Impact of Climate Change on Livestock

Introduction

Global warming is the long-term warming of the Earth’s climate due to human activities, primarily the burning of fossil fuels, which increases levels of heat-trapping greenhouse gases in the Earth’s atmosphere. The term “Global warming” is often used synonymously with “climate change”. Climate change is a long-term change in average weather patterns that determine the Earth’s local, regional, and global climate. It is most commonly measured as the average increase in global surface temperature on Earth. The effects of climate change (global warming) can be observed on the health, welfare, production, and reproduction of livestock.

Global warming is increasing, thereby, threatening ecosystems, animal biodiversity, and food security. Farm animals make a significant contribution to global food security, their contribution is particularly important in the developing world where they represent a crucial source of energy, protein, and micronutrients. Climate change is having a significant impact on the ecosystems and natural resources on which livestock farming depends. At the same time, livestock farming contributes substantially to greenhouse gas emissions and climate change. Climate change affects livestock directly through heat stress and increased morbidity and mortality, and indirectly through the quality and availability of forage and animal diseases.

Effects of climate change on animal production

Agriculture is the main source of livelihood for one-third of the world’s population. About sixty percent of people who make a living from agriculture own livestock, making animal husbandry a rapidly growing sector. It accounts for forty percent of global agricultural gross domestic product and is crucial for food security in all regions. Farm animals make an important contribution to the global calorie, protein, and micronutrients such as vitamin B12, iron, and calcium, which is evident from the fact that they produce seventeen percent of the calories consumed worldwide and thirty-three percent of the protein. Furthermore, livestock can increase the world’s edible protein balance by converting inedible protein found in the forage into the forms that humans can digest.

In addition, livestock is a key asset for rural communities, providing a range of essential services including savings, credit, and buffering against climate shocks and other agricultural crises. They also provide transport and traction power for field operations. Climate change poses a serious threat as rising temperatures, shifts in precipitation distribution, increased frequency of occurrence of extreme weather events, and consequently increased heat stress, as well as reduced water availability have both direct and indirect adverse effects on livestock production and productivity. 

The direct impact of climate change

i) On grazing system

• Increased frequency of extreme weather events
• Increased frequency and magnitude of droughts and floods
• Productivity losses resulting from physiological stress due to higher temperatures
• Changes in water availability, may increase or decrease depending upon the region

ii) On non-grazing system

• Increased frequency of extreme weather events, with the impact being less acute than for extensive systems
• Changes in water availability, may increase or decrease depending upon the region

The direct impact of climate change: Agroecological and ecosystem shift leading to

i) On grazing system

• Alteration in food quality and quantity
• Change in host-pathogen interaction resulting in an increased incidence of emerging diseases
• Disease epidemics

ii) On non-grazing system

• Increased resource price (feed, water, and energy)
• Disease epidemics
• The increased cost of animal housing (cooling system)

The vulnerability of livestock to climate shocks depends on their exposure, which is determined by the duration, frequency, and severity of the shock and the location of the herd and associated assets (feedstock, housing, water points). It also depends on their sensitivity, which is determined by the breed. Socioeconomic factors that have a particular impact on disease prevalence include changes in land-use patterns, host abundance, international trade, mitigation, and public health policies.

These environmental conditions can affect livestock health by causing metabolic disorders, oxidative stress, and immunosuppression, leading to infection and death. Hot summer conditions disrupt multiple reproductive processes, resulting in a marked reduction in conception rates in dairy animals worldwide. When body temperature reaches 39.5 °C, severe impairment of reproductive processes such as impaired oocyte viability, weakened embryonic growth, and early embryonic death due to impaired hormone secretion, change in growth dynamics of ovarian follicles, suboptimal development of the corpus luteum, and weakened uterine endometrial responses may occur.

Applying efficient cooling is a must, and a requirement to minimize heat stress. However, sometimes reducing summer heat stress alone is not enough to maintain reproductive function, even after the stressor ends. So, it is recommended to combine cooling with other treatments to improve fertility. In particular, treatments to improve the timing of ovulation, increased removal of impaired follicles, induction of ovulation from healthy follicles, embryo transfer, and progesterone supplementation before and after artificial insemination may be required to improve fertility in heat-stressed dairy cows. Heat stress also has a negative effect on milk and meat production, with not only the quantity but also the quality of animal products being strongly and negatively affected by a hot environment.

Effects of climate change on animal health

Infectious diseases and their transmission cycles represent complex interactions between hosts, pathogens, and the environment. These occur mainly due to changes in the host-pathogen environment. Among these, most diseases are zoonotic; meaning that they are transmitted from animals to humans and have serious consequences for public health, affecting the economy of the livestock sector and biodiversity conservation.

Climate change, and particularly global warming, affects animal health by affecting the interaction between host, pathogen, and the environment both directly and indirectly. The direct effects are more likely to affect diseases related to vector transmission, water or food, soil, rodents, air temperature, and humidity. The indirect impacts of climate change are more complex and include those arising from changes in land use and biodiversity, animal’s attempts to adapt to these climatic changes or the impact of climate on microbial populations, distribution of vector-borne diseases, and the host’s resistance to infectious agents or food-borne diseases. Climate variability in rainfall, temperature, humidity pattern and extreme weather events such as floods, drought, and heatwaves are important indicators for monitoring and predicting the occurrence of animal diseases.

Impact of livestock farming on climate change

The livestock sector is a major contributor to climate change, generating significant emissions of greenhouse gases (carbon dioxide, methane, and nitrous oxide). Livestock contributes to climate change by emitting greenhouse gases either directly (through enteric fermentation and manure management) or indirectly (feed production, conversion of forests to pastures).

For the past quarter-century, the livestock sector has focused on improving productivity, regulating the micro-environment of the animal, and improving nutritional management rather than improving stress resilience. This approach dramatically increased the productivity of these animals but also increased their sensitivity to hot environments. The processes by which domestic animals respond to changes in their environment are critical to survival but often negatively impact the productivity and profitability of livestock systems. Acclimation and acclimatization are coordinated phenotypic responses to environmental stressors and the response will decay if the stressors are removed. If chronic stress persists over several generations, the acclimatization response will become genetically “fixed” and the animal will be adapted to the environment.

It is well known that the selection of animals for high production levels has increased the animals’ vulnerability to environmental problems. On the other hand, using lower-performing cows could reduce heat stress, but reduced production efficiency can lead to increased greenhouse gas intensity. While a single stressor can be important, the cumulative effects of multiple stressors (in addition to heat stress) can be significant and must be considered. Adaptation strategies include production system adjustments and genetic improvement in thermotolerance. In addition to adaptation, mitigation strategies should also be discussed, these include changes in animal husbandry systems (nutritional interventions, manipulation of the rumen ecosystem, provision of shade, housing, fans, and sprinklers). Multidisciplinary approaches including animal husbandry, nutrition, housing, and health are needed to reduce the adverse impacts of climate change on livestock. 

Therefore, the implementation of mitigation strategies aimed at reducing emissions from the livestock sector is the need of the hour to limit the environmental burden from food production while ensuring a sufficient supply of food for a growing world population. Mitigation can be done directly by reducing the amount of greenhouse gases emitted or indirectly by improving production efficiency. To increase the effectiveness of these strategies, the complex interactions between the components of animal production systems must be considered to avoid ecological trade-offs’.

Also, read | Disease Management in Poultry Farm

Authors:

Swati Thakur¹, Souvik Dhara², S. Ramanarayanan³ and Manita Dangi⁴

 ¹PhD scholar, Department of Veterinary Physiology and Biochemistry, LUVAS, Hisar

²PhD scholar, Department of Animal Reproduction, Gynaecology and Obstetrics, AAU, Guwahati

³PhD scholar, Department of Veterinary Pharmacology and Toxicology, GADVASU, Ludhiana

⁴PhD scholar, Department of Animal Genetics and Breeding, LUVAS, Hisar