Vie CONG. INTERN. REPROD. ANIM. INSEM. ARTIF., PARIS, 1968, VOL. li

SPIN FREEZING OF SEMEN*

A.H.J.Rajamannan
Eastern A.l. Cooperative Inc., lthaca, N.Y.

E. F. Graham
University of Minnesota, St. Paul, Minn.

  

The "problem bull" with poor or non-freezable semen and the normal freeze kill during
freezing of semen are problems that need solution. These problems could well be one but with
varying degrees of severity. The culling of the "problem bull" and increasing the semen con-
centration to make up for the freeze kill do not solve these problems.

A variety of temperature profiles have been shown to occur within a system when a liquid
is frozen in either cylindrical or spherical models (1, 2). A similar variation in the temp-
erature profile occurring during freezing and thawing of semen frozen in an ampule has been
observed in our laboratory. These differences in freezing rates at various sites within an
ampule affect the recovery pattern of semen from these sites. The nosition of the thermo-
couple in the ampule affects the temperature curve that is recorded. Stallion and Boar semen
frozen in large bulk are bound to be affected by an exaggeration of the above differences.

The different freezing rates obtained within a single ampule makes it quite difficult to study
precisely the freezing rates necessary for optimum survival of semen. The entire mass of se-

men frozen and thawed in an ampule therefore cannot be said to have been subjected to a speci-
fic cooling or warming velocity.

Rapid freezing and rapid thawing considered necessary for improved survival (3, 4, 5) is
virtually impossible, especially when semen is frozen in large bulk.

To achieve a uniform cooling and warming velocity through the entire mass of semen, to
enable one to subject such a mass to rapid freezing and thawing, the semen should have a maxi-
mum surface area for a given volume.

The spin freeze method described here was developed as a means of subjecting the semen
not only to a uniform cooling and warming velocity, but also to cause simultaneous nucleation
through the entire mass.

MATERIALS AND METHODS

Bull semen was extended in Minn Go (6) and Raffinose-yolk-glycerol (7) G. W. Extender
(an experimental extender tested by Graham) according to directions and frozen four hours af-
ter addition of the glycerol portion of the extender. The semen was frozen regular and spun
in the vapour phase of an M.V.E. 9000 unit.

SPIN FREEZE METHOD

Semen ampules | cc, pharmeceutical ampules of 50 and 100 cc volumes were used for con-
tainers. Semen was taken in the containers from 1/10 to 7/10 of their volume. A special
holder was made that secured the ampules to a variable speed motor. The ampule of semen was
secured to this motor. The motor was started slowly, the speed increased until the semen
coated the insides of the container. The whole apparatus was lowered into the vapour phase
of semen storage unit. When the sides of the ampule turned opaque, the motor was stopped and
the freezing allowed to continue for five minutes more.

As an alternate method the ampule connected to the motor was lowered into the vapour
phase and super-cooled for two minutes or until just prior to crystallization. At this time
the motor was started and the semen froze on the sides in a thin layer.

A special apparatus was manufactured that could spin an entire cane or five canes at a
time. The whole apparatus could be loaded with canes and lowered into the vapour phase of
the large mouthed M.V.E. 9000 unit. After a | minute pause for super-cool ing the motor con-

* gcientific Journal series No. 6583.

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