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More than just skin deep
By Richard York
One of the most important selection criteria that
needs to be considered in wildebeest, as well as
other game, is the colour of the hair and skin. An
antelope’s skin refers to the whole area that covers
its body and which is covered in hair. It is also the
biggest organ in its body and comprises approximately 7 to 8% of
the animal’s live mass.
The skin is the shield between the antelope’s body and the
external environment. Thus the efficient functioning of this organ
is of vital importance when the animal has to adapt to the
circumstances to which he is exposed. The condition of the hair
is also a direct reflection of the condition of the animal, and it
indicates whether its hormone balance and nutritional status are
in a good state.
Buffalo with their dark skins rest in the shade for most of the day in order to
avoid sunlight. (Photograph by Richard York)
A heat regulator
Another special characteristic of the skin is that it is the most
important heat regulator of the animal. Wildebeest are warmblooded,
and the speed and efficiency with which several mechanisms
are implemented to neutralise the stress caused by heat
and cold, is also an indication of the animal’s adaptability.
Heat is released in the body on a continuous basis due to physiological
and metabolic processes. The body needs to get rid of
heat continuously in order to prevent an excessive increase in
body temperature. The animal gets rid of heat through the following
methods:
• Radiation, conduction and convection.
• Vaporisation of water from the skin and respiratory passages.
• Excretion of faeces and urine.
Sunlight’s enormous influence
Radiation from the sun is intense in tropical areas and consists of
rays in three different wavelengths:
• Long wavelength – infrared or heat rays.
• Medium wavelength – colours of the rainbow for which the
eyes are very sensitive.
• Shortwave or ultraviolet rays – invisible to the naked eye.
It was found that the colour and hair type of an antelope have
a direct influence on the efficiency of the reflection of both the
infrared and light rays.
Professor Jan Bonsma compiled a test to determine the reflection
ability of Afrikaner cattle with different skin colours. Cream,
light yellow, golden, light red, red and dark red skin colours were
used in the test. It was clear from the tests that the lighter the animal’s
skin colour, the more efficient its ability to reflect sunlight.
More studies by Bonsma in the Mussina district showed that
the influence of sunlight on a black cow during an 8,5-hour day
is enough to boil 13 litres of water. Except for the heat generated
A herd of wildebeest in the sunlight. (Photograph by Tamlyn Smith)
by metabolic energy, animals must also get rid of an enormous
amount of sun energy to maintain thermal equilibrium in a tropical
environment. Therefore buffalo which have a dark skin colour,
must spend many hours during the day in deep shade and will
rather graze and wallow in mud holes late in the evening, at night
or during the early of the morning.
Luckily the shortwave ultraviolet rays that cause cancer are
reflected effectively by yellow, brown and black skin colours. It is
therefore clear that a pigmented, light-coloured skin is the ideal
combination to protect an animal against high temperatures and
intense radiation.
Golden Breeders believes it is not a coincidence that these
highly adaptable colour variations of blue wildebeest occur naturally
under the free-roaming wildebeest of the Limpopo River
catchment area. The vegetation of this area is described as semisweet
bushveld – one step away from the Kalahari desert, and it
is one of the hottest, driest areas in South Africa.
Golden Breeders believes that the golden wildebeest is proof
that we are spectators of the process of evolution. Golden wildebeest
are well adapted to resist climate change in an increasingly
warmer and drier South Africa.
(Adapted from the Golden Wildebeest Manual compiled by Golden
Breeders.) SB
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