Epidemiological Investigation And Characterization Of Bacterial Community Of Rumen From Dairy Cow During Laminitis Challenge In Linqu County

Laminitis is a classic problem in the farms,which seriously hinders the development of dairy industry and causes huge financial loss.Laminitis is a diffuse,aseptic,serous and non suppurative inflammation.Although it received considerable attention,the etiology and pathogenesis of laminitis have no unified consensus.In reviewing the literature,the lesions resulted from three distinctly different pathological processes.There were microcirculation of blood,failure of suspensory apparatus and Interference with horn production?keratogenesis?.Rumen is a special digestive organ of ruminant,which is regarded as a natural fermentation tank for continuous inoculation of microorganisms.The dairy cow rumen harbored a diverse commensal microbiome.Under the interaction,the ingested feed is fermented to produce nutrients for energy supply.With disturbed rumen fluid composition,vasoactive substances?histamine and endotoxins?are released and enter the blood circulation through the rumen wall,leading to the occurrence of metabolic diseases.Several reports have shown that laminitis is a local manifestation of systemic metabolic disease.Therefore,the relationship between rumen flora and laminitis was established to provide a basis for studying the etiology and pathogenesis of laminitis.This study was based on the epidemiological investigation of laminitis in Linqu Country,Weifang city,Shandong province and the analysis of two aspects of rumen flora and blood index detection during the laminitis.Firstly,we did the epidemiological investigation of the incidence of dairy cow laminitis in Linqu Country,Weifang city,Shandong province.As the results shown,the average incidence of laminitis in this region was 5.81%,accounting for 14.98% of the total hoof diseases.Different variables have been found to be related to laminitis.A healthy and balanced diet and a strict medicine bath can effectively reduce the incidence of laminitis.The incidence of primiparous cows is 28.57%,which decreased with the increase of parity,and showed a negative correlation.The incidence rate was higher in dairy cows with higher milk production,with the highest incidence of lactation at 20-30 kg/day at 35.71%.The incidence is related to other diseases,especially the higher the incidence of laminitis with a history of metabolic diseases.Secondly,the serum of healthy and laminitis dairy cows collected from farms was used to detect concentrations of LPS,lactic acid,and histamine by the detection kits.The results showed that there was a significant increase in LPS and lactic acid in the laminitis group,while that of histamine had no difference.Overall,this study indicated that lactic acid and endotoxins may be important pathogenic factor of laminitis.Finally,this study used 16 S rRNA sequencing to identify the differences in the bacterial community.The results showed that there was no significant difference in alpha diversity in rumen fluid between healthy and laminitis cows,but there was a significant difference in multi-sample comparison analysis?Beta Diversity?.At the phyla level,the relative abundance ofCorynebacterium,Saccharibacteria,andSR1_{Absconditabacteria}significantly increased?p<0.05?.At the genera level,the relative abundance ofCandidatus Saccharimonas,SaccharofermentansandErysipelotrichaceae UCG-009 significantly increased.At the species level,the relative abundance ofClostridium papyrosolvensandrumenaceae AE2021 significantly increased,while that ofPrevotella ruminicola,Prevotella sp.CA17,andTreponema saccharophilumdecreased significantly.In summary,the laminitis group increased the abundance of bacteria with acid metabolites,reduced rumen pH and affected the metabolic function of the rumen flora.To sum up,this article confirmed that feeding conditions affected the incidence of laminitis.After improper feeding,the rumen flora of dairy cows was disturbed and metabolic functions were dysfunctional.The abundance of bacteria with acid metabolites increased.There was a marked reduction in ruminal pH.Then gram-negative bacteria dead and consequently endotoxin released in rumen.The lactic acid and endotoxins could be harmful to the organism,lead to laminitis.