- Welfare-related traits are measurable characteristics that describe aspects of an animal’s physical health, behavioural functioning, emotional state, comfort, ability to cope with its environment, and overall quality of life. They are increasingly important in modern animal breeding because genetic improvement can influence not only productivity and efficiency but also animal welfare, health, resilience, behaviour, and longevity. Welfare-related traits can include disease resistance, injury resistance, lameness, temperament, fearfulness, stress response, body condition, mortality, survival, reproductive health, maternal behaviour, and other indicators of physical and behavioural well-being.
- Animal welfare is a multidimensional concept, and no single trait can fully describe it. Welfare depends on the animal’s physical condition, health, behaviour, environment, social relationships, nutrition, ability to perform important behaviours, and capacity to cope with challenges. For this reason, welfare-related traits should generally be considered as a group of complementary indicators rather than as one universal measurement. Genetic evaluation can help identify animals with favourable characteristics, but appropriate management and housing remain essential for maintaining good welfare.
- Welfare-related traits are influenced by both genetic and environmental factors. A simplified quantitative-genetics model can be expressed as P=G+EP = G + E, where observed welfare-related performance is influenced by genetic effects and environmental effects. Genetic differences can affect disease resistance, susceptibility to injury, temperament, stress responsiveness, reproductive performance, body structure, and resilience. Environmental influences include nutrition, housing, climate, stocking density, handling, hygiene, disease exposure, transport, management practices, and social conditions.
- Many welfare-related traits are complex quantitative traits controlled by multiple genes and influenced by multiple environmental factors. 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 sufficient additive genetic variation exists, welfare-related characteristics can potentially be improved through selective breeding.
- Health-related traits are among the most important indicators of animal welfare. Disease, injury, chronic inflammation, poor body condition, metabolic disorders, and other health problems can compromise an animal’s ability to function normally and may reduce survival, productivity, and quality of life. Traits such as disease incidence, disease resistance, disease severity, somatic cell count, hoof health, udder health, respiratory health, and metabolic health can therefore contribute to genetic evaluations aimed at improving welfare.
- Lameness and locomotor health are particularly important in many livestock species. Lameness can result from genetic predisposition, hoof structure, infectious disease, housing, flooring, nutrition, body weight, and management. Because lameness can cause pain, reduced mobility, altered feeding behaviour, reduced reproductive performance, and premature culling, genetic selection for improved leg and hoof health may contribute to better welfare when combined with appropriate environmental management.
- Temperament is another important welfare-related characteristic. Animals differ genetically and environmentally in their responses to handling, humans, novel situations, restraint, transportation, and social interactions. Excessive fearfulness or inappropriate aggression may increase stress, create handling difficulties, and increase risks to both animals and people. Selection for suitable temperament and improved docility can therefore contribute to welfare, provided that behavioural traits are evaluated carefully and not reduced to a single simplistic measure.
- Stress response is closely connected to welfare. Animals must respond to challenges, but excessive, prolonged, or poorly regulated stress can negatively affect health, behaviour, reproduction, immunity, and productivity. Genetic variation may influence how animals perceive and respond to stressful situations and how effectively they recover. This makes stress-related traits potentially useful indicators of resilience and adaptation.
- Resilience describes an animal’s ability to maintain health and performance or recover efficiently when exposed to environmental challenges. Challenges can include disease, heat stress, nutritional fluctuations, transportation, social stress, and other disturbances. Resilient animals may be better able to maintain normal function under variable conditions. Genetic selection for resilience can therefore support both welfare and sustainable production, especially in changing environmental conditions.
- Survival and longevity are also closely related to welfare. Animals that remain healthy and productive for longer periods may experience fewer episodes of severe disease, injury, reproductive failure, or premature removal. However, longevity alone should not be interpreted as proof of good welfare. An animal may survive for a long time while experiencing poor health or chronic discomfort. Welfare-oriented breeding therefore emphasizes healthy productive longevity, rather than simply maximizing lifespan.
- Reproductive health can also be considered a welfare-related area. Difficult births, reproductive disorders, repeated breeding failures, prolonged reproductive intervals, and poor maternal performance can create health and welfare challenges. Traits such as calving difficulty, lambing difficulty, farrowing difficulty, fertility, conception rate, stillbirth, maternal behaviour, and offspring survival can therefore have welfare implications. Balanced breeding objectives should consider reproductive performance together with health, behaviour, and offspring welfare.
- Maternal behaviour is particularly important because the behaviour of the mother can influence newborn survival, nutrition, protection, bonding, and early development. Appropriate maternal behaviour may support offspring welfare, while poor maternal care may increase risks of starvation, injury, abandonment, or mortality. Maternal behaviour is influenced by genetics, previous experience, environment, nutrition, and reproductive physiology, making it a potential component of welfare-oriented breeding programs.
- Body condition and body composition can also provide welfare-relevant information. Excessively low body condition may indicate inadequate nutrition, disease, high production demands, or other problems, while excessive body condition may contribute to metabolic, locomotor, or reproductive disorders. Genetic selection should therefore aim for appropriate body composition and physiological robustness rather than maximizing production traits without considering the animal’s ability to maintain good health.
- Welfare-related traits can show different levels of heritability. Some traits may have measurable additive genetic variation, while others are strongly influenced by environmental conditions. Binary outcomes such as disease occurrence, injury, or survival may require threshold or survival-analysis approaches, whereas continuous traits such as body condition, activity, or physiological measurements can be analyzed using other quantitative-genetic models. A low heritability estimate does not mean that a welfare-related trait is genetically irrelevant; it indicates that environmental variation contributes substantially to observed differences.
- Accurate phenotypic recording is essential for welfare-oriented genetic improvement. Records may include veterinary diagnoses, disease incidence, treatment frequency, lameness scores, mortality, culling reasons, body condition, behavioural observations, reproductive outcomes, injuries, activity patterns, and physiological indicators. Consistent definitions and standardized recording systems are particularly important because welfare traits may be measured differently across farms, breeds, countries, and production systems.
- Many welfare-related traits are influenced by genotype–environment interaction. Animals with different genetic backgrounds may respond differently to housing systems, climate, stocking density, nutrition, handling, disease exposure, or production intensity. A genotype that performs well under one management system may not have the same welfare advantages under another. Genetic evaluation should therefore consider the environment in which animals will be kept.
- There are often important genetic correlations among welfare-related traits and other economically important characteristics. Health may be genetically correlated with fertility, survival, longevity, production, feed efficiency, growth, and behaviour. For example, selection for extremely high production without consideration of health may create undesirable correlated responses in some populations. Conversely, including health, resilience, temperament, fertility, and longevity in a balanced breeding objective can help maintain a broader biological balance.
- Modern animal breeding programs can use estimated breeding values (EBVs), BLUP, and genomic selection to evaluate welfare-related traits. Genomic information can improve the accuracy of breeding-value prediction, particularly for young animals with limited individual records. Genome-wide association studies (GWAS) and quantitative trait loci (QTL) analyses can also identify genomic regions associated with health, behaviour, resilience, and other welfare-related characteristics.
- Because welfare is multidimensional, selection should not focus on one indicator alone. A breeding program that improves disease resistance but increases undesirable behaviour, or improves production while increasing structural problems, may not produce the desired overall welfare outcome. A balanced selection index can combine welfare-related traits with production, fertility, growth, feed efficiency, survival, and other breeding objectives according to their biological and economic importance.
- Technology is creating new opportunities to measure welfare continuously. Precision livestock farming technologies can use cameras, accelerometers, microphones, electronic identification, automated weighing systems, activity sensors, and other tools to detect changes in behaviour, movement, feeding, drinking, lying, social interaction, and physiological status. These systems may provide early indicators of disease, injury, heat stress, nutritional problems, or behavioural changes. However, automated indicators must be biologically validated before being used as reliable welfare traits in genetic evaluation.
- Welfare-oriented breeding also has important implications for sustainability. Healthy animals that remain productive for longer may require fewer replacements and may use resources more efficiently over their lifetime. Improved disease resistance, fertility, resilience, and longevity can potentially reduce treatment requirements, mortality, replacement costs, and production losses. However, sustainability should not be pursued by sacrificing welfare; good animal welfare is an essential component of responsible and sustainable livestock production.
- Genetic improvement of welfare-related traits must also consider genetic diversity and inbreeding. Strong selection for a small number of traits can reduce genetic diversity or increase the risk of undesirable correlated responses. Maintaining sufficient effective population size and monitoring inbreeding are therefore important components of long-term breeding programs. Balanced selection can help improve welfare while preserving genetic resources for future adaptation.
- Welfare-related traits are also connected to animal adaptation and evolution. Behaviour, health, reproduction, stress response, and survival influence biological fitness and adaptation to different environments. Genetic variation in these characteristics can therefore contribute to natural selection. Under artificial selection, breeders can change the frequency of favourable alleles associated with welfare-related characteristics, provided that appropriate phenotypes and breeding objectives are used.
- The goal of welfare-oriented genetic selection is not to create animals that are simply more productive or less reactive. The objective is to develop animals that can remain healthy, cope effectively with environmental challenges, reproduce successfully, behave appropriately, and maintain good physical and behavioural functioning under their production conditions. Genetics is one component of this process, alongside nutrition, housing, veterinary care, management, handling, biosecurity, and environmental design.
- Overall, welfare-related traits are an important part of modern animal breeding because they connect genetics with health, behaviour, resilience, reproduction, survival, productivity, sustainability, and ethical livestock management. By accurately measuring welfare indicators and incorporating them into balanced breeding objectives, genetic improvement can contribute to animals that are healthy, resilient, manageable, productive, long-lived, and capable of experiencing good welfare throughout their lives.
