Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF,, PARIS, 1948, VOL. i

FERTILITY OF FROZEN STALLION SEMEN AND SOME FACTORS AFFECTING TO
e

H. OSHIDA, S. HORIUCHI*, H. TAKAHASHI*, T. TOMIZUKA** AND
H. NAGASE#*#*

Haramachi Livestock Hygine Service Center, Haramachi-shi,
Fukushima

* Hokuren-Kitami Division, Kitami-shi, Hokkaido

** National Institute of Animal Industry, Chiba-shi, Japan

Nagase et al =3 developed successfully the freezing
method of stallion semen in concentrated pellet from since 1963.
Other researchers also reported successful results using pellet
frozen stallion semen (4.5). Ampoule and straw methods for
frozen stallion semen also have been used successfully. (6.7).

A field trial using the pellet frozen stallion semen was
conducted in Fukushima prefecture and Kitami districts, Hokkaido,
in 1967.

MATERIALS and METHODS. Semen collected from 5 stallions
(Percheron, Breton 3, Pony 1) was prediluted 1:1 with 5 per cent
glucose solution contained 5 per cent egg-yolk for centrifugation.
The sperm fraction was concentrated by 20 min. centrifugation at
1,300 g and the supernatant removed. This was rediluted 1:2-3
with the extender composed of 10 parts of yolk, 5.5 parts of
glycerol and mixed sugar medium 84.5 parts. The sugar medium

for freezing was mixed from each stock solution containing 7.5
per cent glucose, 10 per cent lactose and 18 per cent raffinose
in 30, 40 and 30 parts respectively.

After cooling to 5°C and equilibrating with glycerol for 2-3
hrs, 0.2 ml of the semen was frozen in pellet from on dry ice in
a freezing box. The pelleted frozen semen was transplanted to
small plastic tubes and sealed by a special electric heat sealer
using alminium-polyethylene film in the freezing box. During
sealing, the plastic tubes were held in dry ice. Then the
pelleted frozen semen were stored in liquid nitrogen until use.

Technicians carried- the semen to farmers from the storing
unit in a small Dewar flask with dry ice or liquid nitrogen.

Inseminations were carried out soon after thawing, using
3-5 pellets of semen in 20 ml of the thawing media kept at
3501Gs

Ingredients of the thawing medium were as follows; skim
milk 500 ml. 1.3% Sod. carbonate--12.5 ml, 1.5% potassium
carbonate--12.5 ml, 3.0% sod. citrate--237.5 ml and 6.5%
glucose. The pH of the medium was adjusted to 7.0 using 5.5%

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