Abstract: Squalene is a natural all-trans triterpene compound,which is the precursor of sterols,hopanes and triterpenes,and plays a key role in metabolism.Squalene plays an important role in improving animal growth,protecting intestinal health and improving stress resistance due to its good antioxidant,anti-inflammatory and antibacterial properties.Squalene can regulate nuclear factor E2-related factor 2(Nrf2) to promote the transcription of corresponding antioxidant enzymes and detoxification enzyme genes, improve the antioxidant level of the body, down-regulate the inflammatory response pathway through mitogen-activated protein kinase (MAPK),nuclear factor kappa-B (NF-κB),matrix metalloproteinases (MMPs) and peroxisome proliferator-activated receptor γ (PPARγ), and increase the expression of anti-inflammatory factors to terminate the inflammatory response.In terms of animal disease resistance,squalene can improve the immune function of animals,increase the level of antibodies in the serum,and thus improve the ability of animals to resist pathogens and poisons.In terms of maintaining intestinal health,squalene can effectively improve intestinal antioxidant function,maintain intestinal mechanical barrier form and permeability homeostasis,provide a place for intestinal probiotics to attach,and then significantly improve intestinal tolerance and digestive function of livestock and poultry.In addition,squalene plays an important role in improving animal reproductive performance,such as inducing estrus,improving semen quality and improving embryo health.In conclusion,squalene has good application value and research potential as a natural antibiotic substitute in animal production.In this paper,the development and biological functions of squalene were reviewed in order to provide theoretical basis for the incremental expansion of squalene production and its application in animal production.

Key words: squalene; antioxidant; inflammatory response; intestinal health