The objective of this study was to determine effect of occurrence and severity of mastitis before first service on reproductive performance and culling. A total of 389 Friesian cows (108 primiparous cows and 281 multiparous) were categorized based on occurrence of mastitis before first service: healthy cows (Control) and cows with mastitis. Cows with mastitis were divided into three groups based on severity of mastitis: subclinical mastitis, clinical mastitis and acute mastitis. Mastitis cases were categorized based on somatic cell count (SCC) in milk. Days of first services, number of services per conception, days open, conception rate and calving interval were recorded. Also, effects of mastitis on culling percentage of cows were evaluated. Results showed that, days of first service, days open, calving interval and number of services per conception were significantly increased in cows with mastitis (124.68±32.47, 177.91±24.43, 456.56±23.91 days and 2.67±1.08 services,
respectively) than the control cows(89.03±7.93,105.40±9.18, 384.52±9.35 days and 1.53±0.50 services, respectively). Moreover the conception rate was lower in cows with mastitis (49.39%) than the control cows (68.44%). Also, the results indicated that, the negative effects of mastitis on the reproductive performance were most pronounced in multiparous cows in comparison with primiparous cows. Where the days of first service, days open, calving interval and number of services per conception were higher in multiparous cows with mastitis in comparison with primiparous cows with mastitis, while first service conception rate in multiparous cows with mastitis was better. When the severity of mastitis increased, the day's
open, calving interval and number of services per conception increased. The cows with subclinical mastitis showed days of first service longer and first service conception rate greater. Culling rate was higher in cows with mastitis (14.63%) than the control cows (8.44%) and it was high for cows with acute clinical mastitis (28.57%). Culling rate for primiparous cows was affected by mastitis more than multiparous cows, especially primiparous cows with acute mastitis (33.33%). It was concluded that, cows experiencing mastitis before first service had a low reproductive performance compared with healthy cows and response effect was observed based on severity of mastitis cases. So that, to maximize reproductive efficiency, breeders need to recognize the effect of mastitis on reproductive performance and focus on preventing mastitis during critical period of breeding.

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