Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of an endo-1,4-β-xylanase (Beltherm MP/ML), produced by a genetically-modified Bacillus subtilis strain, as a zootechnical additive for laying hens, minor poultry species and all avian species. The additive is authorised for use in feed for poultry species for fattening or reared for laying/breeding, weaned piglets, pigs for fattening and minor porcine species for fattening. The safety and efficacy of the additive for those species have been evaluated previously by the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP Panel). The current application is for an extension of use of the additive. No viable cells were detected in the additive, but the data provided to support the absence of DNA in the additive was not sufficient to conclude on the absence of recombinant DNA in the additive. However, the Panel concluded that no safety concerns would arise from the presence of DNA from the production strain in the additive. In the current assessment, the FEEDAP Panel concluded that the additive is safe for all avian species at the recommended level of 100 ADXU/kg feed. Similarly, the FEEDAP Panel concluded that Beltherm MP/ML is safe for the consumer and the environment. Concerning the user safety, the FEEDAP Panel concluded that the additive is not toxic by inhalation or irritant for skin or eyes, but it is considered a potential dermal and a respiratory sensitiser. In a previous opinion, the efficacy of the additive in poultry species for fattening was shown. However, owing to the insufficient data submitted in previous and current assessments, the Panel could not conclude on the efficacy of the product for the target species for which the application was made.