FREEZABILITY AND FERTILITY OF FROZEN-THAWED KABASHI ECO-TYPE DESERT RAMS SEMEN PROCESSED WITH TRIS-SOYBEAN AND TRIS-EGG YOLK BASED EXTENDERS
Keywords:
Desert ram, semen, freezability, ervical insemination, lecithin, soybeanAbstract
The present study was desinged to examine the effect of season and type of
extender on the freezability and fertility of Kabbashi ram semen. Freezability
was assessed by comparing the motility and viability of the frozen-thawed semen
processed with a commercial soybean-based semen extender (AndroMed) with
home-made Tris-based glucose/egg yolk extender. Fertility of the frozen-thawed
semen processed with the two extenders was measured by the non-return rate to
oestrus (NRR) after cervical insemination of ewes (n=60) treated with an
intravaginal sponge containing 40 mg fluoroprogesterone acetate (FGA) for 12
days and an im injection of 500 IU eCG at the time of FGA sponge removal.
Insemination was carried out 56 hours after removal of the FGA sponge. Season
had no significant effect on post-thawing motility. Significant interaction
between the effects of season and the type of extender on the post-thaw motility
was observed (P < 0.001). The highest post-thawing motility for AndroMed was
recorded in autumn while that for the home-made extender was in winter. The
lowest value was observed in summer for the home-made extender . The NRR
were not significantly different among semen samples processed with AndroMed
(67.9%), and the Tris (74.1%) extenders. The overall conception and lambing
rates were 71 and 25%, respectively. The prolificacy rates from ewes
inseminated with frozen-thawed semen processed with AndroMed and the Tris
(1.14, and 1.0, respectively) were also not significantly different. The present
results indicated no significant seasonal effect on post-thawing motility.
Significant interaction between season and type of extender was observed with
consistent performance for AndroMed in all seasons. Thus, an egg yolkcontaining semen extender can be replaced with the lecithin-based extender
(AndroMed), which could be used for cervical insemination using frozen-thawed
ram semen without reducing its fertility
