❞ كتاب Exogenous control of follicular wave emergence in cattle ❝

Exogenous control of follicular wave emergence in cattle

Exogenous control of follicular wave emergence in cattle من كتب طب بيطرى

EXOGENOUS
CONTROL
OF
FOLLICULAR
WAVE
EMERGENCE
IN
CATTLE
G.A.
Bo’,
G.P.
Adams’,
R.A.
Pierson3
and
R.J.
Mapletoft’
‘Departments
of
Herd
Medicine
and
Theriogenology,
and
2Veterinaty
Anatomy,
W.C.V.M.
3Department
of
Obstetrics
and
Gynecology,
College
of
Medicine,
University
of
Saskatchewan,
Saskatoon,
Saskatchewan,
Canada
S7N
OWO.
ABSTRACT
Variability
in
ovarian
response
to
superstimulatory
treatments
and
in
the
interval
from
PGF20
treatment
to
es&us
in
cattle
is
largely
attributable
to
the
status
of
follicular
wave
development
at
the
time
of
treatment.
To
date,
most
treatments
designed
to
control
follicular
wave
development
have
been
based
on
removal
of
the
suppressive
effect
of
the
dominant
follicle,
either
physically
(by
electrocauterization
or
ultrasound-guided
follicle
ablation)
or
hormonally
(by
GnRH
or
estradiol
and
progestogen
treatment),
and
thereby
induce
the
emergence
of
a
new
follicular
wave
at
a
specific
time
after
treatment.
Treatment
of
progestogen-implanted
cattle
with
estradiol-17P
(E-17P)
resulted
in
suppression
of
the
dominant
follicle
and
emergence
of
a
new
follicular
wave
4.3
d9.1
d
later.
Superstimulatory
treatments
initiated
4
d
after
E-17P
treatment
in
progestogen-implanted
cattle
resulted
in
a
superovulatory
response
comparable
to
that
of
cattle
in
which
superstimulatory
treatments
were
initiated
on
the
second
follicular
wave.
In
another
study,
induced
follicular
wave
emergence,
regardless
of
the
stage
of
the
estrous
cycle,
resulted
in
similar
superovulatory
response
and
higher
fertilization
rates
in
heifers
than
when
superstimulatory
treatments
were
initiated
8
to
12
d
after
estrus
(traditional
approach).
Finally,
es&us
synchronization
treatments
with
E-17P
plus
progesterone
and
PGF2,
have
resulted
in
synchronous
estms
and
ovulation.
Overall,
it
. المزيد..