- Climate-adaptation traits are measurable characteristics that influence an animal’s ability to survive, remain healthy, reproduce, and maintain acceptable productivity under climatic conditions and climate-related environmental challenges. These traits are becoming increasingly important in animal breeding as livestock populations face changes in temperature, rainfall patterns, drought frequency, feed availability, disease pressure, and the occurrence of extreme weather events. Genetic improvement for climate adaptation aims to develop animals that can maintain appropriate levels of health, fertility, resilience, welfare, and productivity under the environmental conditions in which they are expected to perform.
- Climate adaptation is not controlled by a single trait or gene. It is a complex biological characteristic involving interactions among genetics, physiology, behaviour, metabolism, immune function, reproduction, and environment. Important climate-adaptation traits can include heat tolerance, cold tolerance, drought tolerance, water-use efficiency, nutritional adaptability, disease resistance, parasite resistance, thermoregulation, fertility under heat stress, resilience, survival, and stability of production under environmental stress.
- The genetic and environmental basis of climate adaptation can be described using the quantitative genetics relationship P = G + E, where phenotype is influenced by genetic effects and environmental effects. Climatic conditions such as temperature, humidity, solar radiation, rainfall, drought, wind, and seasonal feed availability can strongly influence animal performance. Management factors such as housing, shade, ventilation, water supply, nutrition, stocking density, and disease control also affect how animals respond to climate. Consequently, observed differences in climate-related performance cannot automatically be interpreted as genetic differences.
- Many climate-adaptation traits are complex and polygenic. Multiple genes can influence thermoregulation, metabolism, immune function, coat characteristics, behaviour, fertility, and the ability to maintain body condition during environmental stress. Genetic variation may involve additive genetic effects, dominance, and epistatic interactions. Additive genetic variation is particularly important for breeding because it contributes to predictable genetic response and forms the basis of breeding value estimation.
- The heritability of climate-adaptation traits varies substantially among traits, populations, species, and environmental conditions. Some physiological indicators of heat tolerance or morphological characteristics associated with adaptation may have moderate heritability, whereas complex outcomes such as survival, fertility during heat stress, or long-term production stability may have lower heritability. A low heritability does not mean that genetic improvement is impossible. Reliable phenotyping across sufficiently large populations can allow genetic differences to be identified and incorporated into breeding programs.
- Heat tolerance is one of the most important climate-adaptation traits in livestock. High environmental temperatures can reduce feed intake, alter metabolism, increase maintenance requirements, impair immune function, reduce fertility, decrease growth and milk production, and increase mortality in severe cases. Animals differ genetically in their ability to regulate body temperature and maintain physiological stability during heat exposure.
- Measurements used to evaluate heat tolerance may include body temperature, respiration rate, panting score, sweating rate, heat-shock responses, feed intake, production changes, activity patterns, fertility, and recovery following heat exposure. Combining physiological measurements with production and reproductive records can provide a more complete assessment of genetic heat tolerance.
- Thermoregulation is a central biological component of climate adaptation. Animals use behavioural, physiological, and metabolic mechanisms to maintain body temperature within an appropriate range. These mechanisms may include sweating, panting, changes in blood flow, altered activity, shade seeking, changes in feed intake, and metabolic adjustments. Genetic differences in thermoregulatory capacity can therefore influence how animals respond to hot environments.
- Cold tolerance is also important in regions where animals experience low temperatures, wind, snow, or prolonged cold exposure. Coat characteristics, body size, insulation, metabolism, energy reserves, behaviour, and physiological responses can influence cold adaptation. However, the expression of cold tolerance depends strongly on housing, shelter, moisture, wind exposure, nutrition, and management.
- Drought tolerance is particularly relevant in production systems where water availability and forage production fluctuate substantially. Drought can reduce pasture availability, decrease feed quality, increase competition for water, and increase nutritional stress. Animals that maintain body condition, reproductive function, survival, and acceptable productivity under limited resource conditions may have greater adaptive value in drought-prone environments.
- Water-use efficiency is another important climate-adaptation characteristic. Water availability directly affects thermoregulation, digestion, feed intake, metabolism, reproduction, and survival. Genetic differences may exist in water requirements and physiological responses to water restriction. However, genetic adaptation should not be considered a substitute for adequate access to clean drinking water.
- Climate adaptation is also strongly connected with nutritional adaptation. Changes in rainfall and temperature can alter pasture growth, forage quality, crop availability, and seasonal feed supplies. Animals may therefore need to maintain acceptable performance when feed quality or quantity fluctuates. Genetic differences in feed utilization, digestion, body-condition maintenance, metabolic efficiency, and resilience to nutritional stress can contribute to climate adaptation.
- Disease resistance and parasite resistance are increasingly important components of climate adaptation because climate can influence the distribution, abundance, and seasonal activity of pathogens and parasites. Changes in temperature and humidity may alter vector populations, parasite development, and disease transmission. Animals with greater genetic resistance or tolerance may therefore be better able to maintain health under changing disease environments.
- An important distinction should be made among resistance, tolerance, and resilience. Resistance refers to an animal’s ability to prevent or limit infection or infestation. Tolerance refers to its ability to maintain health and performance despite a challenge. Resilience refers to the ability to withstand environmental disturbances and maintain or rapidly recover normal function. All three characteristics can contribute to climate adaptation but represent different biological mechanisms.
- Fertility under heat and environmental stress is another important climate-adaptation trait. High temperatures can affect reproductive cycles, conception, embryo survival, semen quality, and maternal performance. Animals that maintain reproductive function during periods of environmental stress may have greater lifetime fitness and economic value. Genetic evaluation of fertility under realistic climatic conditions can therefore help identify animals that are better adapted to future environments.
- Climate adaptation is also influenced by behavioural responses. Animals may seek shade, change grazing times, alter activity, modify feeding behaviour, change social spacing, or adjust water-seeking behaviour when exposed to environmental stress. Genetic variation in behavioural responses may contribute to differences in climate resilience. Technologies such as activity monitors and automated cameras can provide new opportunities to measure these responses objectively.
- A major consideration in climate-adaptation breeding is genotype–environment interaction (G×E). This occurs when the relative genetic performance of animals changes across environments. An animal that performs exceptionally well under cool, high-input conditions may not necessarily be the best animal under hot, dry, disease-challenging, or low-input conditions. Climate-adaptation breeding therefore requires genetic evaluation in environments that are representative of the conditions where animals will be used.
- G×E can also occur across seasons and years. An animal may have a high breeding value for production under favourable conditions but experience a larger production decline than another animal during heat waves or drought. This makes stability of performance an important consideration in climate-resilient breeding. Breeding programs may therefore evaluate both average performance and performance under environmental stress.
- Accurate phenotyping is essential for genetic improvement of climate-adaptation traits. Useful records may include body temperature, respiration rate, heat-stress scores, feed intake, water consumption, body condition, production, fertility, disease incidence, parasite burden, survival, recovery following stress, and behavioural responses. Environmental information such as temperature, humidity, rainfall, solar radiation, drought indicators, and forage availability can greatly improve the value of these records.
- Modern precision livestock farming technologies can make climate-adaptation phenotyping more efficient. Sensors, automated weather stations, infrared thermography, wearable devices, accelerometers, cameras, electronic identification systems, and automated feeding and watering systems can generate repeated measurements of physiological and behavioural responses. Combining these data with genomic information can improve the evaluation of genetic differences in environmental resilience.
- Traditional genetic evaluation methods such as BLUP (Best Linear Unbiased Prediction) can be used to estimate breeding values for climate-related traits. Estimated Breeding Values (EBVs) can incorporate individual, pedigree, relative, environmental, and repeated-performance information. Appropriate statistical models can account for systematic environmental effects and allow genetic differences to be estimated more accurately.
- Genomic selection provides an important opportunity for climate-adaptation breeding. Genomic Estimated Breeding Values (GEBVs) combine DNA marker information with pedigree and phenotypic data. This can be especially useful for traits that are difficult or expensive to measure, such as lifetime survival, heat tolerance under natural conditions, disease resistance, or fertility during periods of climatic stress.
- Research tools such as GWAS (Genome-Wide Association Studies) and QTL (Quantitative Trait Locus) mapping can identify genomic regions associated with climate-related traits. Genes or genomic regions involved in thermoregulation, immune response, metabolism, coat characteristics, heat-shock responses, and other physiological mechanisms may contribute to climate adaptation. However, most climate-adaptation traits are highly polygenic, meaning that individual genes usually explain only a small part of the total genetic variation.
- Climate-adaptation traits can have important genetic correlations with production, fertility, health, feed efficiency, behaviour, and longevity. For example, selection for higher production may sometimes increase sensitivity to heat stress if physiological demands increase. Conversely, improving resilience and heat tolerance may help animals maintain production under challenging conditions. These relationships should therefore be considered when constructing a balanced breeding objective.
- A selection index can combine breeding values for climate adaptation with production, reproduction, health, welfare, and economic traits. This prevents breeding programs from focusing exclusively on production while ignoring the ability of animals to cope with changing environments. The appropriate weighting of climate-adaptation traits will depend on the production system, climate, economic conditions, and expected future environmental risks.
- Climate adaptation also has an important relationship with animal welfare. Animals that cannot cope effectively with heat, cold, drought, disease, or nutritional stress may experience discomfort, impaired health, reproductive failure, or reduced quality of life. Genetic selection for appropriate climate adaptation can contribute to welfare, but it should complement rather than replace good husbandry. Shade, shelter, water, appropriate nutrition, ventilation, disease prevention, and other management practices remain essential.
- Maintaining genetic diversity is particularly important for long-term climate adaptation. Future climatic conditions cannot be predicted perfectly, and new diseases, production challenges, and environmental pressures may emerge. A genetically diverse population contains a broader range of genetic variation that can provide opportunities for future adaptation. Excessive selection for a narrow set of traits may reduce this adaptive capacity.
- Climate-adaptation breeding is therefore not simply about selecting animals that survive extreme weather. The goal is to identify animals that can maintain an appropriate balance of health, fertility, welfare, productivity, resilience, and survival under realistic environmental conditions. In some production systems, the most valuable animal may not be the one with the highest production under ideal conditions, but the one that maintains reliable performance when conditions become challenging.
- Climate-adaptation traits are likely to become increasingly important as livestock production systems respond to climate change and environmental variability. Breeding programs can contribute to long-term adaptation by integrating genetic information with environmental data, precision phenotyping, genomic selection, and multi-environment evaluation. The most effective strategies will combine genetic improvement with changes in nutrition, housing, water management, disease control, grazing systems, and other management practices.
- Overall, climate-adaptation traits describe the genetic and functional characteristics that help animals cope with climatic and climate-related environmental challenges. Important traits include heat tolerance, cold tolerance, drought tolerance, water-use efficiency, nutritional adaptability, disease resistance, parasite resistance, thermoregulation, fertility under heat stress, resilience, robustness, and survival. Their genetic improvement requires accurate phenotyping, appropriate genetic evaluation, consideration of genotype–environment interaction, and the responsible use of genomic technologies.
- The ultimate goal of climate-resilient animal breeding is to develop animals that are healthy, fertile, resilient, productive, welfare-compatible, and capable of maintaining stable performance under changing environmental conditions. Genetic adaptation is most effective when combined with appropriate management and environmental support, creating production systems that can remain productive and sustainable while protecting animal health and welfare.
