| Pig production is the pillar industry of Chinese agriculture.The excellent reproductive performance of sows,good maternal performance and high survival rate of piglets before weaning are the most important guarantee for high economic benefit of pig industry.As a severely failed maternal behavior,sow maternal infanticide directly causes the death of piglets and brings huge economic losses to pig industry.Maternal infanticide behavior of sows is affected by many factors,such as genetics,feeding management and environments.A growing number of studies have shown that the gut microbiota influences host behavior through the gut-brain axis.However,whether gut microbiota affects sow maternal infanticide behavior is unknown.In this project,fecal and serum samples were collected from 72 sows showing maternal infanticide and 75 full-or half-sibs sows having normal behaviors in two populations within 5 days before parturition and within 24 hours after delivery to study the mechanism of gut microbiota on sow maternal infanticide.High-throughput sequencing of 16 S r RNA gene V3-V4 region and metagenomic sequencing were used to analyze the composition of gut microbiome in feces.Non-targeted or widely targeted metabolome and lipidome measurements were performed to analyze the metabolite profiles of serum samples from experimental sows,widely targeted metabolome and lipidome were used to analyze the metabolites in feces.Serum hormones and neurotransmitters as well as fecal short-chain fatty acids were also measured.By analyzing multi-omics data between maternal infanticide and normal sows around parturition,we identified the gut microbial species,serum and fecal metabolites closely related to maternal infanticide.We first analyzed the changes of gut microbiota and serum metabolites around parturition.We found that the α-diversity of gut microbiota gradually decreased from later pregnancy(LP)to postpartum(PO).A total of 30 bacterial genera and 56 bacterial species were changed in relative abundances around parturition.Lactobacillus and Streptococcus and its related species,such as Lactobacillus johnsonii and Streptococcus suis were mainly enriched at the LP stage,while Escherichia,Bacteroide,Campylobacter and its related species,such as Escherichia coli,Bacteroides fragilis and Campylobacter coli had higher abundances at the PO stage.In terms of the serum metabolome,the main metabolic pathways including taurine and hypotaurine metabolism,and arginine biosynthesis and metabolism were enriched at the LP stage,while the pathways of vitamin B6,glyceride and glycerophospholipid metabolism had higher abundances at the PO stage.Furthermore,all six kinds of SCFAs were measured in feces samples and showed higher concentrations at the LP stage.These results suggested the distinct changes in gut microbiome and serum metabolome around parturition.We next analyzed the correlations between gut mcirobiota and sow maternal infanticide and primarily elucidated the possible mechanisms.We found that Lactobacillus delbrueckii,Coprococcus cutus,Turicibacter sanguinis,and several species from Lactobacillus,Clostridium,Lachnospiraceae and Ruminococcaceae were enriched in the gut of infanticidal sows.Meanwhile,Ruminococcus torques and five species from Lactobacillus were enriched in the gut of infanticidal sows at postpartum.These taxonomies have been reported to be associated with the concentration and transportation of serotonin(5-HT)in the intestinal tract and related to the use of antidepressant.Therefore,they are probably important species responsible for maternal infanticide.Using metagenomic sequencing data,we found that the pathways of phosphotransferase system(PTS),Staphylococcus aureus infection and amoebiasis were enriched in the gut microbiome of infanticidal sows before parturition,while lipoic acid metabolism,mineral absorption,tetracycline biosynthesis and several other functional pathways were enriched in the gut microbiome of normal sows.KEGG pathways,such as PTS,Staphylococcus aureus infection,lipolysaccharide synthesis,and arachidonic acid metabolism,were also enriched in the gut microbiome of infanticidal sows after delivery,while tetracycline biosynthesis,O-glycoside biosynthesis and mitochondrial autophagy were enriched in the gut microbiome of normal sows after delivery.Measurements of serum metabolites,reproductive hormones and neurotransmitters showed that thyroxine,taurine,dopamine,norepinephrine,oxytocin,estradiol,L-glutamate,7α-dehydroepiandrosterone,lipopolysaccharides and PGE2 1-triglyceride were enriched in the serum samples of infanticidal sows before parturition,while tetrahydrocorticosterone(THCC),citalopram and PGE2 were enriched in the serum samples of normal sows.There were also significant differences in fecal metabolites between infanticidal sows and normal sows.L-thyroxine,histamine and testosterone were all enriched in the fecal samples of infanticidal sows,while androsterone,citalopram,pantothenic acid,THCC and deoxycorticosterone(DOC)were enriched in the normal sows.There were significant correlations between differential serum and fecal metabolites,and differential bacterial species.For examples,Lactobacillus delbrueckii was positively associated with Lthyroxine which can promote body metabolism and excitement,while Ruminococcus flavefaciens and Limosilactobacillus reuteri were positively correlated with THCC and DOC which have been reported to show anti-anxiety and sedative effects.The results of this study preliminarily revealed the correlation between gut microbiota and infanticide behavior of sows,identified the bacterial taxa related to infanticide behavior of sows,and preliminarily explained the possible mechanism of gut microbiota affecting infanticide behavior by combining the results of metagenomics,metabolome and reproductive hormone measurement. |
