Vle CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. I

PROTECTIVE EFFECTS OF POLYOLS AGAINST FREEZING INJURY OF BULL
SPERMATOZOA I. PROTECTIVE EFFECTS OF XYLITOL

H. NAGASE
National Institute of Animal Industry, Chiba-shi, Japan

There are very few observations on protective effects of
polyhydric alcohols on survival of spermatozoa during freezing,
and they have afforded only limited protection (1, 2y Triats
were conducted to elucidate the protection of polyols on survival
of bull spermatozoa in the pellet freezing.

MATERIALS and METHODS., To determine optimum level of polyols,
Holstein semen was diluted 1:9 with yolk (20%)-polyol
(erythritol, adnitol, xylitol, mannitol, sorbitol and inositol)
extender. The concentrations of each polyols were used from
isoosmotic level to 3.72M.

The diluted semen was incubated for one hr. at 20°C and then
spermatozoan motility was estimated,

In freezing trial 1, the diluted semen at the ratio 1;2 with
yolk (20%)-polyols was precooled to 5°C and frozen in pellet
form, 0.1 ml size, after 3 hrs of equilibration. The pelleted
frozen semen was thawed on a metal plate kept at 40°C and the
motility was estimated on the thawed samples with and without the
thawing solution (3).

In freezing trial 2, the semen extenders used were egg-yolk
isotonic basic media (sod. citrate, tris buffer (4), and glucose)
plus different levels of xylitol.

RESULTS and DISCUSSION, Fig. 1 shows the spermatozoan motility
in different levels of polyols—egg yolk solution without basic
solutes after one hr. incubation at 20°C. Best motility of each
polyols was obtained in levels of 0.31M inositol and mannitol,
0.62M in sorbitol, and 2.48M in xylitol, adnitol and erythritol.
These phenomena suggest that these sugar alcohols are permeable
to bull spermatozoa to differing degrees, Samples using low
molecular polyols (erythritol, xylitol and adnitol) in all levels
showed lower motilities of spermatozoa than those of higher
molecular ones (inositol, mannitol and sorbitol). Polge (5) and
Nagase (6) reported that bull spermatozoa died immediately after
dilution with egg yolk-ethylene glycol or - glycerol (lower
molecular substances than the sugar alcohols) solution without
any basic solutes, such as citrate and salt., Inositol seemed to
does not permeate to the spermatozoa.

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