Anuario Raza Polo Argentino Anuario2018 | Page 250

Regardless of ethical considerations regarding
abortion in pregnant mares, this system presents
a drawback in that we can only diagnose gender
of pregnancy through ultrasound screening when
it is two months pregnant. During that period the
breeder does not know for certain if he/she has the
desired female pregnancies or not, which makes
decision-taking a game of chance.
Since 2011 we began an embryo-sexing program
by means of embryo biopsy, which has enabled
us to discover its sex immediately after flushing,
when the embryo measures between 300 and
1000 microns approximately. Thus, only females
are transferred and if the embryo is male, it is
simply not transferred or may be frozen and kept in
a thermos indefinitely.
Biopsy sexing eliminates the disagreeable situation
of having to cause a mare to abort male pregnancies
and allows the breeder to know the sex of the
embryo immediately, even before knowing if that
embryo has actually become a pregnancy or not.
Embryo-biopsy procedures require a high level of
technology and equipment as well as great fine-
tuning effort. After several years working on this we
have reached excellent efficiency levels that do not
put embryo viability at risk during biopsy and are
highly reliable as regards diagnosis. Throughout
the 2019 season we have performed around 300
pregnancies from biopsy-sexed embryos, with
pregnancy percentages reaching over 75%, which
does not differ significantly from that obtained
through non-biopsied embryos. many advantages for the breeder on a local level.
We freeze sexed embryos in such a way that these
remain available for transfer at any time. Inasmuch
as the conditions in which nitrogen thermoses are
kept are adequate, those embryos maintain their
viability indefinitely.
Fort the local market, embryos are sexed first and
then frozen. In this way the breeder finishes the
season with a frozen embryo production which
he/she may transfer when he/she wishes; the year
he/she wishes to do so and at the moment he/she
desires. This has huge advantages for the breeder
who may season his/her foaling and decide which
embryos to transfer and which to keep for the
future.
2012 Embryo Cryopreservation Embryo production all year round: through
aspiration of follicles present in the ovary, it is
possible to obtain multiple immature oocytes.
Sometimes up to 20 oocytes that later mature
in vitro and are then injected individually with a
spermatozoon. This procedure may be carried out
The possibility of freezing embryos in order to be
able to transfer them at the best time of the year
is something that not many breeders are aware of
as yet, but it is technically possible and provides
248
2019: Today it is ICSI
This consists of the mechanical injection of a sperm
cell into the mature oocyte and its incubation in an
incubator for about 8-9 days approximately. This
technique has been used in humans for over 25
years for cases of masculine and feminine infertility.
It is only a few years ago and in very few places
around the world that this technique is being used
in horses with advantages and applications that
are much broader than those seen in its use in
human medicine. At Doña Pilar this year, the first
commercial offspring produced through ICSI were
born, and currently our laboratory has added this
technique as a new routine procedure. The most
outstanding advantages of ICSI for the breeder are: