Use of sex-sorted and unsorted frozen/thawed sperm and in vitro fertilization events in bovine oocytes derived from ultrasound-guided aspiration

Abstract

The objective was to investigate the effects of sex-sorting on early fertilization events in ovum pick up (OPU) derived oocytes fertilized in vitro with frozen-thawed sperm at different co-incubation lengths. Eighty-four OPU sessions were carried out in 18 cyclic, dry and non-stimulated Holstein Friesian and German black pied cows. Ovum pick up oocytes were matured in vitro for 24 hours and fertilized with frozen-thawed sex sorted or unsorted sperm from the same ejaculate. Fertilization was achieved by two experimental protocols: 1) short gamete co-incubation length: 4, 8 and 12 hours; and 2) long gamete co-incubation length: 18 and 24 hours. After in vitro fertilization, ova were fixedandstainedtoidentifyearlyfertilizationevents. Sperm penetration, monospermy, pronuclear formation and syngamy did not differ, whether sexed or unsexed sperm was used. Overall, the findingsdemonstratesimilarfertilizingpotentialbetweensex-sortedandunsortedsperm. © Sociedade Brasileira de Zootecnia.