Relationship of field and in vitro fertility of dairy bulls with sperm parameters, including DAG1 and SERPINA5 proteins

Authors: ZOCA, SAULO - University Of Tennessee; WALKER, JULIE - South Dakota State University; KLINE, ADALAIDE - South Dakota State University; ANDREWS, TAYLOR - South Dakota State University; RICH, JERICA - Arkansas State University; EPPERSON, KAITLIN - Texas A&M University; DRUM, JESSICA - South Dakota State University; ORTEGA, MARTHA - University Of Wisconsin; Cushman, Robert - Bob; PERRY, GEORGE - Texas A&M University

Submitted to: Frontiers in Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2023
Publication Date: 6/5/2023
Citation: Zoca, S.M., Walker, J.A., Kline, A.C., Andrews, T.N., Rich, J.J.J., Epperson, K.M., Drum, J.N., Ortega, M.S., Cushman, R.A., Perry, G.A. 2023. Relationship of field and in vitro fertility of dairy bulls with sperm parameters, including DAG1 and SERPINA5 proteins. Frontiers in Animal Science. 4. Article 1180967. https://doi.org/10.3389/fanim.2023.1180967.
DOI: https://doi.org/10.3389/fanim.2023.1180967

Interpretive Summary: Semen from bulls that pass a breeding soundness exam still differs in fertility. We evaluated two proteins as markers of fertility in bull semen. We developed assays to characterize the abundance of the proteins in semen. We measured the proteins in ejaculates from bulls with different levels of fertility. There was no relationship between abundance of these proteins and fertility. There is still a need to develop methods that accurately differentiate bull fertility.

Technical Abstract: Even among bulls that successfully pass a breeding soundness exam; there are differences in fertility. For consideration of a protein as a potential marker of fertility, there must be variability expressed among animals. Sperm interacts with the female reproductive tract and oocyte through proteins, these cell-to-cell interactions may play a role in sperm fertility. The proteins dystroglycan (DAG1) and plasma serine protease inhibitor (SERPINA5) have been reported to play a role in cell-to-cell interaction. Thus, the first objective of this study was to characterize DAG1 and SERPINA5 proteins localization and abundance variability on bovine sperm, and the second objective was to investigate the relationship of DAG1 and SERPINA5 with field fertility (sire conception rate; SCR), in vitro fertility (in vitro embryo production; IVP), and sperm parameters. Dairy bulls (n = 22) were classified as High-SCR (SCR > 1.0) or Low-SCR (SCR < -4.0), and Good [blastocyst (BL) by Cleavage (CL) ratio (BL/CL) > 39%] or Poor (BL/CL < 38%) BL/CL. Sperm were evaluated for DAG1 and SERPINA5 immunolocalization, and concentration in two separate ejaculates. The GLM procedure was used to determine if variance was greater between bulls compared to within bulls. The GLIMMIX procedure was used to evaluate the relationship of SCR and IVP classification on DAG1 and SERPINA5 concentrations, percentage of tail labeled for SERPINA5, SCR, sperm total and progressive motility, sperm viability, CL, BL, and BL/CL, also, correlation between these variables were evaluated. Both SERPINA5 and DAG1 were localized on the sperm head; however, SERPINA5 was also localized on the sperm tail. There was greater variance in concentration among bulls compared to within bull for both DAG1 (P < 0.0001; 69.4 vs 49.1, respectively) and SERPINA5 (P < 0.0001; 325.8 vs 285.4, respectively). There was a positive correlation between concentration of DAG1 and SERPINA5 (P = 0.01; r = 0.54), and percentage of sperm tail labeled for SERPINA5 was correlated with viability (P = 0.05; r = 0.44). There was no relationship between SCR and IVP classifications and DAG1 (P = 0.55), SERPINA5 (P = 0.54), or percentage of sperm tail labeled for SERPINA5 (P = 0.22). In conclusion, DAG1 and SERPINA5 were localized to the sperm head, and tail (SERPINA5). Concentrations of DAG1 and SERPINA5 on the sperm head were correlated with each other. The percentage of tail labeled for SERPINA5 was correlated with sperm viability; however, neither protein was associated with SCR or IVP. Thus, the present study indicates that DAG1 and SERPINA5 concentrations are not good fertility markers for bull sperm.