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 and efficacy of an additive consisting of Propionibacterium freudenreichii DSM 33189 and Lentilactobacillus buchneri (formerly Lactobacillus buchneri) DSM 12856 as a technological additive for all animal species. The additive is intended to improve the production of silage at a proposed application rate of 1 × 10⁸ colony-forming units (CFU)/kg fresh material. The bacterial species P. freudenreichii and L. buchneri are considered by EFSA to be suitable for the qualified presumption of safety (QPS) approach to assessment. As the identity of the strains has been clearly established and no acquired antimicrobial resistance determinants of concern were detected, the use of the strains as a silage additive is considered safe for livestock species, for consumers and for the environment. The additive is not irritant for eyes or skin but should be considered a respiratory sensitiser. In the absence of data, the FEEDAP Panel could not conclude on the potential of the additive to be a skin sensitiser. The additive at the proposed application rate of 1 × 10⁸ CFU/kg fresh plant material showed the potential to improve the aerobic stability silage with dry matter content ranging from 30% to 70%.