Relationships between Seminal Plasma Metabolites, Semen Characteristics and Sperm Kinetics in Donkey (Equus asinus)

Abstract

This study aimed to evaluate donkey seminal plasma metabolites and relate this information to the main characteristics of sperm quality. Sperm kinetics from 10 donkey stallions were analyzed with a computerized system at the time of collection (T0) and after 24 h storage at 4 °C (T24). Seminal plasma was frozen at −80 °C for subsequent proton nuclear magnetic resonance (1H NMR) spectroscopy. On three stallions, semen collection was repeated monthly for three times and sperm analysis also included mitochondrial activity and oxidative status. One stallion was azoospermic and a second semen collection was performed after one month. In the seminal plasma, 17 metabolites were identified; their levels showed numerous significant variations between the azoospermic and the normospermic individuals and grouped in well-defined clusters in a multivariate analysis. Comparing individuals with high and low sperm motility, the only discriminating metabolite was phenylalanine, whose levels were lower in the latter, as in the azoospermic individual. Phenylalanine was also the only metabolite highly correlated with all sperm kinematic parameters at T24. In conclusion, the present study has provided relevant information on the chemical characteristics of donkey semen, identified relationships between seminal metabolites, semen parameters, and sperm kinetics, and offered insights for future technological applications.

Extracellular Reactive Oxygen Species (ROS) Production in Fresh Donkey Sperm Exposed to Reductive Stress, Oxidative Stress and NETosis

“…This generates a broad research field in this animal species that could even serve to take it as a model to better understand what happens in other species. Likewise, the presence of several metabolites that could have a role in the maintenance of ROS balance has recently been described [ 57 ] and could become a potential research field in the donkey.…”

Oxidative profile and protease regulator potential to predict sperm functionality in donkey (Equus asinus)

“…The resulting liquid matrix, the seminal plasma (SP), carries the sperm from the male into the female genital tract and plays relevant roles by preserving sperm functions, interacting with the female genital tract and modulating immune response as well as by promoting fertilization and successful pregnancy outcomes 1 , 2 ,. The molecular composition of SP is species-dependent and represented by lipids, glycans, inorganic ions, and small molecule metabolites to biopolymers, such as cell-free DNA, RNA, microRNAs, peptides, proteins, and oligosaccharides 3 , 4 . Following the sperm placing into the female genital tract, the spermatozoa leave the SP for carrying out their procreative function and escape the female immune defenses appointed to counter the entry of foreign components.…”