260 Bulletin UASVM Animal Science and Biotechnologies, 67(1-2)/2010 Print ISSN 1843-5262; Electronic ISSN 1843-536X The Influence of the Dilution Rate and Glycerol Concentration on Ram Semen Preservation Vasile MICLEA, Anca DASCĂL-CIORNEI, Marius ZĂHAN, Vasile DASCĂL-CIORNEI, Ileana MICLEA University of Agricultural Sciences and Veterinary Medicine, Faculty of Animal Science and Biotechnologies, 3-5 Manastur Street, 400372 Cluj-Napoca, Romania; vasilemiclea21@yahoo.com Abstract. The goal of our research was to establish the semen quality of some rams from the Tsigai breed, the hill ecotype and it’s suitability to conservation thru refrigeration. After the examination of the fresh semen, ejaculates with 0.9-1.0 mobility were further diluted with Triladyl and another extender prepared in hour laboratory named G Extender. 2.5%, 5%, 7%, 10% and 12.5% Glycerol was added to the G Extender. The fresh semen was diluted with 1:1, 1:2, 1:3 and 1:4 ratio with the two diluents with different glycerol concentrations, and further refrigerated. The fresh semen was diluted at 37 0 C. The temperature was decreased to 5 0 C within 2 hours. Periodically mobility determination was performed to al experimental trials. Dropping the temperature to 5 0 C has little influence on the semen mobility. Major differences between trials regarding the spermatozoa mobility appeared when the semen was conserved at 4 0 C, and the best results were obtained when the G Extender with 7% glycerol is used. The 10% and 12.5% glycerol concentration provided the lower results. Regarding the dilution rate, both Triladyl and Extender G gave the best results when the semen was diluted 1:3 and 1:4. The semen prepared with the 1:4 dilution with 7% glycerol in the G Extender maintained the insemination quality 480 hours. Keywords: rams, Tsigai, ecotype, semen, glycerol INTRODUCTION The semen conservation presumes that the spermatozoa metabolism is decreased to increase the time interval when they maintain their fecundity. During the conservation at 5 0 C, the spermatozoa metabolism is completely stopped, the de-assimilation products appear and combined with the temperature effects cause a gradually degeneration of the morphological integrity of spermatozoa and decreases the semen fertility (Jones and Martin, 1973; Maxwell 1978; Menchaca et al., 2005; Zlatarev et al., 1988). To avoid the refrigerated semen fertility decrease, some authors recommend that the temperature must be decreased slow and uniform in the equilibration period (Decuadro-Hansen, 2004; Fiser and Fairfull, 1984; Graham, 1978) and the usage of diluents with addition of crioprotectants. Decreasing temperature rates, the type o cryoprotectant agent, it’s concentration, dilution rate, osmotic pressure, the temperature of the extender when the semen is diluted (Anel et al., 2006; Donovan et al., 2001; Molinia et al., 1994; Salamon and Maxwell, 2000) are the factors witch influence the success of the artificial insemination with refrigerated semen in sheep. The negative effects caused by the decreasing of the temperature on the rams spermatozoa are controlled by increasing the concentration of cryoprotectant agents in the diluents and the addition of these agents before the diluted semen reaches 5 0 C (Gil et al., 2000; Gil et al., 2003; Salamon and Maxwell, 1995).