Abstract This review is intended to draw attention to the importance of the culture media composition on the health of the embryos, fetuses, newborns, and adults derived from assisted reproductive technologies (ART). Although current research and industry trends are to use chemically defined media because of their suitability for manufacturing, commercialization, and regulatory purposes, compelling evidence indicates that those media fail to adequately account for the biological demands of early embryogenesis. Here, we list the main undesirable consequences of the ART described in the literature and results we and others have obtained over the past decade exploring an alternative and more natural way to support embryo growth in vitro: inclusion of endogenous reproductive fluids as additives in the ART culture media for pigs, cows, and humans. This review systematically assesses the pros and cons of using reproductive fluid additives, as well as the requirements to implement this approach in the future.

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 fixed and stained to identify early fertilization events. Sperm penetration, monospermy, pronuclear formation and syngamy did not differ, whether sexed or unsexed sperm was used. Overall, the findings demonstrate similar fertilizing potential between sex-sorted and unsorted sperm.