Efeito da retenção de placenta e mastite clínica pós-parto na eficiência reprodutiva e expressão gênica de citocinas e receptores esteroidogênicos no endométrio de vacas leiteiras mestiças

Abstract

The postpartum uterine and non-uterine diseases impact the reproductive efficiency of dairy cows. However, in addition to little knowledge regarding crossbred cows, it is not yet clear how these diseases negatively affect fertility. The hypothesis of this study was that crossbred cows with placenta retention (RP) and clinical mastitis in the postpartum period have worse reproductive rates because these pathologies interfere with endometrial innate immunity and expression of steroidogenic hormone receptors at the end of the puerperium. Therefore, the objectives with this study were: a) to evaluate the effect of PR and postpartum clinical mastitis on reproductive efficiency, service period and interval between birth and first artificial insemination (AI) of crossbred dairy cows (experiment 1); b) to evaluate the effect of these diseases on innate endometrial immunity and steroidogenic hormone receptors (experiment 2). For exp. 1, 232 cows were evaluated and divided into the healthy, PR and clinical mastitis groups. Cows were inseminated as estrus was observed or submitted to the IATF protocol. The assessments of the occurrence of diseases took place after delivery until the end of the voluntary waiting period and the diagnosis of pregnancy around 32 days after AI. For exp. 2, 30 cows were used, divided into three groups (n = 10) equal to experiment 1. Between 40-50 days postpartum clinical examination, gynecological examination and endometrial sample collection by cytobrush for endometrial cytology and gene expression by IL1β, IL6, CCL5, ESR1 and PGR qRT-PCR technique. In exp. 1, the conception rate in the first AI and the percentage of pregnant cows at 150 days were lower in sick animals (PR, mastitis) and the days of the birth-first AI interval and service period were higher in sick animals. In exp. 2, 26.7% (8/30) of the animals had subclinical endometritis. IL1β showed higher expression in sick groups, IL6 showed less expression in RP group and CCL5 had no difference between groups. There was no difference in the gene expression of ESR1 and PGR steroid receptors between sick and healthy cows. It was concluded that cows with placenta retention and clinical mastitis in the postpartum period present worse reproductive indexes, alteration in the endometrial gene expression of the cytokines IL1β and IL6, however, they do not present changes in the expression of steroidogenic hormone receptors at the end of the puerperium.

2022-08-19