Location: Reproduction ResearchTitle: The effect of varicocele on semen quality in boars exposed to heat stress
|GRUHOT, TASHA - University Of Nebraska|
|WHITE, BRETT - University Of Nebraska|
|MOTE, BENNY - University Of Nebraska|
Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2020
Publication Date: 1/17/2020
Citation: Gruhot, T.R., Rempel, L.A., White, B.R., Mote, B.E. 2020. The effect of varicocele on semen quality in boars exposed to heat stress. Translational Animal Science. 4(1):293-298. https://doi.org/10.1093/tas/txaa003.
Interpretive Summary: Varicocele is the most common condition in men with infertility issues and reduced semen quality. Varicocele is diagnosed when the pampiniform plexus, the vasculature that provides blood to and from each testicle, has chronic dilation and vasculature lesions. Varicocele can cause inappropriate blood flow and thermal regulation especially during moderate heat stress, such as summer or autumn seasons. Using ultrasonography, boars at six months of age were diagnosed with or without varicocele. Semen samples were collected from mature boars prior to and for 6 weeks following a 7-day heat stress exposure. Boars with varicocele had reduced semen quality before and after thermal stress including: increased distal droplet appearance (typically an indicator of abnormal sperm maturation) and reductions in sperm concentration, number of sperm per ejaculate, and sperm head area. The use of ultrasonography in young boars to determine presence of varicocele will improve semen production and economic efficiency within commercial boar units during warm periods, such as late summer and early autumn, when semen production quality can be most variable.
Technical Abstract: Semen quality has a dramatic impact on reproductive efficiency in the swine industry, influencing both conception rate and litter size. The objective of this study was to assess whether the presence of varicocele hinders semen quality in both thermoneutral and heat stress (HS) conditions. At approximately 6 mo of age, ultrasonography was used to measure left and right pampiniform plexus area in order to detect varicocele in maternal line boars at the University of Nebraska – Lincoln. Between 10 and 12 mo of age, semen was collected from each boar (n=28) twice weekly. Boars were collected under thermoneutral conditions, were then heat stressed for 7 d to exacerbate any semen quality issues, and semen was collected post-HS for 6 wk. Sperm characteristics were determined by computer-assisted semen analysis. The presence of varicocele had a significant effect on sperm concentration (P = 0.04) and trended toward significance for mean sperm head area (P = 0.06) throughout the duration of the study. An interaction existed between varicocele and collection time point at weeks 2 - 5 post-HS for distal droplet percentage, suggesting that boars with varicocele were more susceptible to heat-stress-induced semen quality issues than boars without varicocele. Moreover, semen quality was reduced in boars with versus without varicocele under both thermoneutral and HS conditions. Therefore, detection of varicocele by ultrasound could represent a potential marker of fertility in young boars or as a component trait in selection indices for fertility.