Anatomy & Physiology of the Reproductive System ANATOMY & PHYSIOLOGY 13-14.
Review of Reproductive Physiology
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Transcript of Review of Reproductive Physiology
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Review of Reproductive Review of Reproductive PhysiologyPhysiology
Jeffrey S. Stevenson, Ph.D.Jeffrey S. Stevenson, Ph.D.
Ontario Association ofOntario Association ofBovine PractitionersBovine Practitioners
Reproductive SymposiumReproductive Symposium
Department of Animal Sciences
and Industry
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20 inches(508 mm) 20-24 inches
(508-640 mm)28-32 inches(711-813 mm)
32-36 inches(813-914
mm)36-40 inches
(914-1016 mm)
>40 inches(>1016 mm)
24-28 inches(640-711 mm)
Annual Precipitation
State of KansasState of Kansas#1 in wheat#1 cattle slaughtered#1 in sorghum grain (milo)#1 in sorghum silage produced#2 in acres of crop land#2 cattle and calves#5 in agricultural exports#10 in milk yield per dairy cow#18 in milk produced
Manhattan
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Gonadotropin-Gonadotropin-Releasing Hormone Releasing Hormone
(GnRH)(GnRH)• Secreted by the GnRH-secreting neurons of
the anterior and medial basal hypothalamus• Stimulates release of LH• Stimulates release of FSH• Induces ovulation through LH release• Marketed as gonadorelins: Cystorelin,
Factrel, Fertagyl, and OvaCyst or as GnRH agonist: Buserelin or Receptal
Hypothalamus
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Follicle-Follicle-Stimulating Stimulating
Hormone (FSH)Hormone (FSH)
• Secreted by the anterior pituitary gland• Initiates cyclic waves of follicle growth• Recruits pre-antral follicles to develop an
antrum and become antral follicles• Stimulates biosynthesis of estrogen by
granulosa cells from thecal cell derived androgen precursors
Hypothalamus
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• Secreted by the anterior pituitary gland• Stimulates antral follicle maturation• Induces ovulation of mature antral or
pre-ovulatory follicles• Stimulates secretion of androgens by
theca cells from cholesterol• Stimulates secretion of progesterone
by the corpus luteum
Luteinizing Luteinizing Hormone (LH)Hormone (LH)
Hypothalamus
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Theca cell Granulosa cell
Follicle basement membrane
Cholesterol
Pregnenolone
Progesterone
Androstenedione
(+)
Testosterone
Estradiol-17
Cholesterol
Pregnenolone
Progesterone
LH
LH
FSH
(+)
Estradiol-17Estradiol-17(blood) (follicular fluid)
(–)(–)
(+)
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• Secreted by the follicle• Induces sexual behavior• Induces pre-ovulatory surge of
LH• Stimulates development of
reproductive tract• Synergizes with progesterone to
induced proliferation and function of uterine glands and their secretions
Estrogen Estrogen (Estradiol-17(Estradiol-17)) Ovary
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ProgesteroneProgesterone
• Secreted by the corpus luteum• Induces development of uterine
endometrium• Prevents estrus and ovulation by
negative feedback inhibition of LH secretion
X X
OvaryCL
OvaryX
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LH
E2
Onset of estrus
Onset of ovulation
27 hrEstrus
P4
0 2 4 0 2 4 0 2 4HoursHours Hours
E2
LH
E2
LH
E2
LH
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Prostaglandin Prostaglandin
FF22
• Secreted by the uterus• Induces death (lysis) of the corpus
luteum (CL)• Initiates early uterine contractions
as a smooth muscle stimulator• Marketed as Lutalyse, Prostamate,
In-Synch, EstroPlan, and Estrumate (agonist) X
Ovary
CL
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5 10 15
PGF2
21
LHLH
P4
Days of the Bovine Estrous Cycle
OvulationE
stru
s
FSH
E2
Metestrus Diestrus Proestrus
Ovulation
0
Est
rus
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02468
1012141618
0 3 6 9 12 15 18 21Days of Cycle
Pro
gest
eron
e (n
g/m
L)
0
20
40
60
80
100
Lute
olyt
ic r
espo
nse
(%)
Progesterone Luteolytic Response DF1 DF2
The Estrous Cycle: Follicle Waves, The Estrous Cycle: Follicle Waves, Progesterone, and LuteolysisProgesterone, and Luteolysis
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Normal Interval to EstrusNormal Interval to Estrus
02468
1012141618
0 3 6 9 12 15 18 21Days of Cycle
Fol
licle
dia
met
er (
mm
)
PGF2
Estrus
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Shorter Interval to Estrus after Shorter Interval to Estrus after PGFPGF
02468
1012141618
0 3 6 9 12 15 18 21Days of Cycle
Fol
licle
dia
met
er (
mm
)
Est rus
PGF2
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Longer Interval to Estrus after Longer Interval to Estrus after PGFPGF
02468
1012141618
0 3 6 9 12 15 18 21
Days of Cycle
Fol
licle
dia
met
er (
mm
)
Estrus
PGF2
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GnRH-Induced Ovulation of GnRH-Induced Ovulation of Dominant FolliclesDominant Follicles
02468
1012141618
0 3 6 9 12 15 18 21Days of Cycle
Fo
llicl
e d
iam
ete
r (m
m)
Estrus
LH dependent
XX
XX
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02468
1012141618
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
02468
1012141618
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150
Days postpartumStagg et al. (1995)
*
* *
*
Growth and Developmentof Dominant Follicles
(Suckled Cow)
Fol
licle
dia
met
er (
mm
)
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Early Postpartum Follicular Early Postpartum Follicular WavesWaves
(Milked Cow)(Milked Cow)
0
5
10
15
20
0 2 4 6 8 10 12 14 16 18 20
Days postpartum
Fo
llicl
e d
iam
ete
r, m
m
Ovulation
Beam and Butler, 1996
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Frequency of LH PulsesFrequency of LH Pulses
0
1
2
3
4
0 2 4 6 8 10 12 14 16
Hours
LH
( n
g/m
L)
Week 1 Week 2-3 Week 4-6
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Weeks from energy balance nadir (0)
Cow 3 2 1 0 +1 +2 1 1 3 6 5 2 1 2 3 4 5 3 2 6 7 4 0 3 7 8 7 5 1 4 6 6 6 0 2 3 4 5 7 7 0 5 6 7 8 2 4 4 5 6 9 0 3 5 5 6 7 10 3 8
No. of LH Pulses/8 hr - Milked No. of LH Pulses/8 hr - Milked CowsCows
Canfield and Butler, 1990
First ovulation followed the last blood
collection series by 2.5 0.4
days.
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Energy BalanceEnergy Balance
IntakeMetabolism
and Partitioning
Expenditures
Feed
Liver
Oxidizable metabolic
fuels
Adipose tissue
Fat stores
Reproduction
ThermoregulationCell
maintenance
Growth (NEG)
Milk yield (NEL)
Locomotion
(+) (–)
NEM
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Energy Balance and First Energy Balance and First OvulationOvulation
Item
Mean of 17 dairy cows
SE
Body weight, kg (lbs) Calving Change during anovulation
729 (1607) 56 (123)
13 8
Energy balance, Mcal/day Anovulation
17.5*
4.2
Interval, days Calving to EB nadir EB nadir to ovulation Calving to ovulation
8.7 15.4 24.1
1.1 1.2 1.5
Zurek et al. (1995)
*Sufficient energy to produce
57 lb (26 kg) of milk/day
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Uterine InvolutionUterine Involution
0
50
100
150
200
250
5 10 15 20 25 30 35 40 45 50
Days postpartum
Ute
rine
horn
dia
met
er,
mm
Gravid horn
Nongravid horn
Marion and Gier, 1968
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E2
FSH
LH
IGF-I
Calving
Days postpartum
Ovulation
Nadir of EB
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1015202530354045
2.25 2.50 2.75 3.00 3.25 3.50 3.75
BCS at 70 days in milk
Ano
vula
tion,
%
Body Condition Scores of Dairy Body Condition Scores of Dairy Cattle at 70 DIM and AnovulationCattle at 70 DIM and Anovulation
Santos et al., 2004
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Body Weight Loss in Dairy Body Weight Loss in Dairy CowsCows
-80
-60
-40
-20
0
20
40
60
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Weeks postpartum
kg
3x Milked
6x Milked
Suckled
Bar Peled et al. (1995)
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Dry Matter Intake for Dairy Dry Matter Intake for Dairy CowsCows
0
5
10
15
20
25
1 2 3 4 5 6 7 8 9 10
Weeks postpartum
kg/d
ay
3x Milked
6x Milked
Suckled
Bar Peled et al. (1995)
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Estimates of Cycling StatusEstimates of Cycling Status
010
2030
4050
6070
8090
100
1 2 3 4 5 6 7 8
Herd-Year
% c
yclin
g
2-yr-old cowsOlder cows
• Cycling status during 1 to 3 wk before the end of the VWP (estimated by measuring blood progesterone)
793 first-lactation cows averaged 74.2%
1,126 multiple-lactation cows averaged 80.5%
Stevenson, 2001
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Prebreeding Anestrus inPrebreeding Anestrus inLactating Holstein CowsLactating Holstein Cows
Item
Early Late Very late
No. of cows 25 14 15 Days to first ovulation 22 43 Days to first estrus 47 73 110 4% milk, kg/day 34 32 29 DM intake, kg/day 19 18 15 BW change, kg/day 0.8 0.8 1.2
Staples et al. (1990)
Onset of First OvulationOnset of First Ovulation
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Milking Frequency - Exp. 1Milking Frequency - Exp. 1
Trait
Milked 3x
Milked 6x for 6 wk
Milked 3x + Suckled 3x
Days to 1st ovul. Days to 1st estrus Days to pregnancy 6-wk milk yield, kg/d Nadir of EB, Mcal/d Week at zero EB
26 46
112 35 9 6
37 76
184 43 14 10
48 48
100 50 19 8
Bar-Peled et al. (1995)
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Milking Frequency - Exp. Milking Frequency - Exp. 22
Trait
Milked 3x
Milked 6x for 3 wk
Milked 6x for 6 wk
Days to 1st ovul. Days to 1st estrus Days to pregnancy 6-wk milk yield, kg/d 6-wk weight loss, kg Week at zero EB
22 45
105 35 24 6
30 61
148 40 29 -
39 75
189 42 32 10
Bar-Peled et al. (1995)
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Thank you!
Department of Animal Sciences
and Industry
Ontario Association ofOntario Association ofBovine PractitionersBovine Practitioners
Reproductive SymposiumReproductive Symposium