الفهرس 
Seasonal dynamics of testicular blood flow and their association with reproductive performance in rams
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Abstract
The present detailed study aimed to establish for the first time reference values for ultrasound measures of testicular dimensions and Doppler measures of blood flow in the supratesticular artery (STA) of rams over a 12-month period, and to investigate a possible association between monthly changes in dynamics of testicular blood flow from one hand and testicular volume, plasma testosterone and estradiol -17Ý concentrations as well as semen characteristics from the other hand. Five fat-tailed rams weighing 45-60 Kg and aging 2-4 years old were subjected to semen collection, jugular blood sampling, ultrasonographic scanning of the testes and Doppler examination of testicular artery twice monthly for a period of one year. Testis dimensions were measured by a linear-array ultrasound transducer (7.5 MHz) whereas Doppler indices, including resistive index (RI) and pulsatility index (PI), were measured by color pulsed-wave Doppler. The overall mean (±SD) values of testicular volume, calculated by using the formula: length {u00D7} thickness {u00D7} width{u00D7} 0.71, as well as RI and PI, respectively were 71.84±5.33 mm3, 0.378±0.102 and 0.642±0.208. Both ultrasound testicular volume and Doppler measures displayed a definite trend throughout the study period. Average testicular volume was the lowest in June (59.44±6.83 mm3) and reached its maximum (84.43±8.52 mm3) in November after 42.2% increase (p< 0.01). Mean values of RI were lowest between September and March (range 0.100-0.400), increasing significantly (p< 0.01) in April (53%) reaching highest value in June (0.564±0.158). from the lowest value recorded in October through February (range 0.200-0.600), the average PI values increased significantly (p< 0.05) in March (41%) to reach maximum value in July (0.940±0.368)