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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Nutrition, Growth and Physiology » Research » Publications at this Location » Publication #424392
Research Project: Optimizing Nutrient Management and Efficiency of Beef Cattle and Swine

Location: Nutrition, Growth and Physiology

Title: Longitudinal characterization of mature beef bull seminal fluid and blood serum metabolome during a 65-day breeding season

Author
item WILLIAMS, JORDAN - California Polytechnic State University
item Crouse, Matthew
item LA FRANO, MICHAEL - Salk Institute Of Biological Studies
item CAMPOS-CHILLON, L - California Polytechnic State University
item CUNNINGHAM-HOLLINGER, HANNAH - University Of Wyoming
item FIELD, CHAD - California Polytechnic State University
item MCFARLANE, ZACHARY - California Polytechnic State University

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2025
Publication Date: 3/12/2026
Citation: Williams, J.D., Crouse, M.S., La Frano, M.R., Campos-Chillon, L.F., Cunningham-Hollinger, H.C., Field, C.E., McFarlane, Z.D. 2026. Longitudinal characterization of mature beef bull seminal fluid and blood serum metabolome during a 65-day breeding season. Translational Animal Science. 10. Article txag005. https://doi.org/10.1093/tas/txag005.
DOI: https://doi.org/10.1093/tas/txag005

Interpretive Summary: This study aimed to identify metabolites present in the blood serum and seminal fluid of actively breeding Angus beef bulls. Metabolites may serve as biological markers of physiological processes occurring at the time of collection. Samples were obtained throughout a 65-d breeding season and assessed for metabolite relative abundance using mass spectrometry. Metabolites found in clear abundances were analyzed for significant fluctuations throughout the breeding season based on the expected “workload” of those bulls. Ideally, these findings will serve as foundational data for future metabolomic studies concerning beef bull reproductive physiology. In this dataset, the most conclusive metabolites for further exploration were related to purine metabolism.

Technical Abstract: The metabolic impact of the breeding season on beef bulls has not been extensively studied. The change in plane of nutrition and intensive activity demands induce body weight loss and metabolic changes that may influence fertility and long-term management. The use of metabolomics to characterize the metabolic changes or adaptations during the breeding season will aid in developing hypotheses for future research in beef bulls. The objective of this study was to identify metabolites in both serum and seminal fluid (circulating vs. excretory) that were affected temporally throughout a 65-d breeding season and by bull workload (bull: cow). Over a two-year period, purebred Angus bulls (year 1: n=8, year 2: n=9) owned and housed by the Cal Poly beef unit were surveyed using serum (collected via the coccygeal vein) and seminal fluid (collected via elec­troejaculation) at the beginning (dO), middle (d30), and end (d65) of a 65-d, post-Al breeding season. Bulls were subjected to one of three workload groups: high (HIGH), moderate (MOD), or low (LOW). Samples underwent HPLC-MS to identify metabolites within the fluids. Data were stratified for sample day and workload and compared using ANOVA for sample day and workload in a 3 x 2 factorial design. Within seminal fluid and blood serum, purine and pyrimidine metabolism pathways were the most affected (P