230. Effects of Indoor and Outdoor Rearing Systems on Carcass Characteristics, Meat Quality, and Muscle Composition of Duroc Pigs.

Abstract The objective of this study was to evaluate the impact of conventional indoor confinement (IN) versus an outdoor free-range system (OUT) on the carcass traits, meat quality, and longissimus dorsi (LD) muscle composition of pigs. Twenty-four Duroc pigs (approximately 3 months of age) were randomly assigned to either IN (n = 12) or OUT (n = 12) systems for a 45-day trial. All pigs were fed the identical commercial corn-soybean diet ad libitum. Post-slaughter, carcass measurements were recorded, and LD muscle samples (10th to 12th ribs) were collected for meat quality and chemical analysis. Data were analyzed using an independent samples t-test. The rearing system had no significant effects (P > 0.05) on final body weight, hot carcass weight, hot carcass percentage, backfat thickness, or carcass length. However, meat quality evaluation revealed that pigs in the OUT group exhibited significantly higher (P < 0.05) redness (a*) and cooking loss compared to the IN group, while pH at 24 h postmortem, lightness (L*), yellowness (b*), and puncture force remained unaffected (P > 0.05). Chemical analysis demonstrated that OUT pigs had lower (P < 0.05) intramuscular fat content (10.05% vs. 11.32%) than IN pigs, with no differences in moisture, protein, or solid contents. Furthermore, outdoor rearing significantly decreased (P < 0.05) muscle sodium (Na) concentration and tended to increase (P = 0.078) phosphorus (P) content, while other evaluated minerals (Ca, K, Mg, Cu, Fe, Mn, Zn) were not altered. In conclusion, while outdoor rearing does not impact overall carcass yield, it alters meat quality by enhancing redness, reducing intramuscular fat and sodium content, and increasing cooking loss, indicating a shift in chemical profiles that may influence consumer visual preference and water-holding capacity.