Animal Welfare. John Webster
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Название: Animal Welfare

Автор: John Webster

Издательство: John Wiley & Sons Limited

Жанр: Биология

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isbn: 9781119857082

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СКАЧАТЬ require to achieve a sense of physical and mental wellbeing. With this information to hand, we can devise management policies that seek to address these needs whenever we modify their natural habitat to suit our own needs for food, companionship, sport, safety or scientific endeavour.

      The second approach is to present animals with a set of questions relating to their perceived needs and measure their responses. This is the science of motivation analysis (16). The simplest version of this approach is the Preference Test. In a typical experiment, the animal is given a choice, e.g. between two foods or two environments and invited to demonstrate a preference. The choice may be between options that we guess might create more or less satisfaction (e.g. two types of bedding material for pigs), or between options that may be more or less aversive (e.g. barren vs. enriched cages for hens). One classic approach is to place the animal in a T maze that allows it to choose between the two options of taking the path to the right or the left. This can tell us quite a lot. Pet food manufacturers may discover flavours preferred by cats (although cats are fickle creatures). Designers of enriched environments for intensively reared pigs or chickens can get some idea of the fixtures and fittings that these animals appear to favour or avoid. However, preference tests can sometimes reveal evidence to indicate that the scientist and the experimental animals are not thinking the same way. In one such experiment, mice were asked to choose between two environments deemed by the scientist to be more or less enriched by traversing a narrow tunnel between the two. Most mice chose to spend the majority of time in the tunnel. For them, this was better than either of the choices on offer (66). The scientists had assumed the mice would choose on the basis of comfort, whereas, in their minds, we must assume that the primary need was for a sense of security. The scientists posed a specific question to these mice and got an unexpected answer. It was the wrong question, but they had a better understanding of mice as a result.

      The main limitation of the preference test is that it makes no distinction between choices that are trivial and those that really matter. A more advanced approach to motivation analysis is to measure the strength of motivation by how hard an animal is prepared to work to get a reward in the form of a pleasant experience such as food, or relief from an unpleasant experience such as cold, pain, isolation, or a barren environment (16,45). Examples of the currency used to measure cost include the number of times the animal has to press a lever, or the amount of pressure it has to exert on a gate to obtain the reward. Specific rewards are ranked as more or less price elastic or price inelastic. Most animals, unless satiated, will continue to work for a food reward as the price is increased, which makes it price inelastic. The marginal reward of a different lying surface, e.g. straw vs. wood shavings may be price elastic: i.e. not worth too much effort. While the preference test can do no more than establish behavioural priorities, motivation analysis can determine how much these things matter.

      There is another profound conclusion to be drawn from studies such as these; one that is key to our understanding of the minds of our fellow mortals. Presented with a specific question, which can be quite complex, the rat or chicken has analysed the problem, worked out a satisfactory response and memorised the actions necessary to achieve that response without recourse to the uniquely human medium of the spoken and written language. Moreover, as we shall see later, the ability to solve simple problems set by scientists in the laboratory can be a very limited measure of an animal’s mental capacity. It pales into insignificance when set, for example, alongside the detailed large‐scale maps that a pigeon needs to carry in its head if it is to navigate its way home. Animals with sentient minds have the ability to acquire and retain a great deal of knowledge and understanding without the need for language as we understand it nor reference to external banks of information stored in libraries and/or Google. What is more, these animals may be able to convey this understanding to their offspring, i.e. to engage in the process of education. We are only just beginning to understand the capacity of non‐human animals to develop thought without language and convey these thoughts to others, but it is an ability worthy of the greatest respect.

      Two main themes run throughout this exploration of the minds of sentient animals.

      Theme 1: The needs of a sentient animal are defined entirely by its own physical and emotional phenotype, its environment and its education, and these are independent of our own definition of the animals as:

       Wild: subsets, game, (e.g. fox) vermin (rat), protected (badger)

       Domestic: subsets, pet (dog), farm (pig), sport (horse)

      Theme 2: It is an anthropocentric fallacy to assume that the greater the similarity of an animal species to the human species, the more intelligent they are and the more worthy they are of our concern and respect.