~1H-NMR Based Metabolic Profiling Of Milk Whey In Postpartum Dairy Cows With Inactive Ovaries

In recent years,with the development of the intensification and scale in dairy farm,and the selection of milk-producing genes,the milk production of dairy cows has continuously increased,while the reproductive efficiency has been gradually declining.It has seriously affected the sustainable and healthy development of China's dairy industry.Inactive ovaries is one of the types of postpartum anestrus in dairy cows,which is caused by temporary disturbance of the ovaries and no cyclical activity of follicles.Inactive ovaries is the result of multiple factors,lactation and nutrition(negative energy balance)are the two most important factors.However,there is no report on the milk whey metabolomics and the relationship between milk whey and serum metabolomics in postpartum dairy cows with inactive ovaries.Therefore,in this study,1H-Nuclear Magnetic Resonance(1H-NMR)of metabolomics technology was used to obtain the differential metabolites in milk whey and serum of cows with inactive ovaries,to clarify interaction among the differential metabolites and their effects on the dairy cows with inactive ovaries,and to provide a scientific basis for the pathogenesis of inactive ovaries in dairy cows.60 healthy cows that had similar age,parity,body condition and milk yield(nearly 10 tons in the last year),were randomly selected 45 to 60 days postpartum from an intensive dairy farm in Heilongjiang Province as the test animals.According to the estrus manifestations,the B-ultrasound scan,rectal examination and reproductive hormone tests,14 cows were assigned into normal estrus group(A)and 14 cows into inactive ovaries group(B).The clinical blood pathology was analyzed in two groups of dairy cows,then milk whey and serum from two groups of dairy cows were detected by 1H-NMR,combined with multivariate statistical analysis and univariate analysis,to screen the differential metabolites between two groups,and to clarify the relationship between metabolic pathways of differential metabolites and inactive ovaries in dairy cows by bioinformatics.Results showed that 1)Inactive ovaries cows presented the state of negative energy balance,which was low GLU,high NEFA and BHBA in the blood.In addition,the reproductive hormones changes of inactive ovaries and estrus cows were consistent with their pattern andserum E2 level of the inactive ovaries cows was significantly reduced.2)13 differential metabolites in milk whey and 13 differential metabolites in serum of dairy cows with inactive ovaries were screened by1H-NMR,combined with multivariate statistical analysis and univariate analysis.Compared with the normal estrus cows,the inactive ovaries cows had the increased levels of succinate,phosphocreatine,glycine,glycolate,orotate and myo-Inositol,and the decreased levels of alanine,creatinine,phosphocholine,lactose,taurine,galactose,glucose-1-phosphate in milk whey;and the increased levels of BHBA,acetate,glutamine and glycine,and the decreased levels of alanine,succinate,citrate,creatinine,phosphocholine,GLU,myo-Inositol,tyrosine,histidine in serum.There were same changes of alanine,glycine,creatinine and phosphocholine in milk and blood,but most of the differential metabolites were different,which indicated that there were a big difference in metabolites between milk and blood of cows with inactive ovaries,both showed abnormal changes in glucose metabolism,lipid metabolism,and amino acid metabolism.Conclusion obtained that this study clarified the clinical blood pathological features in postpartum dairy cows with inactive ovaries caused by negative energy balance.The metabolic profiles and differential metabolites in milk whey and serum of dairy cows with inactive ovaries were obtained,and an interactive network of metabolic pathways was constructed in milk and blood of dairy cows with inactive ovaries.It played an important role that clarify the major abnormal pathways of glucose metabolism,lipid metabolism,and amino acid metabolism in the occurrence of inactive ovaries in postpartum dairy cows.This will provide a new direction for further study of mechanism and control strategy in dairy cows with inactive ovaries.