A Study on Differential Biomarkers in the Milk of Holstein Cows with Different Somatic Cells Count Levels

SIMPLE SUMMARY: Mastitis is one of the most common diseases in the dairy industry in the world, and its treatment cost is also the most expensive of all diseases in the dairy industry. The research on the rapid diagnosis of cow mastitis is of great significance to the development of the dairy cow industry all over the world. In this study, we use microbiology and metabolomics techniques to explore the differential microbiota and metabolites in cow milk at different somatic levels, to find new biomarkers for the diagnosis of cow mastitis and provide a new plan for the diagnosis, prevention, and treatment of mastitis in the future. ABSTRACT: Dairy cow mastitis is one of the common diseases of dairy cows, which will not only endanger the health of dairy cows but also affect the quality of milk. Dairy cow mastitis is an inflammatory reaction caused by pathogenic microorganisms and physical and chemical factors in dairy cow mammary glands. The number of SCC in the milk of dairy cows with different degrees of mastitis will increase in varying degrees. The rapid diagnosis of dairy cow mastitis is of great significance for dairy cow health and farm economy. Based on the results of many studies on the relationship between mastitis and somatic cell count in dairy cows, microflora, and metabolites in the milk of Holstein cows with low somatic cell level (SCC less than 200,000), medium somatic cell level (SCC up to 200,000 but less than 500,000) and high somatic cell level (SCC up to 5000,00) were analyzed by microbiome and metabolic group techniques. The results showed that there were significant differences in milk microbiota and metabolites among the three groups (p < 0.05), and there was a significant correlation between microbiota and metabolites. Meanwhile, in this experiment, 75 differential metabolites were identified in the H group and L group, 40 differential metabolites were identified in the M group and L group, and six differential microorganisms with LDA scores more than four were found in the H group and L group. These differential metabolites and differential microorganisms may become new biomarkers for the diagnosis, prevention, and treatment of cow mastitis in the future.