Research Summary - 4
Evaluation of welfare in bulls subjected to weekly electroejaculation
| Date/Time: |
9/13/2025
16:30
|
| Author: |
Dane W Schwartz |
| Clinic: |
Auburn University |
| City, State, ZIP: |
Auburn, AL 36832 |
D.W. Schwartz, DVM
1
;
C. Armstrong , DVM, MS, DACT
1
;
K. Gassipard , None
2
;
J. Cowley , DVM, MS, DACT
3
;
C. Foradori, PhD
4
;
J. Bayne , DVM, MS, DACVIM
1
;
B. Chaves-Cordoba, PhD
5
;
J. Klabnik, DVM, MPH, PhD, DACT
1
;
1Department of Clinical Sciences, Auburn University, Auburn,
2National Veterinary School of Toulouse, Toulouse, France
3Department of Large Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Blacksburg, VA, USA
4Department of Anatomy, Physiology, and Pharmacology, Auburn University, Auburn,
5College of Agriculture, Auburn University, Auburn, AL
Introduction:
Electroejaculation (EEJ) is a consistent and reliable method for semen collection but is subject to welfare concerns due to occasional outward vocalization and perceived discomfort. There is no study which has investigated the impacts of repeated EEJ. The first objective was to compare plasma Substance P concentrations, Pen Score (PS), Chute Score (CS), and Exit Velocity (EV) between control bulls (CTL) and treatment (TX) that experienced electroejaculation weekly. The second objective was to compare the same parameters for the last two weeks of the weekly electroejaculations and two alternating days in which both groups were processed but TX bulls were not ejaculated. For both objectives, we hypothesized that there would not be significant differences in Substance P, PS, CS, nor EV between groups (for Objective 1 and 2) or within group (for Objective 2).
Materials and methods:
Eleven single-source, crossbred Bos taurus beef bulls ~7 months in age were randomly assigned to either CTL (n=4) or TX (n=7).
Bulls were processed using low-stress handling techniques prior to and throughout the study period. Two sampling periods were established: 1)EEJ: TX bulls underwent weekly EEJ for 5 months. CTL bulls were processed similarly except they did not undergo EEJ. 2)Between EEJ: For the last 2 weeks of the study, all bulls were processed on additional days between EEJ collection days but did not undergo EEJ, such that handling occurred every 3-4 days.
At all processing dates, PS (1-Docile to 5-Aggressive) and EV, measured by two laser-transmitter-receiver pairs, were determined. Chute Score and blood sampling occurred at all processing dates during the Between EEJ period, but every 2 weeks during the EEJ period. Based on 30 second videos taken within ~2 minutes of EEJ, CS (1-Calm to 5-Twisting, Rearing, Struggling) was determined by three masked independent observers and averaged.
Approximately 15 minutes after EEJ (TX) or a comparable time (CTL), blood was collected in K3EDTA tubes with Aprotinin added and immediately centrifuged. Plasma was stored in -80*C until processing. Substance P quantification was assessed using a Bovine substance P ELISA Kit (AFG Bioscience, Northbrook, IL, USA).
Within the EEJ period, data were analyzed using linear mixed-effects models with treatment and week of the study as the independent variables using R in RStudio (version 4.5.1). To compare the sampling periods, data were analyzed utilizing a generalized mixed model ANOVA with repeated measures with treatment and sampling period as the fixed effects. Random variables included Bull ID (all models), scorer ID (PS models), or date (when comparing between sampling period).
Results:
When evaluating the EEJ period, there was no significant difference for interaction between week and treatment (p=0.17) for PS. The main effect of treatment was not significant (p=0.4) but scores significantly decreased with time (p=0.004). For CS, the interaction between time and treatment was not significant (p=0.19). However, scores significantly decreased in the treatment group compared to the control group (p=0.02) and decreased with time (p=0.0004). For EV, the interaction (p=0.75) and main effect of treatment (p=0.45) was not significant, but the velocity did decrease over time (p<0.0001). When analyzing the last two weeks of the EEJ period compared to the Between EEJ period, there was no significant interaction between time and treatment (PS: p=0.48; CS: p=0.17; EV: p=0.20) nor main effect of time (PS: p=0.42; CS: p=0.80; EV: p=0.94) nor treatment (PS: p=0.92; CS: p=1; EV: p=0.14). Substance P quantification is pending.
Significance:
Based on the preliminary results of this study there is no evidence for nociceptive effects for repeated EEJ. Extrapolation of these results of this study must be interpreted with care due to the relatively small sample size on peri-pubertal bulls, differences of values assigned using a subjective scoring system, and inherent bias due to processing facility.
