Cryosurvival of turkey semen at different freezing rates

""Optimizing poultry cryopreservation involving freezing rate and the use of straws for semen packaging (better identification and safety of frozen semen) should therefore be a goal.. The aim of this paper was to freeze the turkey semen in straws by exposure to liquid nitrogen vapour using different heights above the nitrogen vapor.. Seven pools of semen (9-12 ejaculates\\\/pool) were collected from Hybrid Large White toms, an aliquot from each pool was taken for the analysis of fresh semen, and the remaining part of pooled semen was cooled at 5°C for 25 minutes. Each pool was diluted 1:1 (v:v) with the freezing medium composed by Tselutin extender containing DMA (final concentration of 8% DMA). Thus the semen diluted was aspirated into 0,25 ml plastic straws, equilibrated at 5°C for 20 min and then frozen by exposure to liquid nitrogen vapor for 10 minutes using three different heights above the liquid nitrogen surface : 1 cm (-140° C), 5 cm (-120° C) and finally 10 cm (- 90° C) respectively. The straws were plunged into liquid nitrogen for storage (-196°C). The samples were thawed at 50°C for 10 seconds. . Sperm mobility (phase contrast microscopy), viability and osmotic-resistance (SyBr-PI staining) were examined on fresh and post-thawed spermatozoa. The results obtained showed that the cryopreservation deteriorated the post-thaw quality of turkey spermatozoa respect to fresh semen. However, the quality the frozen semen was affected from different freezing rates. Better results of motility and viability were obtained utilizing the height of 1cm resulting significantly respect to the 5 cm. The results of this research showed that utilizing as cryoprotectant DMA at concentration of 8% and the height of 1 cm above the nitrogen vapor better results were recorded. Further studies are needed to evaluate the effects between concentrations and type of cryoprotectant and different heights of freezing on quality of frozen turkey semen.. ""