Table 2.

Proposed assessments for each proposed environmental enrichment (EE) classification using science-based indicators of animal welfare. Short-term refers to days, weeks or months depending on the species and long-term refers to the whole life or production cycle of the animal

Proposed EE classification	Welfare improvements	Welfare indicators
Environmental enrichment for meeting basic needs	Short-term improvements to biological functioning and health which may, or may not, be accompanied by short-term positive hedonistic experiences	Reduction in injuries & lameness Reduction in pre-clinical and clinical disease Improved biological functioning
Environmental enrichment for pleasure	Short-term positive hedonic experiences and long term sustained use Enrichment does not improve biological functioning. In some cases, there may be an increased risk to health (i.e. prevenance or severity of injury, disease or mortality).	Sustained use of enrichment Preference Strong motivation to access Secretion of neurotransmitters associated with positive affect (i.e. dopamine and opioids)
Environmental enrichment for positive welfare balance	Accumulation of positive hedonic experiences and reduction in negative affective experiences that result in a positive welfare balance and long-term welfare benefits beyond immediate survival	Stress resilience, increased flexibility and ability to adapt to challenge Positive moods (i.e. cognitive bias)