damage due to freezing is a result of electrolyte concentration
within the cell.

In the freezing and thawing experiments, spermatozoa motility
was highest using Methods A and D, respectively. The results of
glycerol concentration freezing showed that 7 percent glycerol was
the most effective in Trials I to IV. Recently, Shaffner (11) found
that 8 percent glycerol is the maximum amount that can be used, to
successfully protect against the harmful effects of freezing.

Superior motility maintenance was obtained in semen samples
equilibrated at 5°C in contrast to those equilibrated at 10°C and 20°C.
Since glycerol equilibration for fowl semen has been little studied
(except #or the experiment of Brown and Harris (10) who equilibrated
the semen samples at 2°C in their experiment), this study attempts to
show the influence of freegzing on spermatozoa motility.

Of the semen samples stored at 20°C, 30°C, and 37°C after thaw-
ing, those stored at 20°C had a significantly higher motility. The
results of the present study agree with those of Brown and al (10).

As for the effect of various equilibration times in freezing
the spermatozoa, best results were obtained when the semen samples
equilibrated at 5°C for 60 minutes in Trials I, II, III and IV. When
the equilibration time exceeded 180 minutes, motility was quickly
reduced, and became zero when equilibrated over 360 minutes.

In the correlation experiments between the various periods for
freezing fowl semen and the motility of semen after thawing, there
were no remarkable differences between, 1, 7, 1%, 30, 90, 150, 180,
and 365 day storage at -79°C. Previously Shaffner (2) indicated that
time is no an important factor in motility retention during the first
year when fowl semen is constantly maintained at the temperature of
solid COQ.

The successful results of insemination making use of semen
samples stored for 30, 90, and 100 days were 29. 1 %, 25.0 %, and
14.3 % in the first week, and 8.6 %, 0 %, and 25 % in the second week,
respectively. This non-fertility in the second week of 90-day storage
was due to the fact that laying no longer occured from the 8th week
onward because the hen molted seriously and stopped laying at that
season. Throughout the experiment, fertility was poor in comparison
to the motility of the semen after thawing. The cause of this poor
fertility is not well known yet, and we have tried to clarify the
question in this study.

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