Fermentation techniques in feed production

With restrictions and bans on the use of in-feed antibiotics in animal agriculture, it is a great challenge to produce feed that meets the nutritional requirements of animals and maintains robust intestinal microbiota for gut function. Strategies developed over the last decades are to either produce alternatives to antibiotics such as probiotics, prebiotics, synbiotics and plant extracts or improve feed quality. The latter is achieved by removing anti-nutritional factors and toxins from feedstuffs by chemical and mechanical treatments, the addition of enzymes and absorbents, plant breeding or feed fermentation. Fermentation of feed not only preserves high-quality feedstuffs for long-term use, but also degrades toxins, anti-nutritional factors, and harmful microorganisms in low-quality ingredients. However, challenges still exist for the production of high-quality fermented feeds that have high nutritional value and are stable and safe for use over time. Here we review the major advances in methods for fermentation of feeds, with emphasis on liquid fermentation, solid-state fermentation, and ensiling. The application of microbial and non-microbial additives, innovations in fermentation processes, as well as the effects of fermented feeds on animal growth and health are also highlighted. Innovative multi-disciplinary network is of utmost importance to ensure the production of high-quality fermented-feed using cutting-edge technologies for sustaining animal agriculture in the post-antibiotic era.