Biomedical Engineering Reference
In-Depth Information
limitedly by sweating. Excessive work or expo-
sure causes a rise in body temperature, pulse rate
and respiration rate, and general discomfort
increases more quickly in buffaloes than those of
cattle. During a trial in Egypt, 2-h exposure to the
sun caused the temperature of the buffalo to rise
by 1.3°C, whereas temperatures of cattle rose by
only 0.2-0.3°C. In the shade, however, controlled
field studies on Egyptian buffaloes showed that
the thermoregulatory mechanism functions more
efficiently in buffaloes than in cattle, when the
speed of recovery from the effect of stress is
taken as a measure of efficiency (Mullick
1960
) .
Pandy and Roy (
1969
) con fi rmed these results in
their studies on the changes which are orderly
manifestations of various physiological adjust-
ments necessary for adaptation to higher environ-
mental temperature, that is, the seasonal changes
in body temperature, cardiorespiratory and hae-
matological characteristics, body water content
and electrolytic status of buffaloes under conven-
tional farm management.
Regarding the behavioural characteristics,
buffaloes prefer to wallow and cool off their body
in a pond rather than seek shade. They may wal-
low for whole day and remain immersed in water
or mud and chewing with half closed eyes. When
temperature and humidity are high, buffaloes
wallow or roll in mud during hot or even cool
periods, cold seasons. Artificial cooling also pro-
vides comfort to buffalo and alleviates body heat.
Ragab et al. (
1953
) reported that sprinkling adult
females for 2 h showed an average fall of 0.9°C
in body temperature. Cockrell (
1974
) added that
the body temperature of buffaloes in the hot sun
could only be kept normal by wallowing or by
quasi-continuous application of water, preferably
with an air draught or wind to dry it off. Titto
et al. (
1996
) reported that sprinkling young
female buffaloes for 15 min caused a quick
decrease in physiological parameters expressed
as high reduction in rectal temperature and respi-
ratory rate, and Ablas et al. (
2007
) concluded that
water for immersion or shade is an essential
benefit to buffaloes' production in warm climates.
This type of behaviour is more efficient than
keeping in low temperature housing, although an
artificial wallow becomes fouled by excreta
unless the water is continually flowing (Cockrell
1974
) . Experimental evidence has indicated that
for maintaining proper homeothermy, the buffalo
has to be provided with wallows or showers in the
summer months and be protected from cold during
the winter months preferably by housing them
(Aggarwal and Singh
2008
) . The wallowing was
found to be more beneficial than showers for alle-
viation of heat stress in lactating Murrah buffa-
loes. In wallow or in shade, buffaloes cool off
quickly, perhaps because the black skin, which is
rich in blood vessels, conducts and radiates heat
efficiently, but buffaloes cool off more quickly
than cattle in the shade. In Australia, Trinidad,
Florida, Malaysia and elsewhere, buffaloes grow
normally without wallowing as long as adequate
shade is available. In Egypt, buffaloes were raised
successfully without wallowing in a desert new
reclaimed land (Marai et al.
2009
) . Particularly,
buffaloes maintained only on shaded pastures of
silvopastoral systems have achieved gain of
weight of 0.911 kg/day in Brazil (Castro et al.
2008
). Such practices are beneficial due to the fact
that the use of sprinklers is expensive and water
consuming and become of utmost importance in
the areas which suffer from scarcity of water.
5
Thermoregulatory Mechanisms
Similar to other homeotherms, cattle regulate
their internal body temperature by dissipating the
heat produced due to metabolic activity in body
and maintain balance heat flow from the animal
to the surrounding environment. Heat flow occurs
through processes dependent on surrounding
temperature (sensible heat loss, i.e. conduction,
convection, radiation) and humidity (latent heat
loss, evaporation through sweating and panting).
The magnitude of sensible heat loss via conduc-
tion and convection is dependent on the surface
area per unit body weight, the magnitude of the
temperature gradient between the animal and the
air and the conductance of heat from the body
core to the skin and from the skin to the surround-
ing air. Heat exchange by radiation depends upon
surface area as well as the reflective properties of
the hair coat. Light-coloured hair coats and sleek
