Effect of mastitis during the first lactation on production and reproduction performance of Holstein cows.

The aim of this study was to evaluate the effect of postpartum mastitis between first calving and subsequent conception on production and reproduction performance as well as culling of Holstein cows. A data set of 9,183 first lactation cows was used. Results showed that the first cumulative 100 days' milk production and the milk yield standardized to 305 days were affected by the interval from calving to first mastitis (P < 0.05). Cows with one episode of mastitis produced more milk than those with repeated episodes of mastitis (P < 0.01). Increase in the number of mastitis episodes and also decrease in interval between first calving and mastitis increased services per conception (P < 0.001). Mastitis episode and the interval between calving and first mastitis had no apparent impact on the calving to conception interval (P > 0.05). Calving year, calving difficulty score, and cumulative first 60 days milk production had significant impacts on mastitis risk (P < 0.05). The interval from calving to the first incidence of mastitis decreased over the period studied (P < 0.001). Productive life tended to be decreased due to mastitis (P = 0.07). Survival analysis showed a significant difference between the lengths of productive life for cows with different intervals from calving to first mastitis (P < 0.01). The results demonstrated that clinical mastitis between first calving and conception reduced production and reproduction performance with an increase in chance of culling.