By Fungai Hove
 
Livestock plays  a key  role in the agricultural sector in Africa  and is a major contributor to economic development.
 
Global demand for foods of animal origin is growing and  the livestock sector will need to expand, according to the United Nations Food and Agricultural Organisation, FAO.
 
Like all sectors,  livestock are adversely affected by the negative  effects of extreme weather.
 
Climatic extremes and seasonal fluctuations in herbage quantity and quality will affect the quality  of livestock, and will lead to a decline in production and reproduction efficiency (Sejian, 2013).
 
Climate Change is a major threat to the sustainability of livestock systems globally. 
 
Adaptation to, and mitigation of the detrimental effects of extreme climates has played a major role in combating the climatic impact on livestock (Sejian et al., 2015a). 
 
Climate Change  can impact the amount and quality of product, reliability of production, and the natural resource base on which livestock production depends. 
 
Climate Change  is an important factor in  agricultural productivity and  is expected to severely impact livestock production systems.
 
While the increasing demand for livestock products offers market opportunities and income for small, marginal, and landless farmers, livestock production globally faces increasing pressure because of negative environmental implications, particularly because of greenhouse gas (GHG) emissions.
 
Higher temperatures caused by GHG, will   result in a decline in dairy production, reduced animal weight gain, reproduction, and lower feed-conversion efficiency in warm regions.
 
Incidence of diseases among livestock and other animals is likely to be affected by Climate Change, since most diseases are transmitted by vectors such as ticks and flies (development stages of ticks and flies are often dependent on ambient temperature).
 
Cattle, goats, horses, and sheep are also vulnerable to an extensive range of nematode worm infections, most of which have their developmental stages influenced by climatic conditions. Climate Change will have far-reaching consequences for dairy, meat, and wool production systems that rely primarily on grass and rangelands and this will likely detrimentally affect vulnerable pastoral communities which engage in extensive livestock production systems in drylands.
 
Direct impact of Climate Change
The productivity of the animals is affected by Climate Change due to the behavior of the animals as the climate is drastically changing.
 
The produce from these animals is fast becoming inadequate to meet the demands of this world.
 
Difficulties  facing livestock is weather extremes like  intense heat waves, floods and droughts.
 
In addition to production losses, extreme events also result in livestock death (Gaughan and Cawsell-Smith, 2015).
 
Animals can adapt to hot climates, however the response mechanisms that are helpful for survival may be detrimental to performance.
 
In this article we make an attempt to project the adverse impact of Climate Change on livestock production.
 
The most significant direct impact of Climate Change on livestock production comes from the heat stress.
 
Heat stress results in a significant financial burden to livestock producers through decrease in milk component and milk production, meat production, reproductive efficiency and animal health.
 
Indirect effects of Climate Change on livestock
Most of the production losses are incurred via indirect impacts of Climate Change largely through reductions or non-availability of feed and water resources.
 
Climate Change has the potential to impact the quantity and reliability of forage production, quality of forage, water demand for cultivation of forage crops, as well as large-scale rangeland vegetation patterns.
 
In the coming decades, crops and forage plants will continue to be subjected to warmer temperatures, elevated carbon dioxide, as well as wildly fluctuating water availability due to changing precipitation patterns.
 
Climate Change can adversely affect productivity, species composition, and quality, with potential impacts not only on forage production but also on other ecological roles of grasslands (Giridhar and Samireddypalle, 2015).
 
Due to the wide fluctuations in distribution of rainfall in different  regions of the world, the forage production will be greatly impacted.
 
With the likely emerging scenarios that are already evident from impact of the Climate Change effects, the livestock production systems are likely to face more of negative than the positive impact.
 
In addition, Climate Change influences the water demand, availability and quality.
 
Changes in temperature and weather may affect the quality, quantity and distribution of rainfall, snowmelt, river flow and groundwater.
 
Climate Change can result in a higher intensity precipitation that leads to greater peak run-offs and less groundwater recharge.
 
Longer dry periods may reduce groundwater recharge, reduce river flow and ultimately affect water availability, agriculture and drinking water supply.
 
Deprivation of water affects animal physiological homeostasis leading to loss of body weight, low reproductive rates and a decreased resistance to diseases (Naqvi et al., 2015).
 
More research is needed into water resources’ vulnerability to Climate Change in order to support the development of adaptive strategies for agriculture.
 
Emerging diseases including vector borne diseases that may arise as a result of Climate Change will result in severe negative impacts on livestock production.
 
Impact of Climate Change on livestock production
Animals exposed to heat stress reduce feed intake and increase water intake, and there are changes in the endocrine status which in turn increase the maintenance requirements leading to reduced performance (Gaughan and Cawsell-Smith, 2015).
 
Environmental stressors reduce body weight, average daily gain and body condition of livestock.
 
Declines in the milk yield are pronounced and milk quality is affected: reduced fat content, lower-chain fatty acids, solid-non-fat, and lactose contents; and increased palmitic and stearic acid contents are observed.
 
Generally the higher production animals are the most affected. Adaptation to prolonged stressors may be accompanied by production losses. Increasing or maintaining current production levels in an increasingly hostile environment is not a sustainable option.
 
It may make better sense to consider using adapted animals, albeit with lower production levels and  lower input costs rather than try to infuse ‘stress tolerance’ genes into non-adapted breeds (Gaughan, 2015).
 
Impact of Climate Change on livestock adaptation
In order to maintain body temperature within physiological limits, heat stressed animals initiate compensatory and adaptive mechanisms to re-establish homeothermy and homeostasis, which are important for survival, but may result in  reduction in productive potential.
 
The relative changes in the various physiological responses like  respiration rate, pulse rate and rectal temperature give an indication of stress imposed on livestock.
 
The thermal stress affects the hypothalamic–pituitary–adrenal axis.
 
Corticotropin-releasing hormone stimulates somatostatin, possibly a key mechanism by which heat-stressed animals have reduced growth hormone and thyroxin levels.
 
Animals thriving in the hot climate have acquired some genes that protect cells from the increased environmental temperatures.
 
Using functional genomics to identify genes that are up- or down-regulated during a stressful event can lead to the identification of animals that are genetically superior for coping with stress and to the creation of therapeutic drugs and treatment that target affected genes (Collier et al., 2012).
 
Studies evaluating genes identified as participating in the cellular acclimatisation response from microarray analyses or genome-wide association studies have indicated that heat shock proteins are playing a major role in adaptation to thermal stress.
 
Adapting livestock systems
There are many options that can help stockpersons  adapt to a changing climate.
 
These  include changes in livestock breeds and species, improved feeding,  better grazing, manure management  and use of weather information and weather-index insurance.
 
Many livestock adaptation changes will in addition,  involve transformation of farmers’ livelihoods.
 
Recent examples of such transitions include the adoption of camels and goats in addition to, or as a replacement for, cattle in drylands as a result of changing drought frequency and declining feed availability.
 
Although a number of adaptation options are available, and proven successful, there appears to be no options  that are widely applicable which do not have constraints and trade-offs.
 
In addition, little evaluation of the long-term sustainability of these transformations and their potential impacts on food security and livelihoods exist.
 
Conclusion
There is considerable research evidence showing substantial decline in animal performance inflicting heavy economic losses when subjected to heat stress.
 
With the development of molecular biotechnologies, new opportunities are available to characterize gene expression and identify key cellular responses to heat stress.
 
These tools will enable improved accuracy and efficiency of selection for heat tolerance.
 
Systematic information generated on the impact assessment of Climate Change on livestock production may prove very valuable in developing appropriate adaptation and mitigation strategies to sustain livestock production in the changing climate scenario.
 
As livestock is an important source of livelihood, it is necessary to find suitable solutions not only to maintain the  sector  as an economically viable enterprise but  to enhance profitability and decrease environmental pollutants by reducing the ill-effects of Climate Change.
 
Top Pic: Boer Goat Buck
 -ACCCKF