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 the feed additive consisting of Lactobacillus acidophilus CECT 4529 (tradename: Lactobacillus acidophilus D2/CSL) when used as a zootechnical additive for all poultry species and categories and all ornamental birds. The additive is authorised for use in laying hens, chickens for fattening, cats and dogs. With this application, the company requested a new authorisation for use in feed and water for drinking for all poultry species and categories and ornamental birds. The Panel concluded that Lactobacillus acidophilus D2/CSL is presumed safe for the target species, consumers and the environment. As in previous opinions, the Panel also concluded that it is considered an eye/skin irritant and a skin/respiratory sensitiser. Lactobacillus acidophilus D2/CSL when supplemented at 1 × 10⁹ CFU/kg complete feed or 5 × 10⁸ CFU/L water for drinking has the potential to be efficacious in to improving either laying or growing performance in all poultry species/categories and ornamental birds.