Dr. Todd Bilby presented this information on March 5th, 2012 as part of DAIReXNET's Spring 2012 Heat Stress Webinar Series.

1. texasdairymatters.org
Strategies to Improve Reproduction
during Heat Stress in Dairy Cattle
Dairy Heat Stress Roadshow
Todd R. Bilby, Ph.D.
Associate Professor and Extension Dairy Specialist

2. Heat Stress in the U.S.
New York losses ~$20 million
annually
Heat Wave in 2006 cost ~$1
billion in milk and animals
Annual loss to American Dairy Industry is $897 MILLION!
St-Pierre et al., 2003 J. Dairy Sci. E52-E77.
July 11 and 12, 1995, ~3700
cattle deaths
2 day heat wave in 1999 lost
~$20 million in cattle deaths
and performances losses

3. Effect of milk yield on seasonal variation
in pregnancy rate in lactating dairy cows:
Florida & Georgia
100
<4536 kg
90 4536-9072 kg
>9072 kg
80
Pregnancy rate (%)
70
60
50
40
30
20
10
0
J F M A M J J A S O N D
Month
Al-Katanani et al., 1999

4. Fertilization Rate in Lactating Dairy Cows Exposed
or Not Exposed to Heat Stress
80
70 88
Fertilization Rate (%) 60
50
40 55
30
20
10
0
Heat Stress Non - Heat Stress
Sartori et a., 2002 2010
Sartori et al.,

5. Heat Stress and Embryo Development
Susceptibility to HS
Single 4-cell Morula Early Expanded
Blastocyst
cell embryo Blastocyst Blastocyst
Day 1 Day 1-2 Day 5 Day 6 Day 7 Day 7-9
Oviduct Uterus

6. Day 15 – 19 Bovine Uterus
PGF2α CL
)
Embryo
IFN-τ
Ovary
Heat Stress:
Decreased weights of embryos on d 17 (Biggers et
Progesterone and PGF2α
Up to 40 % of total embryonic losses occur between Days 8 and 17 of
Non-Pregnant uterus
Pregnant uterus al., 1987)
pregnancy (Thatcher et al., 1994, 1995).
D17 → post-estrus
D17 failures in maintenance of CL ?71 %
post-estrusDecreased IFN-τ by (Putney et al.,
1988b)
Increased endometrial secretion of PGF2α (Putney
et al., 1988b)
Day

7. Embryo Loss for Different THI
14
12
12
10
Summer vs. Winter: 8
8
3.7 times more likely to lose embryo
6
5.4 times more likely to lose embryo if twins
4 (Lopez-Gatius et al., 2004)
%
o
n
p
e
a
g
y
c
s
r
)
(
2
l
2 1
0
0
<55 55-59 60-64 65-69 >69
Max THI
Adapted from Garcia-Ispierto et al., 2006

8. Strategies to Reduce the Negative Effects
of Heat Stress
•Bull Breeding vs. Timed AI
•Synchronization and Timed AI
•Induction of Accessory CL
•Embryo Manipulation and Transfer

9. NATURAL SERVICE VS. TIMED AI

10. Semen Quality Before, During and After
Heat Stress
Breed Initial Motility Abnormal Spermatozoan
Spermatozoa Concentration
Period % % Initial % % Initial 106 ml-1 % Initial
Holstein 3 wk prior to HS 53 100 9 100 1194 100
1 wk of HS 45 85 13 144 1303 112
1-3 wk after HS 34 64 53 589 537 48
7-9 wk after HS 42 79 29 467 460 39
Ambient Temperatures above 27 °C (80 °F) for 6 h per day
can reduce semen quality in bulls!
Johnston et al., 1963

11. Motile Sperm Before, During and
After Heat Stress
Meyerhoeffer et al., 1985

12. Economic Comparison of NS vs AI
(Overton, 2005)
• 60% of the time AI was more profitable than natural service
• Predicted NM$ Gain/Milking Herd = $ 37,480
• In average, use of NS resulted in loss of $ 10.27/cow/year compared with AI

13. Conclusion: Natural Service vs. AI
• Reduced Genetic Progress and Profitability
• Dangerous, cause lameness and injury
• Bull Breeding during Heat Stress
– Heat stress decreases sperm concentration, motility, and
increases % of abnormal sperm
– Does not return to normal for 2 months!!
• IF YOU ARE GOING TO USE BULLS YOU MUST MANAGE
THEM
– Rotate, BSE scores, vaccinations, etc..
By-pass negative effects by using A.I.

14. SYNCHRONIZATION AND TIMED AI

15. Timed AI vs. Bred on Estrus during
Summer
120 P < 0.01
100
100
TAI
80 BOE
%
60
P < 0.01 P < 0.05
40
23 27
18 17
20 13
0
Insemination Rate Conception Rate 120 d PP
De la Sota et a., 1998

16. Timed AI vs. Bred on Estrus during
Summer
100 P < 0.05 P < 0.01
90 91
90 TAI
80 78
BOE
70
59
60
50
Days
40
30
20
10
0
Days Open for Cows Conceiving Interval to First Service
De la Sota et a., 1998

17. Using TAI to Enhance Summer
Cumulative Pregnancy Rates
70
*P<.05; † P<.06 BOE-1
60
50
* TAI-1
BOE-2
40
TAI-2
30 †
%
n
P
e
a
g
r
t
20
10 *
0
1st AI 90-d PP 120-d PP
Aréchiga et al., 1998

18. INDUCED OVULATION WITH
GNRH AT ESTRUS

19. Daily Progesterone during Spring and
Summer in Holstein Cows
No Heat Stress
Heat Stress
Howell et al., 1994

20. Progesterone Concentration and Embryo Production of
Interferon-τ
12 20000
Interferon-t (units per uterus)
Progesterone (ng.ml-1)
9 15000
6 10000
3 5000
**
0 0
0 2 4 6 8 10 12 14 16 Large Small
Day of cycle embryo embryo
Day 16 **P<0.01
Adapted from Mann et al. (1999) interferon

21. Effects of GnRH at Estrus on Fertility in
Dairy Cows during Summer
60 P < 0.05 GnRH
52
50 Control
Conception Rate (%)
P < 0.05
40 35
29 31
30
21
20 18
10
0
Kaim et al., 2003 Ullah et al., 1996 Lopez-Gatius et al., 2006

22. INDUCED ACCESSORY CL AFTER AI

23. Estrous Cycle
Ovulation
hCG PGF2a E2
GnRH
Ovulation
Hormone Concentration
CL Progesterone
Estrus 5 10 15 Estrus
Courtesy of W. W. Thatcher

24. Effect of GnRH Agonist and hCG on Progesterone
Concentration in Dairy Heifers
18.0
25
Progesterone (ng/mL)
20
hCG
15
CON
10 hCG
25
5 9.7
0
11.7
Progesterone (ng/mL)
20
10
14
16
12
0
2
4
6
8
15 GnRH CON Days of the estrous cycle
10 GnRH
5
8.5
0
12
14
16
10
0
2
4
6
8
Days of the estrous cycle
Adapted from Schmitt et al. (1996)

25. Effect of hCG/GnRH on d 4 or 5 post AI during
Summer on Conception Rates
hCG or GnRH
40 38 P < 0.01 Control
35 32
30 P < 0.05
26
25 24 24 24 23
20 19
15
10
5
0
C. Fischer- Karami et al. (2010) Schmitt et al. Gandy et al. (2002)
Tenhagen et al. (1996)
(2010)

26. Effect of GnRH on d 5 or 11-15 post AI during
Summer on Conception Rates
P < 0.08 Control
40 d5
35
35 32 d 11 - 15
30
25
20 20 19
20
15
10
5
0
Franco et al. (2006) Willard et al. (2003)

27. Effect of GnRH on d 0 and d 12 post AI during
Summer on Conception Rates
Control
P < 0.05
60 d0
52 d 0 and 12
49
50
42 b P < 0.05
40
b
a 35
31
30 c
21 b
20
a
10
0
Ryan et al., (1991) Lopez-Gatius et al. (2006)

28. EMBRYO MANIPULATION AND
TRANSFER

29. Heat Stress and Embryo Development
Embryo
Susceptibility to HS Transfer
Single 4-cell Morula Early Expanded
Blastocyst
cell embryo Blastocyst Blastocyst
Day 1 Day 1-2 Day 5 Day 6 Day 7 Day 7-9
Oviduct Uterus

30. Effectiveness of ET vs. AI in Summer
Putney et al., 1989 45 Drost et al., 1999
45
Pregnancy rate (%)
Pregnancy rate (%)
40 40 35.4%
35 29.2% 35
30 30 24.1% (48)
25 (113) 25 18.8%
20 13.5% 20 (84)
15 15 (48)
10 (524) 10
5 5
0 0
AI MOET fresh AI MOET IVF
Frozen
45 45
Ambrose et al., 1999 Al-Katanani et al., 2002
Pregnancy rate (%)
Pregnancy rate (%)
40 40
35 35
30 30 26.7%
25 17.5% 25 (20)
20 20
15 6.7% 15
6.1% 5.0% 7.4%
10 10
5 5 (39)
(46)
0 0
TAI Fresh Frozen TAI Fresh Vitrified
TET TET

31. EFFICACY OF EMBRYO TRANSFER IN LACTATING DAIRY
COWS DURING SUMMER USING FRESH AND VITRIFIED,
SEXED IN-VITRO PRODUCED EMBRYOS
Stewart et al., 2010

32. IVF Embryo Production
Oocytes collected and graded
(Only grades 1 and 2 fertilized)
Maturation of oocytes
(21-24 h, 38.5° C + 5 % CO2)
Fertilization 8h
Percoll (IVF-TALP)
Gradient
Sex-Sorted Culture
Semen (BBH-7)
% Cleaved at d 3
Expanded Blastocyst d 7 Embryo Transfer

33. EXPERIMENTAL PROCEDURES FOR
EMBRYO TRANSFER AND AI

34. Experimental Design
• Two commercial freestall dairies in Central Texas (~3000 milking)
– July to October 2009.
• Primi- and multiparous (n = 722) lactating Holstein dairy cows
– Assigned randomly by lactation number, number of previous AI, and
projected 305 d milk yield
• 1 of 3 treatment groups following a synchronized estrus (study d 0)
• AI (Control): AI with conventional semen on d 0 (n = 227)
• ET-V: Embryo transfer-vitrified on d 7 (n = 279)
• ET-F: Embryo transfer-fresh on d 7 (n = 216)
Stewart et al., 2010

35. Synchronization and Treatment Protocol
Ovsynch
Heat GnRH or Pregnancy
GnRH PGF Estrus AI+BS US diagnose
Detection
AI
Heat GnRH or Pregnancy
Detection GnRH PGF Estrus BS VIT+US diagnose
ET-V
Heat GnRH or Pregnancy
GnRH PGF BS FR+US diagnose
Detection Estrus
ET-F
Experiment Day -10 -3 -1 0 7 40 ± 7 97±7

36. Plasma Progesterone Concentration
• Plasma P4 concentration was used to determine
conformation of a synchronized estrus
–Synchronized
• if P4 was < 1 ng/mL on d 0 and presence of CL on
d7
Stewart et al., 2010

37. RESULTS

38. Percentage of Cows Pregnant at d 40
All Cows Synchronized Cows
TRT - P < 0.01 TRT - P < 0.01 a, b
a,b,c - P < 0.01 - P < 0.01
x, y– P = 0.10
Stewart et al., 2010

39. Percentage of Cows Pregnant at d 97
All Cows Synchronized Cows
Stewart et al., 2010

40. Total Births (%) and Live Births (%)
Treatment Total Births (%) Live Births (%)
All cows Synch cows All cows Synch cows
(n = 550) (n = 460) (n = 550) (n = 460)
AI 14.6a 17.9a 14.6a 17.9a
ET-V 20.1a 20.9a 17.1a 18.1a
ET-F 31.2b 33.9b 27.5b 29.9b
a, b
Values within column with different superscripts differ (P < 0.05)
x, y
Values within column tend to differ (P ≤ 0.10)
Stewart et al., 2010

41. Total Heifers (%) and Live Heifers (%)
Treatment Total Heifers (%) Live Heifers (%)
All cows Synch cows All cows Synch cows
(n = 113) (n = 107) (n = 113) (n = 107)
AI 50.0a 53.9a 50.0a,x 53.9a,x
ET-V 80.0b 79.0b 72.5y 73.7y
ET-F 88.4b 88.4b 79.1b 79.1b
a, b
Values within column with different superscripts differ (P < 0.05)
x, y
Values within column tend to differ (P ≤ 0.10)
Stewart et al., 2010

42. Take Home Messages
To Improve Fertility During Summer….
•Aggressive heat detection
– Two heat detection aids are better than one
•Robust synchronization and timed AI programs can improve
fertility vs. heat detection
– Watch lock up times and compliance
•AI can improve fertility and genetic gain compared to bulls
– Bulls can achieve acceptable pregnancy rates but must be aggressively
managed

43. Take Home Messages
To Improve Fertility During Summer….
•GnRH or hCG on and(or) after AI may improve summer fertility
– Results are inconsistent
•Embryo transfer can improve fertility and number of heifers
born
– Large scale implementation can be difficult
– Need to improve fertility from frozen embryos

44. texasdairymatters.org
Thank You!
Todd R. Bilby, Ph.D.
Associate Professor
Dairy Extension Specialist
Texas AgriLife Research and Extension
trbilby@ag.tamu.edu
This project was supported by Agriculture and Food Research
Initiative Competitive Grant no. 2010-85122-20623 from the USDA
National Institute of Food and Agriculture.