Animal Welfare Science began to gradually develop in the 60´s, probably as a consequence of the publication of the book “Animal Machines” by Ruth Harrison , which denounced several practices that were done without regard for animal suffering. Since then, much research has been conducted aiming to identify the welfare states of animals. Firstly, an animal was considered to have good welfare when it was physically healthy, feeding, and producing well. Everyone can easily understand the importance of these characteristics and believe they may be part of animal welfare considerations, but welfare may not be restricted to this. How the animal behaves may also indicate if it is in a better or a worse condition. Thus, a healthy and productive animal or even an animal that is feeding well may be in a poor welfare condition if it is, for example, expressing some stereotypic behaviour. Stereotypies are defined as a series of movements regularly repeated with no apparent purpose or goal , probably induced by frustration, repeated attempts to cope and/or brain dysfunction.
Caroline Marques Maia