An Analysis of Growth Processes in Cattle Coats and their Relations to Coat Type and Body Weight Gain

Abstract

Hair regrown on a clipped patch of skin during each of nine intervals covering a period of 13 months was sampled, counted, and measured. Methods of estimating the rate of appearance of new hairs, the proportion of follicles with growing hairs, the duration of growing and resting phases of follicles, and linear growth rate of hairs are described. Results obtained from 70 animals are presented. Seasonal changes in the various parameters, and their roles in producing seasonal changes in coat type, are analysed and discussed. Replacement of hairs occurred continuously and amounted to slightly more than two hairs per follicle per year; rates of replacement were highest in spring and in summer. The number of growing hairs and the time for which each hair grew were much lower in summer than in autumn.