Behavior of domestic pigs under near-natural forest conditions with ad libitum supplementary feeding

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Today's livestock agriculture faces major changes in domestic pig husbandry—besides animal health and productivity, aspects of animal welfare and animal-friendly husbandry systems for pigs increasingly gain attention. To get a basic and current overview of the behavior of pigs in a near-natural habitat, we studied two groups of 20 domestic fattening pigs kept in two free-range forest enclosures in southern Germany. The pigs had ad libitum access to supplementary concentrate feed (CF), green fodder (GF), water and shelters. During the 6-month observation period, we found that the pigs showed no biphasic activity rhythm. The activity phase began at ca. 05:15 and ended at 21:00 in summer, and it shortened in winter. The peak of activity was between 14:00 and 18:00. The individual behaviors were assessed on 16 observation days during three direct-observation-intervals each (morning: 08:00 to 10:00; midday: 12:00 to 14:00; evening: 16:00 to 18:00). In the course of a day, some of the occurring behaviors such as rooting and locomotion continually increased from morning to evening. In contrast, resting occurred the least in the evening. Feed and water uptake were observed without noticeable influence of the daytime during the entire daylight period. Despite ad libitum availability of CF and GF at the feeding place, the pigs spent only about 13% of the observation time eating (including food uptake in the forest), with the total time and average duration being greater for GF than for CF uptake. Furthermore, the pigs spent about 24% of the time rooting. Thus, rooting seems to be an essential behavior of domestic pigs without the primary motivation of hunger. Resting made up 47% of the total observation time. The remaining 16% of the observation time was spent with several short-lasting active behaviors, such as interacting with the environment, locomotion, playing and comfort behavior. Based on the results of our study, we provide recommendations for adequate management practices in modern, animal-friendly pig stalls and free-range enclosures.