Biomedical Engineering Reference
In-Depth Information
12%
Pulmonary surface
evaporation
Skin evaporation
88%
Fig. 3
Relative contribution of sweating and pulmonary evaporative losses in buffaloes (Aggarwal and Upadhyay
1998
)
Colditz
1975
; Krishana et al.
1975
; Saxena and
Joshi
1980
; Daniel et al.
1981
) . In buffaloes' body,
the water vaporisation loss was 6 and 18 kg/day
(Raghavan and Mullick
1961
) or 5.3 and 19.2 L/
day (Ghosh et al.
1980
), during winter and sum-
mer, respectively; Raghavan and Mullick (
1961
)
also stated that cattle lost similar amounts
although they drank much less water. In Jersey,
Brown Swiss and Holstein heifers, water vapori-
sation increased from 4 to 14 L/day when envi-
ronmental temperature increased from 15.0 to
35.0°C (Kamal et al.
1962
) . Water losses from
the skin increase sharply. Evaporative loss through
pulmonary surface and through skin in indigenous
and crossbred cows has been shown in Fig.
4
(Aggarwal and Upadhyay
1998
) . Skin vaporisation
accounts for 16-26% of the dissipation of body
heat at air temperature of 10°C and from 40 to 60%
at 27°C and over 80% at air temperatures above
38°C, in cattle (Roubicek
1969
) . Skin water loss
was found to be negatively correlated with skin
temperature and rectal temperature (Aggarwal
and Upadhyay
1998
) . Water losses through the
lungs increase gradually as ambient temperature
increases. Pulmonary surface evaporative loss of
buffaloes was 64.5 ± 4.1 g/m
2
/h before exposure to
direct solar radiation, and increased by 98% after
4 h of exposure (Aggarwal and Upadhyay
1998
).
Respiratory vaporisation as g/h/kg body weight
increased from 0.13 to 0.22 in Brahman, from 0.17
to 0.38 in Santa Gertrudis and from 0.28 to 0.42 in
Shorthorn, when environmental temperature
increased from 20.6 to 37.8°C, respectively
(Kibler and Yeck
1959
). In lactating Holstein cows,
significant increase in respiratory vaporisation was
recorded with rising air temperature (Kibler et al.
1965
) . Kibler et al. (
1962
) reported breed differ-
ences in respiratory vaporisation. Concerning
the effect of relative humidity at high ambient
temperature on respiratory vaporisation, Kibler
and Brody (
1953
) reported that respiratory vapori-
sation decreased with rising relative humidity at
high ambient temperature. Particularly, the buffalo
calf showed little or no evaporative heat loss, and
all internal temperatures were the same and rose
progressively with time, when high environmental
temperature was accompanied by high relative
humidity. The buffalo calf has shown little or no
evaporative heat loss with no changes in internal
temperatures; however, temperature increased
progressively with time at high environmental
temperature and relative humidity.
At high environmental temperature and low
relative humidity, some evaporation of water from
the mucosa occurs during inspiration and helps in
cooling the mucosa. Air humidity governs the
evaporative cooling of the mucosa and deter-
mines the extent of water regain by condensation
