| Abstrakt: |
Context. Concerning the epithelial tissue in the skin, including hair, vitamin A is required for the integrity of epithelial cells, strengthened by compounding keratin fibres. Further, the complex hormonal changes seen in pregnancy may contribute to the hair growth. Thus, the structure of the cattle coat hair may change depending on the conditions of vitamin A deficiency or pregnancy. Aims. The effects of several diseases, i.e. vitamin A deficiency, pneumonia, chronic pneumonia, and chronic renal failure, or pregnancy, on the structure of the coat hair were investigated. Methods. Physical properties of the coat hair, collected from Japanese black cattle (Bos Taurus) and Holstein cows (Bos taurus Taurus), were investigated to study the effects of vitamin A deficiency, other diseases, or pregnancy on the formation of hair. Key results. When vitamin A concentration was lowered to about half of the minimum concentration for vitamin A adequacy of 20 µg/dL in plasma (i.e. deficiency level was high), we could perceive the interference in the self-assembly of the keratin fibrils. However, we also confirmed structural modifications of the keratin fibres obtained from the cattle suffering chronic renal failure. The coat hair collected from the pregnant cows tended to show superior tensile strengths to those of the hair from the non-pregnant ones when compared at the same diameter level, although pregnancy might have increased cortisol affecting the hair follicle function. Further, from the X-ray diffraction measurements, the non-pregnant cow coat hairs, having exhibited the inferior tensile properties, were found to be structurally modified. Conclusions. The structure of the coat hair could be modified when the vitamin A concentration was severely reduced (vitamin A deficiency). The physiological conditions during pregnancy may be advantageous to serve the regular formation of the hair. Implications. Hair has a function serving as a proxy of health status for a certain period of animal life. [ABSTRACT FROM AUTHOR] |
