The Relationship between the Testicular Blood Flow and the Semen Parameters of Rams during the Selected Periods of the Breeding and Non-Breeding Seasons

SIMPLE SUMMARY: There is a rising demand for sheep products such as meat, wool, and milk. Within the sheep flock, rams are the most valuable animals as they represent 50% of the genetics of every sheep flock. To improve productivity, monitoring of the rams’ semen quality allows breeders to maximize fertility. This study aimed to introduce the advanced semen evaluation tests and evaluate the correlations between the parameters of the basic and advanced semen evaluation tests and the dynamics of testicular blood flow. Semen was collected from eighteen rams, and a pulse wave Doppler examination was conducted in three routine ram examination periods in Poland: before the breeding season (BBS), during the breeding season (BS), and after the breeding season (ABS). Routine and advanced semen analysis, including computer-assisted sperm analysis (CASA), sperm chromatin dispersion test (SCD), and motile sperm organelle morphology examination (MSOME), were conducted. In Doppler ultrasonography, the peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) were calculated. The high-quality semen was derived during BS, whereas BBS semen demonstrated high sperm abnormalities related to sperm cells DNA fragmentation and vacuolization. The features of higher sperm abnormalities correlated with an increase in RI, PI, and EDV, respectively. ABSTRACT: The study aimed to conduct advanced semen evaluation tests during routine ram examination periods in the breeding and non-breeding seasons and to investigate their correlation with the dynamics of testicular blood flow. Semen was collected from eighteen rams, and pulse wave Doppler examination before (BBS), during (BS), and after the breeding season (ABS). Routine and advanced semen analysis, including computer-assisted sperm analysis (CASA), sperm chromatin dispersion test (SCD), and motile sperm organelle morphology examination (MSOME), were conducted. In Doppler ultrasonography, the peak systolic velocity (PSV), end-diastolic velocity (EDV), resistive index (RI), and pulsatility index (PI) were calculated. In BS period, high sperm concentration (p < 0.0001) and total sperm number/ejaculate (p = 0.008) were noted. During the BBS period, a low percentage of forwarding motility (p = 0.017) and high sperm abnormalities (p = 0.005) were found. Also during this period, both SCD and MSOME revealed high sperm DNA fragmentation (p < 0.0001) and signs of vacuolization (Grade II-IV, p < 0.05). The advanced features of higher sperm abnormalities (Grade IV of MSOME) correlated with an increase RI (ρє <0.60;0.61>) and PI (ρє <0.46;0.52>), whereas the basic percentage of sperm abnormalities correlated with the EDV (ρє <0.44;0.73>) value. One may conclude that the current preliminary study requires further research concerning the monthly examination of a ram to provide full yearly characteristics of the relation between advanced semen evaluation tests and the dynamics of testicular blood flow.