Feed additives are compounds used in swine diets with the purpose of enhancing performance and health. Many non-antibiotic feed additives have been proposed or evaluated for improving growth performance, regulating gut microbiota, supporting immunity, ameliorating environmental challenges, and enhancing reproductive performance. However, the main challenge with non-antibiotic feed additives is the fact that many have not generated consistent effects or have not been economically justified.
To evaluate the effects of a feed additive, it would be ideal to perform multiple experiments and validate the experiments under the conditions of the production system. Evidence of repeatability across experiments increases confidence that the effects will be achieved under commercial practice. Also, an adequate number of replications is essential to be able to detect a response in growth or reproductive performance, especially considering that the improvements in performance obtained with non-antibiotic feed additives are generally modest. Furthermore, it is important to be aware of publication bias, as many studies without evidence for efficacy of feed additives are often not published in the scientific literature.