Autogenous toxoid-bacterin treatment for Staphylococcus aureus subclinical mastitis in lactating cows

To evaluate clinical effects of autogenous toxoid-bacterin treatment for Staphylococcus aureus subclinical mastitis in lactating cows, 22 cows which had at least one S aureus infected quarter were selected from one S aureus prevalent dairy farm, of which 11 cows were injected their own autogenous toxoid-bacterin and the others were maintain as noninjected control. In the toxoid-bacterin injected group, 27% of infected quarters were cured during the 12 weeks trials as compared to 5% in the control group. New intramammary infections with S aureus were only detected in three-quarters of the control group. Mean IgG antibody titers against S aureus somatic antigens and $\alpha$-toxin in serum and milk were significantly increased in the toxoid-bacterin injected group (p < 0.05) and remained higher than those of the control group which showed no significant changes (p < 0.05). From 3 weeks after second injection (at 7 week), mean S aureus CFU/ml in milk samples from previously infected quarters with S aureus of the toxoid-bacterin injected group was lower than that from preinjection state (p < 0.05). In the toxoid-bacterin injected group, significant decrease of mean SCC was detected from milk samples from previously infected quarters with S aureus from week 7 to week 10 (p < 0.05). These data suggested that autogenous toxoid-bacterin treatment aganist S aureus subclinical mastitis in lactating cows might increase the cure rate of the infections, reduce the severity of the infections and also prevent occurrence of the new infections.