Weekly electroejaculation did not negatively affect substance P and temperament scoring in young bulls

Objective: To evaluate the impact of weekly electroejaculation on substance P and temperament scores in young bulls. Methods: Plasma substance P and temperament scores were determined in Bos taurus bulls during 3 periods from August 27, 2024, through February 3, 2025: (1) precollection, prior to initiation of treatment; (2) collection, treatment period in which treatment bulls underwent 21 weekly electroejaculation; and (3) between collection, alternating dates between collection dates in which treatment bulls did not undergo electroejaculation. Data were analyzed in SAS (version 9.4) using a generalized mixed-model ANOVA with repeated measures (continuous data) or GLIMMIX cumulative logit link function with multinomial distribution and χ2 analysis (ordinal data), with significance if P ≤ .05. Results: In the precollection period, substance P, pen score, chute score, and exit velocity were not different between control (n = 4) and treatment (10) bulls. In the collection period, substance P, pen score, and exit velocity did not differ. The frequency of lesser pen scores increased as the number of electroejaculations increased. Treatment bulls had a lesser chute score compared to control bulls, and their score frequencies were parabolic in response to increasing electroejaculations. In comparing treatment bulls in the last 2 collection dates to the between-collection dates, no findings were significant. Conclusions: Weekly electroejaculation did not negatively affect temperament scoring and substance P. Clinical Relevance: Electroejaculation did not adversely affect measured welfare indicators in this study population.