Bovine semen, body fluid subject to environmental changes, which can change their quality and influence survival rates of sperm, has several molecules not yet described. Among them are the microRNAs, recognized as fundamental for fertilization and early embryonic development. However, there are few studies describing the profile of seminal microRNAs and their relation with fertility in cattle. Therefore, our hypothesis is that miRNAs present in the semen are associated with fertility. For this, the study aims to investigate the miRNAs present in bull sperm and seminal plasma, and relate them to the embryo development in vitro and in vivo, and to fertility rates in cattle. Two experiments will be performed. First experiment will assess sperm quality and sperm and seminal plasma miRNAs profile. Six bulls, with different sperm qualities, will be used being made 3 semen samples of each bull (n=18). The semen and seminal plasma will be cryopreserved. Two semen straws containing sperm will be thawed and sperm evaluations will be performed: kinetics characteristics, plasma, acrosomal and mitochondrial membranes integrity and microRNA profile. The seminal plasma will be also thawed and will be assess its miRNA profile. In experiment 2, semen cryopreserved in experiment 1 will be used to in vitro and in vivo embryos fertilization and artificial insemination of cows. The obtained data (blastocyst rate, embryo quality and microRNA profile of embryos produced in vitro and in vivo and pregnancy rate) will be compared between groups determined in experiment 1. The data of different groups defined by the experiment 1 will be submitted to ANOVA and Tukey's test at 5% significance level. It is expected to find miRNAs associated with fertility. Results of this project will serve to create new bovine ejaculated analysis tools.
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