Effects of intelligent sorting system for fattening pigs on pig behavior and production performance

The Intelligent Sorting System has been increasingly applied in modern large-scale pig farming, with functions including enhancing slaughter weight uniformity, reducing the labor intensity of manual grouping, and minimizing the stress responses of pigs during management. Despite its growing adoption, systematic evaluations of its effects on both behavior and production performance of fattening pigs remain limited. Therefore, this study aimed to comprehensively assess the impact of the Intelligent Sorting System by comparing traditional small-group feeding with large-group feeding supported by this system, through two independent but complementary experiments.In the behavior experiment, two treatments were established: a control group with traditional small-group feeding (6 pigs per pen, 4 pens in total) and an experimental group with the Intelligent Sorting System (60 pigs per pen, 1 pen). On days 3, 35, and 75 of the experiment, cameras were installed above the pens to continuously record 24-hour behavioral videos. The frequency and duration of feeding, drinking, defecating, urinating, and fighting behaviors were analyzed using a combination of continuous manual observation and video playback. These behavioral data were then processed into group-based averages per pig, allowing for comparison across experimental treatments.In the production performance experiment, the control group consisted of 7 pigs per pen across 8 pens, while the experimental group had 63 pigs in a single pen supported by the Intelligent Sorting System. The experimental period, initial weight, final weight, and feed intake of pigs were recorded. Based on these data, average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), and slaughter weight uniformity were calculated to evaluate the influence of the Intelligent Sorting System on growth performance.The results demonstrated clear advantages of the Intelligent Sorting System. In terms of behavior, the feeding duration of the experimental group decreased by 45.1% compared with the control group, indicating that the system substantially reduced ineffective or redundant feeding behaviors and improved feeding efficiency. Fighting behavior, a key indicator of social stress, was also greatly reduced: fighting duration decreased by 75.1% and fighting frequency by 68.0% compared with the control group. This shows that the system can effectively mitigate aggressive competition and improve group social stability.Regarding excretion, the proportion of defecation and urination on slatted floors in the experimental group decreased by 16.4% and 24.9% respectively. At the same time, the behavioral frequencies per square meter of slatted floor increased by 7.1 and 13.9 events, suggesting that pigs maintained a preference for slatted floor excretion, and that the excretory behaviors were more concentrated per unit area, although the relative proportion of slatted area was insufficient, highlighting the need for further optimization of functional area allocation in pen design.In terms of production performance, although the experimental group had a slightly lower average daily feed intake, its average daily gain was higher, and the feed conversion ratio decreased by 10.1% compared with the control group. Furthermore, slaughter weight uniformity improved by 18.8 percentage points, demonstrating that the system can reduce growth variability within the group. This indicates that the Intelligent Sorting System not only enhances individual growth efficiency but also contributes to more uniform market-ready pigs, which is of great economic importance for commercial farms.In conclusion, the Intelligent Sorting System shows significant potential for improving both behavioral efficiency and production performance of fattening pigs. By reducing stress-related behaviors such as fighting, optimizing feeding efficiency, and increasing slaughter weight uniformity, the system supports welfare-oriented precision pig farming practices. As a modern technology for livestock management, it offers a feasible pathway toward sustainable, efficient, and animal-friendly production systems. Future studies should focus on refining the design and spatial layout of functional areas within the system to further improve its effectiveness and to validate its long-term impact under different housing and management conditions.