Effects of Clinical Mastitis on Reproductive Performance in Holstein Cows

The objective of this study was to determine the effects of clinical mastitis on reproductive performance in 135 early lactation cows. The animals were divided into two groups according to the occurrence of mastitis as follows: group I (n = 45), clinical mastitis prior to the first artificial insemination breeding; group II (n = 45), clinical mastitis after artificial insemination and being diagnosed pregnant. Forty-five cows without any mastitis served as control group. Calving to first service intervals were significantly longer ( P < 0.05) in cows with clinical mastitis before first service (group I; 95.2 ± 5.4 d) than in cows with clinical mastitis after first service (group II; 77.4 ± 8.2 d) and in control cows (75.9 ± 6.3 d). Calving to conception interval with clinical mastitis before first service (119.1 ± 10.6 d) and in cows with clinical mastitis after first service (141.7 ± 14.0 d) was significantly longer ( P < 0.05) than in control (94.1 ± 10.3 d) cows. On the other hand, the number of services per conception was larger ( P < 0.05) in cows with clinical mastitis after first service (3.4 ± 0.9) than in cows with clinical mastitis before first service (2.1 ± 0.9) and in cows with no clinical mastitis (1.8 ± 0.8). This study indicated that clinical mastitis during early lactation in Holstein cows had a negative impact on their reproductive performance.