The objective of this study was to evaluate the efficiency of two commercial mastitis vaccines (Mastivac ® and Startvac ® ) under field conditions. In total, 164 Holstein dairy cows were selected and divided into 3 groups. Three milk samples were collected from each cow at the day of drying- off, 3 days and 2 weeks after parturition. The first group (n = 55) received Mastivac ® vaccine following the label regimen. The second group (n = 54) received Startvac ® vaccine following the label regimen, and the third group (n = 55) was left unvaccinated as negative controls. The data were analyzed by using SPSS software (SPSS Inc., 22). Analysis of the mastitis prevalence after parturition in triple groups was performed using chi- square test. The comparison of the severity of infection and also the duration of treatment in all groups were analyzed by using Kruskal- Wallis test. The differences between groups with a p- value <0.05 were considered significant. In total, within one month after parturition, 70 cases of clinical mastitis occurred in the 3 study groups, but we detected no significant difference in the prevalence of clinical mastitis between any of the 3 groups. The average severity of clinical cases in three groups were 1.36, 1.24 and 1.45 for Mastivac ® , Startvac ® and control group, respectively and not significant. Duration of treatment did not differ between groups and was 3.7, 3.29 and 3.6 days for Mastivac ® , Startvac ® and control group, respectively. New infection rate after parturition was assessed by CMT and did not differ between groups. New infection rates were 38.5% for Mastivac ® , 26.5% for Startvac ® and 34% for control group respectively. In general, we observed no significant difference in above- mentioned variables between any of the 3 groups.

Keywords