Growth performance and salivary cortisol levels did not significantly differ between the two housing systems. On the other hand, skin lesions and behaviors were significantly affected by the housing system. The number of skin lesions was higher in the indoor system. In addition, piglets in the outdoor system showed more investigative and social-play behaviors than those in the indoor system. Piglets in the indoor system showed more resting, drinking, moving, fighting, and conflict behaviors than those in the outdoor system.
We conclude that investigative, social-play and conflict behaviors may be effective indexes of the welfare level of piglets, especially investigative and conflict behaviors.
K. Nakamura, T. Tanaka, K. Nishida, K. Uetake. Behavioral indexes of piglet welfare: Comparison of indoor and outdoor housing systems. Animal Science Journal. 2011. Vol. 82 (1): 161-168.