Changes in testicular size, echotexture, and arterial blood flow associated with the attainment of puberty in Dorper rams raised in a subtropical climate

There is a paucity of information on the relationships of testicular morphology, echotextural attributes, and blood flow dynamics with pubertal development of rams raised in a subtropical climate. Forty‐five Dorper rams (24 rams aged 8–11 months and 21 rams aged 12–24 months) were examined using a portable ultrasound scanner connected to a 7.5‐MHz transducer. Computer‐assisted analyses of testicular ultrasonograms utilized commercially available Image ProPlus® analytical software. Spectral Doppler scans of testicular arteries were performed immediately after scrotal (B‐mode) ultrasonography to determine peak systolic velocity (PSV), end‐diastolic velocity (EDV), resistive index (RI = [PSV−EDV]/PSV), and pulsatility index (PI = [SPV–EDV]/mean velocity) of the blood vessels. The length of the testes (9.7 ± 0.3 compared with 9.0 ± 0.2 cm) and scrotal circumference (33.3 ± 0.5 compared with 31.8 ± 0.4 cm) were greater (p < 0.05) but testicular depth (4.5 ± 0.1 compared with 4.9 ± 0.08 cm) was less (p < 0.05) in sexually mature compared with peripubertal rams. [Corrections added on 9 Jan 2019 after initial online publication: The testicular size values in the sentence were corrected.] There were no differences (p > 0.05) between the two age groups of Dorper rams in blood flow indices of testicular arteries. Mean numerical pixel values (100.5 ± 4.1 compared with 89.2 ± 4.8) and pixel heterogeneity (25.6 ± 0.6 compared with 23.6 ± 0.5) of testicular parenchyma were greater (p < 0.05) in peripubertal than in postpubertal rams. Semen volume was negatively correlated with PI of testicular arteries (r = −0.57, p = 0.04). In summary, the attainment of sexual maturity in the rams of the present study was associated with significant changes in testicular length and depth, scrotal circumference, and parenchymal echogenicity/hetrogeneity but not in testicular volume and blood perfusion rates. Testicular artery PI can be used to predict the volume of ejaculate in rams.