LAUSR

DOLEŽALOVÁ MARTINA, PTÁČEK MARTIN, STÁDNÍK LUDĚK, DUCHÁČEK JAROMÍR. 2017. Effect of Different Thawing Methods on Bull’s Semen Characteristics. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 65(3): 815–822. The aim of the study was to evaluate the influence of different thawing methods on bull’s semen characteristics. The semen was collected and processed from 8 bulls (Holstein, n = 4; Czech Fleckvieh, n = 4) kept in private Sire insemination Centre. Four different thawing methods were tested: control thawing methods (temperature = 38.5 °C, time = 30 seconds), slow thawing method (temperature = 30 °C, time = 50 seconds), moderate thawing method (temperature = 50 °C, time = 15 seconds), rapid thawing rate (temperature = 70 °C, time = 3 seconds). The percentage rate of total and progressive motile spermatozoa above head as well as movement characteristics of straight‐line velocity (VSL, μm/s) and linearity (LIN, %) were recorded using CASA system immediately after thawing and after 2 hrs. of heat incubation (±38 °C). Subsequently the differences between semen characteristics measured immediately after thawing and after 2 hours of incubation were calculated. The data were analyzed with SAS software. All the evaluated semen traits reached significantly lowest values in total motility (−8 % to −10.5 %, P < 0.05), progressive motility (−5.6 % to −10 %, P < 0.05) VSL (−3.9 μm/s to −9 μm/s, P < 0.05) and LIN (−1.5 % to −4.8 %, P < 0.05) in control thawing method immediately after the thawing compared to others. However, these differences were negligible after 2 hrs. of incubation. The highest values of progressive motility and movement characteristics after thawing and after 2 hours incubation were detected using slow thawing method. Moreover, the rapid method of thawing showed the significantly the lowest results in progressive motility (−3.6 % to −6.6 %), VSL (−3.2 to −5.6 μm/s) and LIN (−3 % to −4.6 %) characteristics assessed after 2 hrs. of incubation compared the others (P < 0.05). Control method of thawing was most stable during the incubation and showed the significantly lowest decrease of total motility (−7.6 % to −11.8 %, P < 0.05), progressive spermatozoa motility above head (−7.5 % to −9.8 %, P < 0.05) and VSL characteristics (−2.4 to −9.7 μm/s, P < 0.05) during incubation. Therefore, this thawing protocol can be recommended at this study based on the lowest spermatozoa characteristics decline during incubation for using artificial insemination.