Relationships between Biomarkers of Oxidative Stress in Seminal Plasma and Sperm Motility in Bulls before and after Cryopreservation.

This study aimed at evaluating the relationship between biomarkers of oxidative stress (OS) in seminal plasma and sperm motility in bulls before and after cryopreservation. Three ejaculates per bull were collected from 20 young bulls. Each ejaculate was analyzed for motility before and after cryopreservation (by CASA), and the SP concentration of Advanced Oxidation Protein Products (AOPP), thiols, and carbonyl groups (CT) were examined. Then, based on their motility, the ejaculates were grouped into: high motility fresh (HMF), low motility fresh (LMF), high motility thawed (HMT), and low motility thawed (LMT) groups. Higher AOPP and thiol concentrations on SP were related (p < 0.05) to the higher LIN and BCF and lower ALH of fresh semen. In addition, AOPP and thiols were significantly higher in HMF than LMF. As a confirmation of this, the Receiver Operating Characteristic (ROC) curve analysis showed that AOPP and thiol concentrations in SP were able to discriminate between HMF and LMF ejaculates (Area Under the Curve of 71.67% and 72.04%, respectively). These observations give an alternative perspective on the relationship between sperm motility and the OS parameters of SP, which need further investigations.

Extracellular vesicles from seminal plasma to improve fertilizing capacity of bulls.

Seminal plasma contains extracellular vesicles (EVs) that vehicle RNA, proteins, and other molecules able to influence the biological function of sperm. The aim of this study was to improve the fertilizing capacity of male gametes of low-fertility bulls using EVs isolated by ultracentrifugation from the seminal plasma of a bull of proven fertility. After dose-response curve, 10×106 sperm of low-fertility bulls were co-incubated for an hour with 400×106 EVs/ml. In addition, it has been verified that the incorporation of EVs, which takes place in the sperm midpiece, is maintained for 5 hours and even after cryopreservation. Subsequently, the spermatozoa of low-fertility bulls, with EVs incorporated, were used for the in vitro production of embryos. The rate of blastocyst at seventh day yield in vitro, with the use of sperm with EVs incorporated, increased by about twice the yield obtained with the same sperm in the absence of EVs: bulls having an average embryonic yield of 6.41±1.48%, 10.32±4.34% and 10.92±0.95% improved their yield to 21.21±1.99%, 22.17±6.09% and 19.99±5.78%, respectively (P<0.05). These encouraging results suggest that it might be possible to keep breeding bulls with poor fertility. Further studies will be needed to evaluate the in vivo fertility of sperm treated with EVs and understand how the content of EVs is involve in the sperm-vesicle interaction and in the improved sperm performance.