Span. j. agric. res. Span. j. agric. res. Sperm quality and seminal plasma proteins in three sheep breeds under high altitude and tropical conditions Carvajal-Serna M. Universidad de Zaragoza Cardozo J.A. Grajales-Lombana H. Cebrián-Pérez J.A. Universidad de Zaragoza Muiño-Blanco T. Universidad de Zaragoza 2018 research-article