Number of sweat glands per unit area of skin, their size, and their depth below the epidermis were compared in skin biopsy specimens obtained from the midside region of two Zebu and three European breeds of dairy cattle. Within Zebu breeds, comparisons were made between sweat glands from the midside and the dewlap. Zebus were found to have much larger and more numerous sweat glands than European animals. Within Zebus, sweat glands were slightly larger, and much more numerous, on the midside than on the dewlap. They are much closer to the skin surface in Zebu cattle than in European. In Zebus sweat glands are longer and of greater diameter than in European cattle. In appearance they are sac-like, with few convolutions, whereas sweat glands in European cattle are rarely sac-like, and quite convoluted.
Measurements were made on the skins of 1363 cattle from different European breeds. The mean values of these measurements have been tabulated for each breed and the skin types present in each breed or group of breeds have been determined using sweat gland shape (LID) and hair follicle depth (FrY) as the principal bases of comparison.Two extreme skin types, I, with an LID < 8·0 and F D < 1· 5 mm, and II, with an LID> 12·0 and F D > 2·0 mm, were distinguished. Type I was found in almost all the cattle in the Jersey breed while type II was present in relatively high proportion in the Scottish Highland breed. Varying proportions of animals with these types and others with intermediate skin types were found in the other European breeds. About 0·5% of the cattle population studied exhibited "follicle giantism" which was characterized by a low hair follicle density, long thick hairs, and large sweat glands. No simple relationship between skin type and habitat was found.
A relatively simple technique for measuring the size of apocrine glands in biopsy cattle-skin sections was shown to be reliable. Duplicate skin samples were compared and the repeatability of the sweat gland size measurements found to be 81.0 per cent., and that of density 95 per cent. There were highly significant differences in sweat gland size between strains of cattle, and between cattle within strains.
Observations were made of a number of skin characters in five breeds of European (Bos taurus L.) dairy cattle. Skin samples were taken from the cattle in January and July. There were differences between breeds in sweat gland volume and length! diameter ratio, in skin and papillary layer thickness, in the ratio skin thickness/papillary layer thickness, and in the degree of shrinkage in transverse sections cut from the papillary layer. There were no differences between breeds in density of follicle population (and hence sweat glands) per unit area of skin. Sweat gland volume, skin thickness, and papillary layer thickness were larger in winter than in summer, but there were no such differences for sweat gland length/ diameter ratio, the ratio skin thickness/papillary layer thickness, and follicle population density. The only significant overall correlations between characters were those between sweat gland volume and sweat gland length/diameter ratio, and sweat gland volume and papillary layer depth.
On three occasions during the period l91S-1956 field observations were made on coat shedding in B. indicus, B. taurus, and B. indicus x B. taurus cattle, and hair and skin samples taken. Measurements of hair length, diameter, and weight per unit area of skin were made, and stages of hair growth within the follicle observed. On two occasions hair data included measurements of length and diameter on individual hairs. Two shedding periods were observed. in spring and in autumn. Approximately 4 months was required for the complete change from m-inter to summer coat, the change in appearance being dramatic. Less time was required for autumn shedding and there was a less dramatic change in the appearance of the coat. Histological data from skin samples supported these observations and showed that during shedding almost all mature hairs were lost from the skin follicles. All types of cattle had characteristically short, light summer coats and long, heavy winter coats. No difference in hair diameter was observed between summer and winter coats in B. taurus, but in B. indicus hair diameter was much greater in the summer coat. In all seasons 01 the year B. indicus had the shorter and lighter coats. The minter coat in long-coated B. tauws did not appear to hare an undercoat, whereas short-coated B. taurus and B, indicus had distinct undercoats. In B. indicus x B. taurus F1 crossbreds coats were as'short in summer as those of B. indicus, and as long in winter as those of B. taurus. Differences between species in shedding, and in coat characteristics at different seasons of the year, may be of ecological importance.
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