Ultrasound-assisted liquefaction of dromedary camel semen

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The current investigation aimed to evaluate the rheological and physical properties of camel semen subjected to liquefaction by high-power low frequency ultrasound. Ejaculates (n=18) were collected during the rutting season from 2 adult male camels, Camelus dromedarius, (9 ejaculates each) using a modified artificial vagina. Immediately after collection, each ejaculate was split into 3 aliquots by a split-sample technique. The first aliquot (raw) was evaluated for rheological, physical and morphological properties, whereas the other 2 aliquots were diluted (1:3) with Tris-lactose egg yolk extender. An aliquot of diluted semen served as control and was evaluated for the aforementioned criteria immediately after dilution (T0) and after an equilibration period of 3h at 5°C (T180). Meanwhile, the other diluted specimen was exposed to 4 sets of a 40kHz ultrasound nominal frequency, 2min each at 2min interval, at 37°C for physical viscosity elimination. Throughout the exposure period, semen rheological properties and sperm physical characteristics were evaluated. Thereafter, sperm kinetics of equilibrated control and ultrasonic-treated semen were objectively assessed by a computer-assisted sperm analysis (CASA) unit. Time of exposure to the ultrasonic waves was negatively correlated (P<0.01) with each of viscosity score (r=−0.95) and thread length (r=−0.93), whereas it was positively correlated (P<0.01) with the percent of progressive motility (r=0.87). Furthermore, ultrasonic-treated semen recorded higher (P<0.05) motility, viability and sperm dynamics criteria than those of control. These results point to the successful application of ultrasound technology to improve handling, evaluation and processing of camel semen.