Vaccination programs, parity, and calving season as factors affecting the risk of fetal losses and mummified fetuses in Holstein cows

Abstract

Aim of the study: To investigate vaccination programs, parity, and calving season as factors affecting the risk of abortion and mummified fetuses in Holstein cows.Area of study: Hot zone of Northeast Mexico.Material and methods: Multiple logistic regression models were used to examine the relationship between peripartum disorders, parity, previous occurrence of abortion, season of calving, vaccination program, incidence of abortion, and mummified fetuses in Holstein cows.Main results: For 7014 pregnancies (2886 cows), the percentage of cows aborting and having mummified fetuses was 17.7% and 1.1%, respectively. As the number of brucellosis vaccinations increased, the incidence of abortion increased (10.4% for a single vaccination and 38.0% for 6 accumulated vaccinations). Abortion for cows having 1-2 previous abortions (56%) and >2 abortions (77%) was fivefold and sevenfold greater (p<0.01), respectively, than that for cows without previous abortion. Other important risk factors for abortion were number of calvings (19.8% for nulliparous and primiparous vs. 13.8% for >3 parturitions; OR=1.7, p<0.01), leptospirosis vaccine application <55 days postpartum (dpp; OR=1.3, p<0.05), viral vaccine application >37 dpp (OR=1.3, p<0.01), brucellosis vaccine application >20 dpp (OR=1.6, p<0.01), and no application of clostridial vaccine (OR=3.7, p<0.01). Significant risk factors for mummified fetuses were application of ≥3 brucellosis vaccinations (OR=3.3, p<0.01), no application of 10-way clostridial vaccine (OR=2.3, p<0.01), >2 previous abortions (OR=18.4, p<0.01), and calving in autumn (OR=0.4, compared to winter, p<0.05).Research highlights: Risk of abortion and mummified fetuses in Holstein cows has been found to be related to vaccination programs