Biological factors influencing the nature of goat skins and leather
The effect of a goat’s sex, age, slaughter weight and nutrition on its skin and leather quality were investigated through chemical, biochemical, histological and hydrothermal analyses of dried skins, and physical testing of leathers. This work formed part of a larger project sponsored by the Natural Resources Institute, who provided the Brazilian goat skin raw materials. The basic chemical constituents (moisture, fat and nitrogen) of skins were influenced by both the age and sex of the animal. Their effect on the biochemical components (GAG and collagen contents) were less defined and probably a reflection of the early maturing nature of these components in the skin. Under different nutritional conditions only the fat content of skins varied significantly, being higher in skins of animals on a high plane of nutrition. The GAG contents of low nutritional skins were slightly higher than the corresponding high nutritional skins. A positive correlation between the slaughter weight of animals and GAG content of the skins was found. The weight, age, sex and nutritional conditions all influenced the thickness of the skin. The main influences were the slaughter weight (linked to age and nutrition) and the sex of the animal. The increase in thickness predominantly occurred in the corium layer of the skin. Differences in corium fibre structure, in particular the compactness and angle of weave, were related to skin thickness. Physical properties of the leathers were directly related to the thickness of the skin (and weight), grain to corium ratios and corium collagen structure. The leathers became stronger and gave lower distentions with increasing age and nutritional stress. The physical properties of the leathers were also linked to the sex of the animal. The strongest leathers were obtained from male animals. Softness of leathers was infuenced by the sex of the animal and slaughter weight
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