Impact of climate change on livestock
Climate change (CC) and global warming are important phenomenon and these two are entirely different terms but the link between these two is very strong. Global warming is an increase in the atmospheric temperature near the surface of earth while CC is more diverse and concerned to any change in climatic parameters like temperature, humidity and wind which last for a long time duration. The important among these two is global warming which is an increase in temperature and blamed largely causing greenhouse effect. Geographically, Pakistan is located in between industrial countries like China and India that’s why Pakistan is most vulnerable to climate change while contributing only 1% of global greenhouse gases (GHG’s). Global warming alters volumetric flow rate of major rivers due to glacier shrinkage and affects millions of people from last few decades and is expected to be continued. By the end of this century, global temperature may rise up to 6.5°C. Theories on global warming revolve around GHGs emissions, which are accumulated in the atmosphere and enhance the greenhouse effect by captivating thermal radiation emitted by the land and water bodies. CC is a blazing issue now a days as temperature and humidity of earth is rising day by day. As a result of this climatic change, living conditions for every species altered. These changes in climate threaten environment, water and food supply.
Global increase in population makes the role of livestock sector more critical as demands of livestock products are increased and are predicted to be almost doubled at the end of 2050. Due to CC species of animals present in a particular habitat are badly affected by temperature spikes, increase in extreme events like cyclone, drought, floods, changes in rainfall, increased carbon dioxide and plant growth and rise in sea level. The magnitude of the influence caused by CC depends on various factors. An intensively managed livestock system is less proned as compared to extensively managed one such as rain-fed pastoral system. The magnitude of change in climate can be assessed in two ways either directly on livestock which are easily detected as increased spread of existing vector borne parasitic infestations, altered incidence of disease occurrence, circulation of new diseases, changing rainfall pattern and inclined breeding and reproduction efficiency of livestock. While the complex, indirect effects on livestock production systems in under-developed countries of Asia & Africa. These indirect effects are shown by the animal itself as body status and production potential, these indirect effects include: heat stress, water availability, feed quality and quantity, disease vectors, changes in biodiversity, changes in livestock production systems and other indirect impacts. There are some indirect effects of changing climate on livestock. The major one is disease occurrence among livestock holders and human populations who are actively involved in livestock production. These diseases may influence the livestock systems indirectly by reducing the man power availability, less productivity and relocation of human communities.
Hot and humid conditions leads to heat stress on livestock which can cause metabolic and behavioral changes. These also cause less water and feed which ultimately decrease the production. Livestock can maintain their body temperature according to their thermal comfort zone. If temperature exceeds, that zone will disrupt the heat exchange phenomenon affecting their growth, feed intake, digestibility, reproduction and production; ultimately increased mortality within livestock populations. However, susceptibility of livestock to heat stress is variable and depends on their, breed, specie, rearing system, life stage, nutritional status and genetic potential. According to the report, heat stress reduces the milk yield by half or 1/3. Apart from decrease in milk yield, increased energy deficiencies due to heat stress may influence the fertility, fitness and the longevity of cow.
Globally, among all of water resources, only 2.5% are of fresh water and 70% of these resources are present in the form of glaciers. In future, changes in climate will considerably reduce the availability of water which has direct effect on livestock drinking water resources and also have a negative impact on production of livestock feed and grassland yield.
CC has also been predicted to reduce the quality of forages. For example, rising temperature enhances lignin content in plant cell wall which may decrease the digestibility of plant tissues that results in reduced livestock productivity and livelihood of smallholders. Only modified grazing management practices may fill the gap between production and feed quality and quantity of grasslands. Vector-borne diseases are transmitted by arthropods including ticks and mosquitoes. Their spread is enhanced by following factors like rainfall, high humidity, and increased temperature. Increased rainfall provide more breeding sites to vectors which results in their increased population. Similarly, increase in temperature and humidity provide ambient conditions for breeding of arthropods. Cold weather is a natural way to kill a lot of disease carrying vectors. Increased duration of summer season leads to survival of vectors and this coupled with the heat stress on animals and reduces the ability of animals to cope with the diseases.
Like other countries of the world, climate is also rapidly changing in Pakistan. This demands a change in policies regarding livestock production with respect to change in climate. The best way is to manage the dairy animals in a wise and economical way during Summer and enable them to dissipate body heat and provide a comfortable environment to animal as much as possible. These managemental practices allow animals to grow faster, improve their reproductive efficiency and allow them to produce at their maximum potential when they are in production. Certain measures like weather forecast, protection of animals from rain and sun, improved feeding especially in cooler parts of the day, offering easily digestible food varieties, decreased dry matter intake, use of hay and silage, provision of fresh clean and sufficient water, breed improvement, housing managements like tunnel ventilation and use of water sprinklers help animals to cope with extreme conditions of weather which ultimately boost their production.
The livestock representatives in the Climate Change Chair (CCC), of US. Pakistan Center for Advanced Studies in Agriculture and Food Security (USPCAS-AFS) are striving hard to standardize tools for CC impact assessment, mitigation and adaptation strategies with reference to livestock production system in Pakistan.
This article is collectively authored by Muhammad Awais Adil Institute of Soil and Environmental Science”
University of Agriculture, Faisalabad and Dr. Muhammad Sohail Sajid Associate Professor Department of Parasitology, University of Agriculture Faisalabad.