Histological and physical-mechanical characteristics of the skin of Dorper sheep related to residual feed intake and the confinement environment.

The aim was to evaluate the effect of residual feed intake (RFI) on the histological, physical and mechanical characteristics of the sheep skin confined in full sun or shade. Dorper sheep (n = 64), male, with an initial bodyweight of 17.8 ± 2.43 kg was confined for 40 days to determine the RFI. After classification, 30 animals with positive RFI and 30 animals with negative RFI were selected, which were distributed in 2 confinement environments. This was a factorial arrangement of 2 (groups of animals-positive RFI and negative RFI) × 2 (environments-full sun and shade), with 15 animals for each combination of factors. The sheep remained in confinement for 60 days. After slaughter, skins were divided in half, and fragments were collected from the right portion for histological sections. The left part of each skin was subjected to tanning. Interaction effect RFI × environment was found in the evaluation of leather fragments in the horizontal direction on elongation at break, leather thickness and tear strength (p < 0.05). An isolated effect of the environment was found on elongation at break of leather fragments in the evaluation on the vertical direction (p = 0.01) and on the number of secondary follicles during the histological evaluation of the dorsal and lateral regions of the skin (p < 0.05). An effect of the interaction RFI × environment was observed for the thermostatic layer of the hip region (p = 0.03). Sheep with positive RFI and kept in confinement in full sun have a leather with greater elongation at break and tear strength, important aspects in determining the quality of the product by the leather industry.