Transcript Review of Reproductive Physiology

Ontario Association of
Bovine Practitioners
Reproductive Symposium
Review of Reproductive Physiology
Jeffrey S. Stevenson, Ph.D.
Department of Animal
Sciences and Industry
State 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
20 inches
(508 mm)
20-24 inches
(508-640 mm)
Manhattan
24-28 inches
>40 inches
32-36 inches
28-32
inches
(640-711 mm)
(813-914 36-40 inches (>1016 mm)
(711-813 mm)
(914-1016
mm)
mm)
Annual Precipitation
Gonadotropin-Releasing
Hormone (GnRH)
Hypothalamus
• 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
Follicle-Stimulating
Hormone (FSH)
Hypothalamus
• 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
Luteinizing Hormone (LH)
• 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
Theca cell
Cholesterol
(+)
Pregnenolone
(–)
Progesterone
Androstenedione
Estradiol-17
(blood)
Granulosa cell
Cholesterol
(+)
Pregnenolone (–)
Testosterone
(+) Progesterone
Estradiol-17
Estradiol-17
(follicular fluid)
Follicle basement membrane
Estrogen
(Estradiol-17)
• 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
Ovary
Progesterone
CL
Ovary
• Secreted by the corpus luteum
• Induces development of uterine
endometrium
• Prevents estrus and ovulation by
negative feedback inhibition of LH
secretion
X
X
X
Ovary
Estrus
27 hr
E2
P4
LH
0
2
Hours
Onset of
ovulation
Onset of
estrus
E2
E2
E2
LH
LH
LH
4
0
2
Hours
4
0
2
Hours
4
Prostaglandin F2
• 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)
CL
X
Ovary
Ovulation
Ovulation
Diestrus
Estrus
Estrus
Metestrus
E2
P4
LH
LH
PGF2
FSH
0
5
10
15
Days of the Bovine Estrous Cycle
21
The Estrous Cycle: Follicle Waves,
Progesterone, and Luteolysis
Luteolytic Response
DF1
DF2
18
16
14
12
10
8
6
4
2
0
100
80
60
40
20
0
0
3
6
9
12
Days of Cycle
15
18
21
Luteolytic response (%)
Progesterone (ng/mL)
Progesterone
Follicle diameter (mm)
Normal Interval to Estrus
18
16
14
12
10
8
6
4
2
0
PGF2
E
s
t
r
u
s
0
3
6
9
12
15
Days of Cycle
18
21
Follicle diameter (mm)
Shorter Interval to Estrus after PGF
18
16
14
12
10
8
6
4
2
0
PGF2
0
3
6
9
E
s
t
r
u
s
12
15
Days of Cycle
18
21
Follicle diameter (mm)
Longer Interval to Estrus after PGF
18
16
14
12
10
8
6
4
2
0
PGF2
E
s
t
r
u
s
0
3
6
9
12
15
Days of Cycle
18
21
Follicle diameter (mm)
GnRH-Induced Ovulation of
Dominant Follicles
18
16
14
12
10
8
6
4
2
0
LH
dependent
X
X
E
s
t
r
u
s
X
X
0
3
6
9
12
15
Days of Cycle
18
21
18
16
14
12
10
8
6
4
2
0
Growth and Development
of Dominant Follicles
*
(Suckled Cow)
*
0
10
20
30
40
50
60
70
80
90 100 110 120 130 140 150
18
16
14
12
10
8
6
4
2
0
**
0
10
20
Stagg et al. (1995)
30
40
50
60
70
80
90 100 110 120 130 140 150
Days postpartum
Early Postpartum Follicular Waves
(Milked Cow)
Follicle diameter, mm
Ovulation
20
15
10
5
0
0
2
Beam and Butler, 1996
4
6
8 10 12 14 16 18 20
Days postpartum
Frequency of LH Pulses
Week 1
LH ( ng/mL)
4
Week 2-3
Week 4-6
3
2
1
0
0
2
4
6
8
Hours
10
12
14
16
No. of LH Pulses/8 hr - Milked Cows
Cow
1
2
3
4
5
6
7
8
9
10
3
0
Weeks from energy balance nadir (0)
0
+1
+2
2
1
1
3
6
5
First ovulation
1
2
3
4
5
followed the
2
6
7
last blood
0
3
7
8
7
collection
1
4
6
6
series by 2.5
2
3
4
5
7
 0.4 days.
0
5
6
7
2
4
4
5
6
0
3
5
5
6
7
3
8
Canfield and Butler, 1990
Energy Balance
(+)
Intake
Feed
Metabolism and
Partitioning
(–)
Expenditures
Liver
Reproduction
Oxidizable
metabolic
fuels
Adipose tissue
Fat stores
Thermoregulation
Cell maintenance
Locomotion
Growth (NEG)
Milk yield (NEL)
NEM
Energy Balance and First Ovulation
Item
Body weight, kg (lbs)
Calving
Change during anovulation
Energy balance, Mcal/day
Anovulation
Interval, days
Calving to EB nadir
EB nadir to ovulation
Calving to ovulation
Zurek et al. (1995)
Mean of 17
dairy cows
SE
729 (1607)
56 (123)
13
8
17.5*
4.2
8.7
15.4
24.1
1.1
1.2
1.5
*Sufficient energy to produce
57 lb (26 kg) of milk/day
Uterine Involution
Uterine horn
diameter, mm
250
Gravid horn
200
Nongravid horn
150
100
50
0
5
10 15 20 25 30 35 40 45 50
Marion and Gier, 1968
Days postpartum
Nadir of EB
IGF-I
Ovulation
E2
FSH
LH
Days postpartum
Calving
Anovulation, %
Body Condition Scores of Dairy
Cattle at 70 DIM and Anovulation
45
40
35
30
25
20
15
10
2.25 2.50 2.75 3.00 3.25 3.50 3.75
BCS at 70 days in milk
Santos et al., 2004
Body Weight Loss in Dairy Cows
kg
60
3x Milked
40
6x Milked
20
Suckled
0
-20
1 2 3 4
5 6 7
8 9 10 11 12 13 14 15 16 17 18
-40
-60
-80
Weeks postpartum
Bar Peled et al. (1995)
Dry Matter Intake for Dairy Cows
25
kg/day
20
15
3x Milked
6x Milked
Suckled
10
5
0
1
2
Bar Peled et al. (1995)
3
4
5
6
7
Weeks postpartum
8
9
10
Estimates of Cycling Status
• 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%
% cycling
2-yr-old cows
Older cows
100
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
6
Herd-Year
7
8
Stevenson, 2001
Prebreeding Anestrus in
Lactating Holstein Cows
Onset of First Ovulation
Item
No. of cows
Days to first ovulation
Days to first estrus
4% milk, kg/day
DM intake, kg/day
BW change, kg/day
Staples et al. (1990)
Early
25
22
47
34
19
0.8
Late Very late
14
15
43

73
110
32
29
18
15
0.8
1.2
Milking Frequency - Exp. 1
Trait
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
Bar-Peled et al. (1995)
Milked Milked 6x Milked 3x +
3x
for 6 wk Suckled 3x
26
46
112
35
9
6
37
76
184
43
14
10
48
48
100
50
19
8
Milking Frequency - Exp. 2
Trait
Days to 1st ovul.
st
Days to 1 estrus
Days to pregnancy
6-wk milk yield, kg/d
6-wk weight loss, kg
Week at zero EB
Bar-Peled et al. (1995)
Milked
3x
22
45
105
35
24
6
Milked 6x Milked 6x
for 3 wk for 6 wk
30
61
148
40
29
-
39
75
189
42
32
10
Ontario Association of
Bovine Practitioners
Reproductive Symposium
Thank you!
Department of Animal
Sciences and Industry