Dead spermatozoa in raw semen samples impair in vitro fertilization outcomes of frozen-thawed spermatozoa

Abstract

To evaluate the influence of dead spermatozoa present in raw semen samples before and during freezing on the functionality and fertilization ability of frozen-thawed spermatozoa. Cryopreservation of raw semen samples with different known proportions of dead spermatozoa: native semen samples (<10%) and samples with 25%, 50%, and 75% dead spermatozoa. A university-based veterinary andrology laboratory. Five healthy and sexually mature boars. Sperm killed by three fast-freezing cycles. Assessment of intracellular generation of reactive oxygen species (ROS), nuclear DNA fragmentation, in vitro fertilization (IVF), and embryo development. High proportions of dead spermatozoa in raw semen samples before and during freezing induce statistically significantly increased ROS generation and nuclear DNA fragmentation in frozen-thawed spermatozoa. These dysfunctional changes resulted in low ratios of in vitro penetrated oocytes and healthy developing embryos. A high proportion of dead spermatozoa present in raw semen samples before and during freezing negatively influences the functionality and IVF outcomes of frozen-thawed spermatozoa.