Comparative Analysis Of Blood Indicators And Screening Of Early Warning Indicators For Hypocalcemia Dairy Cows In Perinatal Period

The perinatal period is also known as transition period,perinatal cows often occur metabolic and productive diseases such as ketosis,hypocalcemia,endometritis and fatty liver due to delivery stress and lactation stress.Cows in perinatal period develop fetal bone and produce large amount of milk causing a rapid reduction of blood calcium concentration.Postpartum cows experience appetite decrease,insufficient nutrient intake and fail to supplement mineral elements such as calcium in time,thus increasing the incidence of hypocalcemia.Hypocalcemia not only damages the health of dairy cows,but also affects the production performance of dairy cows,and even increases the susceptibility to infectious diseases and nutritional metabolic disorder diseases.Therefore,it is crucial to explore the diagnosis and prevention for hypocalcemia cows in perinatal period.This experiment collected the blood of perinatal healthy cows,clinical and subclinical hypocalcemia cows,isolated plasma and serum,using biochemical methods and ELISA method,detected and compared the differences of mineral elements,glucose（Glu）and lipid metabolism,hormone indicators,liver injury,inflammatory indicators and bone,collagen metabolism of clinical,subclinical hypocalcemia and healthy cows,and the correlation between the above indexes and blood calcium concentration.Furthermore,we investigated the incidence and the time distribution of subclinical hypocalcemia,and screened of potential early warning indicators for subclinical hypocalcemia.In this experiment,20 healthy cows,20 clinical hypocalcemia cows and 20 subclinical hypocalcemia cows were selected to detect mineral elements,glucose and lipid metabolism,hormones metabolism,liver injury,inflammatory indicators and bone,collagen metabolism indicators.The result showed that,in contrast to the healthy dairy cows,concentration of calcium（Ca）was significantly reduced,and potassium（K）,sodium（Na）magnesium（Mg）and 1,25（OH）₂D₃also were significantly reduced in both clinical and subclinical hypocalcemia cows.It showed significant positive correlation with the blood calcium concentration.Non-esterified fatty acids（NEFA）,β-hydroxybutyrate（BHBA）,interleukin-1β（IL-1β）,interleukin-6（IL-6）,tumor necrosis factor-α（TNF-α）,haptoglobin（HP）,serum amyloid A protein（SAA）,tartrate resistant acid phosphatase（TRAP）and leptin（LP）concentrations were increased significantly,and the concentration of phosphorus（P）was increased.Aspartate aminotransferase（AST）,alanine aminotransferase（ALT）andγ-glutamyl transpeptidase（GGT）activities were significantly increased.It showed a significant negative correlation with the blood calcium concentration.K,P,Glu,NEFA,LP,IL-6,TNF-α,SAA,TRAP,1,25（OH）₂D₃concentrations and GGT activity were strongly correlated with blood calcium concentration in subclinical hypocalcemia cows and could be used as sensitive indicators for the diagnosis of subclinical hypocalcemia.Through further analysed with the receiver operating characteristic curve（ROC curve）is used to compare the area under the curve（AUC）,sensitivity（Se）,specificity（Sp）and the cut-point value of corresponding detection indicators.In this way,the effectiveness of related indicators in diagnosing subclinical hypocalcemia was compared,and indicators that can be effectively used for early warning of subclinical hypocalcemia were screened out.The results showed that AUC（TRAP）=0.760,AUC（P）=0.555,AUC>0.5,they had the practical diagnostic value.TPAP（Se=0.90,Sp=0.4）,P（Se=1.00,Sp=0.80）,they had the diagnostic significance.And the increase of TRAP and P concentration in dairy cows increased to cut-point value before the decrease of blood calcium concentration.The above results indicated that hypocalcemia cows had serious constant element metabolic imbalance,glucose and lipid metabolism disorder,hormone metabolism disorder,liver injury,systemic inflammation and bone,collagen metabolism disorder,and the metabolic disorder in clinical hypocalcemia cows was more serious.The concentration of TRAP is 956.27 pg/m L and the concentration of P is 1.255 mmol/L could be used as potential early warning indicators for subclinical hypocalcaemia in perinatal cows and monitored of subclinical hypocalcemia in perinatal cows.This study provided data support for clarifying the perinatal metabolic characteristics of hypocalcemia cows and early warning monitoring of subclinical hypocalcemia in large-scale pastures.