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Domestic animals’ fear of humans and its effect on their welfare |
Cahiers Agricultures. Volume 8, Number 6, 461-70, Novembre - Décembre 1999, Dossier : Bien-être animal
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 Résumé
Article gratuit
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Author(s) : Jeffrey Rushen, Allison A. Taylor, Anne-Marie de Passillé |
Summary : The way animals are handled, and the fear of humans that they can consequently develop, has a major impact on their welfare, regardless of the type of housing system used. Animals’ fear of humans can be a major source of stress, lead to considerable production losses, and make handling difficult and dangerous for both animals and handlers. Much of this fear results from certain forms of handling which are aversive to the animals. In this paper, we review a number of studies showing that roughly or aversively handled farm animals learn to associate handling with individual people, and that this learned fear of individual people can have marked effects on production. We also explore the issue of whether farm animals react differently to different individuals or generalize their experiences with one person to all people, and we propose some explanations for the apparently contradictory evidence in this area. Finally, we suggest steps that producers could take to reduce fear among their animals, and minimize the deleterious effects on the animals’ behaviour, productivity and welfare.
Behavioural studies of pigs, poultry and cattle revealed a relationship between animals’ fear of humans and their productivity. Comparisons between farms indicated that much of the between-farm variance in mean production levels could be explained by the animals’ level of fear to humans. Some differences between animals in the extent to which they are afraid of people may reflect genetic differences. However, it could also reflect the way that animals have been handled. Many studies have experimentally varied the type of handling in order to change the animals’ level of fear of humans, thus highlighting the effect of fear on productivity. This experimental approach indicates that the amount and type of handling received directly affects the fearfulness of the animals, which in turn reduces productivity. It is not surprising that an animal’s fear of humans can have a direct negative effect on productivity, given the evidence on physiological disturbances ("stress") associated with this fear-especially increases in hypothalamo-pituitary adrenal activity (HPA), cortisol levels, sympathetic nervous system activity (SNS), heart rate or catecholamine secretion. Poor handling of farm animals, thus increasing their fear of humans, is likely to prompt a number of other undesirable effects such as an increased risk of injury to both animals and attendants. Several lines of evidence indicate that the amount of fear shown by farm animals to humans is affected by the behaviour of the individual herd attendant. It has long been recognized that there are marked between-attendant differences in terms of the ultimate productivity. This difference may partially reflect differing levels of technical competence, but research results have revealed that the degree of fear that animals show towards an individual herd attendant can be a major factor underlying productivity differences. Handling can involve very subtle behaviours that may be difficult to detect by normal observation methods. High and low-producing herd attendants have been found to have a number of different personality attributes. However, it is not clear if these personality differences had effects on productivity by influencing how the attendant handled the animals, or whether these effects were associated with differing levels of technical competence or the use of different management techniques. One important question concerns the extent to which animals are able to distinguish between individual people. A number of experiments have shown that animals tend to generalize aversive experiences with one handler to all people. In contrast, a small but growing number of studies have systematically examined the extent to which domestic animals can distinguish individual people. The ability to recognize individual attendants has now been clearly demonstrated for many species of farm animals, and studies have focused on understanding the cues animals use to distinguish between people. Pigs appear to use multiple cues to distinguish people, although visual cues are clearly important. Cows can readily learn to distinguish between two people wearing different coloured clothes, but it is more difficult for them to distinguish between people wearing the same colour. Furthermore, cows’ responses to people change markedly when clothing colour is changed, although this does not seem to be true for poultry. Whether animals will behave differently to individual people may also depend also on the context. For example, the likelihood that animals will learn an association between aversive handling and the individual herd attendant, and develop a fear of that attendant, may be reduced if the treatment is carried out in a special place. Animals can learn to associate an aversive treatment with a particular place, and there is evidence that some dairy calves do not generalize aversion to one person - learned in one place - to other places. The behaviour of a herd handler can be an important factor affecting the animals’ fear level, and hence their productivity and welfare. To come up with solutions, it is essential to accurately determine the most important aspects of a handler’s behaviour. Increased contact with humans, particularly during rearing, can markedly decrease the animals’ fear level. This has been shown for most species of farm animals, but recommendations to farmers rarely stress the importance of early contact. Whether an animal is more sensitive to human contact at some times than at others is open to speculation. Certain behaviours or postures while in close contact can frighten or startle animals. Many quite reasonable recommendations have been made concerning the most appropriate behaviours (talking quietly, avoiding sudden movements, touching the animal at first approach). However, it should be noted that none of these recommendations have actually been tested. While this may seem unnecessary in some cases, assessment is essential for the most hypothetical recommendations, e.g. suggestions on how far into an animal’s "flight zone" a handler should penetrate, the best places to touch animals, or the necessity of establishing dominance. A number of authors have suggested that handling could be improved if handlers adopted the species-specific behaviours used by the animals themselves when establishing social bonds or social relationships. However, these recommendations remain imprecise since little is actually known about social behaviour and communication in farm animals. Much aversive handling of farm animals occurs when the animals are being moved, especially when handling facilities are poorly designed, causing the animals to frequently baulk. Improvement in handling facilities, leading to easier flow of animals, would greatly reduce the amount of rough handling farm animals receive, and would likely result in tamer and less fearful animals and consequently reduce injuries. Regular aversive handling can induce animals to learn an association between aversive treatment and a specific handler or humans in general. Recommendations are often given to avoid aversive treatments, but apart from the obvious ones such as electric shock, there is little knowledge on what handling treatments cattle actually find aversive. Determining the most aversive handling techniques is essential to achieve progress in this area.
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