high quality pre-freeze.

The fourth ram in the group (Finland) gave poor quality semen and
there was considerable deterioration over the period.

A further series of collections carried out twelve months ago included
six different breeds of rams - Suffolk, Galway, Border Leicester, Dorset
Horn, Blackface, Finland. These rams were divided into two groups of
fifteen and collected by electro-ejaculation every fourteen days. The
technique adapted was the same as in the previous series. The period
covered was June 1967 to September 1967.

The quality of raw semen from the different breeds of ram did not
show a wide variation over the four months collection period. The dead/
alive average of 90% was maintained in all breds. Very occasionally a
ram failed to give a sample.

The semen was maintained in a water bath at 37°C and added to the
diluent at this temperature. The diluent used in this series was: 75 cc
of an 11% lactose solution, 20 cc egg yolk, 5 cc glycerol. As in the
previous series an equilibration period of four hours was allowed.

Recovery after one year storage at -196°C varied from 60% to 85%
live sperm dependent on the quality of the fresh semen and the individual
ram. As with the bull some ram semen appears to freeze better than others.
This may be related to the fructose content in the ram semen. Fructose
estimations carried out on ten samples of ram semen showed a wide varia-
tion in the range 40 to 360 mg per cenit. This variation was observed
even in the same ram in different collections taken on the same day.
Unfortunately it was not possible to freeze these samples. Early freezing
was carried out in 1 cc straws, later 0.5 cc straws were in use and finally
mini straws.

The 0.5 cc and mini straws gave the best results, It is hoped to
carry out tests for fertility with the long term stored semen in the near
future.

Conclusions.  Ram semen can be successfully frozen in lactose-
yolk-glycerol in straws. Long term storing in liquid nitrogen does not
appear to affect the recovery rate. Only semen of the highest quality
is suitable for freezing.

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