Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety of a feed additive consisting of Duddingtonia flagrans NCIMB 30336 (BioWorma®) for all grazing animals. The safety and efficacy of the additive have been already assessed previously, however the FEEDAP Panel could not conclude on the safety of the additive for the target species and the consumers due to the limitations in the dataset provided. For the current assessment, the applicant submitted a new tolerance trial in dairy cows and new toxicological studies. After the assessment of the new data submitted, the FEEDAP Panel concluded that the use of the feed additive in animal nutrition under the conditions of use proposed is of no concern for dairy cows. This conclusion can be extrapolated to all dairy bovines, ovines and caprines, but not to fattening and rearing animals of those species. Due to the lack of data, the FEEDAP Panel cannot conclude on the safety of the additive for other grazing species/categories. The FEEDAP Panel concluded that the additive is safe for the consumers.