| At present,as the intensive dairy farms have continuously expanded and the average milk proudction per cow has constantly increased,the reproductive disorders is also increasingly serious,which may seriously obstacle the health development of dairy industry in China.Anestrus postpartum in dairy cows is one of the most common reproductive disorders,which often show no heat or the exending estrus cycle.Inactive ovary(IO)is one of the most common anestrus postpartum.The negative energy balance(NEB)has been accepted as the most important factor of anestrus postpartum.However,there has been rarely reports on overall metabolic status in dairy cows with IO so far.Therefore,aim of this research is to identify the differential plasma metabolites between normal estrus cows and cows with IO caused by NEB using liquid chromatograph/mass spectrometry(LC/MS)technique,combining with multivariate statistical analysis and bioinformatics analysis to reveal the relationship between IO and metabolic pathway.It will provided the new clues for exploring the mechanism,prevention and treatment of IO in future.In this research 147 multiparous Holstein cows with similar age,BCS and parity were randomly selected from 14 d to 21 d postpartum,and blood samples were collected for detecting biochemical indicator of the cows.According to the plasma levels of ?-hydroxybutyric acid(BHBA),non-esterified fatty acid(NEFA)and glucose,these cows were divided into positive energy balance(PEB)(BHBA<1.00 m M,NEFA<0.50 m M,glucose>3.00 m M)and NEB(BHBA>1.20 m M,NEFA>0.50 m M,glucose<2.80 m M)groups,which were tracked until 60 d to90d postpartum.16 estrous cows in PEB group(E group)and 16 IO cows in NEB group(IO group)were determined according to clinical estrus signs,rectal examination and B ultrasound.The plasma differential metabolites from dairy cows with IO may be determined to investigate the role of metabolites using LC/MS,combining with multivariate statistical analysis and bioinformatics analysis,and then ELISA method was use to prove these differential metabolites.Results showed that: 1)plasma level of phosphorus(P)(P < 0.05)and magnesium(Mg)(P< 0.01)were lower,BHBA and NEFA were higher(P < 0.01),and Glc was lower(P < 0.01)in NEB group compare with PEB group from 14 d to 21 d postpartum.2)Cows in IO group had higher milk yield(P < 0.05),lower body condition score(P < 0.05)and low reproductive performance,compared with in E group.Plasma level of P and NEFA were higher(P < 0.01,P <0.05),and E2 was lower in IO group compare with E group from 60 d to 90 d postpartum.3)20plasma differential metabolites between two groups were obtained using LC/MS andmultivariate statistical analysis,which cholic acid,p-chlorophenylalanine and arachidic acid were reduced in IO group,and tyramine,betaine,L-phenylalanine,L-glutamate,D-proline,L-alanine,and L-pyroglutamic acid were increased in IO group.These differential metabolites mainly involve the metabolic pathway of the glutathione metabolism,phenylalanine,tyrosine and tryptophan biosynthesis,arginine and proline metabolism,D-glutamine and D-glutamate metabolism,alanine aspartate and glutamate metabolism and so on.It suggested that carbohydrate metabolism,lipid metabolism and protein synthesis were closely related with IO.4)ELISA experimental results were accorded with that of LC/MS,cholic acid was positively correlated with FSH,LH and E2,L-alanine were negatively correlated with E2.Conclusions obtained that this research clarifies blood pathological features of IO in dairy cows caused by NEB,determines the differential metabolites in plasma of dairy cows with IO using LC/MS technique,and reveales the metabolic abnormality in the development of IO and relationship between the different metabolites in dairy cows with IO caused by NEB.This study preliminarily explores the mechanism of IO,and it will provide the theoretical basis for exploring the mechanism,prevention and treatment of IO in future. |
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