Study On Hematology And Proteomics Of Laminitis In Dairy Cows

Hoof diseaseshave been considered as the third mostserious diseases,following mastitis and reproductive diseases in dairy cows in China.The problem's prevalence is a significant contributor to compromise animal welfare and cause the economic loss in China dairy industry.Laminitis is one of the most common diseases causing lameness in cows.So it is essential to carry out the study on the pathogenesis of laminitis in dairy cows.32 dairy cows with acute laminitis as the sick group and 20 healthy cows as the control group was selected in Gansu cow reproduction center inthis study,blood samples in thedifferent stage of the disease development were collected,and we performed the following experiments:After detected the content of histamine and endotoxin in plasma samples,the results showed that the content of histamine and endotoxin in sick group were significantly higher than that of healthy group.So it indicated that the increase of histamine and endotoxin in dairy cows may be an important factor to cause laminitis.In order to analyze their correlation with the occurrence of laminitis,the blood physiological and biochemical parameters of different development period in sick and healthy cows were examined in this experiment.The results showed that TC was increased,but HDL-C was significantly decreased in plasma of cows with laminitis(P<0.05).It can be inferred that there may be some disorders of lipid metabolism in dairy cows with laminitis.The antioxidant indexes of SOD,T-AOC,GSH-PX and MDA were detected in the plasma of two groups.The results showed that the antioxidant capacity of the cows with laminitis was significantly lower than that of the healthy group(P<0.05).The whole blood viscosity,plasma viscosity and erythrocyte aggregation index in different stages of laminitis were detected in the experiment.The results showed that the plasma viscosity of sick cows was always higher than that of healthy cows(P<0.05),the whole blood viscosity is the same as plasma.It shows that plasma viscosity increased significantly,then the whole blood viscosity increased after dairy cows suffering from laminitis.In the period of S1,erythrocyte aggregation index of laminitis cows was significantly higher than that of healthy cows,and the erythrocyte deformation index was significantly lower than that of healthy cows(P<0.05).With the progress of laminitis,the aggregation index,deformation index and relaxation index of red blood cells,the difference was not significantly changed between the sick and control groups.Mixed samples strategy was adopted in the proteomics study.8 plasma samples included three stages of the process of laminitis were collected from the control and laminitis group.260769 spectrum and 3492 peptides were obtained by i TRAQ technology and 880 proteins were identified by searching in Mascott Database.Repeatability analysis showed that the results were stable and reliable and can be highly repeated.There were 98 different proteins in plasma of laminitis cows compared with healthy cows,which included 35 up-regulated and 18 down-regulated between S1 and C,36 up-regulated and 1 down-regulated in between S2 and C,37 up-regulated and 15 down-regulated between S3 and C,respectively.And there were 14 proteins which showed up-regulated in all stages of the process of laminitis,and 6 proteins down-regulated both in S1 and S3.According to the bioinformatics analysis,GO function of the differential expressed proteins was mainly involved in protein binding,nucleotide binding activity,phosphatase activity and enzyme activity.Pathway enrichment analysis showed that the different proteins mainly involved in the phagosome,complement and integrin degradation pathway,carbohydrate metabolism and absorption,glycerol phosphate metabolic pathway and calcium reabsorption endocrine regulation pathway,calcium signaling pathway,tricarboxylic acid cycle and MAPK signal transduction pathway.Based on a series of research and analysis,lipid metabolism was disordered,immune function was decreased and balance of oxidative stress was broken when laminitis occurred.The increase of blood viscosity causes the disorders of micro circle in hoof local tissue,and then leads to laminitis.Therefore,TC and HDL-C could be considered as biomarkers for monitoring the onset of laminitis in dairy cows.It is suggested that the regulation of lipid metabolism balance can be used for preventing and controlling laminitis.The results provide a novel way for the early diagnosis and monitoring of the disease,and lay a theoretical foundation for further understanding of the pathogenesis of laminitis in dairy cows.