Impact of Climate Change on Livestock

Impact of Climate Change on Livestock

 

Climate change has many elements, affecting biological and human systems in different ways. The considerable spatial heterogeneity of climate change impacts has been widely studied; global average temperature increases mask considerable differences in temperature rise between land and sea and between high latitudes and low; precipitation increases are very likely in high latitudes, while decreases are likely in most of the tropics and subtropical land regions (IPCC 2007). It is widely projected that as the planet warms, climate and weather variability will increase. Changes in the frequency and severity of extreme climate events and in the variability of weather patterns will have significant consequences for human and natural systems. Increasing frequencies of heat stress, drought and flooding events are projected for the rest of this century, and these are expected to have many adverse effects over and above the impacts due to changes in mean variables alone (IPCC 2012).

Livestock play a major role in the agricultural sector in developing nations, and the livestock sector contributes 40% to the agricultural GDP. Global demand for foods of animal origin is growing and it is apparent that the livestock sector will need to expand (FAO, 2009). Livestock are adversely affected by the detrimental effects of extreme weather. Climatic extremes and seasonal fluctuations in herbage quantity and quality will affect the well-being of livestock, and will lead to declines in production and reproduction efficiency (Sejian, 2013).

Climate change is a major threat to the sustainability of livestock systems globally. Consequently, 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).  There is little doubt that climate change will have an impact on livestock performance in many regions and as per most predictive models the impact will be detrimental. Climate change may manifest itself as rapid changes in climate in the short term (a couple of years) or more subtle changes over decades. Generally climate change is associated with an increasing global temperature. Various climate model projections suggest that by the year 2100, mean global temperature may be 1.1–6.4 °C warmer than in 2010. The difficulty facing livestock is weather extremes, e.g. 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.

How is livestock production affected by climate change?

In general climate is the average weather condition in a particular area, often articulated as expected temperature, rainfall or wind conditions with reference to past records. Such that, ‘climate change’ is defined as variability in climate that persists over a prolonged period.Climate change is predominantly triggered by greenhouse gas emissions which result in global warming.

Ironically, the livestock industry significantly contributes towards greenhouse gas emissions through escaping ammonia found in cattle manure. Ammonia emission results in atmospheric and water bodies’ pollution. Imagine a contaminated water source, used for drinking and watering a lucerne field. High quantities of ammonia cause poor lucerne growth, resulting in less forage material for your cattle. In terms of contaminated water sources; water borne diseases may be a challenge to a farmer due to excess ammonia in water for drinking by your cattle.Cattle may succumb to heat stress as a result of stealth change in temperature, which reduces production more especially among dairy cattle. Furthermore, routine movement of cattle to abattoirs can be affected as a result of extreme high temperatures, which may significantly distort meat quality.
Cattle with underlying diseases may die due to high and prolonged temperatures due to poor temperature regulation.
In the long run, excess heat accompanied by prolonged droughts suppresses livestock sustainability, due to competition for resources (forage and water) on ranches. Hence, destocking could be adopted so as to ease pressure on both animals and environment.Furthermore, food security for the growing population is adversely disturbed by climate change, as livestock productivity is negatively affected and mere sustainability is a challenge for most livestock farmers around the globe.

Potential Impact of Climate Change on Livestock

Climate change will affect livestock production and consequently food security . Global warming as a result of Climate change may strongly affect production performance of farm animal and impact worldwide on livestock production and reproduction . Specifically, heat stress is a major source of production loss in dairy and beef industry and whereas new knowledge about animal response to the environment continuous to be developed, managing animals to reduce the impact of climate remains a challenge  . The potential impacts of climate change on livestock include changes in water availability, animal growth and milk production , production and quality of feed crop and forage , diseases and reproduction and biodiversity . These listed above effects are mainly due to an increase in atmospheric temperature and carbon dioxide (CO2) concentration, precipitation variation, and a combination of these factors . The increment in environmental temperature due to climate change also affects most of the critical factors for livestock production, such as water availability, animal production, reproduction and health. Forage quantity and quality are affected by a combination of increases in temperature, CO2 and precipitation variation. Livestock diseases are mainly affected by an increase in temperature and precipitation variation  . High ambient temperature decreases fertility even in poultry, rabbits and horses . Exposure of adult New Zealand White rabbits to severe heat stress strongly reduced conception rate. In a recent study reported changes in ovarian follicle development and ovulation, and a reduction in embryo recovery in exercising mares exposed to hot and humid environment. Those listed effects of climate change on livestock production can be classified in to two as direct and indirect effects

 

Impact of climate change on livestock

 

Some of the greatest impacts of global warming will be visible in grazing systems in arid and semi-arid areas (Hoffman & Vogel 2008). Increasing temperatures and decreasing rainfall reduce yields of rangelands and contribute to their degradation. Higher temperatures tend to reduce animal feed intake and lower feed conversion rates (Rowlinson 2008). There is also evidence that growing seasons may become shorter in many grazing lands, particularly in sub-Saharan Africa. The probability of extreme weather events (droughts, floods) is likely to increase. In the non-grazing systems, which are characterized by the confinement of animals (often in climate-controlled buildings), the direct impacts of climate change can be expected to be limited and mostly indirect resulting from reduction of yields and increased prices of the main feed used in animal production (OECD–FAO 2008). The development of energy-saving programs (biocarburants) may also result in increased energy prices. A warmer climate may also increase the costs of keeping animals cool by the building of adapted housing and the use of cooling devices. With higher temperatures, all countries are likely to be subject to increased animal-disease incidence but poor countries are more vulnerable to emerging diseases because of inappropriate veterinary services. Despite all the expected negative impacts of global warming on livestock, some positive effects can be addressed. For example, higher winter temperature can reduce the cold stress experienced by livestock raised outside. Furthermore, warmer winter weather may reduce the maintenance energy requirements of animals and reduce the need for heating in animal housing (FAO 2009a).

Livestock Disease

Increasing temperature may increase exposure and susceptibility of animal to parasite and disease especially vector-borne diseases . However, little effort has been dedicated to understanding the potential impact of climate change on parasite populations and subsequent effects on animal production. Higher temperatures may increase the rate of development of pathogens or parasites that spend some of their life cycle outside their animal host, which may lead to larger populations. Other pathogens are sensitive to high temperature and their survival may decrease with climate warning. Similarly, those pathogens and parasites that are sensitive to moist or dry condition may be affected by changes to precipitation, soil moisture and the frequency of floods. Changes to winds could affect the spread of certain pathogens and vectors . There may be several impact of climate change on the vectors of disease (midges, flies, ticks, mosquitoes and tsetse are all important vectors of livestock disease in the tropics). Changes in rain fall and temperature regimes may affect both the distribution and abundance of disease vectors, as can changes in the frequency of extreme. It has also been shown that the ability of some insect vectors to become or remain infected with viruses (such as bluetongue) varies with temperature. presented several livestock health problems related to climate change. Prolonged high temperature may affect metabolic rate , endocrine status , oxidative status , glucose, protein and lipid metabolism, liver functionality (reduced cholesterol and albumin) , non-esterified fatty acids (NEFA) , saliva production, and salivary HCO3- content. In addition, greater energy deficits affect cow fitness and longevity . Climate change may alter transmission rates between hosts not only by affecting the survival of the pathogen or parasite or intermediate vector but also by other means. Future patterns of international trade, local animal transportation and farm size are factors that may be driven in part by climate change and may affect disease transmission. Other indirect effects of climate change may also affect the abundance and/or distribution of the competitors, predators and parasites of vectors, thus influencing patterns of disease. It may also be that changes in ecosystems, driven by climate change and other drivers that affect land-use, could give rise to new mixtures of species, thereby exposing hosts to novel pathogens and vectors and causing the emergence of new diseases . Trypanotolerence, an adaptive trait which has developed over the course of millennia in sub-humid zone of West Africa, could be lost, thus leading to a greater risk of disease in the future . The future infectious disease situation is going to be different from today’s.

Mortality

There is a strong relationship between drought and animal death. Projected increased temperature and reduced precipitation in such regions as southern Africa will lead to increased loss of domestic herbivores during extreme events in drought-prone areas . Heat-related mortality and morbidity could increase as temperature increase due to climate change . Warm and humid conditions that cause heat stress can affect livestock mortality .Reported that increases in temperature between 1 and 5 C might induce high mortality in grazing cattle. As a mitigation measure, they recommend sprinklers, shade, or similar management practices to cool the animals. Linked livestock mortality to several heat waves between 1994 and 2006 in the United States and northern Europe.

Climate Influence on Livestock Productivity and reproductively

Of all the factors influencing livestock production and reproduction, climate and location are undoubtedly the most significant. In fact, climatology characteristics such as ambient temperature and rainfall patterns have great influence on pasture and food resources availability cycle throughout the year, and types of disease and parasite outbreaks among animal populations (Elsa Lamy et al 2012). Livestock generally expend more energy and increase their voluntary feed intake in order to maintain their core temperature, resulting in lower feed efficiency (NRC 1981). Maintaining an adequate temperature can be an important factor influencing design of housing and in husbandry decisions for cold susceptible animals such as poultry, swine, and young animals. Low temperatures resulting from particularly cold weather or loss of power to buildings housing confined animals, can cause economic losses from increased animal morbidity or death (Mader 2003)

Climate Influence on Livestock Productivity

The effects of climate change can be direct or indirect. The direct effects of climate change include higher temperatures and changing rainfall patterns, which could translate into the increased spread of existing vector-borne diseases and macro-parasites, accompanied by the emergence and circulation of new diseases. The indirect effects are attributable to changes in feed resources associated with the carrying capacity of rangelands, the buffering abilities of ecosystems, intensified desertification processes, increased scarcity of water resources and decreased grain production. Other indirect effects are linked to the expected shortage of feed arising from the increasingly competitive demands of food, feed and fuel production, and land use systems (Calvosa et al 2009). Smit et al (1996) attributed the indirect effects of climate driven changes in animal performance to mainly alterations in the nutritional environment. 

Climate Change Effects on Livestock Milk Production

Climatic factors or seasonal changes greatly influence the behavior of animals due to neuron endocrine response to climatic elements, consequently affecting production and health of animals (Shelton, 2000; Sejian et al 2010a; Baumgard et al 2012). Climate change is a major threat to the viability and sustainability of livestock production systems in many regions of the world (Gaughan et al 2009). High production animals are subjected to greater influence by climatic factors, particularly those rose under tropical conditions, due to high air temperatures and relative humidity (Gaughan et al 2008; Martello et al 2010).

Heat stress adversely affects milk production and its composition in dairy animals; especially animals of high genetic merit (Wheelock et al 2010). Berman, A.J. (2005) estimated that effective environmental heat loads above 35°C activate the stress response systems in lactating dairy cows. In response dairy cows reduce feed intake which is directly associated with negative energy balance, which largely responsible for the decline in milk synthesis (Wheelock et al 2010). Moreover, maintenance requirements of energy also increased by 30% in heat stress dairy animal NRC. (2007). Therefore, energy intake would not be enough to cover the daily requirements for milk production.  West, J.W. (2003) reported a reduction in dry matter intake by 0.85 kg with every 1°C rise in air temperature above a cow’s the thermo neutral zone, this decrease in intake accounts approximately 36% of the decrease in milk production (Rhoads et al 2009). Drop in milk production up to 50% in dairy animals might be due to reduced feed intake , whereas, rest could be reasons of metabolic adaptations to heat stress as heat stress response markedly alters post-absorptive carbohydrate, lipid, and protein metabolism a part of reduced feed intake (Baumgard, L.H. and Rhoads, R.P. 2013). Increased in basal insulin levels with improved insulin response in heat-stressed cows (Wheelock et al 2010) and in ewes (Sejian et al 2010c) were observed that explains the shift in glucose utilization in non-mammary gland tissue affecting milk synthesis (Rhoads et al 2013). Heat stress during the dry period (i.e., last 2 months of gestation) reduced mammary cell proliferation and so, decreases milk yield in the following lactation. Moreover, stress during the dry period negatively affects the function of the immune cell in dairy cows facing calving and also extended to the following lactation (Tao, S. and Dahl G.E., 2013). Singh et al (2013) also reported negative impacts of stress on lactation length, dry period, calving interval, milk constituents and milk yield in Murrah buffaloes. Hot and humid environment not only affects milk yield but also effects milk quality. Kadzere et al 2002) reported that milk fat, solids-not-fat (SNF) and milk protein percentage decreased by 39.7, 18.9 and 16.9%, respectively. Bouraoui et al (2002) observed lower milk fat and milk protein in the summer season. Zheng et al (2009) observed that hat stress significantly reduces the production of milk, the percentage of milk fat and percentage of proteins, but that it has no effect on the content of lactose in milk.

Climate change Effect on growth performances

 Birth weight and survival of neonatal lambs was improved when shade was provided during late pregnancy (Hopkins et al 1980). This suggests that heat stress has an effect on the uterine environment, substantially reduces the total embryo cell number and placentome size resulting in smaller size of lambs. They would also be more susceptible to dehydration during the early stages of life. Temperatures ranging between 15°C and 29°C do not seem to have any effect on growth performance. The effects of high ambient temperature on growth performance are induced by the decrease of the anabolic activity and the increase in tissue catabolism (Marai et al 2007). This decrease in anabolism is essentially caused by a decrease in voluntary feed intake of main nutrients. The increase in tissue catabolism occurs mainly in fat depots and/or lean body mass. Lamb production is deleteriously affected by exposure to heat stress and this causes an economic loss.

 

Climate Change Effects on reproductive performance

 

High air temperature and humidity affects cellular functions by direct alteration and impairment of various tissues or organs of the reproductive system in both the sexes of the animal. Reproductive functions of livestock are vulnerable to climate changes and both female and males are affected adversely. Heat stress also negatively affects reproductive function (Amundson et al 2006; Sprott et al 2001). The climate change scenario due to rise in temperature and higher intensity of radiant heat load will affect reproductive rhythm via hypothalamo- hypophyseal–ovarian axis. The main factor regulating ovarian activity is GnRH from hypothalamus and the gonadotropins i.e. FSH and LH from anterior pituitary gland (Madan and Prakash 2007). The effects are more pronounced in buffaloes than cattle which may be due to high thermal load in this species as a result of difficulty in heat dissipation due to unavailability of place for wallowing and lesser number of sweat glands (Vaidya et al 2010; Shashikant et al 2010). Therefore, heat mitigation measures and strategies need to be adopted not only to reduce thermal stress but also to curtail fertility losses and other health consequences on animals. The expression of estrus and conception rate was recorded low during summer in crossbred cattle and buffaloes. Low estradiol level on the day of estrus during summer period in buffaloes may be the likely factor for poor expression of estrus in this species (Upadhyay et al 2009).

 

Effects on female reproductive performance

 

Estrous period and follicular growth

 

Heat stress reduces the length and intensity of estrus besides increases incidence of anestrous and silent heat in farm animals (Kadokawaet al 2012). It increases Adrenocorticotropic hormone and cortisol secretion Singh et al (2013), and blocks estradiol-induced sexual behavior Hein, K.G. and Allrich, R.D. (1992). Roth et al (2000) reported that developed follicles suffer damage and become non-viable when the body temperature exceeds 40°C. When female goats exposed to 36.8°C and 70% relative humidity for 48 h follicular growth to ovulation suppresses, accompanied by decreased LH receptor level and follicular estradiol synthesis activity. Reduced granulosa cells aromatase activity and viability also contributed to poor estradiol secretion (Ozawa et al 2005). Low estradiol secretion suppresses signs of estrus, gonadotropin surge, ovulation, transport of gametes and ultimately reduced fertilization (Wolfenson, D., Roth, Z. and Meidan, R. 2000). A temperature rise of more than 2°C in unabated buffaloes may cause negative impacts due to low or desynchronized endocrine activities particularly pineal-hypothalamo- hypophyseal-gonadal axis altering respective hormone functions. They also reported that low estradiol level on the day of estrus during summer period may be the likely factor for poor expression of heat in Indian buffaloes (Upadhyay et al 2009).

 

Fertility

 

Multi-factorial mechanisms involved in reducing fertility of dairy animals depending on the magnitude of HS. HS reduces oocyte development by affecting its growth and maturation. It increases circulating prolactin level in animal’s results to acyclicity and infertility (Singh et al 2013). Moreover, 80% of estrus may be unnoticeable during summer Rutledge, J.J. (2001) which further reduces fertility. A period of high-temperature results to increase secretion of endometrial PGF-2α, thereby threatening pregnancy maintenance leads to infertility (Bilby et al 2008). Plasma follicle-stimulating hormone (FSH) surge increases and inhibit concentrations decrease during HS leading to variation in follicular dynamics and depression of follicular dominance that could be associated with low fertility of cattle during the summer and autumn (Roth et al 2000). However, FSH secretion is elevated under heat stress condition probably due to reduced inhibition of negative feedback from smaller follicles which ultimately affect the reproductive efficiency of dairy animals (Khodaei et al 2011). Conception rates were drop from about 40% to 60% in cooler months to 10-20% or lower in summer, depending on the severity of the thermal stress (Cavestany et al 1985). About 20-27% drop in conception rates Chebel et al (2004) or decrease in 90-day non-return rate to the first service in lactating dairy cows were recorded in summer (Al-Katananiet al 1999). Moreover, severe heat stress, only 10-20% of inseminations were resulted, in normal pregnancies, were also reported (Roth et al 2000). Oocytes of cows exposed to thermal stress lose their competence for fertilization Gendelman, M., and Roth, Z. (2012a) and development to the blastocyst stage (Gendelman, M. and Roth, Z. 2012b). Recently, Lacerda and Loureiro (2015) also reported heat stress decreases fertility by diminishing quality of oocytes and embryos through direct and indirect effects.

 

Embryonic growth and development

 

Embryonic growth and survival also affected during thermal stress in dairy animals. Heat stress causes embryonic death by interfering with protein synthesis Edwards, J.L. and Hansen, P.J. (1996), oxidative cell damage Wolfenson, D., Roth, Z. and Meidan, R. (2000), reducing interferon- tau production for signaling pregnancy recognition Bilby et al (2008) and expression of stress-related genes associated with apoptosis (Fear, J.M. and Hansen, P.J. 2011). Low progesterone secretion limits endometrial function and embryo development (Khodaei et al 2011). Exposure of lactating cows to HS on the 1st day after estrus reduced the proportion of embryos that developed to the blastocyst stage on the day 8th after estrus (Ealy, A.D., Drost, M. and Hansen, P.J 1993). Further, exposure of post-implantation embryos (early organogenesis) and fetus to HS also leads to various teratologies (Wolfenson, D., Roth, Z. and Meidan, R. 2000). The deleterious effects of heat stress in the embryo are most evident in early stages of its development. However, embryos subjected to high temperatures in vitro or in vivo until day 7 of development (blastocyst) showed lower pregnancy rates at day 30 and higher rates of embryonic loss on day 42 of gestation Cardozo et al (2006) and lactation yield as well as postpartum ovarian activity. Fetal malnutrition and eventually fetal growth retardation under thermal stress were also reported (Tao, S. and Dahl, G.E. 2013).

 

Effects on male reproductive performance

 

Bull is recognizing as more than half of the herd and hence, bull’s fertility is equally or more important for fertilization of oocyte to produce a good, viable and genetically potential concepts. It is well known that bull testes must be 2-6°C cooler than core body temperature for fertile sperm to be produced. Therefore, increased testicular temperature results from thermal stress could changes in seminal and biochemical parameters leads to infertility problems in bulls. The significant seasonal difference in semen characteristics was reported by several studies (Bhakat et al 2014). Cardozo et al (2006) reported seasonal effects on changes in testicular volume, hormonal profiles, sexual behavior and semen quality that affect the reproductive performance of males. Balic et al (2012) studied seasonal influence on 19 Bos taurus (simmental) bulls and found summer heat stress declined semen quality parameters. They also reported that younger bulls are more sensitive to elevated air temperatures during the summer seasons. Observed optimal semen qualities during winter, poor during summer and intermediate during rainy season and conclude that hot-dry or summer season adversely affect the various bio-physical characteristics of semen in Karan Fries bulls. Hence, heat stress significantly lowers conception as well as fertility rates per insemination of male and subsequently reduces male’s fitness (Bhakat et al 2014).

Genetic selection 

Advances in environmental modifications and nutritional management in part alleviate the impact of thermal stress on animal performance during the hotter seasons. However, long-term strategies have to be evolved for adaptation to climate change. Differences in thermal tolerance exist between livestock species provide clues or tools to select thermo tolerant animals using genetic tools. The identification of heat-tolerant animals within high-producing breeds will be useful only if these animals are able to maintain high productivity and survivability when exposed to heat stress conditions. Cattle with shorter hair, hair of greater diameter and lighter coat color are more adapted to hot environments than those with longer hair coats and darker colors (Bernabucci et al 2010). This phenotype has been characterized in B. taurus tropical cattle (senepol and carona), and this dominant gene is associated with an increased sweating rate, lower rectal temperature and lower respiratory rate in homozygous cattle under hot conditions (Mariasegaram, et al 2007). There is heat shock gene related to thermo tolerance that was identified and being used as marker in marker assisted selection and genome-wide selection to developed thermo tolerant bull that are used in breeding program. Several reports showed associations of SNP in the Hsp genes with thermal stress response and tolerance in farm animals. Association of polymorphisms in Hsp90AB1 with heat tolerance has also been reported in Thai native cattle (Charoensook et al 2012), Sahiwal and Frieswal cattle (Deb et al 2014), HSF1 gene (Li et al 2011a), HSP70A1A gene (Li et al 2011b), HSBP1 (Wang et al 2013) in Chinese Holstein cattle. There are non-Hsps genes also revealed to undergo changes in expression in response to heat stress. For example ATP1B2 gene in Chinese Holstein cows (Wang et al 2011) and ATP1A1 gene in jersey crossbred cows (Das et al 2015) was observed to have associated with thermo tolerance. These SNPs could be used as markers in marker assisted selection to developed thermo tolerant animal in early ages. Further, thermo tolerant bull can be used in breeding policy to have thermal adapted offspring.

The risk potential associated with livestock production systems due to global warming can be characterized by levels of vulnerability, as influenced by animal performance and environmental parameters (Hahn 1995). When combined performance level and environmental influences create a low level of vulnerability, there is little risk. As performance levels (e.g., rate of gain, milk production per day, eggs/day) increase, the vulnerability of the animal increases and, when coupled with an adverse environment, the animal is at greater risk. Combining an adverse environment with high performance pushes the level of vulnerability and consequent risk to even higher levels. Inherent genetic characteristics or management scenarios that limit the animal’s ability to adapt to or cope with environmental factors also puts the animal at risk. At very high performance levels, any environment other than near-optimal may increase animal vulnerability and risk.

The potential impacts of climatic change on overall performance of domestic animals can be determined using defined relationships between climatic conditions and voluntary feed intake, climatological data, and GCM output. Because ingestion of feed is directly related to heat production, any change in voluntary feed intake and/or energy density of the diet will change the amount of heat produced by the animal (Mader et al. 1999b). Ambient temperature has the greatest influence on voluntary feed intake. However, individual animals exposed to the same ambient temperature will not exhibit the same reduction in voluntary feed intake. Body weight, body condition, and level of production affect the magnitude of voluntary feed intake and ambient temperature at which changes in voluntary feed intake begin to be observed. Intake of digestible nutrients is most often the limiting factor in animal production. Animals generally prioritize available nutrients to support maintenance needs first, followed by growth or milk production, and then reproduction.

Based on predicted climate outputs from GCM scenarios, production and response models for growing confined swine and beef cattle, and milk-producing dairy cattle have been developed (Frank et al. 2001). The goal in the development of these models was to utilize climate projections – primarily average daily temperature – to generate an estimate of direct climate-induced changes in daily voluntary feed intake and subsequent performance during summer in the central portion of the United States (the dominant livestock producing region of the country), and across the entire country. The production response models were run for one current (pre-1986 as baseline) and two future climate scenarios: doubled CO2 (~2040) and a triple of CO2 (~2090) levels. This data base employed the output from two GCMs – the Canadian Global Coupled (CGC) Model, Version I, and the United Kingdom Meteorological Office/Hadley Center for Climate Prediction and Research model – for input to the livestock production/ response models. Changes in production of swine and beef cattle data were represented by the number of days to reach the target weight under each climate scenario and time period. Dairy production is reported in kilograms of milk produced per cow per season. Details of this analysis are reported by Frank (2001) and Frank et al. (2001).

Animal Production Systems

Increases in air temperature reduce livestock production during the summer season with partial offsets during the winter season. Current management systems usually do not provide as much shelter to buffer the effects of adverse weather for ruminants as for non-ruminants. From that perspective, environmental management for ruminants exposed to global warming needs to consider: 1) general increase in temperature levels, 2) increases in nighttime temperatures, and 3) increases in the occurrence of extreme events (e.g., hotter daily maximum temperature and more/longer heat waves).

In terms of environmental management needed to address global climate change, the impacts can be reduced by recognizing the adaptive ability of the animals and by proactive application of appropriate countermeasures (sunshades, evaporative cooling by direct wetting or in conjunction with mechanical ventilation, etc.). Specifically, the capabilities of livestock managers to cope with these effects are quite likely to keep up with the projected rates of change in global temperature and related climatic factors. However, coping will entail costs such as application of environmental modification techniques, use of more suitably adapted animals, or even shifting animal populations.

Climate changes affect certain parasites and pathogens, which could result in adverse effects on host animals. Interactions exist among temperature, humidity, and other environmental factors which, in turn, influence energy exchange. Indices or measures that reflect these interactions remain ill-defined, but research to improve them is underway. Factors other than thermal (i.e., dust, pathogens, facilities, contact surfaces, technical applications) also need better definition. Duration and intensity of potential stressors are of concern with respect to the coping and/or adaptive capabilities of an animal. Further, exposure to one type of stressor may lead to altered resistance to other types. Other interactions may exist, such that animals stressed by heat or cold may be less able to cope with other stressors (restraint, social mixing, transport, etc). Improved stressor characterization is needed to provide a basis for refinement of sensors providing input to control systems. Innovations in electronic system capabilities will undoubtedly continue to be exploited for the betterment of livestock environments with improved economic utilization of environmental measures, and mitigation strategies. There is much potential for application of improved sensors, expert systems, and electronic stockmanship. Continued progress should be closely tied to animal needs based on rational criteria, and must include further recognition of health criteria for animal caretakers as well. The ability of the animal’s target tissues to respond to disruptions in normal physiological circadian rhythms may be an important indicator of stress.

Also, the importance of obtaining multiple measures of stress is also becoming more apparent. However, inclusion and weighting of multiple factors (e.g. endocrine function, immune function, health status, vocalizations) is not an easy task in developing integrated stress measures. Establishing that may result in reduced performance or health are essential. Improved modeling of physiological systems as our knowledge base expands will help the integration process.

In the basic framework of climate change adaptation and food security related to livestock, the following additional support facilities should be included:

(a) Food sustainability • Sustainability in livestock productivity • Long-term food security responses

(b) Development of real-time application-oriented technology • Livestock smart farm development • Breed technology development • Weather station development (c) Supporting facilities • Expansion of agriculture disaster insurance • Expansion of disaster-resilient facilities • Early warning systems • Technology application in disaster risk reduction • Promotion of savings and insurance schemes (d) Sustainable management • Animal waste management process • Livestock disease management • Land and water resource management • Low-carbon agriculture technology • Knowledge management and sharing across sectors • Partnerships with other humanitarian, development, and environmental organisations; research institutions; governments; and the private sector to identify practical and effective responses to climate change and food insecurity.

Direct effects of climate change on livestock

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. Thus, an increase in air temperature, such as that predicted by various climate change models, could directly affect animal performance. Fig.1 describes the various impacts of climate change on livestock production.

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 growing season in several 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. Also 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. The 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. In addition, emerging diseases including vector borne diseases that may arise as a result of climate change will result in severe economic losses.

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 look at using adapted animals, albeit with lower production levels (and also lower input costs) rather than try to infuse ‘stress tolerance’ genes into non-adapted breeds (Gaughan, 2015).

Impact of climate change on livestock reproduction

Reproductive processes are affected by thermal stress. Conception rates of dairy cows may drop 20–27% in summer, and heat stressed cows often have poor expression of oestrus due to reduced oestradiol secretion from the dominant follicle developed in a low luteinizing hormone environment. Reproductive inefficiency due to heat stress involves changes in ovarian function and embryonic development by reducing the competence of oocyte to be fertilized and the resulting embryo (Naqvi et al., 2012). Heat stress compromises oocyte growth in cows by altering progesterone secretion, the secretion of luteinizing hormone, follicle-stimulating hormone and ovarian dynamics during the oestrus cycle. Heat stress has also been associated with impairment of embryo development and increase in embryonic mortality in cattle. Heat stress during pregnancy slows growth of the foetus and can increase foetal loss. Secretion of the hormones and enzymes regulating reproductive tract function may also be altered by heat stress. In males, heat stress adversely affects spermatogenesis perhaps by inhibiting the proliferation of spermatocytes.

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 reduction in productive potential. The relative changes in the various physiological responses i.e. 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. The 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 treatments that target affected genes (Collier et al., 2012). Studies evaluating genes identified as participating in the cellular acclimation 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.

Impact of climate change on livestock diseases

Variations in temperature and rainfall are the most significant climatic variables affecting livestock disease outbreaks. Warmer and wetter weather (particularly warmer winters) will increase the risk and occurrence of animal diseases, because certain species that serve as disease vectors, such as biting flies and ticks, are more likely to survive year-round. The movement of disease vectors into new areas e.g. malaria and livestock tick borne diseases (babesiosis, theileriosis, anaplasmosis), Rift Valley fever and bluetongue disease in Europe has been documented. Certain existing parasitic diseases may also become more prevalent, or their geographical range may spread, if rainfall increases. This may contribute to an increase in disease spread for livestock such as ovine chlamydiosis, caprine arthritis (CAE), equine infectious anemia (EIA), equine influenza, Marek’s disease (MD), and bovine viral diarrhea. There are many rapidly emerging diseases that continue to spread over large areas. Outbreaks of diseases such as foot and mouth disease or avian influenza affect very large numbers of animals and contribute to further degradation of the environment and surrounding communities’ health and livelihood.

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 this industry as an economically viable enterprise but also to enhance profitability and decrease environmental pollutants by reducing the ill-effects of climate change.

Future perspectives

Responding to the challenges of global warming necessitates a paradigm shift in the practice of agriculture and in the role of livestock within farming systems. Science and technology are lacking in thematic issues, including those related to climatic adaptation, dissemination of new understandings in rangeland ecology (matching stocking rates with pasture production, adjusting herd and water point management to altered seasonal and spatial patterns of forage production, managing diet quality, more effective use of silage, pasture seeding and rotation, fire management to control woody thickening and using more suitable livestock breeds or species), and a holistic understanding of pastoral management (migratory pastoralist activities and a wide range of biosecurity activities to monitor and manage the spread of pests, weeds, and diseases). Integrating grain crops with pasture plants and livestock could result in a more diversified system that will be more resilient to higher temperatures, elevated carbon dioxide levels, uncertain precipitation changes, and other dramatic effects resulting from the global climate change. The key thematic issues for effectively managing environment stress and livestock production include (Sejian et al., 2015b):

• development of early warning system;
• research to understand interactions among multiple stressors;
• development of simulation models;
• development of strategies to improve water-use efficiency and conservation for diversified production system;
• exploitation of genetic potential of native breeds; and
• research on development of suitable breeding programmes and nutritional interventions.
• The integration of new technologies into the research and technology transfer systems potentially offers many opportunities to further the development of climate change adaptation strategies. Epigenetic regulation of gene expression and thermal imprinting of the genome could also be an eff The growing human population and its increasing affluence would increase the global demand for livestock products. But the expected big changes in the climate globally will affect directly or indirectly the animal productivity and health and the sustainability of livestock-based production systems. Extended periods of high air temperature compromise the ability of livestock to dissipate excess body heat which affects feed intake, milk production, and reproductive efficiency. However, by minimizing body temperature, greater feed intake could be encouraged. Moreover, the gross efficiency with which dietary nutrients are used by the livestock for performance could also be improved. The loss of electrolytes via skin secretions has to be minimized by improvement of housing and cooling of the animals. Increase pregnancy rate of heat stress livestock could be achieved by improving various manage-mental conditions. Identification of genes associated with thermo tolerance and using these genes as markers in the breeding program or marker assisted selection should be applied to identify animals adapted to thermal stress considering genotype-environment interactions (G × E) in addition to higher productivity. Further research on climate resilient animal agriculture is the need of the hour for sustainability in livestock farming system, especially in hot humid climatic regions.

What can be done to mitigate the effects of climate change on livestock production?

Implementation of “Smart farming” and “Sustainable Farming” around the world, could help farmers minimize contamination of the environment through ammonia emission. Such that, through collective efforts among farming communities, ideas can be shared to improve and sustain good cattle production.

On a ranch, it is always advised to leave some trees uncut, so that they provide shed for foraging cattle. And in intensive units, areas with sheds are encouraged to minimize heat stress on animals.

To sum it all up, climate change is a subject under discussion and as livestock farming communities, we ought to practice smart farming and constantly engage with the global village on ways to counter climatic conditions and all changes associated with it.

Climate change, particularly global warming, may strongly affect production performances of farm animals and impact worldwide on livestock production. The potential impacts of climate change on livestock in the future will result in negative changes in production and quality of feed crop and forage, water availability, animal growth and milk production, disease, reproduction and animal genetics and biodiversity loss. The effect of Heat stress on livestock can be categorized into feed nutrient utilization, feed intake, animal production, reproduction, health, mortality which cause economic losses in about 60% of the dairy farm around the world and also been associated with impairment of embryo development and increase in embryonic mortality in cattle. Climate change may influence patterns of disease and changes in ecosystems, and facilitates that the future infectious disease situation is going to be different from today. Climate change may eliminate 15% to 37% of all species in the world which is high risk of animal genetic extinction. Global warming effects on water availability could force the livestock sector to stablish a new priority in producing animal products that need less water. Increased temperature increase lignification of plant tissues and therefore reduce the digestibility and the rate of degradation of plant species that leads to increase CH4 emission from livestock. Based on the above conclusive statements, the following recommendations are forwarded: • All animal scientists must collaborate closely with colleagues of other disciplines, like agronomists, meteorologists, biotechnologists, ecologists, etc • Selecting animals should not only oriented toward productive traits, but also consider robustness and adaptability to heat stress as well as the genetic potential of individual animal in terms of less enteric CH4 emission.

References

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