Abstract :
This research aimed to evaluate two concentrations of egg yolk inclusion rates (20 and 2.5%)
in the semen extender of goat semen cryopreserved during two seasons of the year. The
study was conducted during a light-induced breeding season (Experiment 1), and during the
natural breeding season (Experiment 2), in the southern hemisphere. Four ejaculates from
each buck (n = 2) were collected in each experiment. After collection, semen was divided,
with each sample being diluted in the semen extender – according to the treatments (T1
– 20% egg yolk or T2 – 2.5% egg yolk, using a glucose–EDTA extender). For T1 treatment in
Experiment 2, the semen was also washed before the semen cryopreservation process. The
semen samples were frozen, and after thawing evaluated for seminal characteristics i.e.
sperm motility, vigor, morphology and membrane integrity. The fertilising capacity of the
frozen-thawed semen was evaluated following a single artificial insemination 12 h after the
onset of estrus in 50 (Experiment 1) and 60 does (Experiment 2). In Experiments 1 and 2,
the mean values for sperm motility and membrane integrity of the frozen-thawed semen
did not differ between the T1 and T2 treatments. However, the mean sperm vigor and
morphological normal sperm were greater (P < 0.05) in T2 than T1 treatment. The fertility
rates recorded did not differ between T1 and T2 treatments in Experiment 1, however, it
was greater (P < 0.05) in the T2 than in the T1 treatment, in Experiment 2. According to
obtained results, it can be recommended to use a glucose–EDTA extender with a low egg
yolk concentration (2.5%) inclusion, for superior fertility results in goats.
