Collagen deposition, crypt morphology, and inflammatory histology in porcine colons across β-agonist-free, hygienic, and natural farming regimens

Swine farming practices significantly influence intestinal health, particularly collagen deposition and inflammatory responses in the colon. This study aimed to investigate the effects of three farming systems including β-agonist-free, hygienic, and natural swine production on histological morphology, collagen distribution, crypt architecture and inflammatory cell infiltration in the colons of four-month-old female pigs (Sus domesticus). Colon samples (proximal, middle, and distal segments) were collected and analyzed histologically by using Masson's Trichrome staining. Measurements included the total layer dimension of the colonic wall, collagen area, crypt length, crypt surface opening diameter, crypt distortion, and inflammatory cell count. Results revealed that natural swine exhibited the lowest total wall dimension of the colon (p < 0.01, all) while demonstrating the highest collagen content across all three layers, particularly in the mucosal and muscularis layers (p < 0.05, all). Notably, natural swine showed significantly less crypt shortening, smaller crypt surface openings, fewest distorted crypts (p < 0.0001, all), and the lowest number of inflammatory cells (p < 0.05, all) in the mucosal layer compared among groups. These findings suggest that natural swine farming practices may maintain connective tissue integrity through enhanced collagen deposition while reducing intestinal inflammation in the colon. These results also indicate a favorable gut environment and improved gastrointestinal health of these swine, providing insights for optimizing animal welfare through sustainable farming methods.