| Bovine mastitis is one of the most serious diseases which caused economic losses to the dairy industry. In this study, it was explored that the incidence of dairy cows mastitis, the prevalence of pathogens caused mastitis in Nanning region, and the distribution of S. aureus virulence genes, the diagnosis of subclinical mastitis (SCM) by milk enzymes, the determination of Chinese herbal medicine compound which treatment of mastitis, the development and evaluate the effectiveness of mastitis vaccines, and the influence of clinical mastitis (CM) on reproductive performance of dairy cows. The results are as following:â…°) We have investigated the prevalence of cows mastitis in a commercial dairy farm which located in Nanning suburb between 2005 and 2009. The average percentages of blind quarter(s) at cow and quarter level were 11.5% and 3.7%, respectively. The incidence of CM at cow and quarter level were 8.7% and 3.7%, respectively, while that of SCM at cow and quarter level were 48.8% and 19%, respectively. In addition, the incidence of CM and SCM were increased with the parity. The positive rate of pathogens in CM and SCM milk was 96% and 34%, respectively. The most common bacterial isolates from CM cases were S. aureus (29.5%), E. coli (25.7%), and C. neoformans (16.2%), however, in SCM they were S. aureus (32.1%), coagulase-negative staphylococci (CNS) (19.7%), and St. agalactiae (17.9%). The antimicrobial sensitivity test indicated that most of the antimicrobial agents we employed and Ruyangxiao showed lower proportion of resistant isolates of all the isolated bacteria. The most toxic pathogens of mastitis were E. coli and S. aureus, the pathogenic rate were 61% and 54%, respectively.ii) A total of 39 bacterial isolates from bovine mastitis were detected the 23 S rRNA sequence, and all identified as S. aureus, they are consistent with the results of biochemical identification. A total of nine genes were detected in the PCR results, they are elf A, tsst-1, nuc, fnbA, hla, hlb, cap5, cap8 and mecA, but sea and fnbB genes were not detected. It was suggesting that more than one virulence genes were exist in a strain of S. aureus, and that the virulence genes chain between strains are more prevalent, and the epidemiology of virulence genes in S. aureus have a certain regionality. â…²) A total of 124 milk samples were collected from lactating glands in the period between the 2nd week after calving and the 1 0th week postpartum. Those which were classified by bacterial culture and the California Mastitis Test (CMT) as positive were deemed to have glands with SCM. The results showed that the periodic incidence rate of SCM was 26.6%. The most common bacterial isolates from SCM cases were S. aureus (47%) and CNS (27%). The mean level of MDA and activities of lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) were significantly higher in SCM milk than in normal milk, while the mean activity of glutathione peroxidase (GPx) was significantly lower in SCM milk than in normal milk. There were no differences in the activities of superoxide dismutase (SOD) and aspartate aminotransferase (AST) between normal milk and SCM milk. Therefore, the measurement of milk MDA level and GPx, LDH and ALP activities appears to be a suitable diagnostic method for identifying SCM in dairy cows. And provide the theoretical basis for the pathogenesis of mastitis to some extent.â…³) It was shown that S. aureus is significantly sensitive to the forsythia and coptis, and . coli is highly sensitive to the dark plum. Medicine terminalia and coptis have the strongest inhibition on the S. aureus, and the minimum inhibition concentration (MIC) was all 8 mg/mL to S. aureus. Dark plum and coptis have the strongest inhibition on the E. coli, and the MIC was all 16 mg/mL to E. coli. By the method of orthogonal design, Orsythia, medicine terminalia, dark plum, and coptis have the positive inhibition effect on S. aureus and E. coli, they would be used as the main component of Chinese herbal medicine prescription which treatment dairy cows mastitis. The MIC of the herbal prescription are 8 mg/mL and 16 mg/mL to S. aureus and E. coli, respectively.â…´) The protection rate of the two developed S. aureus vaccines were more than 60% in mice. According the method of conventional indirect ELISA, we have been optimization the reaction conditions, and initially established the method of indirect ELISA for detection the antibody of S. aureus mastitis in dairy cows. At the same time, we determined the cutoff value (OD= 0.28) and established the standard curve and regression equation of the indirect ELISA. The result of the actual value was consistent with the prediction value by the regression equation. The serum antibody titers of S. aureus were gradually increased after vaccinated 7 to 14 days in dairy cows. The peak of serum antibody titers was shown up in the 14 days after inoculation (1:2995) of the vaccine 1 group cows, and then gradually slows down. While, the peak of serum antibody titers was shown up in the 21 days after inoculation (1:2062) of the vaccine 2 group cows, and then gradually decreased. Until the end of the experiment (150 days after vaccination), the two groups of cows'serum antibody titers are still higher than the cutoff value. â…µ) We have investigated the timing of cows clinical mastitis occurrence and reproductive performance on 152 Holstein dairy cows which are multiparous in a commercial dairy farm in Nanning suburb. The reproductive indexes including days in milk at first service (DIMFS), services per conception (S/C), conception rate at first postpartum AI, days not pregnant (DNP), estrus rate within 70 days postpartum and abortion rate. First clinical mastitis occurred between calving and pregnancy diagnosis group cows (MG) had greater (P< 0.01) DIMFS and DNP compared with control group cows (CG). Group MG had greater (P<0.05) S/C than CG. Group MG had lower (P<0.05) conception rate at first postpartum AI compared with CG. Group MG had lower (P> 0.05) estrus rate within 70 days postpartum than CG. And group MG had higher (P> 0.05) abortion rate compared with CG. First clinical mastitis occurred between calving and first postpartum artificial insemination (AI) group cows (MG1) had greater (P<0.01) DIMFS and DNP compared with CG. Group MG1 had lower (P<0.05) conception rate at first postpartum AI compared with CG. First clinical mastitis occurred between first postpartum AI and pregnancy diagnosis group cows (MG2) had greater (P<0.01) DIMFS and DNP compared with CG. Group MG2 had greater (P<0.05) S/C than CG. Group MG had lower (P<0.05) conception rate at first postpartum AI compared with CG. In conclusion, clinical mastitis occurred between claving and pregnancy diagnosis had a serious negative impact on reproductive performance of dairy cows.
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