Composition And Difference Of Intestinal Flora Of Newborn Piglets At Different Age

Intestinal microbiota in piglets is considered to be critical to disease occurrence and healthy balance,and the intestinal flora plays key roles in the nutrition,immune and metabolic of piglet.Through the analysis of the intestinal flora of piglets of different ages,this study determines the composition of the intestinal flora of newborn piglets and the distribution and changes of the intestinal flora of newborn piglets at different developmental stages,at the same time,this study analyzes the changes of each microflora in piglets and the reasons for their changes,and explores the differences in the intestinal flora of piglets.Three healthy piglets of each different days of age(0,5,10,15,20,25,30 d)were selected for the experiment.After slaughter,their cecal contents were collected,and microbial genomic DNA was extracted for 16 S r RNA high-throughput sequencing to analyze the floral structure.1.Alpha diversity analysis shows that intestinal flora diversity of piglets at different days of age is different.Shannon index and Simpson index at 25 days of age are significantly lower than those of piglets at 5,10,20 and 30 days of age,indicating that community diversity at 25 days of age is lower.Observed species index and Chao1 index decrease gradually at 0 ～ 20 days of age,but increase gradually at 20 ～ 30 days of age,indicating that species richness decrease at 0 ～ 20 days of age,and increase at 20 ～ 30 days of age.2.At the phylum level,the intestinal flora of newborn piglets is mainly composed of two phylum: Firmicutes(43.5%)and Bacteroidota(26.9%),accounting for about 70.4%,but the proportion of the two phyla in each age is different,Firmicutes relative abundance in 0 days of age(36.9%)～ 5 days of age(52.4%)has a rising trend(P > 0.05),This is mainly due to the fact that aerobic bacteria and facultative anaerobes of Firmicutes are the first to colonize and multiply rapidly in the gut at birth.As the intestinal oxygen environment changes,the relative abundance of Firmicutes remains stable from 5 to 20 days of age,and the difference is not obvious(P > 0.05),at 25 days of age(18.7%)due to changes in dietary structure and weaning stress and other factors is significantly decreased(P < 0.05),then the piglets begin to adapt to the new gut physiology,which begin to rise and become stable at 30 days of age(P>0.05).There is no significant difference in the relative abundance of Bacteroidota among different days of age(P>0.05),but the Bacteroidota shows an increasing trend from 0 days of age(14.7%)to 10 days of age(43.9%),which is because Bacteroidota first colonized and multiplied rapidly in the intestinal tract,and then shows a decreasing trend from 10 days of age(43.9%)to 25 days of age(18.9%)under the influence of intestinal environment,competitive inhibition and weaning stress.At the genus level,the intestinal flora structure of newborn piglets is significantly different before and after weaning.Before weaning,the dominant strains in piglet intestinal tract are Lactobacillus(19.7%),Bacteroides(7.2%)and Escherichia-Shigella(7.2%).After weaning,the intestinal flora changes significantly due to dietary changes,and Prevotella,Ruminococcus-UCG-005 and Alloprevotella increased significantly(P<0.05)and begin to dominate.3.Beta diversity analysis results show that the same day age of different individuals is significant difference,especially there are significant differences in species diversity between birthday age(0 days of age)and after weaning age(25 days of age).At birth(0 days of age),individual differences may be caused by genetic factors,while after weaning,individual differences may be caused by different stress responses to weaning.There are significant differences in species diversity and composition of intestinal microflora at birth(0 days of age)and after weaning(25 days of age)compared with 5 days to 20 days of age.At birth(0 days of age),intestinal flora is mainly affected by the mother and the environment of microorganisms and intestinal environment.After weaning(25 days of age),they are mainly affected by dietary structure,weaning stress and other factors,which leads to the difference of microflora structure between them and the lactation period(5 days to 20 days of age).According to the results displayed by high-throughput sequencing,the following conclusions are drawn:1.The diversity of intestinal microorganism of piglets at different days of age changed significantly with the increase of age.2.At different age of piglets,although intestinal flora of piglets is constantly developing and changing,the intestinal flora is composed of Firmicutes(43.5%)and Bacteroidota(26.9%),accounting for 70.4%.Before weaning,Lactobacillus,Bacteroides and other bacteria related to the metabolism of carbohydrates and other nutrients in the intestines of piglets have a high abundance.After weaning,the abundance of Prevotella,UCG-005,and Alloprevotella,and other bacteria related to fiber digestion have a high abundance.3.The intestinal flora structure of Weaned piglets is significantly different from that of Suckling piglets,and the composition of intestinal flora of piglets at the same age group also has individual differences.