Document type: scientific review available before publication in Animal
Authors: I. Veissier, C. Terlouw, R. Botreau, V. Deiss, S. Cowie
Preview: Animal welfare was initially conceived as the absence of negative experiences. More recently, the importance of positive affects has been recognized. This suggests a continuum ranging from very poor welfare, where suffering predominates, to very good welfare, where positive affects predominate, and that the intrinsic hedonic value of the environment—that is, whether it is pleasant or not—determines the level of welfare an animal can achieve on this continuum. In this paper, we question whether environments with a high intrinsic hedonic value are sufficient to ensure good welfare. For instance, pleasant but monotonous environments can induce boredom, which is likely to negatively affect animals. By contrast, complex environments can encourage engagement. In addition, the ability to act freely and efficiently plays a role. Environments that limit behavioral expression or make behavior inefficient can lead to frustration and apathy. By contrast, environments that provide freedom of action and make these actions efficient encourage animals to exercise their agency—through choices, control, problem-solving, free action, or exploration. We argue that intrinsic hedonic value, complexity, and the possibility for action all contribute to welfare. However, a consistently high level of hedonic value may result in a decrease in the hedonic value perceived by the animal. An overly complex environment or one that offers too wide a variety of actions may overwhelm animals. Therefore, rather than being maximized, hedonic value, complexity, and the possibility for action need to be optimized to maximize animal welfare. Where the optimum lies varies between individuals depending on factors such as species, age, physiological status, or individual traits.
