Table 1.

Broom’s [21] five factors illustrating where control, or lack of it, may impact animal welfare.

Factor	Description
1. Difficulties in movements	Environment features that restrict ability to move normally or adopt normal postures or positions.
2. Frustration	Animals knowing how to exercise controlled interactions with their environment, but being thwarted from performing them in a normal way.
3. Absence of specific input	Absence of essential stimuli.
4. Insufficient stimulation	Thwarted innate psychological and behavioral needs for stimuli in a low complexity environment—or sensory deprivation.
5. Overstimulation	Overload of stimuli.