Hyperketonemia In Assessment And Epidemiology In Dairy Cows

Hyperketonemia(HYK)is a common clinical pathological syndrome of postpartum dairy cows.It is associated with decreased performance in early lactation and many diseases.It is necessary to evaluate and study its diagnostic methods.This study sought to establish a plasma ?-hydroxybutyric acid(BHBA)microassay,and simultaneously evaluated the detection rate and reliability of the method and the traditional salicylaldehyde colorimetric method.In addition,the superior method of the above method was used as the HYK detection method to investigate the incidence of HYK in a dairy farm,and to analyze whether the cause and whether Are HYK related to early lactation disease and milk yield decline.Experiment 1:We establish a system of laboratory BHBA enzyme cycle microassay method based on literature and patents and evaluated the precision(CV%),accuracy(deviation,interference)and linear range(detection range)of the method.By repeatedly measuring two different BHBA concentration plasma groups,the total CV%and coefficient variation CV%of the low concentration group were 5.53%and 5.03%,respectively,and the total CV%and coefficient variation CV%of the high concentration group were 5.81%and 4.94%,respectively.The commercial BHBA kit was used as a contrast method to detect 143 plasma(39 of which were BHBA?1.2 mmol/L).The results of the two methods were significantly correlated(R2 = 0.9967,P<0.01).The deviation is 0.149(95%CI =-0.296?0.594).The sensitivity and specificity of the enzyme colorimetric assay were 97.06%and 95.41%,when the threshold for HYK(BHBA?1.2 mmol/L)was used.Three different concentration of triglycerides,bilirubin,glucose,uric acid,and hemoglobin were added to plasma for the interference test.The most disturbing substance was triglyceride at a concentration of 1200 mg/dL.The interference rate was 5.33%.The interference rate was less than 5%,BHBA enzyme cycle microassay interference was small.The linear test determined 5 different concentration plasma(from 0 to 5 mmol/L)each concentration sample detected 4 times,and the linear correlation coefficient was 0.9987.The blank detection limit test was performed by using distilled water as a sample measured 20 times and converted to a concentration,the blank detection limit was 0.1199 mmol/L.Experiment 2:Evaluation of salicylaldehyde colorimetric method,plasma with three different ketone body concentration gradients,plasma with ketone body<0.34 mmol/L was mixed and used as a low concentration ketone body group,and 0.34 mmol/L<ketone body<0.50 mmol/L was medium concentration group,the plasma ketone body>0.70 mmol/L was in the high concentration group,and the precision was evaluated.Each time point the sample was measured twice,each sample was measured in parallel twice,and the CV%of the high and medium concentration groups were found.Less than 5%,the low concentration group CV%is less than 10%.In the recovery test,different volumes of acetone were added to the same plasma sample.Make plasma ketone body was in the range of 0.52-2.58 mmol/L,the recovery rate of the ketone body was between 97.33%to 102.49%.The linearity test showed that the linear coefficient of salicylaldehyde method was 0.9934 at 0?2.75 mmol/L.Using commercial BHBA kit as the comparison method,when the threshold of HYK is BHBA? 1.2 mmol/L,the ROC curve shows that the optimal threshold of salicylaldehyde colorimetric method is 0.5 mmol/L,and the salicylaldehyde method is sensitive.The sensitivity was 95.45%and the specificity was 95.47%.The two methods simultaneously detected 614 plasmas,and the results were extremely significantly correlated(r = 0.714,P<0.001).Experiment 3:From September 2017 to October 2018,an epidemiological survey of a dairy farm in Nanning,China.386 cows between 1 to 6 weeks after calving was conducted for epidemiology.Collect the following information from the cattle farm:parity,the placenta,the milk yield,endometritis,the displaced abomasum,etc.,record the BCS(Body condition score)on the day of calving,and collected dairy cows plasma of 6 weeks after birth,Using BHBA enzyme colorimetry detect HYK method,BHBA?1.2 mmol/L was positive for HYK,and BHBA<1.2 mmol/L was negative.During the test,65 cows were found to have at least one positive result of HYK.The incidence of HYK is 16.8%.Using Nest's case-control study to research whether retained placental,parity,and BCS are associated with HYK.To investigate whether HYK will cause displaced abomasum,endometritis,and decreased milk yield.The results showed that the risk of onset of HYK related to retained placenta,BCS?3.5 or BCS?2.5 and parity?3 were higher than that of cows without exposure to these risks;HYK cow occurred in displaced abomasum was 1.65 times(?2 =1.1,P<0.05)of NHYK cows,HYK cow occurred milk yield decreased was 1.656 times of NHYK cow(?2 = 29.27,P<0.001).HYK cow start up endometritis was not significant with NHYK cattle(P = 0.072).Conclusion:1.The accuracy of BHBA enzyme cycle microassay method is excellent and the deviation from the commercial BHBA kit is small.2.The salicylaldehyde colorimetric method has good precision and is highly correlated with the commercial BHBA kit.3.BHBA enzyme colorimetry was chosen as an epidemiological investigation method.The incidence of HYK in the cattle farm is 16.8%one year.postpartum retained placenta,BCS imbalance,parity?3 will increase the risk of HYK in dairy cows.The cows with HYK have greater risk of induced the displaced abomasum and the milk yield decreased,but not significantly related to endometritis.