Influence of Specific Acoustic Parameters on Responses in Growing Pigs: Towards a Precision Auditory Enrichment...

Improving animal welfare through standardized management protocols remains a key challenge in intensive pig production. Auditory enrichment, such as music, represents a promising non-invasive strategy, yet its application is often empirical, lacking mechanistic understanding and objective assessment tools. This study investigated growing pigs' active preferences for structured musical parameters to establish a precision auditory enrichment framework. Seventy-two crossbred pigs were subjected to a free-choice paradigm under simulated farm conditions, with a 2 × 2 factorial design manipulating musical stimulus type (a guqin string piece vs. a Mozart wind excerpt) and tempo (fast: 200 bpm vs. slow: 65 bpm) was continuously quantified using an enhanced YOLOv11-based automated recognition system (mean average precision mAP₅₀: 90.5% ± 1.5%). Results revealed highly parameter-dependent effects: the slow-tempo GS stimulus and the fast-tempo MF stimulus significantly prolonged occupancy time (p < 0.01) and elicited distinct profiles. The GS stimulus promoted a calm, investigative state, increasing lying, exploration, and drinking time (p < 0.05), while the MF stimulus stimulated an active playful state, characterized by increased walking and playing (p < 0.05). Other musical combinations showed negligible effects, whereas noise exposure consistently triggered stress-related responses. This study establishes an integrated "parametric design → automated assessment → specific output" methodology for precision auditory enrichment, providing an empirical basis for evidence-based acoustic protocols in commercial pig production.