Following implementation of the UK Animal Procedures Scientific Act (1986) there has been a plethora of research combining endocrine titres with behavioural measures to address applied questions in the field of animal welfare science. The goal of these studies has been to measure and optimize animal welfare. An eloquent example is the reduced welfare observed in collared peccaries (Pecari tajacu) as indicated by high glucocorticoid (GC) levels and negative judgment bias in behavioural tests. The latter is associated with space restriction but alleviated by the provision of enrichment. Good animal welfare is essential not only from an ethical standpoint but also to ensure valid scientific outcomes. Animals with good welfare produce more reliable, biologically valid, robust, repeatable scientific data compared to their counterparts with poorer welfare. ‘Happy’ animals live longer, can be used repeatedly and need replacing less often. This leads to a ‘reduction’ of animal use and satisfaction of one of the 3Rs: the guiding principles for the use of animals in research2
