INFLUENCE OF CRYOPRESERVATION ON THE VELOCITY PARAMETERS OF SPERMATOZOA FROM BREEDS OF LACAUNE AND ILE DE FRANCE SHEEP

The spermatozoa of agricultural breeds of ram are susceptible to the action of low freezing temperatures. This process leads to changes in main sperm parameters such as motility and speed. Various factors such as the type of storage media, the addition of some biological substances in the diet and the freezing regimes are influenced by the cryopreservation of the sperm. The aim of our study is to investigate the effect of cryopreservation on the speed parameters of sperm from breeds of Lacaune and Ile de France sheep. The experiment was carried out with 10 sexually mature, pure bred rams during their breeding campaign. The animals were divided in two groups according to the breed - 5 rams of each breed (Ile de France and Lacaune). The assessment of sperm motility, concentration and various kinematic parameters of motile spermatozoa were carried out by Sperm Class Analyzer (SCA, Microptic, Spain). Cryopreservation of semen straws was done by the method of CASSOU [(13)]. The results show that in the Lacaune breed, the amount of static spermatozoa after thawing increases significantly while the Ile de France breeds even slightly decreases. With respect to progressive and non-progressive mobile sperm, both breeds showed a decrease after thawing, but in the case of Ile de France it was much less. All speed indicators (VCL, VSL and VAP) and parameters - percentage of linearity (LIN, %), percentage of straightness (STR, %) and percentage of fluctuations (WOB, %) for Ile de France breed increase, albeit a little after thawing, while the other breed - Lacaune, significantly decreases. In conclusion in the Lacaune breed after cryopreservation there is a significant decrease in both the progressive spermatozoa and the speed parameters, as opposed to the ejaculates of the Ile de France breed.