Effects of clinical mastitis from calving to first service on reproductive performance in dual-purpose cows

To determine the effects of clinical mastitis between calving and the first service on reproductive performance in dual-purpose cows under tropical conditions, the reproductive records of cows with clinical mastitis before first service (n=177) were compared with the records of cows without mastitis (n=205). Mastitic cows had more days to first service (136 days compare to 98 days, P< or =0.05) and days to conception (187 days compare to 143 days, P< or =0.05) than non-mastitic cows. These intervals were affected by parity, where the most severe effect of clinical mastitis was observed in primiparous cows, which showed a delay of 53 days to their first service when compared to control cows (P< or =0.05). Timing of mastitis episode was also an important factor, affecting days to first service and days to conception in multiparous cows only when clinical mastitis occurred over 62 days after calving, while in primiparous cows these effects were observed with mastitis occurring at any time of postpartum period (P< or =0.05). No differences were observed in the numbers of services by conception and first service conception percentage between groups. In conclusion, clinical mastitis before first service is a negative factor that increases the days to first service and the days to conception in dual-purpose cows under tropical conditions. Therefore, measures for mastitis prevention should be implemented to reduce the effect of this additional factor over the postpartum anestrus incidence in dual-purpose cows. Further research to understand the mechanism of the association between mastitis and reproduction should be granted.