Abstract: Medium-chain fatty acid (MCFA) is a kind of energy materials with special physiological functions.Comparing with long-chain fatty acid (LCFA),MCFA has the advantage of shorter carbon chains and faster approach to the liver in a direct way through portal vein,directly entering hepatocyte mitochondria for β-oxidation without transport of carnitine acyl transferase.So MCFA can be absorbed by the animals in a direct and faster way while supplying energy.Besides,MCFA can not only provide energy for the animal,but also possess special physiological functions beyond its energy value,including inhibiting the growth of bacteria,improving the microecology and structure of the animal intestines,participating in the immune regulation and hormone regulation,etc.The nutritional characteristics and physiological functions of MCFA provide the basis for its application in animal production.In terms of animal production and application,MCFA can improve the growth performance of animals,reduce the rumen methane production of ruminants,prevent animal diseases,delay the corruption of livestock and poultry products,and effectively control the infestation of mosquitoes and flies on livestock.Furthermore,the joint use of MCFA and some feed additives not only has synergistic effect,but also can overcome the shortcomings in actual production and application.In recent years,with the increasing calling for safe alternatives to antibiotics,MCFA is getting more and more attention.However,there are differences in the effects of MCFA in research and production application,which may be related to the type,level and way of MCFA addition.In this paper,the nutritional characteristics,physiological functions,the effects of MCFA on animal production and its influence factors were reviewed to provide theoretical basis for further development and rational utilization of MCFA.

Key words: medium-chain fatty acids (MCFA); medium-chain triglycerides (MCT); animal production; application