Bull sperm freezing technique in medium containing polyethylene-oxide.

F.I. OSTASHKO, J.V, KALUGIN, M. kh, GLUZMAN, B,I. DASHESKAYA
Research Institute of Animal Breeding of the Forest-Steppe and Polesje Region,
K harkov, Ukraine, U.S.S.R.

Polyethlene-oxide molecules can, under influence of water and owing to
their meandering structure, "knit together" like oxonic combinations, into
structures with limited molecular mobility. This modifies their crystallization
characteristics and the thermodynamic processus occurring in the sperm during
freezing. The degree of the polyethylene-oxides protecting effect is antibating
to their molecular weights which proves the ability of these substances to
penetrate the cytoplasmatic membrane and affect intracellular structure.

Polyethylene-oxide with a molecular weight of 100, added to the sperm,
augments its adaptability to overcooling, lowers the osmdtic pressure and, in
case of rapid saturation, induces shock in spermatozoa. Bull sperm diluted with
a hypertonic medium (7.8 atm) containing 5% polyethylene-oxide with moleculal
w eight 100, stands freezing well in liquid nitrogen. After thawing, 45-50%
of spermatozoa recuperate their activity. According to preliminary data, 84.3%
of cows were fertilized after the first insemination with sperm conserved in
liquid nitrogen for 2 - 3 months.

Polyethylene-oxide possesses marked antibacterial properties which make
unnecessary the use of antibiotics in deep freezing.

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