INVESTIGATION OF FERTILITY PROTEINS MARKERS IN THE SEMEN OF PRE-PUBERTAL BULLS

Abstract

The bovinoculture is one of the main activities of the national cattle raising, the world economy. The bulls reach sexual maturity after about 24 months of age and only from this stage are considered suitable or not to reproduction. Young bulls selection is a way to avoid spending on animals that will be discarded from breeding. In this regard, the ain of this study will be identify specific proteins of sexually immature bulls present in sperm cells and/or seminal plasma of pre-pubertal animals, related to fertility in adults. For this, successive semen colection of 20 Nelore bulls, kept under the same conditions, will be carried out every 60 days, starting at 8 months of age. Concomitantly, blood samples will be colected for testosterone dosage. The semen samples will be divided into two aliquots (A1 and A2). A1: proteomic analysis will be performed by means of shotgun analysis techniques for identification and quantification of proteins present in seminal plasma and sperm cells; A2: semen analysis to measure total motility (MT), progressive motility (MP), velocity (VAP), linear velocity (VSL), curvilinear velocity (VCL) and percentage of fast moving spermatozoa (RAP) by computerized analysis method (CASA). The evaluation of DNA, plasma membrane and acrosomal integrity will be performed by of flow cytometry, soon after, the samples will be cryopreserved. According to the seminal parameters, freezeability and sperm quality tests associated to the results of the proteomic analysis, five animals with higher and lower fertility potential will be selected,and will be submitted to IVF and FTAI tests as confirmatory tests for this potential. With the results obtained it is expected to identify fertility protein markers in sexually immature bulls, and consequently to produce productive, reproductive and economic returns to the national cattle livestock.