Management Strategies For The Effects Of Climate Change On Livestock
A blog which makes an insight on the importance of implementing management strategies for better livestock environment and attaining maximum
Climate is changing, sadly the main
reason for this is increased human activities which have serious
consequence on both economic and social development. Livestock are
livelihood of weaker segment of the society having poor economic
sustenance with lack of resources to create favorable climate in terms
of shelter or an organized system.
Due
to the increasing human population, the global demand for livestock
products is expected to double during this century. Over the same
period, we are facing big changes in the global climate as well.
Nowadays climate change is one of the most serious long-term challenges
faced by farmers and livestock owners around the globe. About 12% of the
world's population depends solely on livestock for their livelihood.
How climate changes affect livestock
Livestock
is an extremely important source of nutrition and livelihood for
millions of poor people. Temperature and associated seasonal patterns
are critical factors that affect agricultural production systems. Rising
temperatures associated with climate change will likely have a harmful
impact on livestock, crop production, fishery and allied sectors. The
continuous heat waves and drought as a result of climate change has
impacted livestock production resulting in severe economic loss to the
poor and marginal farmers. Models based on different climatic scenarios
suggest that milk production will decrease by tonnes. The first and
foremost stress the livestock are exposed as a result of climate change
is the heat stress. Heat stress is one among the environmental variables
that affect animals in making animal production challenging in many
geographical locations in the world.
Even
though animals are capable of adapting in the hot climate, the response
mechanisms that ensures survival are also detrimental to performance.
The ability to adapt to heat stress varies according to genetics,
species, life stage and nutritional status. Heat stress has severe
consequences both on reproduction and production in livestock.
Growth
imply the increase in the live body mass or cell multiplication and it
is controlled genetically as well as environmentally. Elevated ambient
temperature is one among the environmental factors influencing average
daily growth. Livestock respond to a heat challenge by decreasing feed
intake which then has a direct impact on performance, in the form of
reductions in milk quality, milk yield, meat and egg production. Heat
stress particularly in dairy animals will have long term affects on both
milk production and birth rates. Increased summer temperature leads to
depressed and low feed intake, reduction in body weight of animals, and
lower milk production. Under extreme conditions there may also be an
increase on mortality rates.
Management strategies that could be adopted against heat stress
Animal
housing is one of the best approaches to resist the impacts of climate
change on cattle. Shade reduces the severity of heat stress in animals
that are being exposed to sun. It is an effective method to protect the
animals from radiant heat load and helps to cool the animals. Shades can
be made artificial or natural. Aluminum or galvanized steel roofs are
artificial shades while the roofs made out of straw are of natural
means. Provision of trees and other vegetative covers over the
surrounding area will reduce the effect of radioactive heat load on the
cattle. Roofing materials should always be a bad conductor of heat and
the best housing will have roofs painted in white so as to reflect the
radiation of sun.
Fig.1
- Animal Housing
Physical protection with natural or
artificial shade presently offers the most immediate and cost-effective
approach for enhancing reproductive efficiency of animals. Various
shading systems have been extensively and resulted in improved feed
intake and productivity. The orientation of the shed should be in North -
South direction in the northern hemisphere so that the direct incidence
of solar radiation into the shed is avoided. For effective heat
dissipation in cattle, there should be free flow of air inside the shed,
this can be done by increasing the ventilation by means such as an open
housing system, increasing the height of the building, use of fan etc.
Shade
alone will reduce a cow’s respiration rate by 30%, and adding
sprinklers (evaporative cooling) will reduce the respiration rate by
67%. Both the method of shading and use of sprinklers will effectively
resist temperature rise in livestock. By using fans, especially in
confined structures this helps to move warm air from cow's bodies. One
of the best method to reduce heat stress is to provide adequate cool,
fresh and clean drinking water. Commercial coolers, tunnel ventilation,
shower or fanning stations, fans and center pivots can also be adopted
for additional cooling.
Cows
generate approximately 20% of their gross energy as body heat, which is
released to the surrounding air, making them feel hot, especially under
heat stress conditions. What happens while using fans is that it helps
to remove body heat via convection, thereby cooling down the surface of
the animal. Sprinklers soak the cow’s hair coat to the skin with water,
allowing the loss of body heat through conduction. Fans plus sprinklers
allow for conduction and evaporative cooling, as the fans help to
vaporize the water that has been warmed by the release of body heat.
Marked relief was observed in cows by the use of fans plus sprinklers,
which reduced respiration by 50% to 50 breaths per minute.
Enhancing
heat loss with the help of sprinklers/misters/foggers along with fans
and installation of air conditioners in extreme hot climates are the
main strategies for mitigating the heat stress. Sprinkling animal in the
morning is more effective than sprinkling in the afternoon.Sprinkling
of surface where the animals reside may be as much or more beneficial
than sprinkling the animal. Cooling the surface would appear to provide a
heat sink for animal to dissipate body heat, thus allowing animal to
better adapt to environmental conditions rather adapting to being wet.
Reducing the stocking density during hot weather will help the animals
in dissipating the body heat more efficiently and during cold conditions
the stocking density can be increased.
Controls
Proper
controls are inevitable for effective cooling system. It is essential
that controller keep the cooling fans running whenever the sprinkler
system is operating. It is also essential that the water sprinklers be
shut off to allow the cow's hair to dry. This means that the water
sprinklers are on a short period of time to wet cow's skin and off a
longer period of time to allow the water to evaporate from the cow's
hair coat. It is better to plan to have the sprinklers on for 1 to 3
minutes out of every 10 to 15 minutes. The sprinklers will spray water
for 1 to 3 minutes and are shut off for 12 to 14 minutes over a 15
minute cycle. It is appropriate to select an adjustable 30 minute cycle timer.
The
controls for low-pressure sprinkler and fan cooling systems include
timers, thermostats, and solenoid valves to control the sprinkler system
and the cooling fans. The simplest system has a thermostat in series
with a timer. The thermostat activates the cooling fans and the timer
when the air temperature exceeds the set point temperature. Typically
cooling systems are set to start operating when temperatures reach 24°C
to 27°C and above.
Fig.2 - Cooling System components
Design for a livestock cooling system
Low-pressure sprinkler and fan cooling system design criteria generally include the following factors.
1. Cooling system location
Low-pressure
evaporative and fan cooling systems can be used in naturally ventilated
freestall barns. Sprinklers can be used where the floor can get wet
without significant consequences. Sprinkler systems installed in
freestall barns should be positioned so that it avoid bedded freestalls
and feed wet. The area should have adequate drainage with enough slope
to allow excess water to drain away and to avoid water ponding. Some of
the cooling water will wet the floor and get into the manure system.
This happens on excessive sprinkling and should be avoided.
Fig.3 - Typical sprinkler System for Cooling
2. Nozzle selection
Nozzle
selection is critical to evaporative cooling system performance. Use
either 180 degree (half-circle) or 360 degree (full-circle) low pressure
(1.4 to 1.7 Bar) sprinkler nozzles that produce large droplets gives
shower effect, which readily wet the cow’s skin. A fine mist should not
be used. Irrigation nozzles and solid-cone coarse droplet spray nozzles
with flow rates between 0.05 and 0.1m3/hr work very well. The nozzles
should be placed so that the system provides a uniform distribution of
water and apply most of the water in the middle of the cow’s back. It is
better to provide some overlap also while placing the nozzles. Typical
nozzle spacing ranges from 1.2 to 3m. Locate nozzles high enough (about
2.7m), so that cows cannot reach them.
Fig.4
- Sprinkler System at Feed line (Top View)
3. Water supply and delivery capacity
The
water supply system installed must be able to deliver sufficient water
at the design pressure throughout the sprinkling system and satisfy all
other farmstead water requirements (i.e., drinking water, parlor needs,
flush water, etc.) which occur simultaneously. Consider using a
reservoir system when the water supply flow rate is limited. A reservoir
system accumulates water during off periods.
4. Water Pressure
Normal operating pressures for low-pressure systems are between 1 and
1.4 Bar. Avoid excessive system pressures to eliminate the production of
very fine droplets that do not soak the hair coat, and may drift away
more easily in air currents. Consider installing a pressure regulator to
keep the water pressure within operating limits for the nozzles as
well.
5. Water in line filter
An
in line filter, usually a Y-filter with a flush valve and a 200 to 500
mesh screen, can be included in the system to protect nozzles from
plugging with rust particles and sand. It is important to check and
clean filters periodically.
6. Flushing and shutdown
Consider
providing a valve or removable plug at the end of each lateral to flush
sand and rust from the lines. Make sure that the system and all lines
can be drained prior to freezing weather condition.
7. Distribution Pipe Selection
Various
types of plastic pipes PVC or polyethylene can be used for supply and
distribution lines. In addition to cost and ease of installation,
consider susceptibility to sunlight degradation, durability, and need
for mounting support.
8. Pipe Sizing
Pipe
size requirements will depend on feed line length, number and length of
distribution branches, number of nozzles per branch, nozzle flow rates,
and number of branches on at one time. Water velocities should be
limited to 1.5m per second or less to avoid water-hammer problems. This
can be used to size distribution lines and supply line as well. The
supply line needs to be sized adequately to limit the pressure drop in
the line to 20% of the operating pressure. A factor, reduction
coefficient should be considered for reduced friction loss in pipes with
multiple outlets (i.e., nozzles in this case) due to reduce flow in the
pipe.
9. Fan selection and installation
Low
pressure sprinklers and fan cooling systems include mixing fans to
create a drift past or across the cows. Direct-drive axial-flow fans are
preferred, this is because they retain their performance over time
better than belt-driven fans. Most mixing fans are around 1m in diameter
and normally installed about 3m to 3.6m above the cow feeding alley, or
high enough to clear equipment operating below the fans.
Fans
over freestalls are usually mounted 2.4m above the cow alley or higher
if necessary to keep cows from reaching the fans. The fans are angled
downward at between 15 to 20 degrees. The goal is to create air
velocities around 5m/sec across the cow's backs. The recommended
distance between fans is 9m for 90cm diameter fans and 12m for 120cm
diameter fans. All fans should be blowing air in the same direction.
Most cooling fans seen in naturally ventilated barns are mounted to blow
air toward the East or North.
Management strategies that could be adopted against cold weather
Animals must be provided proper bedding and warmth to protect them from extreme cold, this can be achieved by various heating techniques. Heating system include radiant, floor, air-make up and unit space heaters.
1. Radiant heating
Radiant heaters work well for zone heating of young animals. Animals find comfort by moving closer to or farther from the heater. Energy from a radiant heater passes through air without warming it. When the energy strikes an animal or any other surface, it is absorbed and object warms. The warmed object then warms the air around it. Different types of radiant heaters are infrared heaters, heat lamps, gas catalytic radiant heaters etc.
2. Floor heating
Floor heating is primarily suggested for localized heating. Possible uses of floor heating are in farm shops, small animal housing and other heated work areas. Common floor heaters are electric resistance cables or hot wire pipes which are buried in concrete. Floor heaters evaporate liquid from the floor, which uses heat and increases the building relative humidity. While designing a floor heat system care should be taken not to setup too much heated area, because it might be not efficient and lead to loss of heat. In addition to that, the heating area should not be too less. This may encourage the animals to pile. For better heating effect use waterproof insulating media under the floor, but not in direct contact with the heating elements.
Fig.5 - Floor Heating
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