IMPLICAÇÕES DA REDUÇÃO NA CONCENTRAÇÃO DE GEMA DE OVO NO MEIO GLICINA-GEMA-LEITE SOBRE A CINÉTICA, MORFOLOGIA E INTEGRIDADE DE MEMBRANAS ESPERMÁTICAS EM SÊMEN OVINO CRIOPRESERVADO

Abstract

This study was conducted to determine the effects of reduction in the proportion of egg yolk
in the extender Glycine-yolk-milk (GGL), using four Santa Ines rams and four Dorper rams.
Four ejaculates per ram were obtained by artificial vagina. After the macro and microscopic
evaluation the semen was kept at 32oC and diluted to achieve concentrations up to 400 x 106
spermatozoa/mL in the extender containing 20 % (GGL20), 15 % (GGL15), 10 % (GGL10) or 5 % (GGL5) (v/v) of egg yolk, and packaged in 0.25 mL straws (IMV, France), cooled and
frozen in automated control system. Thawing was performed in a water bath at 40oC/20
seconds. Sperm kinetics was determined in computer-assisted semen analysis (CASA).
Morphology of spermatozoa were observed using a wet preparation examined under phasecontrast microscopy and the integrity of sperm membranes was verified by the combination
of the probes fluorochromes carboxyfluorescein diacetate (DIC) and propidium iodide (IP),
under fluorescence microscopy. The total sperm motility (MT) and progressive motility (MP)
in treatments, GGL10 and GGL5 were higher (P<0.05) than in GGL20. Semen cryopreserved
in both extender, GGL10 and GGL5 had the highest percentage of sperm with intact
membranes than in GGL20 (P<0.05). In conclusion, it is possible to reduce the proportion of
egg yolk in extender Glycine-yolk-milk up to 5 % (v/v) without alteration on the qualitative
and quantitative parameters of cryopreserved ovine semen.