Skim milk-egg yolk based semen extender compensates for non-enzymatic antioxidant activity loss during equine semen cryopreservation

Ano: 2009 | Volume: 6 | Número: 2

Autores: I.C. Bustamante Filho, C.D. Pederzolli, A.M. Sgaravatti, R.M. Gregory, C.S. Dutra Filho, M.I.M. Jobim, R.C. Mattos

Palavras-chave: antioxidants, cryopreservation, equine semen, extender, oxidative stress

Resumo Inglês:

Cryopreservation exposes spermatozoa to
stressful conditions, leading to reduced cell viability.
Several studies propose that overproduction of reactive
oxygen species and decreased antioxidant capacity of
semen may increase the damaging effects of the
technique. The objective of this work was to evaluate
the influence of a skim milk-egg yolk based semen
extender on enzymatic and non-enzymatic antioxidant
activity in equine semen cryopreservation. Fifteen
ejaculates from six fertile Criollo stallions were
cryopreserved using a commercial citrate-Hepes, egg
yolk, skim milk and glycerol extender. Activities of
catalase, glutathione peroxidase and superoxide
dismutase and total radical-trapping antioxidant
potential were assessed in raw semen, semen diluted in
extender and thawed semen. All three enzymes showed
higher activities in raw semen than in diluted or in
thawed semen (P < 0.01), but enzyme activities did not
differ significantly between diluted and thawed semen
samples (P > 0.05). Non-enzymatic antioxidant defenses
did not differ among any of the stages in the
cryopreservation process (P > 0.05). In conclusion, the
present study shows that dilution of semen with
skim milk-egg yolk based extender after centrifugation
compensates for the non-enzymatic antioxidant
protection (but not enzymatic antioxidant defense) lost
with seminal plasma removal. The absence of
correlation between seminal and antioxidant parameters
suggests that the compensation was enough for semen
protection against oxidative stress, or antioxidant
protection plays a minor role on semen from fertile
stallions.