Study On The Changes Of Rumen Microbial Population And Metabolites In Dairy Cow Laminitis Model

Dairy cow laminitis has always been one of the important diseases that threaten dairy production.A large number of cows are eliminated every year due to laminitis,causing significant losses to dairy production.However,there is no active and effective method for the prevention and treatment of dairy cow laminitis,and the mechanism of laminitis is still unclear.In this study,a large amount of fructooligosaccharide was infused to establish a laminitis model,to study the changes of rumen microbial population,rumen fluid,and microbial metabolites in the blood of cows with laminitis,and to determine the changes of microbial content in the rumen and the changes of laminitis.The relationship provides a theoretical basis and basis for elucidating the pathogenesis of dairy cow laminitis and the application of micro-ecological preparations to treat laminitis.In this experiment,five healthy non-pregnant cows with no hoof disease were used as test animals.Each cow was infused into the rumen with 17 g/kg of fructooligosaccharide through a rumen catheter to establish a model of cow laminitis.Observe the clinical symptoms and histopathological changes of hoof tissue.30 m L of rumen fluid and 15 m L of blood were collected at 0 h,6 h,12 h,24 h,48 h and 72 h perfusion of fructooligosaccharide.The rumen fluids at 0 h,6 h,12 h and 24 h were selected for high-throughput sequencing.After sequencing analysis,the species composition and abundance information of the sample flora were obtained.Then through Alpha diversity analysis,Bate diversity analysis and other analysis methods to compare the changes of the rumen microbial population at different times,and then explore the relationship between the rumen microbial population changes and laminitis.At the same time,at 0 h,6 h,12 h,24 h,48 h,72 h perfusion of fructooligosaccharides,the content of lactic acid,histamine and serotonin(5-HT)in rumen fluid and venous blood was detected by high-performance liquid chromatography.The kit detects the content of endotoxin(LPS).Streptococcus bovis begins to grow at 6 h,indicating that the occurrence of laminitis is related to Streptococcus bovis.Lactobacillus multiplication at 24 h is related to changes in catabolism in the rumen.LPS,lactic acid,histamine and 5-HT in rumen fluid increased with time,and reached the maximum value at 24 h(P < 0.01).The changes of lactic acid and 5-HT in blood were consistent with the changes in rumen fluid.However,the levels of histamine and LPS in the blood increased significantly at 12 h,reached the target at 24 h(P < 0.01),and returned to normal levels at 72 h(P > 0.05).The results showed that after a large amount of fructooligosaccharides were implanted,the bacterial flora in rumen fluid changed significantly with time.At the phylum level,the proportion of the predominant bacterium Pachymenae and Bacteroides in the rumen fluid changed.At the genus level,Streptococcus bovis proliferates in the rumen,and Lactobacillus eventually becomes the dominant genus.Changes in the bacterial flora in rumen fluid lead to changes in ruminal fluid and blood related microbial metabolites lactic acid,5-HT content,rumen fluid LPS,histamine changes,these changes may be one of the pathogenesis of dairy cow laminitis.