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Dr. Todd Bilby presented this information on March 5th, 2012 as part of DAIReXNET's Spring 2012 Heat Stress Webinar Series.
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Strategies to Improve Reproduction during Heat Stress in Dairy Cattle
Dairy Heat Stress RoadshowDairy Heat Stress Roadshow
Todd R. Bilby, Ph.D.Associate Professor and Extension Dairy Specialist
texasdairymatters.org
Heat Wave in 2006 cost ~$1 billion in milk and animals
2 day heat wave in 1999 lost ~$20 million in cattle deaths
and performances losses
July 11 and 12, 1995, ~3700 cattle deaths
New York losses ~$20 million annually
Heat Stress in the U.S.
Annual loss to American Dairy Industry is $897 MILLION!St-Pierre et al., 2003 J. Dairy Sci. E52-E77.
Month J F M A M J J A S O N D
Preg
nanc
y ra
te (%
)
0
10
20
30
40
50
60
70
80
90
100<4536 kg4536-9072 kg>9072 kg
Effect of milk yield on seasonal variation in pregnancy rate in lactating dairy cows:
Florida & Georgia
Al-Katanani et al., 1999
0
10
20
30
40
50
60
70
80
Heat Stress Non - Heat Stress
Fertilization Rate in Lactating Dairy Cows Exposed or Not Exposed to Heat Stress
Ferti
lizati
on R
ate
(%)
Sartori et al., 2010
55
88
Sartori et a., 2002
Heat Stress and Embryo Development
Singlecell
4-cellembryo
Morula EarlyBlastocyst Blastocyst Expanded
Blastocyst
Oviduct Uterus
Day 1 Day 1-2 Day 5 Day 6 Day 7 Day 7-9
Susceptibility to HS
Day 15 – 19 Bovine UterusPGF2
Ovary
CL
Non-Pregnant uterusD17 post-estrus
Pregnant uterusD17 post-estrus
IFN-Embryo
Day
Progesterone and PGF2
Heat Stress:
Decreased weights of embryos on d 17 (Biggers et
al., 1987)
Decreased IFN- by 71 % (Putney et al., 1988b)
Increased endometrial secretion of PGF2α (Putney et al., 1988b)
Up to 40 % of total embryonic losses occur between Days 8 and 17 of pregnancy (Thatcher et al., 1994, 1995). failures in maintenance of CL ?
Embryo Loss for Different THI
01
2
8
12
0
2
4
6
8
10
12
14
<55 55-59 60-64 65-69 >69
preg
nanc
y lo
ss (%
)
Max THI
Adapted from Garcia-Ispierto et al., 2006
Summer vs. Winter:
3.7 times more likely to lose embryo
5.4 times more likely to lose embryo if twins
(Lopez-Gatius et al., 2004)
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
NATURAL SERVICE VS. TIMED AI
Semen Quality Before, During and After Heat Stress
Breed Initial Motility Abnormal Spermatozoa
Spermatozoan 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
Johnston et al., 1963
Ambient Temperatures above 27 °C (80 °F) for 6 h per day can reduce semen quality in bulls!
Motile Sperm Before, During and After Heat Stress
Meyerhoeffer et al., 1985
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
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.
SYNCHRONIZATION AND TIMED AI
Timed AI vs. Bred on Estrus during Summer
100
1327
18 2317
0
20
40
60
80
100
120
Insemination Rate Conception Rate 120 d PP
TAI
BOE
De la Sota et a., 1998
P < 0.01
P < 0.01
P < 0.05
%
78
59
90 91
0102030405060708090
100
Days Open for Cows Conceiving Interval to First Service
TAI
BOE
Timed AI vs. Bred on Estrus during Summer
Day
s
P < 0.05 P < 0.01
De la Sota et a., 1998
Using TAI to Enhance Summer Cumulative Pregnancy Rates
0
10
20
30
40
50
60
70
1st AI 90-d PP 120-d PP
% P
regn
ant
BOE-1
TAI-1
BOE-2
TAI-2
*
†
*
Aréchiga et al., 1998
*P<.05; † P<.06
INDUCED OVULATION WITH GNRH AT ESTRUS
Daily Progesterone during Spring and Summer in Holstein Cows
Howell et al., 1994
Heat Stress
No Heat Stress
0 2 4 6 8 10 12 14 160
3
6
9
12
0
5000
10000
15000
20000
0
5000
10000
15000
20000
Day of cycleLarge
embryoSmall
embryo
Day 16interferon
Progesterone Concentration and Embryo Production of Interferon-
**
** P<0.01
Prog
este
rone
(ng.
ml-1
)
Inte
rfer
on-t
(uni
ts p
er u
teru
s)
Adapted from Mann et al. (1999)
Effects of GnRH at Estrus on Fertility in Dairy Cows during Summer
52
29 3135
1821
0
10
20
30
40
50
60
Kaim et al., 2003 Ullah et al., 1996 Lopez-Gatius et al., 2006
GnRH
Control
P < 0.05
P < 0.05
Conc
eptio
n Ra
te (%
)
INDUCED ACCESSORY CL AFTER AI
CL Progesterone
Estrus Estrus5 10 15
Hor
mon
e Co
ncen
trati
on
Ovulation
OvulationPGF2a E2
Estrous Cycle
Courtesy of W. W. Thatcher
hCGGnRH
Effect of GnRH Agonist and hCG on Progesterone Concentration in Dairy Heifers
0
5
10
15
20
25
0 2 4 6 8 10 12 14 16
Days of the estrous cycle
Pro
ges
tero
ne
(ng
/mL
)
CON
GnRH
0
5
10
15
20
25
0 2 4 6 8 10 12 14 16
Days of the estrous cycleP
rog
este
ron
e (n
g/m
L)
CON
hCG
GnRH
hCG
11.7
8.5
18.0
9.7
Adapted from Schmitt et al. (1996)
Effect of hCG/GnRH on d 4 or 5 post AI during Summer on Conception Rates
26
38
24
32
24 24 2319
0
5
10
15
20
25
30
35
40
C. Fischer-Tenhagen et al.
(2010)
Karami et al. (2010) Schmitt et al. (1996)
Gandy et al. (2002)
hCG or GnRH
ControlP < 0.01
P < 0.05
Effect of GnRH on d 5 or 11-15 post AI during Summer on Conception Rates
20 19
32
20
35
0
5
10
15
20
25
30
35
40
Franco et al. (2006) Willard et al. (2003)
Control
d 5
d 11 - 15
P < 0.08
Effect of GnRH on d 0 and d 12 post AI during Summer on Conception Rates
42
21
49
31
52
35
0
10
20
30
40
50
60
Ryan et al., (1991) Lopez-Gatius et al. (2006)
Control
d 0
d 0 and 12
b
P < 0.05
P < 0.05
a
b
a
bc
EMBRYO MANIPULATION AND TRANSFER
Heat Stress and Embryo Development
Singlecell
4-cellembryo
Morula EarlyBlastocyst Blastocyst Expanded
Blastocyst
Oviduct Uterus
Day 1 Day 1-2 Day 5 Day 6 Day 7 Day 7-9
Embryo Transfer Susceptibility to HS
05
1015202530354045
05
1015202530354045
IVF
Frozen
Effectiveness of ET vs. AI in SummerPr
egna
ncy
rate
(%)
AI
(524)
(113)
Putney et al., 1989
(84)
(48)
(48)
AIMOET fresh MOET
Drost et al., 1999
Preg
nanc
y ra
te (%
)
05
1015202530354045
13.5%
29.2%
6.7%
17.5%
6.1%
Preg
nanc
y ra
te (%
) Ambrose et al., 1999
TAI
TET
Fresh Frozen
24.1%
35.4%
18.8%
05
1015202530354045
Preg
nanc
y ra
te (%
) Al-Katanani et al., 2002
5.0%
26.7%
7.4%
(46)
(20)
(39)
TAI
TET
Fresh Vitrified
EFFICACY OF EMBRYO TRANSFER IN LACTATING DAIRY COWS DURING SUMMER USING FRESH AND VITRIFIED,
SEXED IN-VITRO PRODUCED EMBRYOS
Stewart et al., 2010
Oocytes collected and graded(Only grades 1 and 2 fertilized)
(21-24 h, 38.5° C + 5 % CO2)Maturation of oocytes
PercollGradient
Fertilization 8h(IVF-TALP)
Expanded Blastocyst d 7
% Cleaved at d 3
Culture(BBH-7)
IVF Embryo Production
Sex-Sorted Semen
Embryo Transfer
EXPERIMENTAL PROCEDURES FOR EMBRYO TRANSFER AND AI
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
Synchronization and Treatment Protocol
Experiment Day -10 -3 -1 0 7 40 ± 7 97±7
AI
ET-F
ET-V
Pregnancy diagnose
Pregnancy diagnose
Pregnancy diagnose
GnRH orEstrus
PGF BS
PGF
Heat Detection
BS
GnRH
GnRH
GnRH
Heat Detection
Heat Detection AI+BSPGF
GnRH or Estrus
GnRH or Estrus
US
VIT+US
FR+US
Ovsynch
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
d 7
Stewart et al., 2010
RESULTS
Percentage of Cows Pregnant at d 40
TRT - P < 0.01 a,b,c - P < 0.01
TRT - P < 0.01 a, b - P < 0.01 x, y– P = 0.10
All Cows Synchronized Cows
Stewart et al., 2010
All Cows
Percentage of Cows Pregnant at d 97
Synchronized Cows
Stewart et al., 2010
Total Births (%) and Live Births (%)
Treatment Total Births (%) Live Births (%)
All cows (n = 550)
Synch cows(n = 460)
All cows (n = 550)
Synch cows(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
Total Heifers (%) and Live Heifers (%)
Treatment Total Heifers (%) Live Heifers (%)
All cows (n = 113)
Synch cows(n = 107)
All cows (n = 113)
Synch cows(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
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
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
Thank You!Todd R. Bilby, Ph.D.
Associate Professor
Dairy Extension Specialist
Texas AgriLife Research and Extension
texasdairymatters.org
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.