Effects of testicular hemodynamic and echogenicity changes on ram semen characteristics

This study investigated correlations among ram semen quality parameters, testicular vascularity and echotexture. Measurements were performed biweekly for a year, before (BE) and after ejaculation (AE), on seven Chios breed rams [three rams (group A) and four rams (group B) of 2-6 and 9-13 years old, respectively], considering breeding (1) and non-breeding period (2). Hemodynamics [Pulsatility Index (PI), Resistive Index (RI)] were evaluated in each testis. Images of testicular parenchyma were analysed to evaluate echogenicity [Mean Value (MV), Contrast (Con), Gray Value Distribution (GVD), Run Length Distribution (RunLD), Long Run Emphasis (LRunEm)]. Semen volume (V), concentration (C), kinetics (CASA), morphology (Sperm Blue), viability (Eosin-Nigrosin) and DNA fragmentation (Acridine Orange) were assessed. In group A/2, semen V was correlated to left testis PI and right testis RI, BE (r = 0.4, p = 0.013/r = 0.6, p < 0.001, respectively), and to right testis PI and RI, AE (r = 0.5, p < 0.001). In A/1/AE, semen C was correlated to left testis PI (r = -0.5, p = 0.003). In group A/1/BE, RI of both testes was correlated to total and tail abnormalities (left: r = -0.5, p = 0.008/ p = 0.004, respectively - right: r = -0.4/r = -0.5, p = 0.01/ p = 0.008, respectively). In group B/1/BE, sperm tail and total abnormalities were correlated to left testis Con (r = 0.5, p = 0.02/ p < 0.001, respectively), whereas in A/2/BE, they were correlated to left testis LRunEm (r = -0.8/r = -0.7, p < 0.001, respectively). In group A/1/BE, DNA damage was correlated to right testis LRunEm (r = -0.6, p < 0.001) and tail abnormalities to left testis PI (r = -0.5, p = 0.03). In group B/1/AE, right testis LRunEm, GVD, RunLD, were correlated to sperm DNA integrity (r = -0.9, p < 0.001). Immotile spermatozoa and viability were correlated to left testis Con in group B/2/AE (r = -0.6/r = 0.6, p < 0.001) and to right testis MV in group A/1/AE (r = -0.6/r = 0.6, p < 0.001). In conclusion, alterations in both ram testes blood flow and echotexture seem to be moderately correlated with sperm assessed parameters, depending on season and ram age.