Abstract :
Ram semen contains sufficient quantities of superoxide dismutase (SOD) and much lower
concentrations of glutathione peroxidase (GSH-PX) and catalase (CAT) to prevent oxidative
damage. The anti-oxidant capacity of the sperm cell is limited, due to a small cytoplasmic
component, which contains these anti-oxidants to scavenge the oxidants. However, the concentration
of these anti-oxidants may decrease considerably by the dilution of the semen.
The aim of the presentworkwas to study the effect of two anti-oxidants, namely, glutamine
and an amino acid solution (BME) in a Tris-based extender on ram sperm parameters,
lipid peroxidation and anti-oxidant capacity after the cryopreservation/thawing process.
Ejaculates collected from 4 Akkaraman rams were evaluated and pooled at 37 ◦C. Semen
samples which were diluted with the tris-based extender containing glutamine (2.5 or
5 mM), BME (13 or 26%), and no anti-oxidants (control) were cooled to 5 ◦C and frozen in
0.25-ml French straws and stored in liquid nitrogen. Frozen straws were thawed individually
at 37 ◦C for 20 s in a water bath for evaluation. The freezing extender supplemented
with 5mM glutamine led to higher motility rate (68.0±4.4%) and hypo-osmotic swelling
test (HOST) (64.1±5.5%), when compared to glutamine (2.5mM) and BME (13 and 26%)
(P < 0.05). No significant differenceswere observed regarding sperm motility and HOST, following
the supplementation of the freezing extender with glutamine 2.5mM and BME (13
and 26%) after thawing. CAT activity remained significantly higher following the addition
of glutamine 5mM (6.4±0.9 kU/g protein), compared to the other treatments (P < 0.01).
The anti-oxidants at different levels were not effective in the elimination of malondialdehyde
(MDA) formation and maintenance of SOD activities, when compared to the control
(P < 0.05). Findings showed that glutamine (5mM) supplementation in semen extenders,
was of greater benefit to frozen–thawed ram sperm. Future efforts are needed to find the
appropriate anti-oxidants and their effective concentrations to improve post-thaw sperm
parameters (e.g. motility, membrane integrity, fertility) and anti-oxidant activities when
frozen–thawed ram sperm is used.
