Negative effects of occurrence of clinical mastitis from calving to end of the voluntary waiting period on reproduction in Holstein cows

The objective was to evaluate the effects of clinical mastitis (CM) on reproductive performance in high-milk-producing cows before the service period. The data of Holstein Friesian cows (n = 550) in a commercial farm was retrospectively evaluated. The diagnosis of CM was made by the presence of visible abnormalities in milk or symptoms of inflammation of one or more of the quarters. Cows were checked to detect CM prior to each milking. Calving to first service interval (CFSI), calving to conception interval (CCI), and services per conception (SC) were evaluated as reproductive parameters. Calving to first service interval (83.68 +/- 3.18 vs. 74.57 +/- 1.08; P < 0.05) and CCI (168.48 +/- 8.59 vs. 132.86 +/- 3.44; P < 0.001) were prolonged by 11.77% and 26.81%, respectively, and the number of SC (3.16 +/- 0.21 vs. 2.42 +/- 0.09; P < 0.001) was increased by 30.58% in cows experiencing CM. The culling candidate rate in nonpregnant cows was higher in the mastitis group (4.35%; 6/132) than in the healthy group (0.48%; 2/418). Calving season, time period of CM, and lactation number were not associated with the negative effects of mastitis in reproductive performance (P > 0.05). In conclusion, CM in early lactation has an adverse impact on reproductive performance in high-milk-producing dairy cows. The negative effects of CM on CFSI, CCI, and SC were not interrelated with calving season, the timing of CM, or parity.