ARS | Publication request: Effects of level and length of supplementation on leather characteristics of yearling boer and spanish wethers

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2013
Publication Date: N/A

Interpretive Summary: USDA scientists collaborated with the American Institute for Goat Research of Langston University (AIGR) to establish a pilot tannery for the production of goatskin leather using ERRC’s expertise. Some of ERRC’s developed technologies are being transferred to AIGR. Research showed that tanning goat skins using chromium resulted in stronger leather than leather produced using glutaraldehyde as the base tanning agent, perhaps due to the inner structural differences of the tannage. Age effects on decreasing stretch ability (% elongation) and increasing stiffness are similar to results seen in the literature. Dietary supplementation effects were found of lesser importance than applied tannage or age of goat. Boer goat leather was thicker than Spanish wethers leather although tensile strength was unaffected by breed. Goat skins were not shaved to an equal thickness during the tanning process, perhaps leading to some of the breed differences seen. Further research is needed to evaluate characteristics of shaved skins. Results from this collaboration will positively impact U.S. tanneries and goat producers, who are mainly small farmers of minority and underserved populations, by increasing the use of U.S. goatskins domestically and increasing revenue for the goat and leather industries.

Technical Abstract: Thirty 7/8 Boer × 1/8 Spanish (B) and 29 Spanish (S) wethers were used in a trial with 110 (P1) and 108 d (P2) periods. Six B and 5 S were harvested at the beginning of the trial. The remaining animals were assigned to 4 groups, each having 6 B and 6 S, raised on pasture with unlimited access to hay and receiving daily 0.5% or 1.5% BW of a pelleted diet. One H and 1 L group were harvested after P1 and P2. Skins were removed by hand, split down the dorsal midline, and salted. The left half of each skin was chrome-tanned (CT) and the right half was tanned using a glutaraldehyde based tannage (GT). Boer goats were heavier than S goats at the start of the trial (P < 0.05) and at subsequent harvests (P < 0.001). Wethers supplemented at 1.5% body weight (BW) weighed more and had heavier fresh skin weights than those supplemented at 0.5% BW (P < 0.05). Boer goat leather was thicker than S goat leather and goats supplemented at 1.5% BW had thicker skins than those fed at 0.5% BW (P < 0.05). GT leather was thicker than CT leather (P < 0.001) but CT leather had greater fracture energy and tensile strength than GT leather (P < 0.05). Boer goat leather had greater % elongation than S leather (P < 0.01) and % elongation was lower in P2 than P1 (P < 0.001). Leather from S goats harvested initially had greater Young’s modulus than B goat leather (P < 0.05); however, no breed difference was seen in leather after P1 or P2 (P = 0.78). In summary, tanning goat skins using chromium resulted in stronger leather than that produced using glutaraldehyde; increasing age led to decreased % elongation and increased stiffness; supplementation effects were of lesser importance than tannage or age; and Boer goat leather was thicker than S leather although tensile strength was unaffected by breed. Goat skins were not shaved to an equal thickness during the tanning process, perhaps leading to some of the breed differences seen, notably in % elongation and fracture energy. Therefore, further research is needed to evaluate characteristics of shaved skins.