Abstract: Intestinal tract is an important digestive and immune organ of the body.Maintaining intestinal health is important for pig growth and disease prevention.The development of high-throughput sequencing technology has greatly promoted people's understanding of intestinal microbial function,and the research of pig intestinal microbiome is gradually becoming a hot spot.At present,although the intestinal microbiome of pigs at a certain growth stage has been well understood,there is still a lack of comprehensive longitudinal studies on the dynamic changes of intestinal microbiome in the whole life cycle of commercial pigs.However,from birth to marketing,the intestinal microbiome of pigs in the whole growth cycle is not constant,but a dynamic development process.In this paper,the longitudinal changes of intestinal microflora and its main influencing factors in different stages from birth to fattening of pigs during lactation,weaning,fattening and pregnancy were reviewed.It was found that the significant changes of intestinal microbial community structure mainly occurred in the weaning period.At the same time,although the composition of intestinal microorganisms was constantly changing over time,there were still some dominant bacteria.This part of microor-ganisms is called the core flora,and the bacteria that only appear in a specific period are only "passers-by" in the gastrointestinal tract,and they are also the most vulnerable to external factors.Intestinal microbiome is related to many factors,such as age,diet,environment,antibiotic use,etc.,among which diet plays an important role in shaping intestinal microflora.This paper provided a theoretical reference for understanding the dynamic changes of intestinal microflora in pigs at different growth and development stages,and using the technology on microorganisms to improve pig growth performance and health level.

Key words: pig; gut microbiota; microbiome; growth stage