Seasonal changes in coat characters in cattle.

Summary Evidence is presented to show that marked seasonal alteration in the appearance of the coat in cattle is due to morphological variation in fibre characters. The profound influence that seasonal coat changes may have on body temperature regulation is discussed. Cattle go through a regular seasonal cycle of hair growth and shedding, which is presumably adapted to the climate prevailing in their habitat, and which has been shown by Yeates (1955) to be influenced by light in Shorthorns. There is reason to believe that the process of shedding can also be influenced by other things such as the nature of the food supply and the condition of the animal. Hammond (1949) reports distinctive breed differences in cattle coats and within breeds the hair coat differs in appearance according to the seasonal change. Differences in appearance of the coat are due to changes in the hair fibres of which it is composed, but no accurate objective measurements of the variation of hair fibre characters with season have been published. Reported work refers to the coat covering in more general subjective terms. Observations were therefore collected. on the way coat characters vary in Bos indicus and Bos taurus species of cattle under different circumstances.