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Female Reproduction
Anatomy and Physiology
Ryon Walker
PhD Grad Student,
CSU – Dept. of Animal Sciences
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Cow’s Reproductive CycleCow’s Reproductive Cycle
Reproductive
Tract
Follicles and
New CorpusLuteum
Mature Corpus
Luteum
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OvaryFemale Gonad (sex
gland)
Site of Action for LH,
FSH, PGF2alpha
Transient Organs
– Follicle
– Corpus Luteum
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OvaryOvary
GraffianGraffian Follicle (dominant follicle)Follicle (dominant follicle)
-- Fluid filled sacFluid filled sac – – oocyteoocyte developsdevelops-- OocyteOocyte suroundedsurounded by theca and by theca and granulosagranulosa cellscells
-- OvulationOvulation
CorpusCorpus LuteumLuteum (yellow body)(yellow body)
-- Develops at site of ovulationDevelops at site of ovulation
-- LutealLuteal cells develop from theca andcells develop from theca and granulosagranulosa
cellscells
-- Remains if female is pregnantRemains if female is pregnant
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Ovarian Structures
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Hormones
Hypothalamus
– Gonadtropin Releasing Hormone (GnRH)
Posterior Pituitary – Luteinizing Hormone (LH)
– Follicle Stimulating Hormone (FSH)
Ovary – Estrogen
– Progesterone
Uterus
– Prostaglandin F2α (PG)
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Estrous CycleEstrous Cycle
Alternating domination ofAlternating domination of either either ::
-- estrogen from follicleestrogen from follicle
-- Progesterone from corpusProgesterone from corpus luteumluteum
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Follicle ProductionFollicle Production
Pituitary gland releases:Pituitary gland releases:
-- FSH for initiating growth of folliclesFSH for initiating growth of follicles-- LH for steroid hormone production fromLH for steroid hormone production from
folliclefollicle GraffianGraffian follicle produces Estrogenfollicle produces Estrogen
CorpusCorpus LuteumLuteum produces Progesterone produces Progesterone
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Estrous CycleEstrous Cycle LutealLuteal Phase (d 1Phase (d 1--18)18)
Follicular Phase (d 18Follicular Phase (d 18--21)21)
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Estrous CycleEstrous Cycle
Estrus (d 0)Estrus (d 0)
Ovulation (d 1)Ovulation (d 1)
MetestrusMetestrus (d 1(d 1--5)5)
DiestrusDiestrus (d 5(d 5--17)17)
ProestrusProestrus (d 17(d 17--21)21)
Estrus (d 0)…….Estrus (d 0)…….
Follicular
Luteal
Follicular
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Estrus (day 0) Estrus (day 0)
Follicle maturesFollicle matures
Estrogen increases as follicle maturesEstrogen increases as follicle matures
Increase estrogen = increaseIncrease estrogen = increase GnRHGnRH
IncreaseIncrease GnRHGnRH = increase LH= increase LH
LH surgeLH surge
Estrus (standing heat)Estrus (standing heat)
OvulationOvulation
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Ovulation (day 1)Ovulation (day 1)
Oocyte (egg) release
Induced by LH surge
28 hours after first heat
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Metestrus Metestrus (day 1(day 1 – – 5)5)
Corpus luteum formation
Growth and development of follicular wave
Increase in progesterone production
– Non responsive to PG – Prepares uterus to accept fertilized egg
– Maintains pregnancy and prevents heat
– Presence of fetus keeps CL alive
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Diestrus Diestrus (day 5(day 5 – – 17)17)
Mature Corpus Luteum
Maximal progesterone production
GnRH inhibited by progesterone
Maternal recognition of pregnancy
Unfertilized cow: – PG kills CL and stops producing progesterone
around day 16 - 18
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Proestrus Proestrus (day 17(day 17 – – 21)21)
Prostaglandin production by uterus
Luteolysis
– Decreased progesterone production
– CL regresses
GnRH no longer inhibited
Final maturation of dominant follicle
Increased estrogen
..Estrus (d 0) … Ovulation (d 1)....Estrus (d 0) … Ovulation (d 1)..
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Estrous Cycle
0 2 4 6 8 10 12 14 16 18 20 1
H o r m
o n e L e v e l
Progesterone (P4)
Estradiol (E2)
Day of Estrous Cycle
New CL
Forming
Mature CL Present Fol. Size
& CL Size
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Sperm ActivitySperm Activity
Sperm travels and waits in oviduct (Sperm travels and waits in oviduct (ampullaampulla))
-- Sperm life span in female tract (24 hrs.)Sperm life span in female tract (24 hrs.)-- Need sperm in tract hours before egg Need sperm in tract hours before egg
releasedreleased-- Egg life span in female tract after releaseEgg life span in female tract after release
(8(8 -- 12 hrs.)12 hrs.)
-- Ovulation occurs 28 hours after heatOvulation occurs 28 hours after heat
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Approximately 6% of beef cattle
(cows) in Colorado are artificiallyinseminated.
About 18% of heifers in the US areartificially inseminated.
Why?
– According to a national survey the #1reason for not using synchronization or
AI “Time and Labor.”
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Obstacles
- Lack of producer
education.
- Economics of
time and labor.
- Inadequate Facilities
- Cost
- Relative poor conception rates.
- Lack of information
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Benefits of Synchronization
Tighter breeding and calving season
Decreased time needed for estrousdetection
Improved calf uniformity.
Increased time for post partum recovery
Inducement of estrous cycles, anestrous
cows
Increased calf performance.
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Classes of Synchronization
Drugs
1) Prostaglandins
2)Progestins
3) GnRH
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Prostaglandins
PGF2α
Causes regression of the corpus luteum
Stops progesterone block on estrogen and
LH release so follicle can mature andovulate.
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Prostaglandins
Cattle with a functional CL at time of PG
injection will exhibit estrus 2 to 7 days later.
Will only affect cattle in diestrus or the
luteal phase.
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Progestins
Synthetic progesterone - prevents estrusfrom occurring.
Most cows exhibit estrus 2-5 days afterremoval of progestins.
Administration: – Oral administration (MGA)
– Intravaginal insert (CIDR)
– Implant (Syncro-Mate B)
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GnRH
Causes release of LH and FSH.
LH and FSH act on the ovary to stimulate
follicular
development and
ovulation or
regression of
dominant follicle.
Manipulation of dominant follicle
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Manipulation of dominant follicle
with MGA Select Synch
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Follicle Study
Dominant Follicle Corpus Luteum
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Follicle Study
Dominant Follicle Corpus Luteum
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Red Cow Left Ovary
0
2
4
6
8
10
12
14
16
18
20
22
14 15 16 17 18 19 20 0 1 2 3 4 5 6 7 8 9 10 11 12 13
Day of Estrous
S i z e ( m m )
Follicle I
Follicle II
Follicle IIIFollicle IV
S h i ti St d
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Synchronization Study
SJBRC – 2003
Objective – Synchronize heifers to increase fertility with anew progestin (CIDR)
Heifers from three locations
– San Juan Basin Research Center (CO; 39 head)
– Beef Improvement Center (WY; 125 head) – Quinn Cattle CO (SD; 211 head)
P t l
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Protocol
• Control (CON) - Give nothing at breeding
• Treatment (Trtmt) - Give GnRH at breeding
Day 0 Day 7 Day 9
CIDR Insert
CON
54 h Mass Mate
CIDR InsertGnRH
CIDR RemovalPG Trtmt
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CIDRs
“T” shaped device (insert)
Wings collapse to form
a rod and inserted into
the applicator.
Nylon backbone
Progesterone
impregnated intosilicone skin.
1.38 g progesterone
CIDR Application
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CIDR Application
CIDR is applied into the vagina with an
applicator gun and released
CIDR is removed by pulling on tail.Progesterone levels rise dramatically within 1 hour.
F lli l S d SJBRC 2003
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Follicle Study – SJBRC 2003
Objective
– Measure dominant follicles at breeding
– Determine if ovulation occurs
P R lt
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Pregnancy Results
a
52.6 %
a
55 %
a
54 %
a
56.5 %
b
40.4 %
a
54.2 %
0
10
20
30
40
50
60
70
P r e g n a n c y R a
t e T A I , %
Colorado (CO) Wyoming (WY) South Dakota (SD)
CON
TRMT
Follicle Results
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Follicle Results
Follicle Size at Breeding
0
10
20
30
40
50
60
70
80
90
100
P r e g n a n c
y R a t e , %
10 - 11.9
mm
12 - 13.9
mm
14 - 15.9
mm
16 - 18 mm
Follicle
Diameter
Follicle Results
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Follicle Results
Ovulation
0
1020
30
40
50
60
70
80
90
P r e g n a n c y R
a t e , %
Control Treatment
Ovulation, %
Pregnancy Rate, %