The climate change
includes sudden major changes in temperature, precipitation, or wind patterns
vis a vis the normal conditions
during the same period over the years. Under the present paradigm of climate
change, global warming is the major
issue that has arisen because of ongoing rise in global average temperature
near Earth's surface. Increasing
concentrations of greenhouse gases like Carbon dioxide, nitrous oxide, methane
in the atmosphere that
ultimately is causing climate patterns to change abruptly, thus affecting human
and animal life both directly causing disease and heat stress as well as
indirectly by increased incidences of natural disasters. Earth's average
temperature has risen by 1.4°F over the past century, and is projected to rise
another 2 to 11.5°F over the next hundred years. These small changes in the
average temperature of the planet can translate to much larger and potentially
dangerous shifts in climate and weather. Rising global temperatures have often
been accompanied by changes in weather and climate. Some places have
experienced intense rainfall, resulting in more floods while at other places no
rainfall causing droughts, or, as well as more frequent and severe heat waves.
The planet's oceans and glaciers have also experienced some big changes -
oceans are warming and becoming more acidic, ice caps are melting, and sea
levels are rising. As these and other changes become more pronounced in the
coming decades, they are likely to present challenges to our society and our
environment.
Mega Biodiversity
Traditionally,
India has been a mega bio-diversity centre and rearing of domesticated animals
was practiced since time immemorial. Almost all the major livestock species
including cattle, buffaloes, sheep, goats, pigs, camels, horses, donkeys, yak
and mithuns are found in India. Apart from poultry, domesticated species of
avian such as ducks, geese, quails, turkey, pheasants and partridges also exist
in India. In domesticate species there are over 140 well documented and defined
breeds, whereas per FAO watch list there are about 220 breeds. Tharparkar,
Sahiwal and Rathi breeds of cattle and camels are indigenous to hot arid
deserts where they experience excessive heat during day time in summer when
ambient temperature may be as high as 48-50oC. While the same animal stay in open in night
when the outside temperature may be as low as 15-18oC. Like-wise yak (Bos grunniens) is found in
cold arid desert in upper Himalayas where day temperature may be 35-38oC and night temperature may be sub zero. These
highly adapted germplasm have fixed genes and alleles that give them sustenance
in world's most inhospitable climate and can serve as excellent experimental
model for studies related to animal production under changing climate. It is
imperative to identify such alleles and gene combinations in our indigenous
livestock breeds and populations and the develop strategies for gene based
introgression in other populations which are prone to susceptibility to
impending climate change.
Impact of climate change on livestock
Climate
change comes as an additional factor affecting a livestock sector that is
already highly dynamic and facing many challenges. Important objectives of
livestock genetic resource management include ensuring that animal genetic
resources (AnGR) are effectively deployed to meet these challenges (i.e. are
well matched to the production
environments in which they are kept) and that the genetic diversity needed to
adapt production systems to future changes is maintained. At the same time,
many of the specific challenges associated with climate change (high
temperatures, disruptions to feed supplies, disease outbreaks, etc,) as well as
the general unpredictability it brings to the future of the livestock sector,
highlight the importance of retaining diverse genetic options for the future.
Livestock sector is affected by climate change and also contribute in global
warming to some extent. Climate change affects livestock both directly and
indirectly. The direct effects are due variation in air temperature, humidity,
wind speed and other climate factors that influence animal performance viz.,
growth, milk production, wool production and reproduction. The impact of
climate change on animal production has been due to differential availability
of feed grain, pasture and forage crop production and quality, health, growth
and reproduction and, disease and their spread under abrupt climate change.
Thus, an increase in air temperature, such as that expected in different
scenarios of climate change, would affect directly animal performance by
altering the animal heat balance. There are four modes of energy transfer: radiation, convection,
evaporation, conduction, which is governed by several physical parameters
control heat transfer by different modes. Air
temperature affects energy exchanges through convection and evaporation. When
temperature increases, evaporation becomes the most important way of heat loss,
since it does not depend on a temperature gradient. Therefore combination of
temperature and humidity acquire more relevance, since humidity enhances temperature effects. Therefore, it is important to evaluate the environment,
from the heat stress stand-point, through the temperature humidity index (THI).
Dairy cattle show signs of heat stress when THI is higher than 72. The comfort
limit depends on level of production, type of germplasm and its longevity under
given conditions. Animals presenting higher level of production are more
sensitive to heat stress. It is not only intensity of stress, but also the
length of the daily recovery period is important in determining animal
responses to climatic stresses. They fail to dissipate the extra heat load
accumulated during days when there are several hours with THI well above the
comfort limit, and little opportunity to recover. Climate change is likely to lead to changes in
disease epidemiology, severity of outbreaks and spread to other areas. Precise
effects of climate change on disease profile are difficult to predict, but
combined with problems in the sustainability of some conventional disease
control programmes, climate change-related effects are likely to increase the
importance of genetic resistance and tolerance to diseases. Changes in the
distribution and incidence of diseases that kill
large numbers of animal or induce culling measures for disease control may pose
additional threats to animal genetic resources diversity. The poor farmers can adapt to the local scale effects of climate
change to some extent but feed supply by commercial producer is also affected
due to dependence on
world
feed markets and that is again vulnerable to the effects of climate change,
especially on prices.
Sustainability
of livestock especially, the exotic breeds or their crossbreds depends on
better feed and fodder resources
in adequate quantity is influenced more critically than the indigenous ones.
The indigenous breeds have lesser feed/fodder requirements, able to utilize
coarser feed/ fodder resources and can graze on meagre grazing resources that
too when the ambient temperature is high. Therefore, the types of germplasm,
their adaptability under different climate regimen are keys for sustainability especially
under impending climate change.
Studies on impact of climate change in
Indian livestock
The
vulnerability of livestock to climate change has hardly been documented in India.
Isolated experimental studies have been conducted on effects of season and
climate on production, performance and other physiological parameters of dairy
animals. From these studies it has been revealed that milk yield of crossbred
cows in India (e.g., Karan Fries, Karan Swiss and other Holstein and Jersey
crosses) are negatively correlated
with temperature-humidity index. The influence of climatic conditions on milk
production has been also
observed for local cows which are more adapted to the tropical climate of
India. Heat stress has been found to have detrimental effects on the
reproduction of buffaloes, although buffaloes are well adapted morphologically
and anatomically to hot and humid climate. The thermal stress on Indian
livestock particularly cattle and buffaloes have been found to decrease estrus
expression and conception rate. The length of service period and dry period of
all dairy animals was found to be increased from normal during drought. The outbreak
of the disease has often been correlated with the mass movement of animals
which in turn is dependent on the climatic factors.
The higher incidence of clinical mastitis in dairy animals during hot and humid
weather
may be due to
increased heat stress and greater fly population associated with hot–humid
conditions.
Mitigation strategies
Since climate
change could result in an increase of heat stress, all methods by which animals
can cope with heat stress or alleviate the impacts of heat stress to mitigate
the impacts of global change on animal responses and performance need to be
assessed. Three basic management schemes for reducing the effect of thermal
stress have been suggested: (a) physical modification of the environment; (b)
genetic development of less sensitive breeds and (c) improved nutritional
management schemes.
Physical modification of the environment
The
different methods of environmental modification include: shades, ventilation,
combination of wetting and ventilation.
Providing shades to livestock is the simplest method to reduce the impact of
high solar radiation. Shades
can be either natural or artificial. Tree shades have proved to be more
efficient. In traditional livestock rearing, animals are herded under the shade
of trees in pasture or in forests during peak summer hours. When enough natural shade
is unavailable, artificial structures may be constructed. Different aspects
concerning design and orientation of shades have been published. Shades are effective
in reducing heat stress in the dairy cow. Animals presented lower afternoon
rectal temperature and respiration rate, and yielded more milk and protein when
provided adequate shade. The artificial shade structure using heat proof
materials may not differ from tree shades, in terms of the effects on animal
well-being. Increase in air movement is an important factor in the relief of
heat stress, since it helps heat loss due to air convection especially under
high ambient humidity leading to evaporative cooling. Wherever possible,
natural ventilation should be maximized by constructing open-sided constructions.
Forced ventilation, provided by fans, is a very effective method, if properly
designed. An effective way of cooling cattle is spray evaporative cooling.
There are several methods available: mist, fog and sprinkler systems. However,
the single use of a sprinkler and fan system, for 30 minutes before milking,
has proved to be useful to relieve dairy cow's heat stress. In 2030, adoption could restrict losses to 1% of annual production.
Finally, in 2070, milk losses would be reduced to 3 to 4% of annual milk
production, by installing environmental
modifications.
Genetic development of less sensitive
breeds
The
strategies should be to explore all the livestock breed populations keeping
following points in to consideration.
•Documentation
of indigenous breeds for heat tolerance, disease resistance, adaptation to poor
diet, etc. and their comprehensive evaluation of performance and use of animals
in specific production environments;
•Phenotypic
characterization studies on Animal Genetic Resources (AnGR), the surveys should
have data entry on all phenotypic traits specifically;
•Improving
knowledge and awareness of, and respect for, local and indigenous knowledge
relevant to climate-change adaptation and mitigation;
•Identifying
potential climate change-related threats to specific AnGR, ensuring that
long-term environmental threats
are monitored and that urgent action is taken to address immediate threats from
climatic disasters to save small populations at severe risk;
•Modelling
the future distribution and characteristics of production environments, to
support the assessment of threats
and the identification of areas that may be suitable for particular breeds in
the future;
•Improving
knowledge of breeds for their current geographical distributions and to
facilitate planning of climate-change
adaptation measures and AnGR conservation strategies;
Improving
the availability of the above-described knowledge, including via DAD-IS and
other AnGR
information
systems.
Improved nutritional management schemes
The effects of
climate change on livestock production can be mediated through change in feed
resources and feeding schedules. It is known that feed resources can have a significant
impact on livestock productivity, the carrying capacity of rangelands, the
buffering ability of ecosystems and their sustainability, prices of grains,
trade in feeds, changes in feeding options, grazing management and ultimately
the control on greenhouse gas emissions. There are considerable opportunities
to reduce the methane emissions per animal by individual and herd management
changes that reduce the proportion of energy spent in maintenance. Maximised
fecundity, health and maximising daily product output by provision of ad libitum
high digestibility feed or specific supplementation for enhancing digestibility
of coarse feeds and fodders. Reducing total emissions (kg/d) rather than simply
emission intensity (methane/product) from the herd or flock will require
reduction in animal numbers or implementing mitigation strategies such as the inclusion
of fats or oils in the diet. Potential exists to reduce emission without
restricting animal performance by grazing pastures of lesser tannin levels or
by supplementing with oils or white cotton seed and by some small supplementations
of tannin and saponins. Pasture quality, supplementation and selection for NFI
are potential means of reducing the emissions intensity and total methane
emissions from livestock. Efficiency of the whole herd or flock can also be
improved by further increasing productivity
of stock and minimising the proportion of consumed energy utilised in
maintenance. The climate change
could affect animal production and well-being, especially because of increases
in air temperature. However,
the knowledge of animal responses to heat stress during the hot months in
several areas of the world, as well as during extreme heat events, may be used to
evaluate the impacts of global change. Some current practices and adoptions to
reduce heat stress in dairy cows, such as shades, sprinklers and ventilations
will be suitable for mitigating climatic change effects if the economics of heat
stress management do not change radically. However, farmers are not quite aware
about the impacts global warming can produce
in their operation. Therefore, good research work is needed to help them take
strategic and tactical decisions. National Initiative on Climate Resilient
Agriculture (NICRA) launched by Indian Council of Agricultural Research (ICAR)
with the funding from Ministry of Agriculture, Government of India has three
major objectives of
strategic research, technology demonstrations and capacity building. Assessment
of the impact of climate change simultaneous with formulation of adaptive
strategies is the prime approach under strategic research across all
sectors of agriculture, dairying and fisheries. Evolving climate resilient
agricultural technologies that
would increase farm production and productivity vis-à-vis continuous management
of natural and manmade resources
constitute an integral part of sustaining agriculture in the era of climate
change.
Source of Article: Book on Climate Change and
Sustainable Food Security Author: K.M.L. Pathak, Neelam Gupta, Vineet Bhasin,
Rajan Gupta, S.C.Gupta and
B.S. Prakash, ICAR (Indian Council of Agricultural
Research)
