The objective of the present study was to evaluate treated with oral single dose of L-tyrosine (50 g/bull), on semen quality in relation with ultrasonograms pixel intensity and conventional measurements of the testes of Friesian bulls. Twenty Friesian bulls averaging 8.0±0.24 month of age and 195±15.6 kg body weight were used in this study. The experimental bulls were divided into two similar groups (10 each). Bulls in the 1^st group were fed a basal diet and considered as a control group (G1), while  those in 2^nd  group were received an oral dose from L-tyrosine (50 g/bull) at 8.5 months of age. Throughout the experimental period, the percentages of progressive motility, livability and abnormalities of spermatozoa as well as sperm cell concentration were evaluated. At 15 and 20 months of age, testicular breadth, thickness of scrotal layers and seminal cord, the testicular mediastinum thickness and pixel intensity value were recorded using ultrasound scanner. Results showed that testicular breadth, thickness of scrotal layers and testicular cord  of the bulls were not affected significantly by tyrosine treatment. However, testicular breadth of the bulls  at 20 month was higher than at 15 month of age.  Bulls treated with L-tyrosine with the different age did not affect the thickness of testicular mediastinum. However, values of testicular pixel intensity was higher (P<0.01) in treated than in control bulls and at 20 than 15 month of age. Percentages of progressive motility, livability of spermatozoa, and sperm cell concentration of the bulls treated with L-tyrosine were significantly (P<0.01) increased and decreased (P<0.01) sperm abnormalities (10.97 vs. 30.35%) as compared to the control. At 20 month of age, sperm motility and livability as well as sperm cell concentration increased (P<0.01) by about 33.25, 22.52 and 43.8% and sperm abnormalities decreased (P<0.01) by 49.4% as compared to those at 15 month of age. The correlation coefficients between testicular pixel intensity and each of semen characteristics studied were highly significant (P<0.001), being positively the strongest with sperm livability (r= 0.7978), sperm cell concentration (r= 0.7243) and negatively with sperm abnormalities (r= -0.7978),. However, positively lower correlation was recorded between pixel intensity and sperm motility (r= 0.5493).