Following a request from the European Commission, the EFSA 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 Biacton® when used as a feed additive for chickens for fattening, turkeys for fattening and laying hens. Biacton® is a preparation of viable cells of Lactobacillus farciminis CNCM I-3740 intended for use in feed for chickens for fattening, turkeys for fattening and laying hens at a minimum recommended application level of 5 × 108 CFU/kg complete feedingstuffs. L. farciminis is a species considered by EFSA to be suitable for the Qualified Presumption of Safety (QPS) approach to safety assessment which requires the identity of the strain to be conclusively established and evidence that it does not show acquired resistance to antibiotics of human and veterinary importance. The strain was found to meet the criteria for the QPS approach to safety assessment, and since concerns are not expected from other components of the additive, the additive is presumed safe for all target species, consumers and the environment. In the absence of data, no conclusions can be drawn on the irritancy of Biacton® to skin and eyes or on its dermal sensitisation potential. The additive should be considered a respiratory sensitiser. Due to poor reporting and significant limitations in the data available, the FEEDAP Panel cannot conclude on the efficacy of the additive for chickens for fattening, turkeys for fattening and laying hens.