Artificial insemination (AI)Semen w

Artificial insemination (AI)
Semen was collected from a Suffolk ram (3 years old) using an
artificial vagina and was diluted 10 to 15 folds in a water bath (30
C) to give a final sperm concentration of 250 × 106/ml. Three
semen extenders were used: Tris-based extenders containing
297.58 mM Tris, 96.32 mM citric acid, 82.66 mM fructose, 5% (v/
v) glycerol and either 15% (v/v) egg yolk [18] or 10% (w/v) BSA
[15, 19] and AndroMed. The diluted semen was gradually cooled
to 4 C for 2–3 h. The cooled semen was frozen in 0.25-ml straws
according to the methods described previously [19]. In brief, the
semen samples were packed in straws and kept at 4 C before freezing.
They were exposed to liquid nitrogen (LN2) vapor (–125 C to
–130 C) for 3–4 min, plunged into LN2 (–196 C), and stored in LN2
until use for AI.
The frozen straws were thawed at 37 C in a water bath for 20–30
sec, and the motility of the spermatozoa in each straw was evaluated.
The straws with a percentage of motile spermatozoa of
approximately 50% were used for AI.