FIGURE 1.

Visual description of the artificial rearing (AR) environment. This context includes individual pigs each housed in a dedicated cage with ad libitum access to fresh water and milk replacer and no competition for resources. Pigs are able to see, hear, and smell, but not directly touch, neighboring pigs through the clear, acrylic divider between cages on the same vertical level, as well as other pigs in adjacent caging units. Whereas, young pigs have difficulty with thermoregulation due to low body fat stores, the ambient AR environment is maintained at optimal temperatures and relatively humidity levels for each age of pig. Pigs raised in the AR environment are handled by human caretakers at least twice daily, which is why AR pigs appear less anxious relative to SR pigs when exposed to experimental procedures. Whereas, AR pigs are technically raised in their own space, their ability to engage with other pigs both in their home-cage and during daily communal activity periods mean they are not socially isolated and still receive attention from caregivers in the absence of natural maternal care.