ElsitioPorcino.com - Avicultura, Salud Aviar, Bienestar, Enfermedades, Noticias Avícolas, Artículos, Fotos Avícolas

The Poultry Site Backroom

ThePoultrySite Featured Articles

Research approaches

In practice, attempts to understand animal welfare are often based on a combination of several different types of scientific research. For example, observing only the behaviour of an animal without measuring how its body is coping with a situation might be misleading. A chicken that is in pain may sit quietly and appear calm. Yet it may have a faster heart rate and a higher concentration of the stress hormone, corticosterone, than a bird that is apparently panicking.

An example of an integrated approach is the study of the welfare implications of rapid growth in broiler chickens. A problem with modern broilers is that they grow so fast their body conformation produces abnormal walking patterns and the animals develop a variety of orthopaedic diseases. A combination of approaches including genetics, nutritional studies, pathology, morphology and quantitative gait analysis is being deployed to identify ways that breeding companies can improve bird welfare.


Correlating the patterns of activity in different parts of the brain with perception of important stimuli in an individual's environment is a welltested technique used for showing how both humans and other animals interpret, learn about and respond to different social and nonsocial objects.

Comparing the structure and function of the nervous systems of different types of animals in relation with humans can also provide clues about their potential abilities to exhibit complex cognitive abilities, consciousness and different emotional states, including pain.

Animal behaviour

Observations of animal behaviour under carefully controlled conditions can provide indications of how animals respond to threat or fear in their natural environment, and this information may improve understanding of how farm livestock and other domesticated species respond to conditions around them. But great care is needed in interpreting such behaviours. Behaviour that indicates contentment in humans might mean something quite different in other species. It is also important to consider factors that might conceal an animal's behavioural responses. For example, an immobilised animal may experience pain but be unable to respond normally. Furthermore, the survival of a prey animal may often depend on its ability to hide the fact that it is in pain.

Cat owners may recognise that their pet may seem more distressed by what to humans is a relatively minor skin abrasion or abscess than by a broken bone which would be more distressing to a human.

We also need to avoid human-based ideas about, say, the relative intelligence of different species and how that might relate to their needs - for example we need to avoid making arbitrary and unscientific assumptions about say the relative environmental needs of a primate and a mouse.

Studies of animal behaviour can also provide clues about animals' needs and preferences. But such experiments must be carefully designed: fear and stress caused by, for example, overcrowded, unpleasant or alarming situations can impair an animal's ability to make decisions. Another complication is that an animal's requirements may be different, or its priorities may be different, in a captive or domesticated environment compared with the wild.


Measurements of heart rate and levels of hormones and other chemicals in the blood can indicate the extent to which an animal is experiencing stress. But again, careful interpretation is needed.

A human being that is in pain or distress may have a faster than usual heart rate, rapid and shallow breathing, and higher blood levels of the hormone adrenalin. But precisely the same physiological changes may be seen in an individual who is greatly excited and happy, and not in pain at all. Moreover, in a person suffering pain over a long period of time, heart rate, breathing and hormone levels may return to normal. Such confounding effects can be expected in other species.

Pain is both a sensory and emotional experience and there is no single parameter that provides an unambiguous assessment of pain in animals. To assess pain in animals a multidisciplinary approach has been used combining physiology and behaviour. Monitoring the responses of the sensory receptors which measure tissue damage provides an indication of the information that is being relayed to the brain and in humans there is a correlation between this information and the experience of pain. Acute pain produces changes in blood pressure, heart rate and levels of stress hormones, measuring these physiological parameters therefore provides additional evidence of possible pain. The emotional aspects of pain can only be ascertained using behavioural measures such as avoidance, social and guarding behaviours especially shifts in attention. Many of these behavioural changes are species specific and behaviour displayed in an animal will vary depending on the extent, duration and bodily position of the injury or disease.


Individuals differ in their ability to tolerate pain and stress, and this may have a genetic basis. We are also familiar with the idea that different breeds of cattle, dog or chickens are generally more or less docile.

Genetics research can shed light on the relationships between physical traits, such as body composition, behavioural traits and genetic make-up. An example from pig breeding research is the association between extreme body leanness and an increased sensitivity to stress, which can be explained by the influence of a single gene (the halothane gene, so called because pigs carrying it are extremely sensitive to the anaesthetic halothane).

Advances in molecular biological techniques both for identifying the role of different genes, and for "mapping" them so that their transmission between generations can be tagged, means that it is becoming more feasible to identify genes that contribute to particular behavioural traits, and to select for them. This will increase the precision of traditional breeding programmes.

Scientists at the Roslin Institute have explored how genetic factors contribute to poultry's ability to adapt to their environment. For example, fear is more pronounced and feather pecking (see page 31) occurs more in some strains of poultry than in others.

The researchers devised a simple test for predicting chicks' propensity to a range of welfare problems including fear, social distress and, perhaps, feather pecking. This may be used to help to identify genetic markers that could be used by commercial breeders to select for birds with reduced fearfulness, decreased feather pecking and appropriate levels of sociality. This will augment existing selection programmes aimed at "breedingout" some welfare problems faced by poultry producers. Similar studies at Roslin have shown that there is also a strong genetic basis to osteoporosis in poultry (see page 45).

BBSRC priority area on Animal Welfare

The objective is to gain a greater understanding of welfare issues with particular reference to the current situation in the UK, in order to inform improved conditions and management of livestock, companion and laboratory animals. In order to do this, this research area aims to improve our knowledge of:

  • the basic behavioural, neurobiological, immune, metabolic, physiological and tissue responses of farm, laboratory, companion and other managed animals to their environmental conditions, and

  • the consequences of human intervention, genetic selection and management for the normal functioning of animals and the incidence of disease, pain, anxiety and mental disorders.

Specific priorities for research are:
  • COGNITION: including the ways that cognitive animals interpret the actions of others and how this affects their subsequent behaviour; the limits of learning and memory in different species; improved understanding of how animals establish and maintain social relationships.

  • MOTIVATION: development of better indices to assess the effects of conditions important to animal welfare including motivational behaviour as an index of contentment, fear or anxiety; the integration of behavioural, neurobiological or pathophysiological indices is particularly encouraged.

  • PAIN AND DISCOMFORT: understanding the mechanisms underlying different types of pain and their alleviation; methods for the objective assessment of discomfort and pain in animals; understanding individual and species differences in response including the phylogeny of pain mechanisms and pain suppression; the behavioural consequences of discomfort/pain and interactions with fear and anxiety.

Additionally, BBSRC's Agri-Food Committee seeks to support research that increases understanding of the interactions between farmed animals and their environment at the level of the production system (including aquaculture). This may include basic studies of production diseases (e.g., lameness) that can be directly attributed to the system itself, the perception by and responses of animals to complex stimuli such as man or machines, and the welfare implications of more extensive animal production systems.

The aim is to support basic and strategic research that leads to welfare improvement through enhanced livestock fitness. Research is needed to provide knowledge that will underpin improvements in animal husbandry through better understanding and resolution of elements of production systems that are likely to impair fitness. This may be achieved by:

  • identifying, quantifying and resolving specific elements of production systems which may compromise welfare through reduced fertility, chronic injury, disease, physiological exhaustion or psychological distress;

  • breeding animals for improved lifetime performance and quality of life, achieved through improved fertility, resistance to injury or disease, or social behaviour.

Source: The Biotechnology and Biological Sciences Research Council - Summer 2002

¿Quién Está En Línea?