Effect of clinical mastitis on reproductive targets achievement in cows

Abstract

The aim of this study was to determine the effect of clinical mastitis occurring between calving and the first service on the percentage of cows that achieve two reproductive targets: be served before 70 days postpartum and be pregnant before 110 days postpartum (dpp). Relative frequency and odds ratio (OR) with the corresponding confidence interval (CI) were calculated. Fewer mastitic cows were served before 70 dpp than non-mastitic (24.86% vs 36.59% respectively P = 0.0137); mastitic cows had lower odds to be served than non-mastitic cows (OR: 0.57; 95% CI: 0.3679-0.8938, P = 0.0141). Fewer mastitic cows became pregnant before 110 dpp than non-mastitic cows (36.72% vs 50.73%, respectively, P = 0.006) and mastitic cows had lower odds to become pregnant than non-mastitic cows (OR: 0.56; 95% CI: 0.3739-0.8495, P = 0.0062).  Negative effect of clinical mastitis on percentage of cows served only was observed in primiparous cows, with 4.76% of mastitic cows being served in comparison with 30.19% of non-mastitic cows (P = 0.0017); primiparous mastitic cows had lower odds (0.11; 95% CI: 0.0249-0.5374, P = 0.0059) to be served than non-mastitic primiparous cows. Percentage of primiparous mastitic cows pregnant before 110 dpp was lower than non-mastitic cows (16.67% vs 37.74%, P = 0.0245) and mastitic cows had only 0.3300 odds (95% CI: 0.1234-0.8822, P = 0.0271) to become pregnant that primiparous non-mastitic. In multiparous, 42.96% of mastitic and 55.26% of non-mastitic cows (P = 0.0378) became pregnant before 110 dpp and mastitic cows had 0.6098 odd (95% CI: 0.3821-0.9730, P = 0.0380) to become pregnant than non-mastitic. In conclusion, clinical mastitis reduced the possibility of cows to be served and become pregnant during the first 70 and 110 dpp respectively, and the negative impact of clinical mastitis was more harmful in primiparous cows.