 They are commonly regarded as favorable alternatives to antibiotic growth promoters (AGPs) in livestock production.NGPs include predominantly organic acids, probiotics, prebiotics, synbiotics, phytogenics, tannins, feed enzymes and immune stimulants., an ongoing search for alternatives has created a large variety of NGPs for pigs, poultry, ruminants and aquatic species.The main advantage of NGPs over AGPs is that they do usually not bear any risk regarding bacterial resistance or undesired residues in animal products such as meat, milk or eggs.