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Impact of Hair Color on Thermoregulation of Dairy Cows to Direct Sunlight

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The effects of hair coat color on the thermoregulatory responses of heat-stressed cows exposed to direct solar radiation were observed. During August 2000, three white and three black lactating Holstein cows in Hawaii were exposed to 1.5 hr of sunlight for four trials in the morning and four trials in the afternoon with or without spray cooling. Solar radiation ranged between 495 and 971 watts/m 2 and THI ranged between 78 and 81 during the experimental trials. Cows with white hair coat absorb about 66% of the short wave radiation, while cows with black hair coat absorb about 89% of the short-wave radiation. Placing the cows under direct sunlight increased the surface temperature of the black cows by 4.8°C and the white cows by 0.7°C. Rectal temperatures of black cows increased 1.3°C/hr, while the rectal temperatures of white cows increased 0.8°C/hr. Increasing solar load on the skin surface increases the local rate of sweating. Spray wetting alone is not sufficient to cool cows exposed to high solar loads.
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This is not a peer-reviewed paper.
Paper Number 014031
An ASAE Meeting Presentation
Impact of Hair Color on Thermoregulation OF Dairy
Cows to Direct Sunlight
P. E. Hillman , Senior Lecturer
Biological and Environmental Engineering, Cornell University, , Ithaca,
NY 14853
C. N. Lee , Professor
Animal Sciences, University of Hawaii at Manoa, , Honolulu, Hawaii
96822
J. R. Carpenter , Associate Professor
Animal Sciences, University of Hawaii at Manoa, , Honolulu, Hawaii
96822
K. S. Baek , Postdoc
Animal Sciences, University of Hawaii at Manoa, , Honolulu, Hawaii
96822
A. Parkhurst , Professor
Biometry, University of Nebraska, , Lincoln, NE 68583
Written for presentation at the
2001 ASAE Annual International Meeting
Sponsored by ASAE
Sacramento Convention Center
Sacramento, California, USA
July 30-August 1, 2001
Summary:The effects of hair coat color on the thermoregulatory responses of heat-stressed cows
exposed to direct solar radiation were observed. During August 2000, three white and three black
lactating Holstein cows in Hawaii were exposed to 1.5 hr of sunlight for four trials in the
morning and four trials in the afternoon with or without spray cooling. Solar radiation ranged
between 495 and 971 watts/m 2 and THI ranged between 78 and 81 during the experimental
trials. Cows with white hair coat absorb about 66% of the short wave radiation, while cows with
black hair coat absorb about 89% of the short-wave radiation. Placing the cows under direct
sunlight increased the surface temperature of the black cows by 4.8°C and the white cows by
0.7°C. Rectal temperatures of black cows increased 1.3°C/hr, while the rectal temperatures of
white cows increased 0.8°C/hr. Increasing solar load on the skin surface increases the local rate
of sweating. Spray wetting alone is not sufficient to cool cows exposed to high solar loads.
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Abstract.Three black and three white lactating Holstein cows were exposed to 90 minutes of
direct sunlight during August 2000 in the Waianae district, Oahu, Hawaii. Prior to solar exposure
the cows were heat-stressed, having rectal temperatures of about 39.5°C, dorsal skin
temperatures of about 35°C and respiration rates of about 92 breaths/min while under shade with
THI values of 78.5 to 80.8. Upon exposure to solar loads of 495 to 820 watts/m, the dorsal skin
temperatures of the black cows rose about 4.8°C, while white cows only rose about 0.7°C. Rectal
temperatures of the black cows rose 1.3°C/hr, compared to a 0.7°C/hr rise for white cows. The
rate of sweating increases with solar load, nearly doubled from a solar load of 150 watts/m 2 to a
solar load of 1100 watts/m 2 . At a solar load of about 1000 watts/m 2 , evaporative heat loss by
sweating of the irradiated coat was about 750 watts/m 2 for black cows and about 600 watts/m 2
for white cows. This difference is probably attributed to black coats absorbing more energy and
heating the skin more than the white coats for the same solar load. Wetting the hair coat of cows
exposed to direct sunlight failed to stop the rise in rectal temperature, although it did reduce the
rate of temperature rise by about 50%. Respiration rates increased about 8 to 13 breaths/min,
after the cows were exposed to direct sunlight. Neither coat color nor wetting appeared to have
any effect on the observed increase in respiration rate. This study recommends that dairy cows
always have shade available to help keep them cool. Water spray alone is insufficient to keep
them cool under high solar loads.
Keywords: Solar radiation, Hair coat, Spray cooling, Heat stress relief, Dairy cows
INTRODUCTION
Dark colored cows absorb more solar radiation than light colored cows (Fitch et al., 1984). This
difference becomes important when cows are heat-stressed and are exposed to direct sunlight, at
which time coat color impacts both physiological and behavioral thermoregulation. For example,
white Holsteins have lower surface temperatures, body temperatures, and respiration rates than
black Holsteins (Hansen, 1990). Dark colored cows and steers seek shade more than do the light
colored cows and steers (Goodwin, et al., 1997a and Fitch, et al., 1984). White cows require
fewer services per conception in the summer months, than black cows (King, et al., 1988). White
cows have also been shown to have higher milk yields than black cows, when both white and
black cows had access to shade only or to shade and water spray during periods of excessive heat
load (Goodwin, et al., 1977b).
Coat color, sweating, and spray cooling modify the impact of solar load on the cow's surface.
The following field study attempts to elucidate these factors in heat-stressed lactating cows. A
better understanding of the benefits of lighter hair coat, shade, sweating and wetting in the face
of severe solar loads are needed to optimize diary management during periods of severe heat
stress.
The objectives of this study are:
(1) To characterize the impact of solar radiation on surface temperatures, body temperatures,
sweating rates and respiration rates of heat-stressed cows with either black coats or white coats.
(2) To assess the benefit of water spray cooling on heat-stressed cows exposed to direct sunlight.
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EXPERIMENTAL DESIGN
Three black and three white lactating Holsteins cows of approximately equal body weights and
milk production were used for this study (Table 1). In the experimental design, the six cows were
divided into two groups (Table 2). Half the experimental trials were without any wetting ("not
wetted"). For the remaining experimental trials the cows were sprayed water ("wetted") every 10
minutes to keep the hair coat wet. For the wetting trials, the dorsal area was wetted with about 3
liters using a low-pressure single nozzle a period of 1.5 min, which saturated the hair coat
enough that excess water would drip off the side of the cow. One group had two white cows and
one black cow and the other group had two black cows and one white cow. Each group was
exposed to one morning not wetted, one morning wetted, one afternoon not wetted and one
afternoon wetted. Each group had no more than one treatment on a given day. During each
treatment, the cows were restrained in stalls that are about 0.8 m wide and were lined up head-to-
tail. The experiments were conducted within the holding area next to a milking parlor at the
Pacific Dairy farm located in the Waianae district, Oahu, Hawaii.
Each day a cow was used in a trial it was placed in the same stall exposed to direct sunlight
(August 15 to August 20, 2000) with similar environmental conditions (Table 2). The cows were
held in full shade for at least 20 minutes before they were moved to full sunlight exposure lasting
90 minutes.
Rectal temperatures were measured with a digital thermometer (model M525, GLA Agricultural
Electronics, San Luis Obispo, CA) at 10 min intervals, starting at 20 min before each
experiment. Respiration rates were recorded every 5 min by counting the thoracic movement per
unit time. Dorsal surface temperatures, ground and sky temperatures were all measured every 5
min using a handheld infrared thermometer (model 9JM08, Raytek, Santa Cruz, CA) and short
wave radiation was measured every 10 minutes using a pyranometer (model CM 6B, Kipp &
Zonen, Delft, Netherlands). This same pyranometer was used to estimate percent absorption of
the hair coat by measuring the incident and the reflected short-wave radiation. Prevailing wind
was measured with a three-cup anemometer (Totalizer 2100, NRG Systems, Hinesburg, VT).
Ambient air temperature and relative humidity were recorded at 10 min intervals (ten 1 min
readings were averaged) with a data logger (HOBO H8 Pro, Onset Computer Corporation,
Bourne, MA). Evaporative heat loss from the skin surface was measured using a portable
calorimeter over a 10-minute period. Details of the methods for using the portable calorimeter
are identical to those described in Hillman, et al., (2001), except that the temperature of the outlet
is based on two RTD chips, rather than the sensing grid because it was difficult to zero the
sensing grid under direct sunlight. Air velocity over the hair coat surface was set at 1.0 to 1.1 m/s
for all measurements.
RESULTS AND DISCUSSION
Not Wetted Responses
For all the experimental trials, the cows were heat-stressed before they were exposed to direct
sunlight, with pre-treatment rectal temperatures 39.4 to 39.5°C (Table 6) and respiration rates 88
to 95 breaths/min (Table 7). Pre-treatment THI values ranged from 78.5 to 81.9 (Table 3) and
were in the "Alert" to "Danger" zones (Hahn, 1999) and differed little from THI values during
the treatments (Table 4).
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Solar radiation ranged from 495 to 971 watts/m 2 during the experimental trials, with an overall
average of 792 watts/m 2 (Table 4). Cows with white hair coat absorb about 66% of the short
wave radiation, while cows with black hair coat absorb about 89% of the short-wave radiation
(Table 1). Exposing cows under direct sunlight increased the surface temperature of the black
cows by 4.8°C and the white cows by 0.7°C (Table 5). During the first 50 minutes of solar
exposure, rectal temperatures of black cows increased 1.3°C/hr, while the rectal temperatures of
white cows increased 0.8°C/hr (Table 6). Respiration rates for both white and black cows
increased slightly (10 to 15%) when moved to direct sunlight (Table 7).
The rate of sweating increases with higher solar loads on the skin surface (Figure 1), where
evaporation is higher from the black hair coat than from the white hair coat for a given solar
load. Evaporation does increase with an increase in dorsal skin temperature (Figure 2),
suggesting that the higher rate of sweating of black skin at a given solar load is due to greater
local warming of a black coat compared to a white coat (Table 5). Finch, et al. (1982) observed
that the rate of evaporation is strongly related to mean rectal temperature in cattle. Our data
suggests that skin temperature might be the physiological triggering mechanism for high rates of
evaporation (i.e., greater than 500 w/m 2 ), rather than body temperature (Figure 2). Gatenby
(1980) observations support the suggestion that local skin temperature affects the rate of
evaporation at the site of local heating, where the rates of local sweating were greater on the right
back of the steer facing the sun, rather than the shaded, left back of the steer.
The maximum sweating rate of heat-stressed Holsteins in shade under similar ambient air
temperatures and humidity was about 240 watts/m 2 (Hillman, et al., 2001), which is similar to
the sweating rates of cows with a low solar load in this study (Figure 1). Local heating of the
skin may be required to recruit maximum sweating from the skin surface.
Wetted Responses
As expected, wetting cools the dorsal hair coat exposed to direct sunlight, when compared to
temperature of pre-treatment coat in the shade (Table 5). Wetting cooled the white hair coat more
than the black hair coat. Spray cooling did not cool the heat-stressed cows after they were
exposed to direct sunlight (Table 6). This is especially true of the cows with black hair coat.
Respiration rates increased when the cows were moved to direct sunlight with no apparent
differences with white or black cows or whether they were wetted or not (Table 7).
Wetting the hair coat surface resulted in the highest evaporation rates from the skin surface
(Figure 3) with an average evaporation heat loss of 5.9±0.9 watts (12) from the sample area (i.e.,
760±119 watts/m 2 or 1116 gm water/m 2 hr). These rates are similar to the evaporation rates
from the coats of wetted cows in shade (Hillman, et al., 2001). Maximum sweating rates at the
greatest solar loads are similar to the evaporation rates of the wetted coats (Figure 3). This
observation suggests that wetting cows under high solar loads will not enhance natural
evaporative cooling as much as wetting the shaded cow, which underscores the importance of
providing shade when cooling cows.
CONCLUSIONS
When exposed to direct sunlight, the surface of heat-stressed, lactating Holsteins with black
coats rises about 4.8°C compared to about 0.7°C for white Holsteins. This is due to the higher
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absorption of solar radiation of black coats (89%) compared to white coats (66%). Local heating
of the skin surface by the sun appears to maximize sweating, but it is not enough to keep rectal
temperature from rising 1.3°C/hr in black cows or 0.8°C/hr in white cows. Evaporative heat loss
by sweating increases with increasing solar load, reaching over 800 watts/m 2 for black cows or
over 500 watts/m 2 for white cows with a solar load of about 1100 watts/m 2 . Wetting the dorsal
surface only cools the surface of black cows by about 0.6°C for black cows or about 3.1°C for
white cows. Rectal temperatures will still rise about 0.7°C/hr for black cows or about 0.3°C/hr
for white cows, even with the application of water spray. Only providing water spray to keep
cows cool during periods of high solar load is an incomplete strategy. To keep cows cool, shade
must be provided.
ACKNOWLEDGMENTS
This research is supported in part by Regional Hatch Funds and is a contributing project to the
Western Regional Project W-173 of the US Department of Agriculture. The authors sincerely
thank Ms. Monique Vanderstrom and Ms. Robin Dewalo of Pacific Dairy Inc. for the use of the
cows and facilities for these experimental trials.
REFERENCES
1. Hillman, P.E., K.G. Gebremedhin, A. Parkhurst, J. Fuquay, and S. Willard. 2001. Evaporative
and convective cooling of cows in a hot and humid environment. Livestock Environment
VI: Proceedings of the Sixth International Symposium, pp. 343-350, May 21-23, 2001,
Louisville, KY.
2. Finch, Virginia A., I.L. Bennett, and C.R. Homes. 1982. Sweating response in cattle and its
relation to rectal temperature, tolerance of sun and metabolic rate. J. Agric. Sci., Camb.
99:479-487.
3. Finch, Virginia A., I.L. Bennett, and C.R. Homes. 1984. Coat colour in cattle: effect on
thermal balance, behaviour and growth, and relationship with coat type. J. Agric. Sci.,
Camb. 102:141-147.
4. Goodwin, Peter J., John B. Gaughan, Trevor A. Schoorl, Bruce Young and Anita Hall. 1997a.
Shade type selection by Holstein-Friesan cows. Livestock Environment V: Proceedings of
the Fifth International Symposium, Volume II. p. 915-922, May 29-31, 1997,
Bloomington, Minnesota
5. Goodwin, Peter, John Gaughan, Patricia Skele, Maurie Josey, Anita Hall, and Bruce Young.
1997b. Coat color and alleviation of heat load in Holstein-Friesan cows. Livestock
Environment V: Proceedings of the Fifth International Symposium, Volume II. p. 923-927,
May 29-31, 1997, Bloomington, Minnesota
6. Hahn, G.L. 1999. Dynamic responses of cattle to thermal heat loads. J. Anim. Sci. 77 (Suppl.
2):10-20.
7. Hansen, P.J. 1990. Effects of coat colour on physiological responses to solar radiation in
Holsteins. Vet. Record 127:333-334.
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8. King, V.L., S.K. Denise, D.V. Armstrong, M. Torabi, and F. Wiersma. 1988. Effects of a hot
climate on the performance of first lactation Holstein cows grouped by color. J. Dairy Sci.
71:1093-1096.
Table 1. Properties of the lactating Holsteins. [All data are reported as mean±SD( n ).]
white cows cow #5335 cow #4300 cow #138 average
Color (>90% of surface) white white white white
Body weight* 626±5 kg (4) 694±8 kg (3) 677±21 kg
(4) 663±33kg
(11)
Milk production per milking** 11.6±1.1 kg
(15) 9.9±3.1 kg
(14) 12.4±2.7 kg
(15) 11.3±2.6 kg
(44)
Absorption of solar radiation 70 % 61 % 66 % 65.7±4.5 %
(3)
Area wetted 1.2 m 2 1.7 m
2 1.3 m
2 1.4±0.3 m 2
(3)
black cows cow #561 cow # 4769 cow #5112 average
Color (>90% of surface) black black black black
Body weight* 613±11 kg
(4) 678±6 kg (3) 641±11 kg
(4) 641±29 kg
(11)
Milk production per milking** 11.2±3.7 kg
(13) 12.2±5.1 kg
(15) 11.0±2.5 kg
(15) 11.5±3.9 kg
(43)
Absorption of solar radiation 89 % 88 % 90 % 89.0±1.0 %
(3)
Area wetted 1.1 m 2 1.6 m
2 1.5 m
2 1.4±0.3 m 2
(3)
*Estimated with a commercial
body weight tape
**3 milkings/day
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Table 2. Experimental design showing treatments and scheduling of white and black cows.
Date Start/Stop
Time Treatment Cow
#/color Cow
#/color Cow
#/color
8/15/2000 10:10 -
11:40 not
wetted #4769
(black) #4300
(white) #5112
(black)
8/15/2000* afternoon not
wetted #5535
(white) #561
(black) #138
(white)
8/16/2000 9:50 -
11:20 wetted #5535
(white) #561
(black) #138
(white)
8/16/2000 13:20 -
14:50 not
wetted #4769
(black) #4300
(white) #5112
(black)
8/17/2000* morning not
wetted #5535
(white) #561
(black) #138
(white)
8/17/2000 13:40 -
15:10 wetted #4769
(black) #4300
(white) #5112
(black)
8/18/2000 10:00 -
11:30 wetted #4769
(black) #4300
(white) #5112
(black)
8/18/2000 13:30 -
15:00 wetted #5535
(white) #561
(black) #138
(white)
8/19/2000 10:05 -
11:35 not
wetted #5535
(white) #561
(black) #138
(white)
8/20/2000 14:10-
16:20 not
wetted #5535
(white) #5112
(black)** #138
(white)
* Two of the originally scheduled
treatments (shown in italics) were not
included in the experimental design,
because of cloudy skies. They were
rescheduled to 8/19/2001 and 8/20/2001.
**On 8/20/2001 cow #5112 was
substituted for cow #561, because cow
#561 had mastitis.
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Table 3. Ambient conditions during the 20 min, pre-treatment period.
not wetted
treatments
8/15/2000 AM 8/16/2000
PM 8/19/2000
AM 8/20/2000
PM
T ambient 30.6±0.4 ºC (3)
30.6±0.1 ºC
(3) 29.1±0.2 ºC
(3) 31.6±0.1 ºC
(3)
Relative humidity 48.8±1.3 % (3) 54.9±0.4 %
(3) 53.1±0.5 %
(3) 53.5±1.0 %
(3)
THI* 79.1±0.3 (3) 80.0±0.0 (3) 77.8±0.3 (3) 81.2±0.2 (3)
wetted
treatments
8/16/2000 AM 8/17/2000
PM 8/18/2000
AM 8/18/2000
AM
T ambient 29.4±0.4 ºC (3)
32.6±0.3 ºC
(3) 29.6±0.2 ºC
(3) 33.2±0.2 ºC
(3)
Relative humidity 55.5±1.7 % (3) 50.0±1.2 %
(3) 60.0±1.2 %
(3) 43.0±1.1 %
(3)
THI* 78.5±0.3 (3) 81.9±0.1 (3) 79.6±0.2 (3) 81.3±0.1 (3)
*Computed from the relationship
given by Hahn (1999).
Table 4. Environmental conditions during treatments.
not wetted
treatments
8/15/2000 AM 8/16/2000 PM 8/19/2000 AM 8/20/2000 PM
Solar radiation 820±326 809±79 758±236 495±156
10
watts/m 2 (11) watts/m 2 (12) watts/m
2 (17) watts/m 2 (17)
T ground , low value 26.3±4.6 ºC
(10) 24.4±0.4 ºC
(5) 22.3±0.8 ºC
(13) 29.9±1.7 ºC
(10)
T ground , high value 57.3±7.5 ºC
(10) 61.1±2.6 ºC
(4) 52.5±7.9 ºC
(13) 47.9±2.6 ºC
(10)
T sky , low value -22.2±1.0 ºC
(10) -23.4±0.2 ºC
(5) -23.2±0.2 ºC
(13) -4.8±7.1 ºC (9)
T sky , high value 11.6±1.2 ºC
(10) 8.9±4.2 ºC (5) 14.4±3.2 ºC
(13) 17.3±1.1 ºC (9)
Wind speed 1.9±0.6 m/s
(11) 2.8±0.8 m/s
(11) 1.2±0.5 m/s
(17) 2.1±0.5 m/s
(18)
T ambient 29.9±1.2 ºC
(20) 30.6±0.2 ºC
(20) 30.1±1.2 ºC
(20) 31.4±0.5 ºC
(20)
Relative humidity 53.8±5.3 %
(20) 55.0±0.8 %
(20) 49.4±3.6 %
(20) 53.1±2.1 %
(20)
THI* 78.9±0.8 (20) 80.2±0.1 (20) 78.5±0.3 (20) 80.8±0.3 (20)
wetted
treatments
8/16/2000 AM 8/17/2000 PM 8/18/2000 AM 8/18/2000 AM
Solar radiation 648±343
watts/m 2 (11) 906±76
watts/m 2 (19) 927±203
watts/m 2 (17) 971±115
watts/m 2 (19)
T ground , low value 23.9±1.6 ºC (8) 23.6±1.2 ºC
(16) 23.3±0.9 ºC
(13) 23.8±1.2 ºC
(17)
T ground , high value 51.5±7.6 ºC (8) 61.0±5.2 ºC
(16) 54.1±6.6 ºC
(13) 64.0±4.5 ºC
(17)
T sky , low value -22.7±1.3 ºC
(8) -22.3±1.4 ºC
(16) -20.3±1.9 ºC
(15) -23.1±0.4 ºC
(15)
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T sky , high value 10.7±3.8 ºC (9) 15.3±4.3 ºC
(16) 15.3±1.6 ºC
(15) 15.4±1.2 ºC
(15)
Wind speed 1.6±0.6 m/s
(12) 1.8±0.4 m/s
(19) 1.7±0.4 m/s
(18) 1.7±0.5 m/s
(19)
T ambient 29.9±1.0 ºC
(20) 33.7±0.4 ºC
(20) 30.7±0.7 ºC
(20) 34.3±0.6 ºC
(20)
Relative humidity 53.9±5.1 %
(20) 42.4±3.4 %
(20) 55.0±2.5 %
(20) 39.4±1.5 %
(20)
THI* 78.9±0.7 (20) 81.8±0.2 (20) 80.2±0.6 (20) 82.0±0.5 (20)
*Computed from the
relationship given by Hahn
(1999).
Table 5. Changes of dorsal skin temperature to direct sunlight.
not wetted treatments black cows white cows
T dorsal , pre-treatment in shade 35.3±0.7 ºC (6) 34.4±0.7 ºC (6)
T dorsal , during 90 min exposure to direct sunlight 40.0±1.9 ºC (6) 35.1±1.4 ºC (6)
? T dorsal , due to exposure to direct sunlight 4.8±1.9 ºC (6) 0.7±1.0 ºC (6)
wetted treatments black cows white cows
T dorsal , pre-treatment in shade 35.9±0.9 ºC (6) 33.9±0.3 ºC (6)
T dorsal , during 90 min exposure to direct sunlight 35.3±1.8 ºC (6) 30.8±1.6 ºC (6)
? T dorsal , due to exposure to direct sunlight -0.6±2.4 ºC (6) -3.1±1.5 ºC (6)
Table 6. Changes of rectal temperatures to direct sunlight.
not wetted treatments black cows white cows
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T rectal , pre-treatment in shade 39.5±0.5 ºC (6) 39.4±0.6 ºC (6)
T rectal , last 30 min of 90 min of direct sunlight 41.0±0.3 ºC (6) 40.4±0.6 ºC (6)
? T rectal , first 50 min of exposure to direct sunlight 1.3±0.2 ºC/hr (6) 0.8±0.2 ºC/hr (6)
wetted treatments black cows white cows
T rectal , pre-treatment in shade 39.5±0.6 ºC (6) 39.5±0.5 ºC (6)
T rectal , last 30 min of 90 min of direct sunlight 40.3±0.5 ºC (6) 39.8±0.4 ºC (6)
? T rectal , first 50 min of exposure to direct sunlight 0.7±0.4 ºC/hr (6) 0.3±0.3 ºC/hr (6)
Table 7. Changes in respiration rate (RR) to direct sunlight.
not wetted treatments black cows white cows
RR, pre-treatment in shade 95.3±20.9 breaths/min (6) 88.0±7.3 breaths/min (6)
RR, during 90 min of sun 105.2±10.7 breaths/min (6) 100.9±8.6 breaths/min (6)
? RR, due to exposure to sun 9.9±19.9 breaths/min (6) 12.9±7.2 breaths/min (6)
wetted treatment black cows white cows
RR, pre-treatment in shade 93.0±21.8 breaths/min (6) 78.5±11.6 breaths/min (6)
RR, during 90 min of sun 106.1±17.2 breaths/min (6) 86.9±9.7 breaths/min (6)
? RR, due to exposure to sun 13.1±10.9 breaths/min (6) 8.4±10.8 breaths/min (6)
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Figure 1. Heat loss by sweating from black and white hair coats exposed to different levels of
solar radiation. The low levels of solar radiation were observed on the cloudy periods on
8/15/2000 PM and 8/17/2000 AM. These two treatments were not included for the rest of this
study because of cloudy skies (see Table 2).
Figure 2. Rectal and dorsal skin temperatures for different levels of evaporative heat loss from
the skin surface. Dorsal skin temperatures were recorded by the portable calorimeter while
evaporation was being measured.
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Figure 3. Evaporation from the skin surface by sweating alone compared to the wetted the hair
coat. The straight line represents the linear regression of the sweating alone data (R2 = 0.589) for
both the white and the black cows. The average heat loss from the wetted skin was 5.9 watts.
Absorption of solar radiation by sample area is corrected for the percent absorption by the hair
coat.
Copyright © 2005. American Society of Agricultural and Biological Engineers. All rights reserved.
... Nonaka et al. (2008) depicted a spike in RT by 0.2 and 1.2°C in pre-pubertal HF heifers during exposure to ambient temperatures at 28 and 33°C respectively. In an interesting study, Pereira et al. (2008) Meyerhoeffer et al. (1985) Angus McGuire et al. (1991) HF (lactation) Muller and Botha (1993) H F a n d J e r s e y Marai et al. (1995) H F Omar et al. (1996) H F Hammond et al. (1996) Senepol, Romosinuano, Brahman, Angus and Hereford Itoh et al. (1998) HF (lactation) Guzeloglu et al. (2001) H F Hillman et al. (2001) H F Koubkova et al. (2002) H F Prasanpanich et al. (2002) HF (lactation) Chakravarthi et al. (2004) Ongole Spiers et al. (2004) H F Singh and Singh (2005) KF and Sahiwal Padilla et al. (2006) HF (lactation) Beatty et al. (2006) Angus and Brahman HF (lactation) Muller and Botha (1993) H F a n d J e r s e y Hammond et al. (1996) Senepol, Romosinuano, Brahman, Angus and Hereford Gaughan et al. (2000) Hereford × Angus × Simmental and Hereford × Murray Grey Soley and Singh (2003) K F Spiers et al. (2004) H F Padilla et al. (2006) HF (lactation) Beatty et al. (2006) Angus and Brahman Pereira et al. (2008) Alentejana, Mertolenga, HF and Limousine Nonaka et al. (2008) H F Rhoads et al. Gir, Girolando, Nelore, Sindhi and Indubrasil Mayengbam et al. (2015) Sahiwal and KF Valente et al. (2015) Angus and Nellore Kumar et al. (2017) Hariana and Sahiwal Grewal and Aggarwal (2018) Sahiwal and KF Kim et al. (2018) Korean native beef calves Grewal and Aggarwal (2018) noticed an elevation in RT in periparturient Sahiwal and KF cows during hot humid season (THI=81.11) ...
... Further, Katiyatiya et al. (2017) reported that cows with white-red coat colour had highest RT (39.02°C) whereas cows with fawn coat colour had lowest RT (35.55°C), indicating the influence of coat colour on RT in heat-stressed cows. In addition, RT in dairy cows with black hair coat increased by 1.3°C/h while those with white hair coat increased by 0.8°C/h when exposed to THI at 81 (Hillman et al. 2001), which indicates that black hair coat renders more heat accumulation resulting in more increase in RT than white hair coat colour cows. Omar et al. (1996) found that cooling via forced ventilation and sprinkler reduce RT thereby increase milk yield by 15% in HF cows during summer heat stress. ...
... Earlier, Finch et al. (1984) revealed that dark colour coats receive higher heat waves from solar radiation compared to light colour coats. Further, cattle with black or dark hair coat absorb more short-wave radiations (89%) than cattle with light or white hair coat (66%) and as a consequence black skinned cows witnessed greater SR than white skinned cows to maintain thermal balance (Hillman et al. 2001 ...
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The negative impact of heat stress on cattle growth, development, reproduction and production has been quite alarming across the world. Climate change elevates earth surface temperature which exacerbates the wrath of heat stress on cattle. Moreover, cattle in tropical and sub-tropical countries are most commonly affected by the menace of heat stress which severely wane their production and productivity. In general, cattle exhibit various thermoregulatory responses such as behavioural, physiological, neuro-endocrine and molecular responses to counteract the terrible effects of heat stress. Amongst the aforementioned thermoregulatory responses, behavioural, physiological and neuro-endocrine responses are regarded as most conventional and expeditious responses shown by cattle against heat stress. Furthermore, molecular responses serve as the major adaptive response to attenuate the harmful effects of heat stress. Therefore, present review highlights the significance of behavioural, physiological, neuro-endocrine and molecular responses which act synergistically to combat the deleterious effects of heat stress thereby confer thermo-tolerance in cattle.
... Black-coloured skin and hair coat increase the solar heat load on the skin surface due to enhanced solar absorption (Collier and Gebremedhin 2015) ( Figure 5). The surface temperature of Holstein cows (with mixed coat colour of black and white) increased by 4.8°C than that of white coat coloured cows where there was an increase of 0.7°C only when they were exposed to direct sunlight (Hillman et al. 2001). The higher solar absorption by black coat colour than white could be attributed to the temperature difference in these cattle. ...
... The increase in RT and RF observed in black coat heifers supports the statement that animals with black coat have less ability to maintain thermal balance in the hot environment with high solar radiation during summer season (Maia et al. 2003). In this sense, Hillman et al. (2013) reported that black coat Holstein cows increase body temperature above 1.3 °C compared to white coat cows (0.7 °C) when they were exposed to direct sunlight; this result was attributed to the higher absorption of solar radiation of black coat cows (89%) compared to white coat cows (66%). Likewise, Stewart et al. (1953) indicated that solar radiation can have a major impact on thermal balance on black coat ruminants because white hair color may absorb only 40% solar radiation, meanwhile black hair color until 90%, consequently heat flux in the skin is greater for dark animals. ...
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Two hundred Holstein heifers were divided by hair coat color in black (n1 = 60), white (n2 = 62), and mixed (n3 = 78) to accomplish two objectives: (1) to compare physiological variables using an analysis of variance, and (2) to construct regression equations to predict rectal temperature. In each heifer, rectal temperature (RT), respiration frequency (RF), and body surface temperatures (obtained with infrared thermography in eye, nose, forehead, head, neck, ear, shoulder, flank, belly, leg, loin, rump, and vulva) were measured. Black heifers had more RF and RT (P < 0.01) than mixed and white coat heifers; white heifers had similar RT than mixed color heifers, but they exhibited less RF (P < 0.05). In general, black and mixed coat color heifers had higher BST (P < 0.01) than white heifers in the majority of the anatomical regions measured. For black coat heifers, the best regression model to predict RT included three predictor variables: [RT = 35.59 − 0.013 (RH) + 0.045 (RF) + 0.019 (TEar); R² = 71%]. For white coat heifers, the best model included two predictor variables: [RT = 35.29 + 0.035 (RF) + 0.033 (TForehead); R² = 71%]; and for mixed coat color heifers, the best model included two predictor variables: [RT = 35.07 + 0.022 (RF) + 0.038 (THead); R² = 44%]. Heifers with dark hair coat color showed higher physiological constants than white heifers; the prediction of rectal temperature was more precise in heifers with well-defined hair coat color. Physiological and climatic variables, along with infrared thermography, represent an appropriate combination to predict rectal temperature in Holstein heifers with predominant white or black hair coat color.
... Other possibility to alleviate heat stress is to reduce the effects of sunlight on heat production in the animal body. Black or dark coat colors absorb more solar radiation and increases the solar heat gain (Hillman et al. 2001;Walsberg 1988). Red-and-white Holstein cows have lower rectal temperatures than black-and-white Holstein cows in the hot season (Isola et al. 2020). ...
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The livestock performance in tropical regions has been limited by environmental conditions that causes heat stress and favors the development of parasites and diseases, impairing animal health. Heat stress disturbs animal homeostasis and affects animal production and fertility, with negative impacts on meat and milk quality. Flies and ticks proliferate easily under hot-humid weather, which makes difficult the control of their population, resulting in an increased parasitism. Tropical pastures usually have high dry matter production, but it is challenging to keep high production and quality under different environmental conditions throughout the year, constraining animal performance. Several strategies have been adopted in an attempt to overcome such hurdles in the tropical regions, but definitive solutions are yet to be implemented. In the last 20 years, biotechnologies, such as in vitro embryo production and genomic selection, have played an important role on cattle production in tropical countries. Genome editing (GnEd) is the novel tool in the toolbox for cattle production. GnEd with genomic selection offers the opportunity to boost the genetic gain in breeding programs of tropical cattle in fewer generations. It can be applied for disease resistance, to control parasite population, and to improve pasture quality and tolerance to biotic and abiotic stresses, favoring animal health and nutrition. Moreover, there is a perspective for the use of GnEd to control cattle methane emission by editing genes of methanogens present in the rumen. Although GnEd can already be applied to improve some traits, studies are still required for the identification of candidate genes in animals, tropical pastures, parasites, and microorganisms that can be targeted by gene editing in order to offer a robust contribution to the improvement of cattle production in the hot regions. Some examples of the use of GnEd are presented in this review, focusing on new perspectives of using GnEd to increase cattle production under the challenges of the tropical environments.
... Typically, dark-coated animals have higher heat loads than lightcoloured ones [112] and the light-coloured coat is deemed superior in tropical regions [113]. Additionally, skin pigmentation provides protection for deep tissues against solar short-wave radiation in tropical regions [114]. ...
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Goats play a crucial role in improved livelihoods and food security in Africa. Indigenous and locally developed types exhibit a wide range of phenotypic diversity, but are commonly well adapted to the harsh environment in which they need to survive and produce. They have various functions in communities in developing countries, from providing food security to being a liquid form of cash and playing a role in ceremonial occasions. The Southern African goat population exceeds 35 million animals, most of which are kept in small-scale traditional production systems in communal areas. These traditional production systems are characterised by informal, lowly-skilled labour, small numbers of animals and limited resources. Most goats are part of mixed crop-livestock systems, where different livestock species and crop farming compliment one another. The productivity and offtake from these animals are relatively low. Some goats form part of agropastoral production systems, with marginally higher management and resource inputs. Both of these systems are dependent on a high degree of variability where the keepers/farmers can exploit various resources as and when necessary. Goats possess a range of adaptive mechanisms that enable them to deal with harsh and challenging environments, making them the ideal species for use in these production systems. This chapter aims to provide background information on the current smallholder management practices of goat keepers in Southern Africa.
... The ability of the animals to deal with heat stress resulting from solar radiation depends on the physical characteristics of their skin and coat (Hillman et al. 2001;Da Silva et al. 2003). This is all the more true when we consider that in certain cases (tropical regions), the temperature of the surroundings (e.g. the ground, elements of buildings, fences) during the day is usually considerably higher than the air temperature, a fact that the commonly used THI indices do not A comparison of the most popular indexes to evaluate their suitability for forecasting heat stress in dairy cattle is shown in Table 5. ...
Article
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Considering the significant influence of high ambient temperature and heat waves on the well-being and productivity of dairy cows, it is to be expected that, in the course of the next few decades, climate conditions for raising cattle will deteriorate. Research has shown that heat stress causes many negative consequences in terms of physiological and behavioural disturbances and significant losses in milk production. The effort to reduce the risk of the occurrence of heat stress among dairy cows also involves the search for new environmental methods of predicting heat stress. The aim of this paper is to review and systematise the current state of knowledge on the topic of the most widely used environmental methods of determining and predicting heat stress in dairy cows and also to show the directions of studies for the future. Based on an analysis of the most popular indexes, the study evaluated their suitability for forecasting heat stress related to maintenance systems and climate conditions for cows. However, the negative results of heat stress often appear with a delay, and a carry-over effect may be experienced (summer heat stress may affect the cows until autumn). The time of the year and breed of cows could have a big impact on when animals become sensitive to increasing heat loads. This likely can be a big contributor to the discrepancies within the different heat stress equations. It is essential to prevent the occurrence of heat stress, predicting it by observing local microclimate conditions and using meteorological forecasts. Thanks to these measures, a breeder may prepare and implement suitable solutions for protecting the animals.
Article
Heat stress (HS) reduces production and efficiency in almost every metric of the dairy operation, and it thus compromises profitability and sustainability. If the magnitude of HS progresses, it can become lethal. Death can occur acutely or days following the heat load, even if environmental conditions have become nonstressful. Consequently, lethal heat stress (LHS) is often difficult to identify and almost always misdiagnosed. The precise mechanisms of death when dairy cows succumb to LHS has not been fully elucidated or documented, but the pathophysiology of LHS appears to be conserved among several species. The unique digestive physiology of ruminants adds additional layers of complexity that contribute to failure of multiple systems involved with LHS. Consequently, the ostensible etiology and pathogenesis of LHS described herein is extended from the physiological adaptations cows use to survive HS and pertinent pathology extrapolated from other species. The multifactorial causes of death likely involve dysfunction and imbalance of several interdependent systems as follows: (1) electrolyte dyshomeostasis, (2) unstable blood pH, (3) gastrointestinal tract hyperpermeability, (4) sepsis, (5) severe immune activation-induced inflammation, (6) disseminated intravascular hypercoagulation, (7) systemic endothelial permeability, (8) multiple organ failure, and (9) circulatory failure. Having a better understanding of the mechanisms of LHS will improve diagnosis, enable a more accurate prognosis, and provide insight into strategies aimed at preventing dairy cow mortality and morbidity.
Article
Traditional breeding techniques, applied incrementally over thousands of years, have yielded huge benefits in the characteristics of agricultural animals. This is a result of significant, measurable changes to the genomes of those animal species and breeds. Genome editing techniques may now be applied to achieve targeted DNA sequence alterations, with the potential to affect traits of interest to production of agricultural animals in just one generation. New opportunities arise to improve characteristics difficult to achieve or not amenable to traditional breeding, including disease resistance, and traits that can improve animal welfare, reduce environmental impact, or mitigate impacts of climate change. Countries and supranational institutions are in the process of defining regulatory approaches for genome edited animals and can benefit from sharing approaches and experiences to institute progressive policies in which regulatory oversight is scaled to the particular level of risk involved. To facilitate information sharing and discussion on animal biotechnology, an international community of researchers, developers, breeders, regulators, and communicators recently held a series of seven virtual workshop sessions on applications of biotechnology for animal agriculture, food and environmental safety assessment, regulatory approaches and market and consumer acceptance. In this report, we summarize the topics presented in the workshop sessions, as well as discussions coming out of the breakout sessions. This is framed within the context of past and recent scientific and regulatory developments. This is a pivotal moment for determination of regulatory approaches and establishment of trust across the innovation through-chain, from researchers, developers, regulators, breeders, farmers through to consumers.
Article
Full-text available
Traditional breeding techniques, applied incrementally over thousands of years, have yielded huge benefits in the characteristics of agricultural animals. This is a result of significant, measurable changes to the genomes of those animal species and breeds. Genome editing techniques may now be applied to achieve targeted DNA sequence alterations, with the potential to affect traits of interest to production of agricultural animals in just one generation. New opportunities arise to improve characteristics difficult to achieve or not amenable to traditional breeding, including disease resistance, and traits that can improve animal welfare, reduce environmental impact, or mitigate impacts of climate change. Countries and supranational institutions are in the process of defining regulatory approaches for genome edited animals and can benefit from sharing approaches and experiences to institute progressive policies in which regulatory oversight is scaled to the particular level of risk involved. To facilitate information sharing and discussion on animal biotechnology, an international community of researchers, developers, breeders, regulators, and communicators recently held a series of seven virtual workshop sessions on applications of biotechnology for animal agriculture, food and environmental safety assessment, regulatory approaches, and market and consumer acceptance. In this report, we summarize the topics presented in the workshop sessions, as well as discussions coming out of the breakout sessions. This is framed within the context of past and recent scientific and regulatory developments. This is a pivotal moment for determination of regulatory approaches and establishment of trust across the innovation through-chain, from researchers, developers, regulators, breeders, farmers through to consumers.
Article
Full-text available
Oil palm plantations (OPP) have a temperature-humidity index (THI) higher than the surrounding environment, which affects the physiological conditions of cattle. The study aims to measure the body temperature (BT), respiration rate (RR), and pulse rate (PR) as a comfort indicator of cattle to the environment. Fourteen Bali cattle were used to study the physiological condition of cattle in an OPP based on THI. The THI in the morning, day, and night were tested using a Completely Randomized Design followed by Duncan’s multiple range test. The results showed that the OPP had a different THI (P<0.05): 77.36±1.22, 82.91±1.40, and 79.49±2.63 in the morning, day and night respectively. The BT, RR, and heat tolerance coefficient (HTC) during the day higher (P<0.05) than morning and the night, while the PR was not different. It is concluded that OPP has THI potential to give moderate stress, but the cattle still overcome them through physiological efforts, so it was suitable for Bali cattle grazing area.
Article
The focal point of this limited review is bioenergetic research conducted in the Biological Engineering Research Unit at the U.S. Meat Animal Research Center (MARC), using recently developed instrumentation and analytical techniques. The dynamics of observed thermoregulatory responses in cattle to thermal heat load challenges are explored, with an emphasis on physiological and behavioral parameters of body temperature, respiration rate, and feed intake. Observations of body temperature, especially tympanic temperature, have shown hot environments to cause phase shifts, increased amplitude, and increased means for diurnal rhythms. Fractal analysis of body temperature records obtained at 2- to 10-min intervals has been found to be robust for objectively differentiating among responses of cattle in cool to hot environments, and it indicates a stress threshold of approximately 25 degrees C (coincident with declining feed intake). Other analyses determined a 21 degrees C threshold for increased respiration rate. The reported observations and analyses provide further understanding of how and why the animals respond to environmental challenges, an understanding that is necessary for refining performance models and developing energetic and thermoregulatory models. The dynamic responses are discussed in the context of establishing criteria for proactive environmental management for cattle during hot weather, using heat waves as an example.
Sweating response in cattle and its relation to rectal temperature, tolerance of sun and metabolic rate
  • Virginia A Finch
  • I L Bennett
  • C R Homes
Finch, Virginia A., I.L. Bennett, and C.R. Homes. 1982. Sweating response in cattle and its relation to rectal temperature, tolerance of sun and metabolic rate. J. Agric. Sci., Camb. 99:479-487.
Coat colour in cattle: effect on thermal balance, behaviour and growth, and relationship with coat type
  • Virginia A Finch
  • I L Bennett
  • C R Homes
Finch, Virginia A., I.L. Bennett, and C.R. Homes. 1984. Coat colour in cattle: effect on thermal balance, behaviour and growth, and relationship with coat type. J. Agric. Sci., Camb. 102:141-147.
Shade type selection by Holstein-Friesan cows
  • Peter J Goodwin
  • B John
  • Trevor A Gaughan
  • Bruce Schoorl
  • Anita Young
  • Hall
Goodwin, Peter J., John B. Gaughan, Trevor A. Schoorl, Bruce Young and Anita Hall. 1997a. Shade type selection by Holstein-Friesan cows. Livestock Environment V: Proceedings of the Fifth International Symposium, Volume II. p. 915-922, May 29-31, 1997, Bloomington, Minnesota
Coat color and alleviation of heat load in Holstein-Friesan cows
  • Peter Goodwin
  • John Gaughan
  • Patricia Skele
  • Maurie Josey
  • Anita Hall
  • Bruce Young
Goodwin, Peter, John Gaughan, Patricia Skele, Maurie Josey, Anita Hall, and Bruce Young. 1997b. Coat color and alleviation of heat load in Holstein-Friesan cows. Livestock Environment V: Proceedings of the Fifth International Symposium, Volume II. p. 923-927, May 29-31, 1997, Bloomington, Minnesota