Social Enrichment Improves Affective State and Foraging Behavior Compared to Physical Enrichment, While Maintaining Growth Performance in Broiler Chickens

Environmental enrichment is key for improving the broiler welfare in intensive production systems. This study lasted for 43 days and evaluated the effects of physical and social enrichment on broiler welfare. A total of 96 one-day-old male broilers were divided into two treatments: control treatment, provided with physical enrichment (<i>n</i> = 48) including perches, platforms, and straw bales; and social treatment (<i>n</i> = 48), involving regular positive interactions with a human. The behavioral repertoire, footpad health, taste preferences for sweet and umami compounds, affective states (through tonic immobility and attention bias tests), and growth performance were evaluated. No effects were found for feeding, drinking, locomotion, lying, or standing behaviors, although differences were observed at specific time points: the Social group had more feeding time on day 21 (<i>p</i> = 0.046), while physical treatment showed reductions on days 28 and 35 (<i>p</i> < 0.001). The Social group showed increased drinking on day 42 (<i>p</i> < 0.001), reduced locomotion (<i>p</i> = 0.022), and increased lying (<i>p</i> = 0.046) on day 42. Foraging was higher in the Social group (<i>p</i> = 0.027), but preening showed no differences. Footpad lesions showed no significant differences. The Control group preferred sucrose 100 mM (<i>p</i> = 0.022), but no preference for MSG 300 mM was observed. With regard to tonic immobility, the Control group showed a tendency towards larger durations (<i>p</i> = 0.078), indicating a potential increase in fearfulness. In the attention bias test, although the freezing behavior increased, the latency to begin feeding was shorter in the Social group (<i>p</i> < 0.001), suggesting an improved affective state. Lastly, no significant differences were observed for any of the growth parameters, including average daily feed intake, average daily gain, feed conversion ratio, or final body weight, indicating that the Social group maintained productivity. This approach provides a practical solution for improving the quality of life for broilers in intensive systems.