Study On The Nutritional Metabonomics Related To The Lactation In Dairy Cows

The content and composition of milk protein and fat are important indicators to measure thenutritional quality of milk， its content not only determine the flavor of milk， but also is the corecompetitive strength of dairy enterprise. With the improvement of genetic breeding and dietarylevels， The production of milk has been greatly improved， but the milk quality has notimproved. Now， China’s raw milk indicators of the content of milk protein and fat are still lowerthan the normal content of developed countries， and studies have shown that feeding pattern，environment health and dairy breeds can significantly affect the quality of milk.In this study， we applied we employed quantitative1H nuclear magnetic resonance (NMR) toanalyze the small molecule metabolites in the liver， mammary gland， rumen fluid， arterial andvenous blood， milk and urine of the high and low milk quality group and dry period group dairycows，the purpose was to find the difference in the metabolites between the three groups. We usedNMR technology to detect the small molecule metabolites in rumen liquid between the threegroups，and results showed that the high and low milk quality groups have many differential smallmetobolites compared to the dry period group， and trend of the difference is the same between thetwo groups， and there was no significant difference in the metobolites between the high and lowmilk quality groups. Liver is an imporant substance synthesis and metabolic organ in ruminants.After detected by NMR techniques， PLS-DA analysis showed that the model of liquid metabolitesin liver are successful. The results of OPLS-DA showed that isoleucine， leucine， histidine，glutamine， choline， citrate， fumaric acid and cytidine in the high milk quality group weresignificantly lower than the level of the low milk quality group. For the arterial serum metabolites，the model was successfully established between the high and low milk quality groups， and themetabolites containing isoleucine， leucine， lipids， glucose， lipids， valine and glutamic acidin the high milk quality group were significantly higher than the low milk quality group， andisoleucine， valine， glutamic acid is mainly used for the synthesis of milk proteins and lipids inthe serun were mainly used to synthsis the long chain fatty acid，suggesting that these metabolitesmay be the biomarkers causing the difference in protein and fat rate between the high and low milkquality groups. The mammary gland has an incredible level of organization and a remarkableability to convert circulating nutrients into milk components. By NMR detection and PLS-DAanalysis， the modles of liquid metabolites in mammary gland were successfully establishedbetween the three groups， but the modles of the lipid metabolites were not established. PLS-DA analysis results showed that the levels of the leucine， lysine， methionine， glycine， tyrosine，phenylalanin and alanine in the high milk qulity group were significantly higher than those in thelow milk quality groups， and suggesting that these different metabolites may be the biomarkersinfluencing the synthesis of protein and fat in mammary gland. Detection of metabolites in venousserum by NMR technology， and PLS-DA analysis showed that the models of metabolites invenous serum were successfully established， analysis of OPLS-DA showed that the level oflipids， choline and creatine in the high milk quality group were significantly lower than the lowmilk quality group， lower lipids level in venous serum together with higher lipids level in arterialserum suggested that the great consumption of lipids from serum were used to synthesis the milkfat in the high milk quality group. Milk yield and quality are manifestations of the cows economicvalue， OPLS-DA analysis showed that the histidine， phenylalanine， glutamic acid in high milkquality group were significantly higher than the low milk quality group， which were consistentedwith the results of milk protein hydrolyzate amino acids. According to the detection of NMR andPLS-DA analysis，the results showed that the models of urine metabolites were unsuccessfulbetween the three groups， which can be speculated that there were no significant differences insmall molecules within the three groups.In this study，we also used the amino acid automatic analyzer to determine the content of freeamino acids in the arterial and venous serum of the high and low milk quality groups. Resultsshowed that the contents of essential amino acids Met， Leu， Ile， Thr， Val in the arterial serumof the high milk quality group were significantly higher than the low milk quality group， theuptake rate of Thr， Val， Met， Ile， His in the high milk quality group were significantly higherthan that of low milk quality group. And RT-PCR results showed that the expression of STAT5，AKT1，mTOR which regulate the protein synthesis were at a high level in the high milk qualitygroup.Results of the determination by gas chromatography showed that the content of long chainfatty acids in high milk quality group were significantly higher than that of low milk quality group.OPLS-DA analysis of arterial serum in high milk quality group showed the level of lipids werehigher than that of the low milk quality group， Presumably， this may be the reason for inducingthe high rate of milk fat in the high milk quality group. Results of RT-PCR and enzyme activityassay showed that the expression of the genes and enzymes activity were all at a higher level，which may explain the reason of the high rate of milk fat in the high milk quality group.