Production system-associated hepatic histomorphometric adaptations in swine: Comparative analysis of glycogen...

Swine production systems differ considerably in housing, nutrition, biosecurity, and environmental exposure, all of which may influence hepatic metabolism, immune function, and tissue architecture. Histological indicators such as hepatic glycogen deposition, Kupffer cell abundance, and sinusoid-hepatic cord organization provide valuable insight into physiological adaptations associated with different management practices. However, comparative information on these hepatic characteristics across commercial swine production systems remains limited. This study aimed to compare hepatic glycogen accumulation, Kupffer cell abundance, and hepatic microarchitecture among clinically healthy swine raised under beta-agonist-free, hygienic, and natural production systems in Thailand.

A cross-sectional comparative histomorphometric study was conducted using liver tissues collected from 30 clinically healthy market weight commercial crossbred swine (10 animals per production system). Liver samples were fixed in neutral buffered formalin, processed routinely, and stained using the periodic acid-Schiff method. Histomorphometric analyses included quantification of periodic acid-Schiff-positive glycogen area, zone-specific glycogen distribution within hepatic lobules, glycogen-positive hepatocyte counts, Kupffer cell counts, and the hepatic sinusoid-to-hepatic cord area ratio using digital image analysis. Data were analyzed using one-way analysis of variance followed by Tukey's multiple-comparison test, with statistical significance established at p < 0.05.

Significant production system-associated differences were observed in all major histomorphometric parameters. Beta-agonist-free swine exhibited the greatest hepatic glycogen deposition (34.23 ± 2.74%) and the highest glycogen-positive hepatocyte counts (167.85 ± 12.97 cells/area), followed by natural and hygienic swine (p < 0.05). Zone-specific analysis demonstrated significantly greater glycogen accumulation across periportal, midzonal, and pericentral regions in beta-agonist-free animals. In contrast, natural swine showed significantly higher Kupffer cell abundance (3.97 ± 0.93 cells/area) and a greater hepatic sinusoid-to-hepatic cord area ratio (0.84 ± 0.14) than beta-agonist-free swine (p < 0.05), indicating enhanced hepatic immune surveillance and subtle microarchitectural remodeling. No histopathological lesions, including hepatocellular degeneration, necrosis, or inflammatory infiltration, were observed in any group.

Different commercial swine production systems were associated with distinct hepatic histomorphometric adaptations. Beta-agonist-free production favored greater hepatic glycogen storage, whereas natural production was characterized by increased Kupffer cell abundance and expanded sinusoidal architecture, suggesting differences in hepatic metabolic status and immune microenvironment. These findings provide novel comparative evidence that husbandry practices influence liver structure in commercial swine and establish baseline histological data that may support future investigations into animal welfare, sustainable livestock production, and hepatic health assessment.