X-Message-Number: 24515
From: "Basie" <>
Subject: Improving the success rate
Date: Sun, 15 Aug 2004 23:13:23 -0400

Maybe we can learn something. Salts, nutrients, buffer compounds?

<For successful cryopreservation, sperm must be emersed into a special
solution before freezing. The solution, called an extender, always contains
salts, nutrients, buffer compounds and most importantly, a cryoprotectant>

Frozen semen is a hot topic among horse breeders
by Jenny Tye
(Guelph, October, 1996)

Improving the success rate of stallion sperm preservation will mean an
increase in breeding options, say U of G researchers.

Cryopreservation is the process of deep-freezing cell, tissues or gametes
for later use. However, in horses, variation in sperm survival following
freezing, between individual stallions, hinders this technology.
Veterinarian researchers Claire Plante, John Pollard, Walter Johnson and
DVSc Student Tracey Chenier, theriogenology, are identifying factors which
underlie semen variability in response to freezing.

By studying and improving individual elements of the freezing process they
hope to gain new insight into why variation exists -- and how to overcome
it.

"Currently, only a third of stallion sperm will freeze well; the rest
freezes poorly or not at all," says Chenier. "We want to develop a freezing
method which, upon thawing, will result in the highest number of viable
sperm for the highest number of stallions."

For successful cryopreservation, sperm must be emersed into a special
solution before freezing. The solution, called an extender, always contains
salts, nutrients, buffer compounds and most importantly, a cryoprotectant.

A cryoprotectant is a chemical -- commonly glycerol -- which protects the
cell from damage during freezing. Chenier is testing the toxicity and
permeability of different cryoprotectants in equine sperm. These chemicals,
after long exposure, are potentially poisonous to cells, yet under the right
circumstances they can be used to the researcher=s advantage. Permeability
is an issue because the more easily a cryoprotectant can cross a sperm's
membrane, the more efficiently it protects the cell during freezing.

Plante and Pollard are determining which extender (other than
cryoprotectants) offer the best support for sperm during freezing. They're
examining the individual performance of each ingredient, as well as how
different extender ingredients perform together.

To this end, the researchers are freezing semen in different extenders and
then evaluating the sperm's motility and viability after thawing.

Once the researchers know which cryoprotector and maintenance ingredients
work best in horse semen cryopreservation, the information will be combined
to generate more effective extenders. The next challenge will be to
determine what concentration of each ingredient, when combined, provides the
best freezing support for the majority of horse semen.

Since there are hundreds of possible concentration variations, Plante and
Pollard will be using a computer program called Simplex Optimization,
developed by Statistical Programs, to help with the elimination process. The
sperm from those extender variations which result in good sperm viability
after freezing and thawing will be used to artificially inseminate mares to
collect pregnancy rates.

For each group of solutions used, pregnancy rates, sperm motility and other
variables will be entered into the program. It will sort and analyze the
data and inform the researchers how to alter individual concentrations to
get increased pregnancy rates in future trials.

There are many advantages to deep-freezing techniques in the horse breeding
industry. Of primary interest, the costly and dangerous transport of animals
for the purpose of breeding between countries can be replaced by the
transport of the sperm itself. Long term semen storage is also a valuable
means of banking genetic information for the future.

"Even at this early stage of the project, we're learning new information
about the nature of horse sperm everyday," says Plante. "If we can develop
improved extenders, artificial insemination with preserved semen will become
a more reliable and popular breeding option for horse owners and
veterinarians."

This study is sponsored by the Ontario Veterinary College and the Ontario
Ministry of Agriculture, Food and Rural Affairs.

Frozen semen is a hot topic among horse breeders
by Jenny Tye
(Guelph, October, 1996)

Improving the success rate of stallion sperm preservation will mean an
increase in breeding options, say U of G researchers.

Cryopreservation is the process of deep-freezing cell, tissues or gametes
for later use. However, in horses, variation in sperm survival following
freezing, between individual stallions, hinders this technology.
Veterinarian researchers Claire Plante, John Pollard, Walter Johnson and
DVSc Student Tracey Chenier, theriogenology, are identifying factors which
underlie semen variability in response to freezing.

By studying and improving individual elements of the freezing process they
hope to gain new insight into why variation exists -- and how to overcome
it.

"Currently, only a third of stallion sperm will freeze well; the rest
freezes poorly or not at all," says Chenier. "We want to develop a freezing
method which, upon thawing, will result in the highest number of viable
sperm for the highest number of stallions."

For successful cryopreservation, sperm must be emersed into a special
solution before freezing. The solution, called an extender, always contains
salts, nutrients, buffer compounds and most importantly, a cryoprotectant.

A cryoprotectant is a chemical -- commonly glycerol -- which protects the
cell from damage during freezing. Chenier is testing the toxicity and
permeability of different cryoprotectants in equine sperm. These chemicals,
after long exposure, are potentially poisonous to cells, yet under the right
circumstances they can be used to the researcher=s advantage. Permeability
is an issue because the more easily a cryoprotectant can cross a sperm's
membrane, the more efficiently it protects the cell during freezing.

Plante and Pollard are determining which extender (other than
cryoprotectants) offer the best support for sperm during freezing. They're
examining the individual performance of each ingredient, as well as how
different extender ingredients perform together.

To this end, the researchers are freezing semen in different extenders and
then evaluating the sperm's motility and viability after thawing.

Once the researchers know which cryoprotector and maintenance ingredients
work best in horse semen cryopreservation, the information will be combined
to generate more effective extenders. The next challenge will be to
determine what concentration of each ingredient, when combined, provides the
best freezing support for the majority of horse semen.

Since there are hundreds of possible concentration variations, Plante and
Pollard will be using a computer program called Simplex Optimization,
developed by Statistical Programs, to help with the elimination process. The
sperm from those extender variations which result in good sperm viability
after freezing and thawing will be used to artificially inseminate mares to
collect pregnancy rates.

For each group of solutions used, pregnancy rates, sperm motility and other
variables will be entered into the program. It will sort and analyze the
data and inform the researchers how to alter individual concentrations to
get increased pregnancy rates in future trials.

There are many advantages to deep-freezing techniques in the horse breeding
industry. Of primary interest, the costly and dangerous transport of animals
for the purpose of breeding between countries can be replaced by the
transport of the sperm itself. Long term semen storage is also a valuable
means of banking genetic information for the future.

"Even at this early stage of the project, we're learning new information
about the nature of horse sperm everyday," says Plante. "If we can develop
improved extenders, artificial insemination with preserved semen will become
a more reliable and popular breeding option for horse owners and
veterinarians."

This study is sponsored by the Ontario Veterinary College and the Ontario
Ministry of Agriculture, Food and Rural Affairs.

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