Heat and cold stress management strategies are important for dairy cattle. During heat stress, cows reduce feed intake and milk production when temperatures exceed 21°C. Providing shade, cooling systems like fans and sprinklers, and managing feeding and breeding can help. Cold stress increases energy demands, so feeding more high-fiber feed is key. Ensuring dry bedding and protecting from wind also helps cattle withstand cold. Monitoring weather and increasing feed intake in response to temperature drops below critical levels is important for management.

1. HEAT AND COLD
STRESS
MANAGEMENT
BY
TAMILARASAN K
M.V.Sc
LIVESTOCK PRODUCTION AND MANAGEMENT
SECTION
INDIAN VETERINARY RESEARCH INSTITUTE

2. HEAT STRESS
ENVIRONMENTAL FACTORS
• Sunlight
• Thermal irradiation, and air
temperature,
• Humidity
• Air movement
ANIMAL FACTORS
• Species,
• Metabolism rate
• Thermoregulatory mechanisms
“Stress is the nonspecific response of the body to any demand”.
Heat stress results from a negative balance between the net amount of
energy flowing from the animal’s body to its surrounding environment
and the amount of heat energy produced by the animal.

3. HEAT STRESS
• When air temperature is greater than about 21ºC and relative humidity
is greater than 70%, cows begin to reduce their feed intake, and milk
production is reduced. Jerseys are more tolerant of heat, with
production losses insignificant until 25ºC

4. THERMONEUTRAL ZONE
• For healthy cattle, the thermo-neutral zone lies between 32°F(0°C) and
77°F(25°C).

5. TEMPERATURE HUMIDITY INDEX
THI = 0.72 (W+D) 40.6 (McDowell et al. 1976)
THI >72 = Mild stress
Milk yield
THI >75 = Milk yield
Reproduction
THI 78-82 = Severe Stress
THI >82 = More decline
Death
(Du Prezz et al. 1990)

6. SYMPTOMS
• increased breathing rate and sweating
• increased water intake
• decreased feed intake and
• decrease milk production
• change in milk composition, e.g. fat % and protein % declines
• change in blood hormone concentration, e.g. increased prolactin
• changed behaviour:
• seek shade
• crowd together to shade each other
• refusal to lie down
• change orientation to sun

7. Effects Of Heat Stress On Dairy
Cattle
High loss of Saliva,
Ruminal Acidosis
Laminitis
Increased RR
Decreased
HCO3 in blood
High
sweating,
loss of Na,K
BicarbonateReduced DMI
Reduced
Fertility
Decreased
Miilk yield,
Mastitis

8. WATER
• Lactating cows will typically require more than 100 litres/cow/day and
will drink between two to six times per day.
• Ensure flow rates to troughs are high enough that the trough never runs
dry.
• Most cows drink soon after milking, so install water troughs in races to
meet that need.

9. FEED
• Provide high quality feeds like total mixed rations
• Increase the frequency of feedings
• Feed during cooler times of the day
• Keep feed fresh as much as possible
• Provide high-quality forage
• Provide adequate fibre
• Use of by–pass proteins can enhance the milk yield and protein content.
• Intake of sufficient cool water is probably the most important strategy for
animals to undertake during heat stress.

10. PROVISION OF SHADE
• Shades can reduce the heat load by 30 %
(Bond et al, 1967)
• Trees are an excellent source of shade and if given the choice cows
will generally seek the protection of trees rather than man-made
structures

11. WALLOWING TANK
• Swine, as well as water buffaloes,
are naturally wallowing animals
and wallows for them have been
shown to improve performance
(Dasilva, 2004).
• Cooling during 5-10 min after
exiting the pond.
• But access to streams and farm
ponds has been associated with a
number of infectious disease and
some toxicity to dairy cattle.

12. COOLING SYSTEMS IN THE FARM
• Fans in combination with water sprinkling facility provide the best
cooling option.
• Excessive sprinkling should never be practised as it can result into wet
bedding making animal prone to mastitis and other diseases.
• High Pressure Foggers (>200 psi) disperse very fine droplets of water
which quickly evaporate and cool the surrounding air.
• The farm should be well ventilated.

13. Evaporative Cooling Pads
• Reduces temperature by 8-10 °C, but it causes an increased relative
humidity up to 90%.
• Cooled air must have a short way through the building to avoid high
temperature and high humidity. Cooling efficiency is about 55-75%,but
these water-based systems are prone to plugging and algal growth.
(Shearer et al. 1999)

14. Tunnel Ventilation
• In tunnel ventilation system, large fans (1.2–1.8 m in diameter) are used to
move air through a barn at an air speed (1–3 m/s) fast enough to provide a
beneficial wind chill effect that cools the cows by convection.
• The entire air inlet is located on one end wall of the barn with all of the
exhaust fans located on the opposite end. (Smith et al. 2012)

15. MANAGEMENT
• Reduce the walking distance and speed to the dairy.
• Reduce the time spent in unshaded yards.
• Minimise handling stress.
• Isolate cows most severely affected by heat stress and provide shade
and cooling.
• Milk earlier in the morning and later in the afternoon, or consider
once-a-day milking.
• Cows reared under electric fan produced 1.2 kg/d more milk during
the early lactation (Suriyasathaporn et al., 2006).
• Sprinklers on the roof

16. BREEDING MANAGEMENT
• As cows exhibit lesser heat symptoms during heat stress zones as
compared to thermal comfort periods, it is necessary to adopt a good
heat detection program to detect cows with marginal heat symptoms.
• It is always advisable to continue AI breeding instead of using bulls
because in natural breeding both bull and cows suffers infertility due
to summer stress.
• Genetic selection of heat tolerant animals and inclusion of heat
tolerance as a trait in selection programme will be a boon to the farms.

17. COLD STRESS
MANAGEMENT

18. Factors Affecting an Animal to Withstand the Cold
• Acclimation:
Growing a longer, thicker coat provides additional insulation against cold
weather.
The coat must be clean and dry to provide maximum protection.
Dirt or moisture on the coat reduces its insulation value dramatically.
• Fat Layer:
The fat layer acts as another insulating layer between the animal’s core and
the environment.
• Metabolic Rate:
Cows will also increase their metabolic rate to increase heat production and
help maintain body temperature.
This increases the need for dietary energy, so appetite is usually increased
and cows eat more.

19. EFFECTS OF COLD STRESS ON CATTLE.
• Mild hypothermia occurs with a body temperature of 30°C–32°C, (86°F–
89°F),
• Moderate hypothermia at 22°F–29°C, (71°F–85°F)
• Severe hypothermia below 20°C (68°F).
As hypothermia progresses, metabolic and physiological processes slow
down, and blood is diverted from the extremities to protect the vital
organs.
 Teats, ears and testes are prone to frostbite.
In extremes, respiration and heart rate drop, animals lose consciousness
and die.

20. Feed intake
• The dry matter intake of the animals in general is increased during very
cold weather. (Graham et al. 1982).
• increased voluntary feed intake in cold stressed animals which was
attributed to the activity of the thyroid gland (Gale 1973).
• The elevation of thyroid activity resulted in increased rumino-reticulum
motility and higher rate of passage of digesta (Gonyou et al. 1979).
• Feed with a high fibre content can increase the heat of fermentation in the
rumen, increasing the heat load on the cow.

21. Contd
• From several studies it is estimated that for every one degree below
the critical temperature a cow's energy requirement (TDN) increases
1 percent.
• It is also estimated that for every ten degrees below the critical
temperature the digestibility of the ration decreases by 1 percent.

22. DIGESTIBILITY OFNUTRIENTS
Reducing D.M
Digestibility
1.8% for each
10C
below 20C
Increase
passage
rate
Cold
stress
feed
efficiency
increase fecal and
urinary energy
diverting
nutrients to
heat generation

23. PRODUCTION
• If cows are not fed additional feed or does not allow them to eat
enough to meet their additional energy requirements,
increased neonatal mortality
reduced growth rate in surviving calves
cows usually have delayed return to estrus
poorer reproductive success

24. LOWER MILKPRODUCTION
• Cold exposure may directly limit the synthetic capacity of the
mammary gland by reducing mammary gland temperature (Johnson
1976), or may act indirectly affecting the udder’s blood supply

25. MANAGEMENT FACTORS TO LIMIT COLD STRESS
• Monitor the weather. Monitor temperature and increase feeding in response to
cold weather. Cows in the last trimester require additional grain feeding during
periods when the effective temperature falls below the lower critical level.
• Protect animals from the wind. Wind markedly reduces the effective temperature,
increasing cold stress on animals.
• Bed cows well. Providing adequate dry bedding makes a significant difference in
the ability of cattle to withstand cold stress.
• Keep cows clean and dry. Wet coats have greatly reduced insulating properties and
make cows more susceptible to cold stress. Mud-caked coats also reduce the
insulating properties of the hair.
• Provide additional feed. Feed more hay and grain. If wet feeds are fed, make sure
they are not frozen.
• Provide water. Make sure cows have ample water available at all times. Limiting
water will limit feed intake and make it more difficult for cows to meet their energy
requirements. Frozen troughs and excessively cold water seriously limit water
intake.

26. COLD STRESS IN CALF
• The study found that the wheat
straw bedding could absorb the
most moisture and provided the
most insulation for heat.
• Colostrum contains energy and
helps the calf generate body
heat.
• “The temperature of colostrum
is about 101.5 degrees, and that
in itself has a warming effect on
the calf,”

27. BODY CONDITION SCORING (BCS)
In the last trimester of
pregnancy a cow should have
a score of 5,6 or 7 on a 1-9
scale.
If a cow is going down in BCS
then the ration is inadequate
and should be improved.

28. CONCLUSION
• We can’t control the weather but we can do everything reasonably
possible to reduce the effects of cold on cows.
• This will help reduce costs and improve production efficiency.

29. THANK YOU