Animal behaviour studies are called ‘ethology’. This is derived from the Greek root ‘ethos’ meaning ‘nature’ or ‘disposition’.

Ethologists study the behaviour of animals in a natural setting. Because it is often difficult to study domes-tic animals in a natural environment, Applied Ethology evolved to study domestic and captive animals in environments designed by humans.

The central theme in Applied Ethology is the study of the interface or relationship between people and domestic animals.

This chapter will study:

1. Human–animal interface model

2. Dominance concept

3. Flight distance

4. Crowding and over-crowding

5. Social facilitation

6. Stress and its measurement

 

MAN–ANIMAL INTERFACE MODEL

Traditionally, humans tend to have a dominating influence on domesticated animals, and our relative importance in their social environment varies with the species and with the frequency and duration of the relationship. This influence has become more pervasive as animals have been moved from extensive husbandry systems to the intensive husbandry systems used today in many countries.

DOMINANCE CONCEPT

The first studies of dominance relationships in groups of animals were published in 1922 by Schjelderup-Ebbe. He studied the organisation of flocks of chickens (1922, 1935) and developed a concept of simple dominance where one individual had preferential rights over an-other. This was the ‘peck-right’ (or pecking order) of one hen over another. This concept was widely used until 1942 when Allee reviewed dominance–subordination in vertebrates and noted that irregularities, such as triangular relationships, often occurred in a simple straight-line hierarchy, so that, for instance, a hen with medium or even low status might have the peck-right over some individual that out-ranked her in the linear hierarchy. Since then many variations of the classical hierarchy system have been studied. For example, horses use coalitions so that affiliated pairs in a herd have an accumulative power to displace a third horse that normally out-ranks both of them on a individual basis. That said, linear hierarchies remain a useful construct with valuable properties if used cautiously and if one is aware that the nature of resources being contested may influence the outcome of a contest.

The construction of a dominance hierarchy

A dominance hierarchy is the system of space sharing in a group arranged on a priority basis that keeps friction to a minimum. Once the division of space is complete there is no further strife or challenge to the order unless a young member of the group matures significantly (e.g. reaches sexual maturity) or an aged member becomes senescent (McBride, 1971).

The construction of the dominance hierarchy is based on the observation of a group of animals. The following table shows the number of encounters initiated and received by five animals (A,B,C,D,E) in a group.

1. The observer records the agonistic interactions for a fixed time in a group of animals, making sure to note the initiator and recipient.

2. The frequencies are recorded in a table as shown in the example above.

3. Column totals (T1) indicate which animal initiated the most agonistic interactions. This gives an indication of the most dominant animal, so from the example above it can be seen that the hierarchy is in the form of:

C, B, A, D, E,

The row totals (T2) give an indication of the animal receiving the most agonistic behaviours, in this case D. The model also tells us other facts, e.g. A did not initiate any interaction with B, but B initiated three interactions with A, although A has a slightly lower position than B in the dominance hierarchy. It also shows that E (the most subordinate animal in the hierarchy) did not interact with B or C.

Properties of the dominance hierarchy concept:

1. It is a model that describes some aspects of social relationships within a group.

2. It ignores the role of appeasement behaviours, e.g. active submission that may often have a more critical role in social behaviour than aggression per se.

3. It ignores many individual qualities of different relationships, e.g. are the animals mutually dependent, grazing companions or grooming companions?

4. It deals only with agonistic interactions.

5. It is logically linear, but this is not always so.

It can be useful in husbandry studies and McBride (1968) proposed a model relating production and hierarchy, in which he suggested that a suitable husbandry system ensures that all animals, no matter what rank in the hierarchy, should have equal production opportunities. In adverse conditions the high-ranking animals would have priority in any competitive situation (for food, water, space).

Some consequences of the dominance hierarchy in husbandry systems:

1. Animals culled on productivity tend to be the subordinate animals.

2. Facilities must be placed where all animals can reach them without the group structure being too disrupted. Sometimes it is worth providing one more access point to a given resource than there are animals (e.g. with four horses in a paddock, reduced friction is seen if five piles of hay are provided).

3. The dominant animal usually has mating advantages and also resource advantages when they are limited.

How is a hierarchy maintained?

To maintain a hierarchy every animal must recognise each member of the group and remember the dominance– subordinate relationship. In flocks of poultry (n = 80 birds) it was found that individuals did not move freely but remained attached to a site so they learned to recognise a small sub-group (McBride and Foenander, 1962). It was suggested by these workers that this territorial behaviour should be encouraged in large flocks, such as are commonly found on modern broiler units (e.g. n = 10,000), since it reduces the number of conflicts when strangers meet. A more recent study (Hughes et al., 1974) on spatial behaviour of Shaver 288 pullets shows different results. In a series of six experiments using flocks of 4 to 600 birds, site attachment was not shown by many subjects. This could be due to breed differences, or light intensity, as these observations were conducted under much lower light levels.

Although there are limitations in the dominance model it is a useful construct to look at the social organisation within a group of animals.

FLIGHT DISTANCE

This is the minimum distance of approach to an animal before it flees. A tame animal has a flight distance of zero (Hediger, 1964). The concept is used when droving animals by man or dog, and is of considerable importance in round-pen gentling of horses. Animals can be imagined as having a ‘zone of safety’ around them and when this zone is penetrated the animals will move away. Retreating from the flight zone will cause the animal to stop moving. If an animal starts to turn back the handler should retreat. In round-pen training the flight zone is repeatedly penetrated until the horse shows a reduced fear response. When it shows less fear it is rewarded by having the pressure of  the handler’s presence removed. It therefore learns to walk toward rather than attempt to escape from the handler.

The flight distance during handling is usually 1.5 to 7.6 m for beef cattle raised in a feeding operation and up to 30 m on mountain ranges (Grandin, 1980). Brahman cattle have a larger flight distance than most English breeds (Grandin, 1978). If handlers lean over fences over animals they penetrate the ‘zone of safety’ around the animals and may cause the animals to rear.

CROWDING AND OVER-CROWDING

Crowding begins, not when animals jostle each other, but when they are forced into the personal spaces of their neighbours (McBride, 1971). Animals need space to walk on, space to lie on and also a personal space around them. Rigorous spacing systems operate in Nat Ural populations so that crowding does not occur.

In domestic animals kept close together in various husbandry systems, crowding may become an important problem, often affecting biological fitness and so productivity. At this point it is labelled over-crowding. As animals are forced into each other’s personal space there are interactions, often of a violent nature. At high densities it is difficult for animals to avoid such intrusions as they cannot move away. Some may adapt to the intrusion while others may become so stressed that productivity is affected.

From this discussion it can be seen that the concept of crowding does not only involve the number of animals per m₂ . It involves also the use of the space. So when considering crowding several important questions should be asked:

1. When does crowding occur? This time element is very important, e.g. animals may be crowded only when feeding or moving around, but not crowded when lying down.

2. Where does crowding occur? It may be only around certain service points.

3. For whom does crowding occur? As has been discussed, if productivity is affected it will be the lower-ranking animals that suffer most.

McBride (1971) suggests how some of the effects of crowding may be controlled systematically.

1. Service facilities, such as nest boxes, feeders and waterers, should be adequate and equally attractive to animals.

2. Subdued lighting quietens animals.

3. The partitioning of space to restrict visual or social contacts between animals.

4. Group size can be lowered with the use of partitions so that sub-groups form with their own dominance hierarchy.

Crowding and over-crowding are not simple problems and intensive husbandry systems must take into account these various factors.

SOCIAL FACILITATION

This is an important behavioural phenomenon that can cause problems, especially in intensively housed animals. It is the tendency for animals to join in an activity, e.g. feeding, and means that this activity requires a large space, which can cause competition for the key resources, which leads to crowding stress. It may also increase the quantity of food being eaten. In nursing sows housed together, social facilitation can increase the number of suckling bouts that have to be under- taken by all sows. Grunting by a nursing sow in one pen can cause piglets in a neighbouring pen to approach their own dam and initiate a suckling bout.

STRESS AND ITS MEASUREMENT

The term ‘stress’ means different things to different people, and so a great deal of confusion has arisen in both lay and scientific literature (Selye, 1976). Selye commented that essentially different things such as cold, heat, drugs, sorrow and joy would provoke an identical biological reaction. These agents are known as stressors.

In animal management, stress is often associated with effects due to ‘weaning stress’, ‘transport stress’ or it can refer to ‘behavioural stress’, which are problems associated with intensification.

There have been several proposed definitions of stress for use in animal husbandry conditions:

1. McBride (1968, 1971) used the definition of Lee (1966), who described stress as the pressures acting on individuals to cause strain.

2. Fraser et al. (1975) suggested that in a veterinary context ‘stress’ be used when there was a profound physiological change in the condition of an animal. The definition proposed was, ‘an animal is said to be in a state of stress if it is required to make abnormal or extreme adjustments in its physiology or behaviour in order to cope with aspects of its environment and management’.

However, these definitions still do not tell you what stress actually is.

McBride (1980) proposed a model that suggested how animals adapt to stress at an individual level. There are three levels where adaptation of the animals to stress could occur:

1. Behavioural level

If an animal can avoid an unpleasant stimulus it has removed itself from the stress. In many intensive situations this may be difficult for all animals in a group to do and possibly the dominant animals will be the only ones able to adapt.

2. Psychological level

Those unsuccessful animals must try to adapt by the psychological process of habituation. If they do not habituate to the aversive conditions they may enter a state of learned helplessness or apathy in which they remain distressed but no longer attempt to make appropriate responses to improve their plight.

3. Physiological level

In the animals that still have not adapted, continued arousal generates the General Adaptation Syndrome (GAS) of Selye (1976). There is a general pattern of alarm (alarm reaction) leading to homeostatic resistance to change (stage of resistance) and the stage of exhaustion follows if the stressor is severe enough and is applied for a sufficient length of time. It is at this stage that strain develops and may be characterised by a susceptibility to a variety of infectious or other environmental stressors. In other words, the animal has not been able to adapt to the environment.

It is at this level that problems arise which affect the welfare of the animals. When this happens serious questions should be asked about the suitability of the husbandry system.

Often there are comparisons of the stresses to which free-living and domestic animals are exposed. The sources of these stresses are quite different, but in both conditions the model suggests that there will be environmental challenges that may contribute to the well-being of an animal. It can either adapt and be successful or fail. Failure of an animal to adapt in the wild lays no blame on humans, whereas failure to adapt to husbandry systems is a failure on the part of humans.

Here the HUMAN–ANIMAL INTERFACE MODEL (McBride, 1980) can be used in a systematic approach to examining environments for animals designed by man.

1. All the human–animal interfaces should be examined.

2. Examine the many environmental designs in use and see where, when and how behaviour–environment fits or misfits. It is unfortunately fairly easy to find examples of inadequate design in any intensive situation.

Another point of view is outlined by Beilharz (1982), who cautions against considering only environmental design to fit an animal’s current needs. He points out that there is no evidence to suggest that animals have stopped changing in response to environmental changes so it seems rational to use genetic change, as well as environmental change, in our solution to ‘welfare problems’. He suggests that animals may be selected who suit the environment rather than changing the environment to suit the animals. Clearly, this is a long-term approach and requires many generations to withstand sub-optimal conditions before tolerant strains emerge.

The measurement of stress

1. The physiological reactions of animals to stressors are difficult to measure, especially in the field. Some measurements may require the slaughter of animals (e.g. weighing of adrenal glands) others involve attachment of leads, withdrawal of blood and restraint, all of which may upset the animal. The use of telemetric transmitters taped to an animal, e.g. pig's back (Mayes, 1982), can send signals of the animal’s heartbeat. This technique has shown that as the animal is forced to climb a loading chute, its resting rate increased from 100-160 beats/minute to 250-260 beats/minute. Technological advances including the refinement of microchips are allowing scientists to record large amounts of physiological data from animals wearing implanted and telemetric devices. Meanwhile, the use of ACTH stimulation tests and cortisol assays in samples ranging from blood, saliva, faeces and even eggs is becoming more commonplace as a means of plotting trends in physiological stress responses. However, the importance of diurnal rhythms and the possibility of physiological fatigue as a result of chronic stress mean that such measurements should not be interpreted in isolation from behavioural observations.

2. Changes in behaviour, most notably the appearance of displacement or stereotypic behaviours, may be an early indication of a stressful situation.

It is apparent that the measurement of stress is a difficult problem.

REFERENCES