Comparison of the histology of the skin of the Windsnyer, Kolbroek and Large White pigs

The skin is a protective barrier, and an endocrine, sensory and thermoregulatory organ. We investigated whether the skin of local pigs had beneficial anatomical traits compared to exotic pigs to withstand the increased heat loads predicted under future climate change scenarios. Full-thickness skin specimens were obtained from the dorsal interscapular, lateral thoraco-abdominal and ventral abdominal regions of intact boars (age 6-8 months) of two local breeds of pigs (Windsnyer [n = 5] and Kolbroek [n = 4]) and an exotic pig breed (Large White [n = 7]). The skin sections were stained with a one-step Mallory-Heidenhain stain and Fontana stain (melanin). Sweat gland perimeter was measured using Image J software. The Windsnyer breed had the thinnest dermis layer while the Large White had the thickest dermis layer across all the three body regions (analysis of variance [ANOVA]; p < 0.001). The Windsnyers had widely spaced dermal pegs compared to the other breeds. The Windsnyers had significantly more superficial and larger (~1 mm depth; 4.4 mm perimeter) sweat glands than the Kolbroek (~3 mm depth; 2.2 mm perimeter) and Large White (~4 mm depth; 2.0 mm perimeter) pigs (ANOVA; p < 0.001). The Windsnyers had visibly more melanin in the basal layer, the Kolbroek pigs had very little and the Large Whites had none. The functionality of the sweat glands of the Windsnyer breed needs to be established. The skin from the Windsnyer breed possesses traits that may confer a protective advantage for the increased solar radiation and ambient temperatures predicted with climate change.