- Temperament is a behavioural characteristic describing how an animal typically responds to people, handling, novel situations, environmental changes, and potentially stressful events. It is an important trait in animal breeding because temperament can influence animal welfare, handling safety, productivity, reproductive performance, health, adaptability, and management efficiency. Animals differ in their behavioural responses even when they are raised under similar conditions, indicating that both genetic variation and environmental factors contribute to temperament.
- In animal breeding, temperament is often considered a relatively consistent tendency in an individual rather than a single behavioural reaction. Measures may include responses to handling, restraint, isolation, human presence, novel objects, transportation, or other controlled situations. Terms such as docility, calmness, excitability, fearfulness, and reactivity are sometimes used to describe related aspects of temperament. However, these terms are not always interchangeable, and the exact definition depends on the species, production system, and measurement method.
- Temperament is influenced by both genetic and environmental factors. A simplified quantitative-genetics model can be expressed as P=G+EP = G + E, where observed behavioural performance is influenced by genetic effects and environmental effects. Environmental influences can include early-life experience, nutrition, housing, stocking density, handling practices, social group structure, climate, health status, and previous exposure to stressful situations. Age, sex, physiological state, and reproductive status may also affect behavioural responses.
- Many temperament characteristics are complex quantitative traits influenced by multiple genes. Genetic variation can include additive genetic effects, dominance, and epistatic interactions. The additive component is particularly important for animal breeding because it contributes to differences that can be transmitted from parents to offspring. When meaningful additive genetic variation exists, selective breeding can gradually change temperament across generations.
- Heritability of temperament varies among species, populations, traits, and measurement methods. Some temperament measures show moderate genetic variation, whereas others may have relatively low heritability because environmental and measurement effects are large. A low heritability estimate does not mean that temperament cannot be genetically improved. It indicates that environmental and non-additive sources of variation account for a relatively large proportion of the observed phenotypic differences in the population being studied.
- Reliable measurement is particularly important for temperament because behaviour can be highly dependent on context. An animal may respond differently to a familiar handler than to an unfamiliar person, or differently during routine handling than during transportation or restraint. Standardized testing procedures, consistent scoring systems, repeated observations, and trained observers can improve the quality of phenotypic records used in genetic evaluation.
- One commonly evaluated aspect of temperament is docility, which describes how calmly an animal responds to handling. Calm and manageable animals can be easier and safer to handle during routine activities such as weighing, vaccination, veterinary treatment, milking, hoof care, transportation, and breeding. However, docility should not be interpreted simply as the absence of movement. Behavioural assessment should consider the animal’s overall response, stress level, welfare, and ability to adapt appropriately to its environment.
- Fearfulness is another important component of temperament. Animals with excessive fear may show avoidance, escape attempts, freezing, increased movement, or heightened physiological responses when exposed to humans, unfamiliar objects, or stressful situations. Excessive fear can create welfare concerns and increase handling difficulty. Genetic selection for reduced inappropriate fearfulness may therefore contribute to safer management and improved animal welfare when combined with appropriate husbandry and low-stress handling practices.
- Temperament can also be related to aggression, although these characteristics should be distinguished carefully. Aggression may occur in response to competition, social interactions, resource availability, territorial behaviour, or handling. Excessive aggression can create risks for animals and humans, but normal social and defensive behaviours should not automatically be considered undesirable. Breeding objectives should therefore target appropriate behavioural responses rather than attempting to eliminate natural behaviour.
- Temperament can influence animal welfare through its relationship with fear, stress, handling, social interactions, and environmental adaptation. Animals that are highly reactive to routine management may experience repeated stress when exposed to unavoidable handling procedures. On the other hand, an animal that responds appropriately to environmental challenges may be better able to maintain normal behaviour and physiological function. Genetic selection for temperament should therefore focus on improving welfare-compatible adaptability rather than simply producing animals that are less responsive.
- There can also be relationships between temperament and production traits. Behaviour can influence feeding, movement, grazing, social competition, energy expenditure, and responses to management. In some production systems, temperament may therefore be associated with growth, feed intake, feed efficiency, milk production, meat production, or other performance traits. These relationships are not universal, and breeding programs should evaluate genetic correlations within the relevant population and production environment.
- Temperament may also be associated with reproductive traits. Stress responses and behavioural characteristics can influence mating behaviour, handling during artificial insemination, maternal behaviour, and reproductive management. Genetic correlations between temperament and fertility may therefore be relevant when developing breeding objectives. However, behavioural selection should not be based on assumptions about these relationships; they should be evaluated using appropriate genetic data.
- Maternal behaviour is another important behavioural component that can interact with temperament. The response of a mother to her newborn offspring can influence nursing, grooming, protection, bonding, and offspring survival. Maternal temperament may therefore contribute to early-life performance and welfare. These effects can overlap with maternal genetic effects, maternal environmental effects, milk production, litter size, birth weight, and offspring survival.
- Temperament can also affect health and resilience. Animals differ in their behavioural responses to heat, cold, disease, handling, social stress, and changes in their environment. Activity, feeding behaviour, lying behaviour, social interaction, and responses to stressful events can provide information about an animal’s ability to cope with environmental challenges. Genetic relationships between temperament, health traits, disease resistance, resilience, survival, and longevity may therefore be important in some populations.
- The environment has a particularly strong influence on observed temperament. Early-life experience, handling quality, housing, nutrition, social environment, transportation, and management can modify behavioural responses. Positive and consistent handling may reduce fear responses, while repeated stressful experiences may produce different behavioural outcomes. This means that genetic improvement in temperament should be combined with management practices that provide suitable environmental conditions.
- Genotype–environment interaction may also influence temperament. Animals with different genetic backgrounds may respond differently to the same housing system, climate, stocking density, or handling method. A genotype that performs well under one management system may not necessarily show the same behavioural advantages under another. Breeding programs should therefore consider the target production environment when evaluating temperament.
- Temperament is often assessed using behavioural scoring systems, movement measurements, flight distance, chute or restraint scores, human-approach tests, novel-object tests, and other standardized procedures. Modern precision livestock farming technologies can provide additional information through cameras, accelerometers, electronic identification, microphones, and activity sensors. These systems can measure movement and behavioural patterns continuously, potentially producing more objective data than occasional visual observations.
- The statistical analysis of temperament depends on how the trait is recorded. Some behavioural measures are continuous, such as flight distance or movement duration, while others are categorical or ordinal, such as calm, moderate, and excitable scores. Binary or categorical temperament traits may be analyzed using threshold models when an underlying continuous liability is assumed to produce the observed categories. Appropriate statistical models help separate genetic effects from environmental and measurement effects.
- Repeatability is also important because temperament is expected to show some consistency within an animal, but behavioural responses may change with circumstances. Repeated measurements can help determine whether an observed behavioural difference represents a stable characteristic or a temporary response to a particular situation. High-quality repeated records can improve the reliability of genetic evaluation.
- Modern breeding programs can use estimated breeding values (EBVs), BLUP, and genomic selection to evaluate genetic differences in temperament. Genomic information can increase the accuracy of breeding-value prediction, especially for young animals that have not accumulated extensive behavioural records. Genome-wide association studies (GWAS) and quantitative trait loci (QTL) analyses may also identify genomic regions associated with behavioural variation, although temperament is generally influenced by many genes and complex biological pathways.
- Selection for temperament should be incorporated into a balanced breeding objective. Selecting strongly for a single behavioural characteristic without considering other traits could produce unintended consequences. Temperament should be evaluated together with health, fertility, growth, production, feed efficiency, survival, longevity, and other economically and biologically important traits. Genetic correlations are especially important because selection for one trait can cause correlated changes in another trait.
- The economic importance of temperament depends on the production system. More manageable animals may reduce labour requirements, handling time, injury risk, and management difficulties. Better temperament may also improve the efficiency of vaccination, veterinary treatment, transportation, milking, breeding, and routine husbandry. These potential benefits should be considered alongside welfare and biological performance when determining the economic value of temperament in a breeding program.
- Temperament also has important implications for animal welfare and worker safety. Highly reactive or aggressive animals can increase risks during handling and may experience greater stress during routine procedures. Breeding animals with suitable temperament, combined with low-stress handling and appropriate housing, can contribute to safer interactions between animals and people. Genetic improvement should complement rather than replace good management and welfare practices.
- Behavioural genetics also provides insight into adaptation and natural selection. Behaviour influences survival, reproduction, social relationships, resource acquisition, and responses to environmental challenges. Genetic differences in temperament can therefore affect fitness and may change through natural selection. In managed animal populations, artificial selection can alter these behavioural characteristics according to breeding objectives.
- Overall, temperament is an important behavioural trait connecting genetics with animal welfare, handling safety, health, reproduction, productivity, and environmental adaptation. Because temperament is influenced by both genetic and environmental factors, successful genetic improvement requires accurate phenotyping, reliable genetic evaluation, and appropriate management. When temperament is incorporated into a balanced breeding objective alongside production, health, fertility, survival, and welfare traits, genetic selection can contribute to animals that are calm, manageable, adaptable, productive, healthy, and well suited to their production environment.
