Distocia: fatores de risco e impacto na saúde e produção de vacas leiteiras

Abstract

Parturition is an important process of the dairy production system and imposes a great challenge to the cow. In addition to the risk of clinical and subclinical diseases favored by immunosuppression and hormonal changes, cows may suffer from dystocia, which are difficulty deliveries with prolonged time and sometimes the need for assist in fetal removal. Since it is multifactorial, in addition to the maternal and fetal causes related to dystocia, it could have interaction with behavioral, environmental and management variables. The impact of dystocia on the productive system is related to the occurrence of diseases, which increases the risk of discarding the cows from the dairy and even death of the cows and their offspring, impacting production costs and affecting the composition and longevity of the herd. Therefore, the present dissertation had as objectives: identify the risk factors associated with dystocia and its impact on the diseases of the postpartum transition period and on milk production in dairy cows; and evaluate if dairy heifers born from a dystocic birth had their development, health, reproduction or milk production impaired. In order to respond to the objectives, a retrospective observational study was carried out using records from a dairy farm in Rio Grande do Sul, using Dairy Plan C-21 dairy management software (GEA). The study was divided into two experiments, which the results were published in a scientific paper. In order to achieve one of the objectives of the first experiment, data collected between 2013 and 2017, from 1,001 primiparous Holstein’s heifers and multiparous Holstein’s cows, grouped into normal or difficult birth was analyzed. The variables included as predictors of risk of dystocia were age, category (primiparous vs. multiparous), dystocic birth, calf sex, type of delivery, calf viability, climatic season at calving and year. To determine the impact of dystocia on postpartum diseases and milk production, data from primiparous cows (n = 540)

and multiparous cows (n = 461) were analyzed separately. Rates of clinical diseases such as mastitis, metritis, retained placenta and others, as well as the number of episodes occurred and rates of discard or death were evaluated. The incidence of dystocia was 10.4% and the significant risk factors to the occurrence of dystocia were the birth of male calves, twins, stillbirths and births during winter time. There was a high rate of postpartum clinical disease and an increased risk of developing metritis in distocic multiparous cows. In order to achieve the second experiment, we analyzed the records from 447 calves born at the farm between 2012 and 2015 and grouped as born from normal or difficult births. The impact of dystocia on the health, development and production of heifers was analyzed by weight at birth, 30 and 60 days of age, occurrence of diseases up to 60 days and up to 365 days of age, as well as the number of events occurred in these periods and mortality and discharge rates. The number of inseminations per conception, age at first calving, dystocia and stillbirth rates, clinical mastitis, metritis, retained placenta and others after first calving and milk production at the first lactation were also evaluated. It was observed that heifers born from a dystocic parturition had higher rates of metritis on their first calving. Other parameters were not affected by dystocia.