The Somatic Cell Count In Relation To The Major Acute Phase Proteins And Related Enzymes In Composite Milk From Dairy Cows With Mastitis

Composite milk samples from eight clinical healthy control cows and 22 cows with naturally occurring mastitis were divided into three groups according to somatic cell count(SCC) thresholds(<10×104/ml<50×104/ml>50×104/ml). Serum Amyloid A(SAA), Haptoglobin(HP),α1-acid glycoprotein(AGP) concentrations and Lactate Dehydrogenase (LDH), N-acety1-β-D-glucosaminidase(NAG) activities were analysed, and a correlation were evaluated based on the measurement by the SPSS13.0. It was found that there was no correlation between SAA and AGP concentrations among the three groups. However, there were significant differences between LDH and NAG levels(all p-values were less than 0.05) and no difference in HP level between the control samples and subclinical samples;A extremely significant difference existed in HP and LDH levels(all p-values were less than 0.01) and significant difference in NAG level(P<0.05) between the subclinical samples and clinical samples. There were extremely significant differences existed among HP, LDH and NAG levels(all p-values were less than 0.01). SAA and AGP had poor correlations with SCC, but significant correlation coefficients were found between HP, LDH, NAG and SCC(correlation coefficients were 0.406,0.730 and 0.750, respectively). The linear regression equations of HP, LDH, NAG and lgSCC were established. SCC, SAA, HP, AGP, LDH and NAG were compared by Receiver Operating Characteristics(ROC), and it was founded that SCC had a moderate diagnostic value, SAA and AGP had a low diagnostic value, however, HP had a moderate diagnostic value when clinical mastitis was diagnosed, and LDH, NAG had a high diagnostic value. Among them, the diagnostic value of LDH was slightly higher than that of NAG. Conclusionly, according to the results, the level of SAA and AGP couldn't be used as useful indicators, the level of HP and the activity of LDH and NAG in milk could reflect the severity of cow mammary gland. It was suggested that the activity of LDH and NAG could be used as useful infected indicators of different definitions of a positive mastitis milk, and the level of HP could be used as a useful indicator of milk in which SCC was exceed 50×104/ml. It was useful to detect the activity of LDH and NAG in milk to diagnose mastitis, or to combine SCC with the detection of HP level.