The effect of different extenders on sperm motility and fertility was evaluated during liquid storage of ram semen at 5 °C and 15 °C. The semen was collected, pooled and diluted in three commercial extenders: Inra 96® (INRA) based on skimmed milk, Biladyl® A fraction (BIL) based on egg yolk, and Ovixcell® (OVIX) based on soybean lecithin. Then, sperm motility was evaluated at 0, 6, 24, 48, 72 and 96 h. In order to evaluate fertility, samples stored at 15 °C were used after dilution in INRA and OVIX. Results showed that progressive motility was significantly higher up to 72 h of storage in sperm samples maintained at 5 °C in comparison with 15 °C, similarly for each tested diluent. When samples were stored at 5 °C in OVIX, kinematic parameters such as velocity (except curvilinear velocity, VCL), trajectory [linearity (LIN), straightness (STR), wobble (WOB)], amplitude of lateral head displacement (ALH) and beat/cross frequency (BCF) were higher than in INRA and BIL. No significant differences in pregnancy rate were detected between INRA (62.6%) and OVIX (58.9%). In conclusion, liquid storage at 5 °C with OVIX extender is an interesting option since non-animal components are used, and this extender offers similar in vitro and in vivo efficacy as other extenders containing animal components.
Keywords: CASA; Fertility; extender; liquid storage; ram sperm.