Accession Number : AD0649519

Title :   THERMOREGULATORY FUNCTION OF THE HORNS OF THE FAMILY BOVIDAE.

Descriptive Note : Rept., for May 62-May 63,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS

Personal Author(s) : Taylor,Charles R.

Report Date : DEC 1966

Pagination or Media Count : 111

Abstract : The thermoregulatory function of Bovid horns was investigated, using domestic goats because of their availability and adaptability to laboratory experiments. Goat horns have proper physiological control to be effective in thermoregulation. They vasodilate in response to heat stress, exercise and a blocking of their nerves, and vasoconstrict when the goat is placed in the cold. A typical goat at ambient temperature of 22C and in relatively still air can lose about 2% of its total heat production through the horn. Under simulated natural conditions, maximum heat losses from the horn occurred at a warm ambient temperature of about 30C with a low wind (about 3%), or with vasodilation as a result of running at low ambient temperatures of about 0C (3% while running and 12% after stopping, until horns were vasoconstricted). Possible heat loss from horns of members of the family Bovidae was calculated on the basis of data on goats. Attempt was made to correlate habitat and function of horns. In large desert species there appears to be a trend toward larger horns in both sexes, hence greater heat loss from horns. Three conclusions are drawn: The anatomy and physiology of Bovid horns are consistent with a thermoregulatory function; The morphology distribution, and function of horns are too complex to allow simple correlations; and a clear understanding of these relationships can only be obtained by a field study which encompasses all possible functions of the horns. (Author)

Descriptors :   *GOATS, HEAT PRODUCTION(BIOLOGY), ECOLOGY, ATMOSPHERIC TEMPERATURE, MORPHOLOGY(BIOLOGY), INTEGUMENTARY SYSTEM, BLOOD VESSELS, BLOOD CIRCULATION, CALORIMETRY, EXERCISE(PHYSIOLOGY), STRESS(PHYSIOLOGY), METABOLISM, BODY TEMPERATURE.

Subject Categories : Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE