| Ketosis is a disease which is a multifactorial disorder of energy metabolism with the features of hypoglycemia and ketonemia in post-calving period, and it often happened in high-yielding cows. It can produce great economic losses by lower milk yield, increase incidence of other diseases in transition period, and influence the reproductive performance. Up to now, this diease still occurs in many dairy farms of china. So, ketosis is a topic need to be researched continued yet.1Comparison of Methods Ketone bodies in the samples of blood, milk and urine from sixty-three cows after two months of calving by using the methods of β-hydroxybutyric acid(BHBA) dedrogenase, nitroprusside powder, reagent and strips respectively. The threshold of BHBA consentration greater than1.0mmol/L was justified as case of subclinical ketosis. The compative results were shown that blood powder test was the most accurate method, the coincidence rate was96.83%, then milk powder test, the rate was93.65%; blood powder test was method with the lowest false positive rate, the false positive rate is10%, then milk powder test, the rate was23.08%; milk and urine powder tests were the methods with the lowest omission rate, the result were9.09%. Strip and powder methods are easer with the operation Comparison. The nitroprusside powder method is the cheapest from the cost price comparison.2Clinical Survey Fifty-two fresh cows were random chosen in a dairy farm in shanghai city. Blood samples of each cow in2nd,1st week before calving, and1st,2nd,3th,4th week after calving were taken to detect the concentration of BHBA in serum quantitatively. The threshold of BHBA consentration greater than1.0mmol/L was justified as case of subclinical ketosis. The results suggested that the incidence of subclinical ketosis on this dairy farm was25%. The incidence of the second, third and fourth parity were23.08%,40%and60%, respectively, which were obviously higher. The highest incidence occurred in second and third week after calving and they with the similar with15.38%. The persistent time of ketosis also vary in different cows, and92.31%cases were recovered within four weeks.3Milk Production and Reproductive Performance Eleven cows were chosen from fifty-two fresh cows according to the concentration of β-hydroxybutyric acid in serum (BHBA>1.0mmol/L) as the experiment group, and another eleven healthy cows(BHBA≤1.0mmol/L) with similar age, parity and body condition as the control group to study the effect of sub-clinical ketosis on the milk production and reproduction performances in dairy cows. Milk yield and constituent of milk were detected every ten days and the tested results were compared. Meanwhile, the indexes of reproduction performances were recorded. The results suggested that the average milk yield of cows in the experiment group was significant higher than that of the control group(p<0.01). The persistence time of peak period of milking in the experiment group was shorter than that of the control group, from the eightieth day after calving the milking yield started decreasing whereas the control began decreasing from the ninetieth day. The average milk fat of the cows in the test group was significant higher than that of the control group within forty days after calving(p<0.05), remaining days it was lower than that of the control group(p>0.05). The average milk protein of the experiment group was significant lower than that of the control group in all of the experiment period(p<0.05). Conception rate of the first and the second insemination in the test group were lower than that of the control group.4Changes of Biochemical Indicators Eleven cows were chosen from fifty-two fresh cows according to the concentration of β-hydroxybutyric acid in serum (BHBA>1.0mmol/L) as the experiment group, and another eleven healthy cows(BHBA≤1.0mmol/L) with similar age, parity and body condition as the control group. The concentration of BHBA, glucose(Glu), nonesterified fatty acid (NEFA), total calcium(Ca), inorganic phosphorus(P), albumin(ALB), total protein(TP), alanine aminotransferase(ALT) and Aspartate aminotransferase(AST) in the serum which were taken in1st week before calving and1st,2nd,3th,4th week after calving were detected. Each detected item was compared between two groups and the correlations between detected items were analysised. The results suggested that concentration of serum glucose and NEFA in the experiment group were significant higher than that in the control group(p<0.01); ALB was significant lower than that in the control group(p<0.05); The activity of AST was higher than that in the control group. In the correlation analysis, there was significant negative correlation between serum BHBA and Glu(p<0.05, r=-0.357); There was significant positive correlation between BHBA and AST(p<0.05, r=0.363). There was significant positive correlation between BHBA and NEFA(p<0.05, r=0.327). There was significant positive correlation between Ca and Glu(p<0.05, r=0.350). There was significant negative correlation between Ca and AST(p<0.01, r=-0.476); Glu and TP have significant positive correlation(p<0.01, r=0.524); There was significant positive correlation between Glu and ALB(p<0.05, r=0.348); There was significant negative correlation between Glu and AST(p<0.01, r=-O.5O3); There was significant negative correlation between Glu and NEFA(p<0.05, r=-0.331); There was significant negative correlation between ALB and AST(p<0.05, r=-0.317); There was significant negative correlation between ALB and NEFA(p<0.05, r=-0.355); There was significant positive correlation between ALT and NEFA(p<0.01, r=0.681).The above-mentioned results indicated that milk powder test is suitful for the sub-clinical ketosis’general investigation on dairy farms; the incidence of subclinical ketosis on this dairy farm was25%, the incidence of the second, third and fourth parity were obviously higher, the highest incidence occurred in second and third week after calving; constituent of milk and reproductive performance can be effected by sub-clinical ketosis with higher milk fat and lower milk protein of the cows, increased the incidence of retained placenta and decreased the conception rate of the first and the second insemination; not only BHBA level in the serum can be acted the indicator of subclinical ketosis, the concentrations of serum glucose, NEFA, ALB and the activity of AST also can be acted as the co-indicator. |
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