Screening Of Biomarkers Related To Reproductive Performance In Large White Pigs Based On Microbiomics And Metabolomics

With the rapid development of modern large-scale farming,improving the reproductive performance of sows and increasing the litter size of sows has become an urgent problem to be solved.Based on this,this study focuses on the Large White Pigs as the research object,and uses methods such as intestinal microbiota,non-targeted metabolomics,and short-chain fatty acid detection to analyze and screen biomarkers related to sow reproductive performance.The main research content and results are as follows:16S rRNA gene sequencing was performed on fecal samples from 265 sows,and the changes in the composition and structure of the intestinal microbiota during six different stages of pregnancy(30 days,60 days,90 days,107 days,3days postpartum,and 21 days postpartum)in Large White Pigs were analyzed.The results showed that there were specific ecological successions in the intestinal microbiota of Large White Pigs during the reproductive cycle.Within one reproductive cycle,the α and β diversities of the intestinal microbiota in Large White Pigs changed during different pregnancy stages,with significant statistical differences observed between the pre-and post-partum periods.Selecting 86 pre-partum(107 days of gestation)Large White Pigs,the sows were divided into low-parity group for the first two pregnancies,medium-parity group for the third to fifth pregnancies,and high-parity group for the sixth to eighth pregnancies.The differences in the gut microbiota of the sows in different reproductive cycles(parities)were analyzed using 16 S r RNA gene sequencing.The results showed that the alpha diversity of the gut microbiota in Large White Pigs did not significantly differ among the different parity groups.However,there were significant differences in the beta diversity of the gut microbiota between the low-parity group and the high-parity group/medium-parity group.No significant difference was observed in the beta diversity of the gut microbiota between the high-parity group and the medium-parity group.The genera Planctomycetaceae,Comamonadaceae,and GR-WP33-58 were found to be significantly associated with parity.Using the average litter size per litter as the selection criterion for high and low litter size groups,97 individuals with high litter size and 93 individuals with low litter size were selected from a total of 1019 individuals at different gestational stages ranging from 3 to 6 parity.Fecal samples were collected and16 S r RNA gene sequencing was performed to compare the differences in the intestinal microbiota of the high and low litter size groups in six different gestational periods.The results showed that Methanobrevibacter was the main microbial biomarker in the high litter size group,while the Eubacterium＿coprostanoligenes＿group was the main microbial biomarker in the low litter size group.Fecal samples from 25 multiparous Large White Pigs(4-5 parity)at 107 days of gestation were subjected to metagenomic sequencing to further validate the results of 16 S r RNA gene sequencing analysis and screen for microbial species and metabolic pathways related to pig litter performance.The high litter size group consisted of 13 pigs,while the low litter size group consisted of 12 pigs.The results showed that the differentially indicated bacterial species at the species level in the high litter size group included Methanobrevibacter＿unclassified,while the differentially indicated bacterial species in the low litter size group were Lactobacillus＿reuteri.After removing host contamination,Methanobrevibacter was still a microbial biomarker for the high litter size group of Large White PigsNon-targeted metabolomic analysis was performed on fecal microbiota of high and low litter size groups of Large White pigs.The results revealed a total of 896 differential metabolites between the high and low litter size groups in both positive and negative ion modes.The enriched metabolic pathways of these differential metabolites were mainly associated with carbohydrate metabolism and lipid metabolism.Short-chain fatty acid targeted metabolic detection was performed on the fecal microbiota of high and low litter-size groups of Large White Pigs.The results showed that there were higher levels of short-chain fatty acids in the feces of the high litter-size group,with butyrate,isobutyrate,valerate,and isovalerate being significantly different metabolites between the two groups.The correlation analysis between short-chain fatty acids and the reproductive phenotypic traits of Large White Pigs showed that butyrate,isobutyrate,valerate,and isovalerate were highly positively correlated with the average litter size,with correlation coefficients of 0.65,0.65,0.71,and 0.76,and the standard errors of the correlation coefficients were 0.139,0.135,0.033,and 0.131,respectively.Based on the above analysis results,it is speculated that Methanobrevibacter,Eubacterium＿coprostanoligenes＿group,and Methanobrevibacter＿unclassified are intestinal microbial biomarkers that affect the reproductive performance of Large White Pigs;butyric acid,isobutyric acid,valeric acid,and isovaleric acid are metabolic biomarkers that affect the reproductive performance of Large White Pigs.