Effect of glutamine and sugars after bull spermatozoa cryopreservation

The objective of this study was to evaluate the effects of the addition of different sugars (raffinose, sucrose, and trehalose) on bull spermatozoa cryopreserved in a commercial extender (Optidyl) supplemented with glutamine on semen parameters, fertilizing ability and superoxide dismutase (SOD) activity. Nine ejaculates for each bull were used in the study. Semen was frozen in five different extenders: raffinose 25 mM plus glutamine 3 mM (RGO), sucrose 25 mM plus glutamine 3 mM (SGO), trehalose 25 mM plus glutamine 3 mM (TGO), glutamine 3 mM (GO) and control (O). Insemination doses were processed so that each 0.25 mL straw contained 15 x 10(6)sperm. Groups of GO and RGO resulted in the higher rates of subjective (54.0 ± 1.7% and 64.0 ± 1.1%; P < 0.01) and CASA motilities (53.0 ± 2.7% and 61.0 ± 4.4%; P < 0.001), respectively compared to the other groups. The supplementation of additives did not provide an effect on the level of post-thaw sperm CASA progressive motilities, the sperm motion characteristics and pregnancy rates. GO and RGO provided the better protective effect for sperm acrosome (4.0 ± 0.5% and 12.0 ± 0.6%) and total abnormalities (5.0 ± 0.3% and 13.0 ± 0.7%; P < 0.001), respectively. At the HOST values, the additives did not give to result the protective effect in comparison to Optydil extender without additives (P > 0.05). For pregnancy rates, there were no significant differences among the groups. The supplementation of additives did not provide any significant difference on the level of SOD activity (P > 0.05). It can be also thought that these sugars might have worked with glutamine in a synergy. Thereby, sugars such as raffinose and sucrose with glutamine in freezing extender may be recommended to facilitate bull semen freezability.