104 COMPARING DIFFERENT LEVELS OF OSMOLALITY OF SUCROSE EXTENDER ON THE VIABILITY OF SPERMATOZOA IN BACTRIAN CAMEL (CAMELUS BACTRIANUS)

Abstract

Disaccharides have been used as an extender for dromedary camel semen (Bravo et al. 2000 Anim. Reprod. Sci. 62, 173-193). More recently we have investigated the effect of different concentrations of lactose extender on the viability of Bactrian camel spermatozoa (Mosafer et al. 2005 Reprod. Fertil. Dev. 17, 197). Considering the osmolality (316.1 ± 1.48 mOsm/kg) and pH (7.4 ± 0.03) of Bactrian camel semen (Mosaferi et al. 2005 Theriogenology 63, 92-101), the objective of this study was to investigate the effect of osmolality of sucrose extender on the viability of Bactrian camel spermatozoa. Sucrose at the concentrations of 9, 10, 11, 12, and 13% with osmolalities of 292, 331, 356, 386, and 410 mOsm/kg, respectively, were prepared. All extenders contained 20% egg yolk and antibiotics, with pH adjusted to 6.9. Semen was collected from camels with a sound history of semen quality and fertility (n = 3) using a modified artificial vagina and divided into different treatments after mechanical reduction of semen viscosity (3). Progressive forward motility of spermatozoa was examined at the time of semen collection and at 4, 12, and 24 h after incubation at 4°C. Data were analyzed using the GLM procedure in SAS/STAT after arcsin transformation. At the time of semen dilution, the progressive forward motility of spermatozoa was greater at osmolality of 331 (23%) compared with 292 (1%), 386 (6%), and 410 (3.5%) mOsm/kg (P < 0.05). No progressive forward motility of spermatozoa was noticed after 4 h incubation at 4°C at osmolalities of 292, 386, and 410 mOsm/kg. At this time, a significant decrease (P < 0.05) of progressive forward motility occurred at osmolalities of 331 (4%) and 356 (0.5%) compared with that of the time of dilution. After 12 and 24 h incubation at 4°C, no progressive forward motility of spermatozoa was detected in any of these extenders. In conclusion, 10% sucrose (331 mOsm/kg) at the adjusted pH of 6.9 was the most suitable concentration of this disaccharide for preserving Bactrian camel semen for less than 4 h under chilled conditions.