Impactos das doenças no pós-parto sobre a eficiência reprodutiva de vacas leiteiras mestiças

Abstract

The high incidence of uterine diseases during postpartum of dairy cows is responsible for many impairments to the dairy livestock, primarily by reduction of reproductive efficiency of cows affected by uterine infections. This thesis was subdivided in three chapters. The first chapter approaches general considerations about uterine diseases. On chapter II, the objective was to to evaluate the effects of postpartum diseases such as ketosis, clinical mastitis, lameness, retained placenta (RP), metritis and clinical endometritis during the first 30 days after calving on reproductive efficiency of crossbred dairy cows raised in tropical region. A total of 304 cows were evaluated, which 184 (60.5%) remained healthy after calving and 120 (39.5%) showed one or more cases of disease. Cows that experienced postpartum diseases showed a conception at first artificial insemination (AI) 28% lower (P < 0.05) and days open 65 days longer (P < 0.05) than healthy cows. Pregnancy rate at 150 days in milk was also 26% lower (P < 0.05) for cows with postpartum diseases compared to healthy cows, which demonstrates the negative impact of diseases on reproductive performance. Objectives of the chapter III was to evaluate the effects of uterine disease occurrence, the number of uterine disease cases, parity and body condition score (BCS) on uterine position score, as well as the influence of uterine score on conception rate at first AI postpartum of crossbred dairy cows. A total of 588 from 20 farms were monitored during the first 30 days postpartum for RP, metritis and clinical endometritis diagnoses and then submitted to TAI after the end of voluntary waiting period (VWP). Uterine scores were evaluated and categorized according to uterine size and position: small within pelvic cavity (P1), medium in the transition between pelvic and abdominal cavities (P2) and large within abdominal cavity (P3) between 30 and 45 days postpartum. Disease and number of cases, parity and BCS negatively influenced uterine score (P < 0.01). Conception rate from group P1 (30.03%) tended to be higher (P = 0.088) than groups P2 and P3 grouped (23.67%). In conclusion, uterine disease occurrence during postpartum period affects uterine position score and it tends to compromise reproductive efficiency of crossbred dairy cows.