The heritability of pampiniform plexus vessel size and varicocele in boars.

Ultrasonography was used to capture a coronal-sagittal image of the veins of the pampiniform plexus (PP) and the testicular artery of 327 maternal-line boars at approximately 6 months of age at the University of Nebraska-Lincoln. Varicocele was diagnosed by two methods. Method 1 diagnosed varicocele as when the average vessel area on one side of the scrotum was 1.5 times larger than the average vessel area on the other side of the scrotum. Method 2 diagnosed varicocele when the average vessel area on one side of the scrotum of a boar was 1.5 times larger than the average vessel for the same side of the scrotum of the boar's cohorts (same population and year). Varicocele was diagnosed in 23.17% and 15.1% of boars measured using method 1 and method 2, respectively. Ultrasonography showed to be an effective means to measure PP vessel size in boars and may even allow for earlier detection of varicocele than by using palpation. Animal models were employed to estimate the heritability for: average area of right PP vessels (0.52), average area of the left PP vessels (0.46), varicocele presence using method 1 (0.26), and varicocele presence using method 2 (0.25). These heritability estimates suggest that vessel size and varicocele could be selected against in breeding programs to potentially improve boar semen quality. This article is protected by copyright. All rights reserved.