete, inadequately designed to support the conclusions made, or both,” Dr Masey O’Neill states. “In products claiming multiple activities, it is impossible to assign results to a particular enzyme or enzyme combination unless a complete analysis of each individual component is carried out separately, and all the various permutations of two or more enzymes are also assessed. “Practically, this is difficult to achieve, yet without it there is no clear evidence that the extra activities are producing any additional benefit beyond that achieved by an optimised dose of an appropriately targeted single enzyme.”

In one published evaluation, a purified xylanase extracted from the multi-enzyme product being studied was less than 30% stable at the pH found in the gut, compared to 70% stability for the crude product. Failing to compare ‘like-with-like’ means any performance difference cannot be attributed to the additional enzyme activities present, highlights Dr Masey O’Neill. “Caution needs to be applied when interpreting such data. There is currently no robust evidence showing whether additional activities are beneficial, superfluous or even detrimental, and in the many comparisons carried out to date, it is not usually the enzyme product with the greatest number of activities that results in the best performance.”

A full and open access version of the paper is available via the AJAS.