Photoperiodicity in cattle. II. The equatorial light environment and its effect on the coat of European cattle

Abstract

Thirteen European cattle have been maintained for periods of up to 21 months in a light environment artificially adjusted to provide 12 hr 50 min of light daily, so simulating the equatorial photoperiod. The initial coat reaction of several groups of these animals differed according to the season in which they entered the experiment. Thus transfers in the spring and autumn were followed by complete shedding; those in winter by a rapid partial shed; and those in the summer by rapid growth of hair. On adaptation to the new environment, however, all the groups eventually grew, and thereafter permanently maintained, a similar coat, characterized by intermediate length and furry appearance. The experiments show that the equatorial photoperiod eliminates the natural coat cycle of European cattle, and that it tends to maintain them in a heat-retaining type of coat.