Ram Semen Cryopreservation Using Egg Yolk or Egg Yolk-free Extenders: Preliminary Results

Abstract

Kinematic parameters of thawed ram semen frozen under field conditions were analysed with the use of two commercial (egg yolk vs egg yolk free) semen extenders in different year-seasonal periods. The semen was collected from Suffolk (n = 2) and Charollais (n = 1) rams kept in private breeding farm on 3 test days (pre-mating, at mating, post mating) during year 2016. Two commercial semen extenders (egg yolk-based BullXcell® or egg yolk-free AndroMed®) were used for semen processing. Processed semen was frozen in 0.25 ml plastic cryostraws using the custom-made portable freezing box for ram semen cryopreservation under field conditions. Thawed semen characteristics were evaluated using computer-assisted semen analysis (CASA) system immediately after thawing and after 2 h of heat incubation (±38°C). Significantly higher total motility (+12.3%), straight line velocity (+5.6 μm s-1), and average-path velocity (+6.9 μm s-1) were detected for the semen processed and cryopreserved using egg yolk-based semen extender. Year-seasonal variation and introducing the ram to service had shown to have a significant effect on the cryopreserved ram spermatozoa. These preliminary results confirmed the feasibility of ram semen processing and cryopreservation under field conditions.