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The impact of heat stress on fertility and milk production
1. Zvi Roth (Ph.D.)
Department of Animal Science, Faculty of Agriculture, The Hebrew
University of Jerusalem, Israel
The impact of heat stress on
fertility and milk production
- the Israeli experience
SIRAA, Londrina, Brazil 2018
2. Introduction
• Heat stress - a worldwide problem
About 60% of the world cattle population is
located in hot or warm regions
About 35° north and south of the equator
3. Introduction
• The problem of heat stress is growing
Global worming
Increases in milk yield
Greater metabolic heat production
7. • Increase in respiratory and hart rate
• Increase in oxygen consumption
• Vasodilation
• Decrease in feed intake
• Decrease in rumination
• Decrease in activity
• Increase in standing time
• Increase in body temperature
Physiological and behavioral changes
in dairy cows under heat stress
8. 1) Panting
• Respiratory evaporation
In cattle, is not an efficient
channel of heat loss.
It constitutes about 25% of
total water loss
Heat -Loss via Evaporation
2) Sweating from skin surface.
It constitutes about 75% of total water loss.
9. Sweating rate, in cattle, is relatively low
compared to humans and horses
Cow Man Horse
0
300
600
900
1200
1500
g/hxm2
16. What can we do to alleviate
the effects of heat stress?
Heat production Heat loss
?
17. • Concentrate energy and adjust protein.
• Use high-quality forage and reduce its proportion.
• Replace roughage components with by-products
rich in digestible NDF, such as soy hulls.
• Taking into account the mineral losses (Na, K) via
sweating and urinary excretion.
Feeding approaches to alleviate the
effects of heat stress
18. Control the time of metabolic heat production
throughout the day
• Feed more frequently with fresh food
• Feed in the evening or at night
Feeding time
Adin et al, LS 2008; Adin et al, LS 2009; Adin et al, JDS 2009;
Miron et al, AFST 2009
19. Feeding
manipulations
- 13%Respiratory rate (min-1)
- 0.3Rectal temperature (oC)
+ 8.3%Voluntary DMI (kg/day)
+ 0.05BCS change (1-5 scale)
+ 6.2%Milk yield (kg/day)
Adin et al, 2008
Alleviation the effects of heat-
stress by feeding
20. Using of cooling methods to reduce
the effect of heat stress
1) Without the use of water
(shading, fans)
2) With the use of water
Classification:
28. Effect of provision of shade to low-
milk-yielding cows in summer (Florida, USA)
Shade No shade
Air temperature 29 °C 41 °C
Body temperature 39.2 °C 40.8 °C
Respiration 83 133
pH 7.4 7.5
Food DMI (kg/day) 20.7 16.8
Milk (kg/day) 19.4 17.0
Milk protein (%) 3.37 3.29
38. Aactive only when
cows approach the
feeding line to eat:
1) when fresh food is
offered
2) after milking
3) after cooling in the
holding area of the
milking parlor
Along the feeding line
39. Body temperature of cows cooled
by sprinkling and ventilation
06:00 11:00 13:00 16:00 19:00 23:00 02:00
Day time
38.0
38.5
39.0
39.5
40.0
Bodytemperature(C)
Cooled
Non-cooled
40. Lactation curve of cooled and
control first-calving cows
Production(kg/day)
20
22
24
26
28
30
32
34
36
38
40
1 2 3 4 5 6 7 8 9 10 11
Months after calving
Cooled cows
Control cows
Flamenbaum & Ezra, 2001
(14 herds; 4000 cows)
41. Production(kg/day)
20
25
30
35
40
45
50
1 2 3 4 5 6 7 8 9 10 11
Months after calving
Cooled cow
Control cows
Lactation curve of cooled and
control multiparous cows
Flamenbaum & Ezra, 2001
43. In the milking parlor
Cooling in the feeding Line
Cows were cooled 5 times at
the milking parlor+ in the
feeding lane
37.8
38
38.2
38.4
38.6
38.8
39
39.2
39.4
39.6
39.8
40
40.2
40.4
9:10 11:10 13:10 15:10 17:10 19:10 21:10 23:10 1:10 3:10 5:10 7:10
MILKING FEED LANE
Time
VaginalTemperature(OC)
44. Cooling 5 times a day
37.80
38.00
38.20
38.40
38.60
38.80
39.00
39.20
39.40
39.60
39.80
40.00
40.20
40.40
9:10 11:10 13:10 15:10 17:10 19:10 21:10 23:10 1:10 3:10 5:10 7:10
27/11/13 MILKING FEED LANE
Time
VaginalTemperature(OC)
47. • Dairy cows under heat load were cooled 5 or 8 times
sessions.
• Each cooling period lasted 45 min, comprising cycles
of 30 s of showering and 4.5 min ventilation.
49. Intensive cooling improves
physiological features
5 CS 8 CS P-value
Rumination time,
min/day
410 440 <0.001
Respiration time
breaths/min
(afternoon)
83.0 50.0 0.001
Rectal temp. (oC) 39.3 38.2 <0.001
Honig et al, 2012
50. Intensive cooling increases lying time
and decreases standing time
5 CS 8 CS P-value
Total lying time, min/day 474 484 0.004
Standing time, min/day 834 807 <0.001
Honig et al, 2012
51. • ‘Minimal’
3 wetting periods (before each milking)
• ‘Moderate’
Cooling in the ‘holding pen’
6 cooling periods, 45 min each
total of 4.5 h/day
• ‘Intensive’
Cooling in the ‘holding pen’ + ‘feeding line’
10 cooling periods, 45 min each
total of 7.5 h/day
A large-scale survey evaluating the
effect of three levels of cooling intensity
53. Minimal Moderate Intensive
Winter (%) 43.5 a 45.8 a 46.6 a
(n) (618) (267) (684)
Summer (%) 16.7 c 34.5 b 33.8 b
(n) (222) (172) (572)
Conception rates from first AI
(mature cows )
Ratio (S/W) 38.3% 75.3. % 72.5%
54. • Cooling is the predominant strategy used today to
alleviate the effect of heat stress in dairy farms.
• Cooling can prevent the decline in milk production
in high-yielding cows but it cannot eliminate the
decline in reproduction during the hot season.
• Additional strategies for improving
reproductive responses under heat
stress.
Summary II
55. Effects of heat stress on
reproductive function
• Reduction of the intensity
and duration of estrus
• Attenuation of follicular
development
• Disruption of oocyte
competence
• Disruption of embryonic
development
• Reduction of progesterone
secretion
Fertility
56. Potential strategies to improve
summer fertility in dairy cows
• Synchronization program
• Follicular turnover
• Progesterone supplementation
• Embryo transfer
• Combined treatments
57. Heat stress can affect the follicle and
oocyte during a broad window of time
P.J. Hansen, 2013
58. Heat stress reduces oocyte
developmental competence
Al-Katanani et al., 2002
Gendelman et al., 2010
Ferreira et al., 2011
64. • In commercial dairy farms
• Farms were equipped with efficient cooling
systems
• Animals: control (n = 187), treated (n = 195)
• Cows that appeared to be in estrus were artificially
inseminated
• Pregnancy diagnostic (rectal palpation; 45 PI)
• Logistic regression, SAS: season, milk level, body
condition (BCS), somatic-cell count (SCC), no. of
lactations
Fertility study
Summer and fall, 2008-2009 (Israel)
68. Treatment with GnRH + PG improves
conception rate in cows with low
milk production
Control
Treatment
Friedman et al., 2011 (JDS)
20
30
40
50
60
< 40 kg
Conceptionrate(%)
> 40 kg
51%
36%
30%
*
* P<0.05
70. Association between progesterone
level and embryonic development
0 2 4 6 8 10 12 14 16
Mann et al., 1999
0
3
6
9
12
0
5000
10000
15000
20000
0
5000
10000
15000
20000
Day in cycle 16-day embryo
Progesterone(ng/ml)
Interferont-(unitsperuterus)
Big Small
71. Day of cycle
0 3 6 9 12 15 18 21
5
1
2
3
4
6
7ng/ml
Winter
Summer (chronic stress)
Seasonal effect on progesterone
level in plasma
72. 1 3 5 7 9
Day of culture
0
200
400
600
800
1000
Winter
Summer
Luteinized thecal cells
1 3 5 7 9
Day of culture
0
200
400
600
800
1000
Winter
Summer
Luteinized granulosa cells
ng/105cells
ng/105cells
Seasonal effect on progesterone
production by follicular cells in vitro
73.
74. • In 2 commercial dairy farms
• Farms were equipped with efficient cooling
systems
• Animals: control (n = 195), treated (n = 181)
• Cows were 124 days postpartum; 41 kg/day
• CIDR progesterone (EAZI-BREED™) was inserted on day 5 (±
1)
• Cows that appeared in estrus were artificially inseminated
• Pregnancy diagnostic (rectal palpation; 40-45 PI )
• Logistic regression, SAS (season, milk level, body condition,
somatic-cell count, no. of lactations)
Fertility study
Summer and fall, 2008-2009 (Israel)
75. Day in cycle
0
2
4
6
8
10
0 5 10 15 20
Progesterone(ng/ml)
CONTROL
CIDR
CIDR in
CIDR out
CIDR device increases plasma
progesterone level
Friedman et al., 2012 (JDS)
84. Effectiveness of ET for improving
fertility during heat stress
P. J. Hansen, 2013
85. Short-term exposure
of bovine embryos to
IGF-1 increases
developmental
competence of 5-day
but not 2-day embryos
IGF-1
Bonilla et al., 2011
86. Transfer of in vitro-produced
embryos precultured with IGF-1
Block et al., 2003 Block & Hansen, 2007 Loureiro et al., 2009
87. Embryo transfer (ET)
• A study performed in Brazil examined the
effect of rectal temperature on the transfer day
on pregnancy probability on day 25 of
gestation.
Vaconcelos et al., 2006
88. • Inversely related to
pregnancy rate on day
25 of gestation
• Positively related to
pregnancy loss at 46
days of gestation
Rectal temperature at
the time of ET
Vaconcelos et al., 2006
89. Summary III
• Efficient cooling management is a
prerequisite for other, additional strategies to
improve reproductive responses under heat
stress.
• Hormonal treatment combined with cooling
systems are suggested.
• Embryo transfer combined with CIDR, to
support the embryo should not be ruled
out !