Metabolomic Analysis and Identification of Sperm Freezability Biomarkers in Boar Seminal Plasma

Abstract Background: In the freezing process of boar sperm, there are obvious differences of freezability between individuals. Studies suggest that specific freezability markers might be useful in good (GFE) and poor freezabitity ejaculates (PFE) selection prior to cryopreservation. Some potential markers of boar sperm freezability have been found from spermatozoa, little attention has been paid to seminal plasma. The seminal plasma is composed of secretions from testis, epididymis, and accessory sex glands, and the exposure of spermatozoa to small molecules such as metabolites can affect the sperm functions. However, details and significance of the seminal plasma metabolome related to boar sperm freezability are unknown. Therefore, the main aim of this study was to explore the difference in the metabolic level of seminal plasma between boars with differential freezability, and to explore the biomarkers of semen freezing tolerance. Results: A total of 953 metabolites were identified in boar semen plasma by UHPLC-qTOF-MS analysis, and 50 metabolites show significant change between GFE group and PFE group. Further, twelve metabolites were subjected to metabolic target analysis and three metabolites (D-Aspartic acid, N-Acetyl-L-glutamate (NAG), and Inosine) show differences.Conclusions: There is significant differece on metabolome of seminal plasma between GFE and PFE individuals. The D-Aspartic acid, NAG, and Inosine in seminal plasma may be potential markers for assessing sperm cryopreservation resistance in boars.