Review of immune stimulator substances/agents that are susceptible of being used as feed additives: mode of action and identification of end-points for efficacy assessment

Abstract

Additives may exert a beneficial effect on the immune system and could thus improve the welfare of animals. In most cases, the mode of action of these additives is unknown, which makes assessment of their efficacy difficult. The project OC/EFSA/FEED/2014/01 aims to identify substances/agents used as feed additives aiming to exert a beneficial effect on the immune system of animals. This project considered 1144 scientific articles, which provided data for around 185 substances/agents with the potential to be used as immune feed additives. Of the 185 substances/agents detected, 51 were probiotics, 25 were classified as prebiotics, 92 as plant extract, five as animal by-products, and 12 were included as ‘other substances’. For each substance / agent, the prevalent mode of action for each animal species, interactions with other dietary compounds, relevant end-points that could demonstrate efficacy, methods for the objective measurement of end-points, risks for the safety of the target animals, consumer, users and the environment, existing legislation in third countries, and the patents published until the time of writing were identified.