Safety and efficacy of RONOZYME®WX (endo-1,4-β-xylanase) as a feed additive for laying hens

Abstract

RONOZYME ^® WX is an additive that contains endo-1,4-β-xylanase which is authorised for use as a feed additive in poultry for fattening, weaned piglets and pigs for fattening. The applicant has requested for an extension of the use to laying hens. The Panel on additives and Products or Substances used in Animal Feed (FEEDAP) delivered in 2012 an opinion on the safety and efficacy of RONOZYME ^® WX when used as a feed additive for poultry, piglets (weaned) and pigs for fattening and another one in 2016 on the change of the production strain proposed by the applicant. In those opinions, the FEEDAP Panel concluded that the use of the product as a feed additive raises no concerns for consumer safety or for the environment. Considering the safety for the user, the Panel concluded that the additive is not a skin or eye irritant but could not conclude on its skin sensitisation potential; however, the additive was considered a potential respiratory sensitiser. The Panel considered that the new use of RONOZYME ^® WX would not modify those conclusions. The applicant submitted a tolerance study in laying hens the results of which permitted the Panel to conclude that the additive is safe for laying hens at the recommended dose of 100 FXU/kg feed. In order to support the efficacy of the additive in laying hens, the applicant submitted three long-term trials. In all three trials, the groups receiving the xylanase at the recommended dose showed a lower feed intake and a better feed to egg mass ratio. However, in one of the three trials, these reductions were seen concurrently with a decrease in the laying rate. This result casts doubts on the efficacy of the additive, and therefore, the Panel considered that there was not sufficient evidence to conclude on the efficacy of the product.

Keywords: 4‐β‐xylanase; efficacy; endo‐1; laying hens; safety; zootechnical additives.