Probiotics are the micro-organisms required for the growth of the animal immune system, such as bacteria and fungi. The feed additives supplied to animals by means of food are referred to as probiotics in animal feed. The probiotics are both bacterial and non-bacterial. Types of bacterial probiotics include Bifidobacterium, Lactobacillus, Pediococcus, Streptococcus, etc. Non-bacterial probiotics are fungus and yeast, such as Aspergillus oryzae, Candida Pintolopessi, etc. Probiotics in animal feed industry deal with the production of probiotics, the types of probiotics available, the dosage of feed, and the effects of digestion in animals. Probiotics are usually fed in animal food to benefit the immune system by destroying pathogens that damage the body.