Testicular vascularization at two locations in relation to hormonal levels, and pixel echotexture in bulls at different ages

Objective: To assess the hemodynamic changes that occurred in the main testicular artery at two different locations such as supra and marginal ones in bulls at three different ages. Methods: Eighteen Baladi bulls were divided according to their age into three different age groups: 1 year [n=6; group I with bodyweight (380±10) kg], 3 years [n=6; group II with bodyweight (570±10) kg], and 6 years old [n=6; group III with bodyweight (650±10) kg] Baladi bulls. Circumference of the scrotum, thickness of the mediastinum, testicular dimensions, vascularity, and hormonal levels were measured. Testicular hemodynamics were assessed by Doppler ultrasound scanning. Results: Testicular width, length, and volume were significantly different among the three age groups, with the highest in bulls of group III (P<0.05). The bulls in group III had significantly higher mediastinal line thickness and scrotal circumference than group I (P<0.05), but there was no significant difference between group II and group III. Bulls in group II showed a decline in Doppler indices (resistance and pulsatility indexes) at both testicular branches compared to the other two groups (P<0.05). Supra and marginal end diastolic velocities in the three age groups were significantly different, with the highest in group II (P<0.05). Time average velocity (cm/s) was significantly elevated in group II compared to the other two groups (P<0.05). Both testicular echotextures were significantly decreased in group II (P<0.05). Estradiol and nitric oxide metabolites were significantly high in group II compared to the other two groups (P<0.05). Meanwhile, the level of plasma testosterone was maximum in group III (P<0.05). Positive correlations were found between supratesticular artery resistance and pulsatility indexes (r=0.81; P<0.001), while both resistance and pulsatility indexes had correlated negative with estradiol (r=-0.71 and r=-0.91; P<0.001), and nitric oxide metabolites (r=-0.92 and r=-0.72; P<0.001). Conclusions: Three-year old Baladi bull has the lesser Doppler indices with lesser echotexture and greater nitric oxide with estradiol concentrations, which directs a significant ability for the thermoregulation process. These parameters will help in breeding selection.