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Physiological, Productive, and Economic Benefits of Shade, Spray, and Fan System Versus Shade for Holstein Cows During Summer Heat
Physiological, Productive, and Economic Benefits of Shade, Spray, and Fan System Versus Shade for Holstein Cows During Summer Heat M. O. I G O N O , H. D. JOHNSON, z'2 B. J. STEEVENS, G. F, K R A U S E ? and M. D. S H A N K L I N 4 University of Missouri-Columbia Columbia 65211
ABSTRACT
During the 1984 summer, effects of spray and fan in freestall areas and feeding areas on milk yield, plasma growth hormone and prolactin, freestall utilization, and economic significance for Holstein cows were studied. Weekly milk and rectal temperatures at morning and afternoon milkings were higher for cows in shade than in shade with spray and fan cooling. Compared with rectal temperature, milk temperature measured in the clawpiece provided a more reliable indicator of heat stress than in the milk meter. Diurnal pattern of rectal temperature from 4-h measurements showed an average of 12 h in which maximal rectal temperatures of cows in shade were greater than 39°C, but cows in the shade plus spray plus fan ~roup had rectal temperatures below 39vC all day. Plasma growth hormone was higher and prolactin lower for cows in shade plus spray and fan than cows in shade only. Cows cooled with spray and fan under shade produced 2 kg/cow per d more than cows in shade alone. Eeconomic analysis showed a net income of 22¢Jcow per day for spray plus fan under shade. Results suggest that milk temperature is a practical technique to assess heat stress in dairy cattle, and the use of spray plus fan is a profitable means to maximize cow
Received April 14, 1986. Accepted December 26, 1986. Reprint requests. Department of Dairy Science. a Department of Statistics. 4 Department of Agricultural Engineering. 1987 J Dairy Sci 70:1069-1079
comfort and lessen stress-induced decline in milk production. INTRODUCTION
In studies during the 1982 and 1983 summers in Missouri, significant thermoregulatory and milk production benefits to lactating dairy cows were repeatedly demonstrated with use of water sprays. This benefit was provided by the simultaneous reduction in external heat load (17) with shades and increased conducive and evaporative heat loss from direct spraying of water on the body of cows (13, 14). Similar results relating to heat balance and milk production benefits have been reported with shade (6, 25), fan (7, 11, 15), spray (1, 14, 15, 20), or their combinations (10, 24) in various climates. However, available data on use of water sprays and fans lack information needed to answer critial questions relating to the extent and duration of thermoregulatory and milk production benefits, alterations in hormone concentrations, or economic benefits. These answers are needed before there can be recommendations for development and adoption of environmental modifcations to minimize climatic limitations to animal production. The primary objective of this investigation was to evaluate the physiological, productive, and economic benefits of spray and fan under shade to lactating Holstein cows during temperate summer conditions in Missouri. Specific objectives were a) to evaluate the benefits of shade plus spray and fan versus shade only for milk yields and somatic cell counts; b) to assess the benefits to thermal balance from measures of milk and rectal temperatures; c) to examine the effects of the environmental modifications on plasma growth hormone and prolactin ; d) to study the effects of spray and fan on behavioral action of freestall utilization ; and e) to evaluate the economic benefits of the use of spray and fans under shade. 1069
1070
IGONO ET AL. M A T E R I A L S A N D METHODS
During the summer of 1984, we added fans to the shade plus spray freestall and feeding areas of our 1983 study (14). Air was drawn from outside b y a fan connected to rigid galvanized tin ducts placed on dividers between adjoining freestalls. At each individual freestall, 8.9-cm diameter holes were cut in the duct to provide an air movement of 6.6 m/s (14 mph) over each individual cow. A similar fan system using polypropylene plastic ducts was installed under the shade over the feed bunk. Air movement was provided by use of a .41-m diameter tube axial fan (W. W. Ranger, Inc., St. Louis, MO). Sprays were timed for on and off sequence of 20 and 10 rain, respectively, as in the 1983 study. Sprays and fans were controlled by a thermostat to operate when ambient temperature exceeded 27°C. On June 26, 1984, 12 cows were placed in shade plus spray plus fan freestalls, and another 12 cows in adjacent freestalls served as shade group. Feed was offered ad libitum at 0430 and 1530 h daily. Prior to 1530 h scheduled daily feeding, refusals were weighed on a lot basis. Clean drinking water was available continuously and water consumption was recorded daily on a group basis. Each day, milk production, amount of water sprayed, and hours per day sprayed were measured and recorded. Temperature of spray and drinking water ranged between 18 and 25°C as monitored by thermocouples and recording potentiometer. Reproductive and health records were kept. Every Wednesday, milk temperature (Tmilk) was measured at both a.m. (0430 h) and p.m. (1630 h) milkings both at the claw and milk meter. Following milkings, rectal temperature (Tre) of cows in both groups were measured. To examine further the extent and duration o f cooling offered by fan and spray compared with shade, diurnal pattern of "Ire was characterized from Tre taken at 4-h intervals for cows in both groups once every 2 wk. Blood samples were collected weekly from the tail vein using heparinized vacutainer tubes with 20-gauge needles and placed on ice for transport to the laboratory. Blood samples were centrifuged at 3000 rpm for 30 min at 4°C and plasma samples frozen at - 2 0 ° C until analyzed. Procedures for radioimmunoassay of plasma growth hormone (GH) and prolactin (PRL) Journal of Dairy Science Vol. 70, No. 5, 1987
were as described by Mohammed and Johnson (22). We observed that cows in shade plus spray and fan group tended to utilize their freestalls more than shade group. Therefore, a supplementary study was designed to evaluate the effect of shade or shade plus spray with fan on freestall utilization at the conclusion of scheduled experiments. On d 1, time cows in both groups spent resting in their stalls or alley was observed at half-hour intervals between 1100 and 2400 h. On d 2, the gate between groups was removed to give animals free choice of either shade or shade plus spray and fan; observations were as in d 1. On d 3, ambient temperature did not rise above 27°C, but observations were made as described for d 1. Relative humidity (RH) and black globe (Tg) and dry bulb (Tdb) temperatures were monitored and recorded continuously as described during the 1983 study (13). Data were analyzed b y method of least squares using linear model procedures. Pooled data and sampling day means were compared for differences on a group basis. Linear correlation analysis was between main effects (9). Significance was set at 5%. RESULTS A N D DISCUSSION
Thermal environments during the 1984 summer study are in Table 1. In general, thermal environments were similar between groups. Humidities reported indicated that spraying did not lead to moisture buildup in the freestall areas. Similar observations were reported in the 1983 study (14). In essence, the ability of the animal to dissipate its b o d y heat to the environment may be attributable to the direct effect of the spray and fan treatment on the animals. The effect of spray with fan under the shade during summer on Tre and Tmilk measured in the meter or clawpiece on Holstein cows is presented in Table 2. Morning and afternoon Tre were higher (P<.05) for cows in shade than in shade plus spray with fan, but for both groups the p.m. Tre were higher (P<.05) than a.m. Tre. Values for Tmilk at clawpiece were higher (P<.05) for cows in shade than shade plus spray and fan. Clawpiece Trnak of cows in shade at a.m. and p.m. sampling was higher (P<.05) than for shade plus spray and fan group, but for both groups a.m. clawpiece Tmilk was lower
E N V I R O N M E N T A L SHADE, SPRAY, A N D FAN EFFECTS
1071
TABLE 1. Thermal e n v i r o n m e n t u n d e r shade and shade plus spray plus fan freestall areas during 1984 s u m m e r )
Measurement
Shade + spray + fan
Shade R
SE
R
SE
Dry bulb temperature, ~C 0400 h 1600 h
21.9 31.0
.88 1.04
22.1 30.8
.94 1.03
Black globe temperature, °C 0400 h 1600 h
21,5 43.0
1.11 3.54
21.4 43.6
1.12 3.45
Relative humidity, % 0400 h 1600 h
77.6 43.0
3.86 3.54
77.7 43.6
3.89 3.45
Dry bulb THI ~ 0400 h 1600 h
69.9 78.3
1.57 1.22
70.1 78.2
1.56 1.17
Black globe THI 2 0400 h 1600 h
69.3 81.2
1.80 2.87
69.1 81.7
1.81 2.78
Study conducted between June 27 and August 15, 1984. 2 THI = T e m p e r a t u r e - h u m i d i t y index.
( P < . 0 5 ) t h a n p . m . M e t e r Tmilk w a s s i m i l a r b e t w e e n g r o u p s at a . m . m i l k i n g s , b u t c o w s in shade had higher p.m. values than shade plus s p r a y a n d f a n ( 3 8 . 6 vs. 3 8 . 1 ° C ) . C o l l e c t i v e l y ,
these data demonstrate that spray plus fan enhanced heat loss to minimize heat accumulation during the day and enabled the animals to a t t a i n n o r m a l Tmilk a n d Tre b y a . m . s a m p l i n g .
TABLE 2. Mean milk (Tmilk) and rectal temperature (Tre) of Holstein cows in shade and shade plus spray and fan freestall areas during 1984 s u m m e r in Columbia, MO.
Measurement
Shade + spray + fan
Shade SE
~
SE
Tre, °C a.m. p.m.
38.7A, a 39.2B, a
.05 .08
38.5A, b 38.8B, b
.05 .04
Clawpiece Tmilk , ° C a.m. p.m.
38.6 A,a 39.1B, a
.06 .12
38.2A, b 38.6B, b
.11 .09
Meter Tmilk , °C a.m. p.m.
37.9C, a 38.6A, a
.07 .07
37.8C, a 38.1A, a
.10 .09
a~b,
.
,
.
Lvieans w l t m n rows having different superscripts differ (P<.05).
A'B'CMeans within columns with different superscripts differ (P<.05). a Study conducted between June 27 and August 15, 1984. Journal of Dairy Science Vol. 70, No. 5, 1987
1072
IGONO ET AL. h sampling time during the 56-{t experimental period of 1984 summer study. At 0400 h sampling, THI were similar between groups and generally below the critical value of 72 but near 70 during the last 3 wk. In general, Tmilk and Tre response patterns were similar and followed changes in thermal environment. The THI was about 2 to 9 units above the critical value of 72 at afternoon samplings and the animals gained more heat from the environment than could be dissipated. This is evidenced by the higher Tmilk and Tre values compared with 0400-h samplings as discussed in Table 2. Clawpiece and meter Tmilk responses were remarkably similar to Tre in pattern. These
Failure to regain normal body temperature overnight is a critical factor that limits the productive ability during the heat of the following day (14). In the shade group, clawpiece Tmilk and Tre were similar at both a.m. (38.6 vs. 38.7°C) and p.m. (39.1 vs. 39.2°C) samplings, but both clawpiece Trnilk and Tre were higher (P<.05) than meter Tmilk. A similar pattern existed for cows in shade plus spray and fan. This suggests that Tmilk at the claw site was the preferable site to measure heat effects on the cow. Figure 1 illustrates temperature-humidity index effects on Tre and Tmilk of cows in shade and shade plus spray with fan at 0400 and 1600
1600 h
0400 h
.1I
~
7
2
-!
o
•
oSO.o/ ill
./--- / " ' x ~1
010
|
°/
~0..--0~-01
3 O a t e : 6 2 7 7 o 3 711 718
Y 808
815
o
6 2 7 7 0 3 711 718 7 2 5 8 0 8 815: 1984
Figure 1. A comparative illustration of temperature-humidity index, rectal temperature, and milk temperatures of Holstein cows in shade (e-e) and shade plus spray plus fan (o-o) environments during summer 1984 at 0400 and 1600 h. Journal of Dairy Science Vol. 70, No. 5, 1987
E N V I R O N M E N T A L SHADE, SPRAY, AND FAN EFFECTS
observations of similarity in response of Tmilk and Tre as reported earlier (13, 14) demonstrate the practicability of using Tmi/k to assess the impact of climate and assess body temperature similar to Tre. Figure 2 describes more specifically the diurnal pattern of Tg, Tdb , RH, and Tre of cows in shade and shade plus spray and fan areas during 1984 summer. The thermal environment was generally similar between groups. Between 0800 and 1600 h, Tg was 3 to 5°C higher than Tdb, apparently because Tdb did not account
1073
for solar radiation and windspeed. Overall, Tdb was similar between groups. For about 11 h during the day, Tal~ was greater than 27°C. Relative humidity averaged 48% for both groups during the day but was above 65% at night. The diurnal pattern of Tre showed cows cooled with spray and fan were .3 to 1.2°C lower than for shade. Furthermore, Tre of cows in shade was above 39°C between 1200 and 2400 h compared with 0 h above 39°C during 24 h for cows in shade plus spray and fan.
-in
o
65
~ z
.0_
C
3
E
55
25
K
45
39.5
I,3g
o.
w
n
.J ul ~
I-- ~ ILl
38.5 40
/i,\ 9(/ o-
39 0"
"d
38
/
\
\
\
\
Cows in Estrus
,'
>¢
"\
/
/
/
/
/
-.0//
\o
,i
, hours spray and fan on
I
0400
I
I
0800 1200
I
I
I
I
1 6 0 0 2000 2400 0400
Time of Day,hours Figure 2. Diurnal pattern of black globe (Tg) and dry bulb temperatures (Tdb), relative h u m i d i t y (rh), and rectal temperature of cows in shade ( o - o ) and shade plus spray plus fan ( o - o ) environments during s u m m e r 1984. Journal o f Dairy Science Vol. 70, No. 5, 1987
1074
IGONO ET AL.
These observations, when compared with those of the previous study (13, 14) when Tre of spray cooled cows reached 39.5°C during the day, suggested that fan increased the effectiveness of spray. On sampling days for diurnal Tre, one cow in shade was observed in estrus, whereas 6 cows in shade plus spray and fan were in estrus. Although spray and fan treatment under shade minimized estrus-induced increases in "Ire, cows in estrus in the shade plus spray and fan group could be identified on the basis of their "Ere. Similar observations were made during summer in Louisiana when cows were housed in airconditioned chambers (11). Other researchers have reported estrous-related changes to Tr e or vaginal temperature (2), and telemetry of vaginal temperature has been a practical tool for estrous detection. The correlation estimates among Tmilk and Tre of Holstein cows housed in shade and shade plus spray and fan during 1984 summer are given in Table 3. At both 0400 and 1600-h samplings, the r-values between Tmilk measured in clawpiece and meter were highly significant. A comparison of the correlations and significance of clawpiece Tmilk t o Tre at 0400 and 1600-h samplings were significant (P<.01) for both groups, but the correlations between meter Tmilk and Tre were lower yet significant (P<.05). Because of the similarity in absolute values of elawpiece Tmilk and Tre (Table 2) and the higher correlation between clawpiece Tmilk and Tre than between meter Tmilk and Tre, the clawpiece is the best indicator of b o d y temperature. Observations were similar in other studies using only clawpiece Tmilk (18, 19). Table 4 presents the effects of shade and shade plus spray with fan on milk production. Spray plus fan treatment under shade increased milk yields by 2 kg/cow per d compared with 1.6 kg/cow per d during the 1983 study (13). Although the thermal environments during the 2 yr were not exactly the same, spray plus fan appeared to be more effective than spray alone. Somatic cell count of cows in the shade group at a.m. and p.m. samplings were higher than shade plus spray plus fan (Table 4). A difference in SCC occurred between treatments at 21 and 32°C in association with Tre fluctuations of 1.8°C (23). Data from Arizona showed SCC peaked during the hot summer months from June through November (26), whereas in Wisconsin, peak SCC was from July through Journal of Dairy Science Vol. 70, No. 5, 1987
August (5). Although the differences in SCC appear related to differences in Tre as influenced by heat stress, one study (23) concluded that heat stress per se may not influence SCC in uninfected udders. This is somewhat supported by milk yields that declined as SCC increased and for each doubling of SCC milk yields decreased about .7 kg milk/d (8). Somatic cells comprise displaced alveolar epithelial cells, phagocytes, and white blood cells. The effect of spray plus fan treatment under shade on plasma GH and PRL is shown in Table 5. Plasma GH was higher (P<.05) for cows in shade plus spray with fan than shade, as observed for spray cooling during 1983 (14). The decline in GH in the shade group versus the shade plus spray plus fan group is probably associated with chronic stress of summer (15). Growth hormone is involved in energy partitioning of milk production in dairy cows and its concentration in plasma is positively associated with milk production (3, 12, 16). Because cows in the spray plus fan group had higher plasma GH and produced more milk, hyperthermiarelated alterations of circulating GH may be involved in the mechanism of reduced milk yield during heat stress. This hypothesis has been clearly borne out by the climatic chamber study with GH supplementation to cows during heat stress, which resulted in an 8% increase in milk production (22). That study suggested that SCC in milk increased slightly due to heat, as the milk yields decreased, i.e., SCC appears related to body and environmental temperature. There appears to be no significant effect of exogenously administered GH on SCC during this short experimental period. Plasma PRL was significantly higher for cows in shade than in shade plus spray and fan, as in summer 1983 (14). Thus, plasma PRL increases as Tre and Tmilk increase, whereas GH declines with prolonged increases in heat stress (14). The specific role of PRL response to heat stress is not clear; however, it has been suggested that in the bovine, PRL may be involved in fluid regulation by acting on the kidney tubules to interact either with atdosterone or antidiuretic hormone to influence renal blood flow and water excretion (4). A similar conclusion was reached in a study with humans during exposure to heat stress (21). The effect of spray plus fan under shade on freestall utilization of Holsteins during 1984 summer is in Table 6. Ambient temperature
TABLE 3. Correlation estimates among milk (Tmilk) versus rectal (Tre) t e m p e r a t u r e s for cows in shade and in shade plus spray and fan during 1984 summer. Clawpiece Measurement Clawpiece Tmilk 0 400 h Shade Shade + spray + fan 1600 h Shade Shade + spray + fan Meter Tmilk 0 400 h Shade Shade + spray + fan 1600 h Shade Shade + spray + fan
~7
e~ < o
Tre 0430 h Shade Shade + spray + fan 1630 h Shade Shade • spray + fan INS = Not significant at 5%. *P< .05.
Z
o
7~ oo
* *P<.01.
Tmilk 0400 h
Meter Tmi l k 1600 h
Tmilk 0400 h
Tmilk 1600 h
Tre 0400 h
1600 h Z < Z
1,000 1.000 .627** .619"*
2,
1.000
1.000 2, t-q
.746** .742**
.303* .557**
1.000 1.000
.520** .739**
.870** .542**
.310" .481"*
.655" * .684**
.428" .456*
.333"* .359**
.223" .226*
.627** .681"*
.875** .894**
.253* .268"
.391" * .301"*
7¢
2, 1.000
2, Z
1.000
2, Z
1.000 1.000 .495** .194 NS1
1.000 1.000
c~
1076
IGONO ET AL.
TABLE 4. Milk production and somatic cell counts of cows in shade and in shade plus fan freestalls during 1984 summer at Columbia, MO. 1
Measurement
Shade + spray + fan
Shade SE
Milk production, kg/d a.m. p.m. Total Somatic e e l l c o u n t ( l O 3) a.m. p.m. a b
.
12.8 a 10.5 a 23.3 a
X
.37 .22 .25
293 a 277 a
SE
13.7 b 11.6 b 25.3 b
23 16
.25 .19 .21
238 b 257 b
18 16
.
' Means within rows having different superscripts differ (P<.05).
1 Study conducted between June 27 and August 15, 1984.
d u r i n g o b s e r v a t i o n s o n d 1 r a n g e d b e t w e e n 23.9 a n d 33.3°C. Cows in b o t h g r o u p s s p e n t a considerable p a r t of t h e day s t a n d i n g r a t h e r t h a n lying d o w n . By standing, cows m a x i m i z e evap o r a t i o n f r o m b o d y surfaces a n d also b e n e f i t f r o m c o n v e c t i o n d u e to w i n d . F o r cows in s h a d e plus s p r a y a n d fan, m u c h of t h e s t a n d i n g in t h e s h a d e was w i t h t h e f o r e l i m b s in t h e stall a n d h i n d l i m b s in t h e alley. In this m a n n e r , cows benefited by exposing the body trunk to spray w a t e r a n d fan s i m u l t a n e o u s l y . O n d 2, a n i m a l s were o n p a s t u r e b e t w e e n 1 1 0 0 a n d 1 2 0 0 h for exercise, b u t b e f o r e t h e y r e t u r n e d , t h e gate b e t w e e n g r o u p s was removed. Ambient temperature declined from 32.2°C at 1 2 0 0 h to 17.2°C at 2 4 0 0 h w i t h a O m e a n of 26.2 C. O f all cows (19), o n l y .6 h were s p e n t u n d e r s h a d e o n l y . T h e r e m a i n d e r
were u n d e r t h e s p r a y fan s y s t e m as i n d i c a t e d . Cows p r e f e r r e d t h e t h e r m o r e g u l a t o r y b e n e f i t s o f s p r a y plus fan. However, a f t e r 2 0 0 0 h, w h e n s p r a y a n d fan a u t o m a t i c a l l y t u r n e d off, s o m e cows f r o m s h a d e g r o u p w e n t b a c k to t h e i r s h a d e freestall area a n d s p e n t t h e r e m a i n d e r o f t h e n i g h t lying o n t h e o p e n l o t b e h i n d t h e f e e d b u n k . T h e b e h a v i o r a l p a t t e r n o n d 3 was similar t o d 2. Despite t h e p r e l i m i n a r y n a t u r e of t h e s e b e h a v i o r a l studies, t h e e v i d e n c e was t h a t given choice o f s h a d e versus s h a d e plus s p r a y plus fan freestalls, cows w o u l d c h o o s e s h a d e plus s p r a y plus fan. F e e d i n t a k e , milk yield, a n d e c o n o m i c analysis o f t h e p e r f o r m a n c e o f s p r a y a n d fan treatm e n t is s h o w n in T a b l e 7. Cows in s h a d e plus s p r a y a n d f a n ate m o r e feed a n d p r o d u c e d 2 kg m o r e m i l k c o m p a r e d w i t h cows in shade. It is
TABLE 5. Effect of shade and shade plus spray with fan on plasma growth hormone and prolactin of Holstein cows during summer 1984.1
Measurement
Plasma growth hormone, ng/ml Plasma prolactin, ng/ml
Shade + spray + fan (n=12)
Shade (n=12)
4.6 a 59.9 a
SE
~,
SE
.21 1.79
5.7 b 44.9 b
.31 .94
a'bMeans within rows having different superscripts differ (P<.05). 1 Study conducted between June 27 and August 15, 1984. Journal of Dairy Science Vol. 70, No. 5, 1987
1077
ENVIRONMENTAL SHADE, SPRAY, AND FAN EFFECTS
TABLE 6. Preference of lactating cows for spray plus fan versus shade during summer heat between I i 0 0 and 2400 h during summer 1984. Groups Day Date (1984) No, cows prefer Shade Shade+ 2 Avg. hours per cow Shade Shade+
Restricted 1 8/21 9 10
Choice
Choice
2 8/22
3 8/23
19 19
8 7.8
19 19
.6 6.9
.4 9.0
1Shade over free stalls, alley, and feed bunk. Shade+ = Shade + spray + fan. Spray over alley and rear of feed bunk with fan (air ducts) over rear of feed bunk and with fan (air ducts) over each freestall and feed bunk. 3 Average hours per cow; standing with head in freestall to benefit from fan with rear in freestall alley or in feed bunk area between 1100 and 2400 h. 4 Observations made every 30 min except time of feeding and milking.
TABLE 7. Feed intake, milk yield, and estimated economic analysis of productive performance of cows in shade and shade plus spray and fan freestalls during summer 1984 in Columbia, MO.
Shade
Shade + spray + fan
Difference
Feed intake, kg/d (silage and grain mixture as fed)
32.8
35.1
+2.3
Milk yield, kg/d a.m. p.m. Total
12.7 10.6 23.3
13.7 11.6 25.3
+1.0 +1.0 +2.0
$2.70
$2.89
Economic analysis Input variables Feed intake, $/kg per cow per d, 8.2¢ Water intake, 1 $/L per cow per d, .05¢ Spray water, ~ $/L per cow per d, .05¢ Fan (2 hp, 1 fan), 3 est. kWh per cow per d Total input costs Income from milk, 29.5¢/kg per d Profit, S/cow per d 4
6¢
3¢ $.11 $.10
;2176
$3.13
$37
$6.88
$7.47
$.59 $.22
1Water intake for shade = 133 L/cow per d. Shade + spray + fan = 53 L/cow per d. 2 Spray water = 217 L/cow per d and does not include costs of shade, pipes, and installation labor. 3 Fan (two 1 hp units) operated for 6C/kwh an average of 10 h/d. 4 Other benefits of body weight gain or lack of weight loss due to stress and reproductive efficiency are not considered here. Journal of Dairy Science Vol. 70, No. 5, 1987
1078
IGONO ET AL.
a p p a r e n t , t h e r e f o r e , t h a t t h e s p r a y plus fan t r e a t m e n t , b y m i n i m i z i n g t h e e x t e n t a n d durat i o n of h e a t stress, lessened t h e t h e r m a l inhibit i o n of f e e d i n t a k e t o allow f o r h i g h e r e n e r g y c o n s u m p t i o n a n d m e t a b o l i s m n e c e s s a r y t o sustain high p r o d u c t i v e p e r f o r m a n c e . A conservative e c o n o m i c analysis using local prices s h o w e d a n e t i n c o m e o f 2 2 ¢ / c o w per d for cows in s h a d e plus s p r a y a n d fan over cows in shade. This w o u l d b e a p p r o x i m a t e l y $ 2 2 / d a y per 1 0 0 cows f o r this 56-d s u m m e r h e a t period. T h e costs o f e x t r a feed i n t a k e , s p r a y water, a n d fan e l e c t r i c i t y were d e d u c t e d f r o m i n c o m e , leaving 2 2 ¢ / c o w as n e t profit. However, effects o f c o m f o r t a n d a n y o t h e r a n i m a l physiological b e n e f i t s d u e to l o w e r e d b o d y t e m p e r a t u r e were n o t measured. In s u m m a r y , m i l k t e m p e r a t u r e , especially in t h e claw piece, offers a n o p p o r t u n i t y t o assess t h e i m p a c t o f climate o f dairy cows plus it m a y b e useful in d e t e c t i o n o f mastitis (13) a n d estrus (18, 19). However, t h e possibility t h a t h e a t stress m a y o b s c u r e t h e e s t r u s - i n d u c e d rise in Tmilk d u r i n g s u m m e r n e e d s i n v e s t i g a t i o n a n d clarification, b e c a u s e t h e r m a l e n v i r o n m e n t was n o t i n t e g r a t e d in t h e i n t e r p r e t a t i o n o f t h e d a t a o f Maatje a n d R o s s i n g (19). Overall, s p r a y plus fan u n d e r s h a d e p r o v e d to b e a l o w cost management practice that improved thermal balance, lessened physiological changes, a n d increased m i l k yields, r e s u l t i n g in a greater profit margin for milk production. ACKNOWLEDGMENTS
T h e assistance o f W. A. H a i n e n a n d F o r e m o s t Dairy F a r m S t a f f w i t h a n i m a l m a n a g e m e n t a n d t e c h n i c a l assistance o f Carl H o u c h i n s w i t h i n s t r u m e n t s is a p p r e c i a t e d . REFERENCES
1 Ansell, R. H. 1983. Extreme heat stress in dairy cattle and its alleviation. A case report. Pages 205-306 in Environmental aspects of housing for animal production. J. A. Clark, ed. Butterworths, London. 2 Bane, A., and E. Rajahkowski. 1961. The bovine estrous cycle. Cornell Vet. 51 : 77. 3 Bauman, D. E., J. H. Eisemann, and W. B. Currie. 1982. Hormonal effects on partitioning of nutrients for tissue growth: role of growth hormone and prolactin. Fed. Proc. 41:2538. 4 Becker, B. A., M. A. Bober, F. D. EI-Nouty, and H. D. Johnson. 1985. Prolactin and its involvement in fluid regulation in the bovine. Comp. Biochem. 81A:93--98. Journal of Dairy Science Vol. 70, No. 5, 1987
5 Bodoh, C. W., C. J. Tyler, L. H. Schultz, and G. F. Shook. 1972. Thyroid activities of Holstein cows selected for average or high average milk production. J. Dairy Sci. 55:682. 6 Bond, T. E., C. F. Kelly, S. R. Morrison, and N. Pereira. 1957. Solar, atmospheric, and'terrestrial radiation received by shaded and unshaded animals. Trans. Am. Soc. Agric. Eng. 10:622. 7 Brody, S., A. C. Ragsdale, H. J. Thompson, and D. M. Worstell. 1954. The effect of wind on milk production, feed and water consumption and body weight in dairy cattle. Missouri Agric. Exp. Stn. Res. Bull. 545. 8 Clabaugh, G. A., G. M. Jones, R. E. Pearson, C. W. Heald, and W. E. Vinson. 1981. The effect of DHI somatic cell counts upon milk production. J. Dairy Sci. 64:148. 9 Friend, R. J., and R. C. Littell. 1981. SAS for linear models. SAS Inst. Inc., Cary, NC. 10 Fuquay, J. W., A. B. Zook, J. w. Daniel, W. H. Brown, and W. E. Poe. 1979. Modifications in freestall housing for dairy cows during the summer. J. Dairy Sci. 62:577. 11 Gangwar, P. C., C. Branton, and D. L. Evans. 1965. Reproductive and physiological responses of Holstein heifers to controlled and natural climatic conditions. J. Dairy Sci. 48:222. 12 Hart, I. C., J. A. Bines, and S. V. Morant. 1979. Endocrine control of energy metabolism in the cow: correlations of hormones and metabolites in high- and low-yielding cows for stages of lactation. J. Dairy Sci. 62:270. 13 Igono, M. O., B. J. Steevens, M. D. Shanklin, and H. D. Johnson. 1985. Spray cooling effects on milk production, milk and rectal temperature of cows during a moderate temperate summer season. J. Dairy Sci. 68:979. 14 Igono, M. O., H. D. Johnson, B. J. Steevens, and M. D. Shanklin. 1985. Environmental modifications for cows. Ph.D. thesis, Univ. Missouri, Columbia. 15 Ingraham, R. H., R. W. Stanley, and W. C. Wagner. 1979. Seasonal effects of tropical climate on shaded and nonshaded cows as measured by rectal temperature, adrenal cortex hormones, thyroid hormone and milk production. Am. J. Vet. Res. 40 : 1792. 16 Johnson, H. D., O. DeDios, and A. C. Lippincott. 1976. Environmental stress, TRH, and lactation effects on plasma growth hormone of cattle. Pages 5 5 5 - 5 6 2 in Nuclear techniques in animal production and health. Int. At. Energy Ag., Vienna, Austria. 17 Kibler, H. H., and S. Brody. 1954. Influence of radiation intensity on evaporative cooling, heat production, and cardiorespiratory activities in Jersey, Holstein, and Brahman cows. Missouri Agric. Exp. Sm. Res. Bull. 574. 18 Lira, M., R. G. Rodewald, and S. L. Sphar. 1975. Relation of estrus to temperatures of ear canal, rectum, and milk in dairy cattle. J. Dairy Sci. 58 (Suppl. 1):770. (Abstr.) 19 Maatje, K., and W. Rossing. 1976. Detecting estrus by measuring milk temperatures of dairy cows during milking. Livest. Prod. Sci. 3:85.
E N V I R O N M E N T A L SHADE, SPRAY, AND FAN EFFECTS 20 Miller, G, D., J. B. Frye, Jr., B. J. Burch, Jr., P. J. Henderson, a n d L. L. Rusoff. 1951. The effect of sprinkling on the respiratory rate, b o d y temperature, grazing performance and milk production of dairy cattle. J. A n i m . Sci. 10:961. 21 Mills, D. E., and D. Robertshaw. 1981. Responses of plasma prolactin to changes in ambient temperature and h u m i d i t y in man. J. Clin. Endocr. Metab. 52:279. 22 M o h a m m e d , M. E., and H. D. Johnson. 1985. Effect of growth h o r m o n e on milk yields and related physiological functions of Holstein cows exposed to heat stress. J. Dairy Sci. 68:1123. 23 Paape, M. J., W. D. Schultze, R. H. Miller, and J. W. Smith. 1973. Thermal stress and circulating e n y t h r o c y t e s , leucocytes and milk somatic cells. J. Dairy Sci. 56:84.
Journal of Dairy Science Vol. 70, No. 5, 1987
1079
24 Ragab, M. T., M. A. Ghany, and A. A. Asker. 1953. Effect of shading and sprinkling on cattle and buffaloes in Egypt. Ind. J. Vet. Sci. Anita. Husb. 23:205. 25 Roman-Ponce, H., W. W. Thatcher, D. E. Buffington, C. J. Wilcox, and H. H. Van Horn. 1977. Physiological and production responses of dairy cattle to a shade structure in a subtropical environment. J. Dairy Sci. 60:424. 26 Wegner, T. N., J. D. Shuh, F. E. Nelson, and G. H. Stott. 1976. Effect of stress on blood leucocyte and milk somatic cell counts in dairy cows. J. Dairy Sci. 59:949. 27 Zartman, D. L., D. M. Halford, L. A. Tierney, and M. Y. Hussain. 1983. Reproductive characteristics of Holstein heifers fitted with intravaginal temperature transmitters. Theriogenology 19:541.
ABSTRACT
During the 1984 summer, effects of spray and fan in freestall areas and feeding areas on milk yield, plasma growth hormone and prolactin, freestall utilization, and economic significance for Holstein cows were studied. Weekly milk and rectal temperatures at morning and afternoon milkings were higher for cows in shade than in shade with spray and fan cooling. Compared with rectal temperature, milk temperature measured in the clawpiece provided a more reliable indicator of heat stress than in the milk meter. Diurnal pattern of rectal temperature from 4-h measurements showed an average of 12 h in which maximal rectal temperatures of cows in shade were greater than 39°C, but cows in the shade plus spray plus fan ~roup had rectal temperatures below 39vC all day. Plasma growth hormone was higher and prolactin lower for cows in shade plus spray and fan than cows in shade only. Cows cooled with spray and fan under shade produced 2 kg/cow per d more than cows in shade alone. Eeconomic analysis showed a net income of 22¢Jcow per day for spray plus fan under shade. Results suggest that milk temperature is a practical technique to assess heat stress in dairy cattle, and the use of spray plus fan is a profitable means to maximize cow
Received April 14, 1986. Accepted December 26, 1986. Reprint requests. Department of Dairy Science. a Department of Statistics. 4 Department of Agricultural Engineering. 1987 J Dairy Sci 70:1069-1079
comfort and lessen stress-induced decline in milk production. INTRODUCTION
In studies during the 1982 and 1983 summers in Missouri, significant thermoregulatory and milk production benefits to lactating dairy cows were repeatedly demonstrated with use of water sprays. This benefit was provided by the simultaneous reduction in external heat load (17) with shades and increased conducive and evaporative heat loss from direct spraying of water on the body of cows (13, 14). Similar results relating to heat balance and milk production benefits have been reported with shade (6, 25), fan (7, 11, 15), spray (1, 14, 15, 20), or their combinations (10, 24) in various climates. However, available data on use of water sprays and fans lack information needed to answer critial questions relating to the extent and duration of thermoregulatory and milk production benefits, alterations in hormone concentrations, or economic benefits. These answers are needed before there can be recommendations for development and adoption of environmental modifcations to minimize climatic limitations to animal production. The primary objective of this investigation was to evaluate the physiological, productive, and economic benefits of spray and fan under shade to lactating Holstein cows during temperate summer conditions in Missouri. Specific objectives were a) to evaluate the benefits of shade plus spray and fan versus shade only for milk yields and somatic cell counts; b) to assess the benefits to thermal balance from measures of milk and rectal temperatures; c) to examine the effects of the environmental modifications on plasma growth hormone and prolactin ; d) to study the effects of spray and fan on behavioral action of freestall utilization ; and e) to evaluate the economic benefits of the use of spray and fans under shade. 1069
1070
IGONO ET AL. M A T E R I A L S A N D METHODS
During the summer of 1984, we added fans to the shade plus spray freestall and feeding areas of our 1983 study (14). Air was drawn from outside b y a fan connected to rigid galvanized tin ducts placed on dividers between adjoining freestalls. At each individual freestall, 8.9-cm diameter holes were cut in the duct to provide an air movement of 6.6 m/s (14 mph) over each individual cow. A similar fan system using polypropylene plastic ducts was installed under the shade over the feed bunk. Air movement was provided by use of a .41-m diameter tube axial fan (W. W. Ranger, Inc., St. Louis, MO). Sprays were timed for on and off sequence of 20 and 10 rain, respectively, as in the 1983 study. Sprays and fans were controlled by a thermostat to operate when ambient temperature exceeded 27°C. On June 26, 1984, 12 cows were placed in shade plus spray plus fan freestalls, and another 12 cows in adjacent freestalls served as shade group. Feed was offered ad libitum at 0430 and 1530 h daily. Prior to 1530 h scheduled daily feeding, refusals were weighed on a lot basis. Clean drinking water was available continuously and water consumption was recorded daily on a group basis. Each day, milk production, amount of water sprayed, and hours per day sprayed were measured and recorded. Temperature of spray and drinking water ranged between 18 and 25°C as monitored by thermocouples and recording potentiometer. Reproductive and health records were kept. Every Wednesday, milk temperature (Tmilk) was measured at both a.m. (0430 h) and p.m. (1630 h) milkings both at the claw and milk meter. Following milkings, rectal temperature (Tre) of cows in both groups were measured. To examine further the extent and duration o f cooling offered by fan and spray compared with shade, diurnal pattern of "Ire was characterized from Tre taken at 4-h intervals for cows in both groups once every 2 wk. Blood samples were collected weekly from the tail vein using heparinized vacutainer tubes with 20-gauge needles and placed on ice for transport to the laboratory. Blood samples were centrifuged at 3000 rpm for 30 min at 4°C and plasma samples frozen at - 2 0 ° C until analyzed. Procedures for radioimmunoassay of plasma growth hormone (GH) and prolactin (PRL) Journal of Dairy Science Vol. 70, No. 5, 1987
were as described by Mohammed and Johnson (22). We observed that cows in shade plus spray and fan group tended to utilize their freestalls more than shade group. Therefore, a supplementary study was designed to evaluate the effect of shade or shade plus spray with fan on freestall utilization at the conclusion of scheduled experiments. On d 1, time cows in both groups spent resting in their stalls or alley was observed at half-hour intervals between 1100 and 2400 h. On d 2, the gate between groups was removed to give animals free choice of either shade or shade plus spray and fan; observations were as in d 1. On d 3, ambient temperature did not rise above 27°C, but observations were made as described for d 1. Relative humidity (RH) and black globe (Tg) and dry bulb (Tdb) temperatures were monitored and recorded continuously as described during the 1983 study (13). Data were analyzed b y method of least squares using linear model procedures. Pooled data and sampling day means were compared for differences on a group basis. Linear correlation analysis was between main effects (9). Significance was set at 5%. RESULTS A N D DISCUSSION
Thermal environments during the 1984 summer study are in Table 1. In general, thermal environments were similar between groups. Humidities reported indicated that spraying did not lead to moisture buildup in the freestall areas. Similar observations were reported in the 1983 study (14). In essence, the ability of the animal to dissipate its b o d y heat to the environment may be attributable to the direct effect of the spray and fan treatment on the animals. The effect of spray with fan under the shade during summer on Tre and Tmilk measured in the meter or clawpiece on Holstein cows is presented in Table 2. Morning and afternoon Tre were higher (P<.05) for cows in shade than in shade plus spray with fan, but for both groups the p.m. Tre were higher (P<.05) than a.m. Tre. Values for Tmilk at clawpiece were higher (P<.05) for cows in shade than shade plus spray and fan. Clawpiece Trnak of cows in shade at a.m. and p.m. sampling was higher (P<.05) than for shade plus spray and fan group, but for both groups a.m. clawpiece Tmilk was lower
E N V I R O N M E N T A L SHADE, SPRAY, A N D FAN EFFECTS
1071
TABLE 1. Thermal e n v i r o n m e n t u n d e r shade and shade plus spray plus fan freestall areas during 1984 s u m m e r )
Measurement
Shade + spray + fan
Shade R
SE
R
SE
Dry bulb temperature, ~C 0400 h 1600 h
21.9 31.0
.88 1.04
22.1 30.8
.94 1.03
Black globe temperature, °C 0400 h 1600 h
21,5 43.0
1.11 3.54
21.4 43.6
1.12 3.45
Relative humidity, % 0400 h 1600 h
77.6 43.0
3.86 3.54
77.7 43.6
3.89 3.45
Dry bulb THI ~ 0400 h 1600 h
69.9 78.3
1.57 1.22
70.1 78.2
1.56 1.17
Black globe THI 2 0400 h 1600 h
69.3 81.2
1.80 2.87
69.1 81.7
1.81 2.78
Study conducted between June 27 and August 15, 1984. 2 THI = T e m p e r a t u r e - h u m i d i t y index.
( P < . 0 5 ) t h a n p . m . M e t e r Tmilk w a s s i m i l a r b e t w e e n g r o u p s at a . m . m i l k i n g s , b u t c o w s in shade had higher p.m. values than shade plus s p r a y a n d f a n ( 3 8 . 6 vs. 3 8 . 1 ° C ) . C o l l e c t i v e l y ,
these data demonstrate that spray plus fan enhanced heat loss to minimize heat accumulation during the day and enabled the animals to a t t a i n n o r m a l Tmilk a n d Tre b y a . m . s a m p l i n g .
TABLE 2. Mean milk (Tmilk) and rectal temperature (Tre) of Holstein cows in shade and shade plus spray and fan freestall areas during 1984 s u m m e r in Columbia, MO.
Measurement
Shade + spray + fan
Shade SE
~
SE
Tre, °C a.m. p.m.
38.7A, a 39.2B, a
.05 .08
38.5A, b 38.8B, b
.05 .04
Clawpiece Tmilk , ° C a.m. p.m.
38.6 A,a 39.1B, a
.06 .12
38.2A, b 38.6B, b
.11 .09
Meter Tmilk , °C a.m. p.m.
37.9C, a 38.6A, a
.07 .07
37.8C, a 38.1A, a
.10 .09
a~b,
.
,
.
Lvieans w l t m n rows having different superscripts differ (P<.05).
A'B'CMeans within columns with different superscripts differ (P<.05). a Study conducted between June 27 and August 15, 1984. Journal of Dairy Science Vol. 70, No. 5, 1987
1072
IGONO ET AL. h sampling time during the 56-{t experimental period of 1984 summer study. At 0400 h sampling, THI were similar between groups and generally below the critical value of 72 but near 70 during the last 3 wk. In general, Tmilk and Tre response patterns were similar and followed changes in thermal environment. The THI was about 2 to 9 units above the critical value of 72 at afternoon samplings and the animals gained more heat from the environment than could be dissipated. This is evidenced by the higher Tmilk and Tre values compared with 0400-h samplings as discussed in Table 2. Clawpiece and meter Tmilk responses were remarkably similar to Tre in pattern. These
Failure to regain normal body temperature overnight is a critical factor that limits the productive ability during the heat of the following day (14). In the shade group, clawpiece Tmilk and Tre were similar at both a.m. (38.6 vs. 38.7°C) and p.m. (39.1 vs. 39.2°C) samplings, but both clawpiece Trnilk and Tre were higher (P<.05) than meter Tmilk. A similar pattern existed for cows in shade plus spray and fan. This suggests that Tmilk at the claw site was the preferable site to measure heat effects on the cow. Figure 1 illustrates temperature-humidity index effects on Tre and Tmilk of cows in shade and shade plus spray with fan at 0400 and 1600
1600 h
0400 h
.1I
~
7
2
-!
o
•
oSO.o/ ill
./--- / " ' x ~1
010
|
°/
~0..--0~-01
3 O a t e : 6 2 7 7 o 3 711 718
Y 808
815
o
6 2 7 7 0 3 711 718 7 2 5 8 0 8 815: 1984
Figure 1. A comparative illustration of temperature-humidity index, rectal temperature, and milk temperatures of Holstein cows in shade (e-e) and shade plus spray plus fan (o-o) environments during summer 1984 at 0400 and 1600 h. Journal of Dairy Science Vol. 70, No. 5, 1987
E N V I R O N M E N T A L SHADE, SPRAY, AND FAN EFFECTS
observations of similarity in response of Tmilk and Tre as reported earlier (13, 14) demonstrate the practicability of using Tmi/k to assess the impact of climate and assess body temperature similar to Tre. Figure 2 describes more specifically the diurnal pattern of Tg, Tdb , RH, and Tre of cows in shade and shade plus spray and fan areas during 1984 summer. The thermal environment was generally similar between groups. Between 0800 and 1600 h, Tg was 3 to 5°C higher than Tdb, apparently because Tdb did not account
1073
for solar radiation and windspeed. Overall, Tdb was similar between groups. For about 11 h during the day, Tal~ was greater than 27°C. Relative humidity averaged 48% for both groups during the day but was above 65% at night. The diurnal pattern of Tre showed cows cooled with spray and fan were .3 to 1.2°C lower than for shade. Furthermore, Tre of cows in shade was above 39°C between 1200 and 2400 h compared with 0 h above 39°C during 24 h for cows in shade plus spray and fan.
-in
o
65
~ z
.0_
C
3
E
55
25
K
45
39.5
I,3g
o.
w
n
.J ul ~
I-- ~ ILl
38.5 40
/i,\ 9(/ o-
39 0"
"d
38
/
\
\
\
\
Cows in Estrus
,'
>¢
"\
/
/
/
/
/
-.0//
\o
,i
, hours spray and fan on
I
0400
I
I
0800 1200
I
I
I
I
1 6 0 0 2000 2400 0400
Time of Day,hours Figure 2. Diurnal pattern of black globe (Tg) and dry bulb temperatures (Tdb), relative h u m i d i t y (rh), and rectal temperature of cows in shade ( o - o ) and shade plus spray plus fan ( o - o ) environments during s u m m e r 1984. Journal o f Dairy Science Vol. 70, No. 5, 1987
1074
IGONO ET AL.
These observations, when compared with those of the previous study (13, 14) when Tre of spray cooled cows reached 39.5°C during the day, suggested that fan increased the effectiveness of spray. On sampling days for diurnal Tre, one cow in shade was observed in estrus, whereas 6 cows in shade plus spray and fan were in estrus. Although spray and fan treatment under shade minimized estrus-induced increases in "Ire, cows in estrus in the shade plus spray and fan group could be identified on the basis of their "Ere. Similar observations were made during summer in Louisiana when cows were housed in airconditioned chambers (11). Other researchers have reported estrous-related changes to Tr e or vaginal temperature (2), and telemetry of vaginal temperature has been a practical tool for estrous detection. The correlation estimates among Tmilk and Tre of Holstein cows housed in shade and shade plus spray and fan during 1984 summer are given in Table 3. At both 0400 and 1600-h samplings, the r-values between Tmilk measured in clawpiece and meter were highly significant. A comparison of the correlations and significance of clawpiece Tmilk t o Tre at 0400 and 1600-h samplings were significant (P<.01) for both groups, but the correlations between meter Tmilk and Tre were lower yet significant (P<.05). Because of the similarity in absolute values of elawpiece Tmilk and Tre (Table 2) and the higher correlation between clawpiece Tmilk and Tre than between meter Tmilk and Tre, the clawpiece is the best indicator of b o d y temperature. Observations were similar in other studies using only clawpiece Tmilk (18, 19). Table 4 presents the effects of shade and shade plus spray with fan on milk production. Spray plus fan treatment under shade increased milk yields by 2 kg/cow per d compared with 1.6 kg/cow per d during the 1983 study (13). Although the thermal environments during the 2 yr were not exactly the same, spray plus fan appeared to be more effective than spray alone. Somatic cell count of cows in the shade group at a.m. and p.m. samplings were higher than shade plus spray plus fan (Table 4). A difference in SCC occurred between treatments at 21 and 32°C in association with Tre fluctuations of 1.8°C (23). Data from Arizona showed SCC peaked during the hot summer months from June through November (26), whereas in Wisconsin, peak SCC was from July through Journal of Dairy Science Vol. 70, No. 5, 1987
August (5). Although the differences in SCC appear related to differences in Tre as influenced by heat stress, one study (23) concluded that heat stress per se may not influence SCC in uninfected udders. This is somewhat supported by milk yields that declined as SCC increased and for each doubling of SCC milk yields decreased about .7 kg milk/d (8). Somatic cells comprise displaced alveolar epithelial cells, phagocytes, and white blood cells. The effect of spray plus fan treatment under shade on plasma GH and PRL is shown in Table 5. Plasma GH was higher (P<.05) for cows in shade plus spray with fan than shade, as observed for spray cooling during 1983 (14). The decline in GH in the shade group versus the shade plus spray plus fan group is probably associated with chronic stress of summer (15). Growth hormone is involved in energy partitioning of milk production in dairy cows and its concentration in plasma is positively associated with milk production (3, 12, 16). Because cows in the spray plus fan group had higher plasma GH and produced more milk, hyperthermiarelated alterations of circulating GH may be involved in the mechanism of reduced milk yield during heat stress. This hypothesis has been clearly borne out by the climatic chamber study with GH supplementation to cows during heat stress, which resulted in an 8% increase in milk production (22). That study suggested that SCC in milk increased slightly due to heat, as the milk yields decreased, i.e., SCC appears related to body and environmental temperature. There appears to be no significant effect of exogenously administered GH on SCC during this short experimental period. Plasma PRL was significantly higher for cows in shade than in shade plus spray and fan, as in summer 1983 (14). Thus, plasma PRL increases as Tre and Tmilk increase, whereas GH declines with prolonged increases in heat stress (14). The specific role of PRL response to heat stress is not clear; however, it has been suggested that in the bovine, PRL may be involved in fluid regulation by acting on the kidney tubules to interact either with atdosterone or antidiuretic hormone to influence renal blood flow and water excretion (4). A similar conclusion was reached in a study with humans during exposure to heat stress (21). The effect of spray plus fan under shade on freestall utilization of Holsteins during 1984 summer is in Table 6. Ambient temperature
TABLE 3. Correlation estimates among milk (Tmilk) versus rectal (Tre) t e m p e r a t u r e s for cows in shade and in shade plus spray and fan during 1984 summer. Clawpiece Measurement Clawpiece Tmilk 0 400 h Shade Shade + spray + fan 1600 h Shade Shade + spray + fan Meter Tmilk 0 400 h Shade Shade + spray + fan 1600 h Shade Shade + spray + fan
~7
e~ < o
Tre 0430 h Shade Shade + spray + fan 1630 h Shade Shade • spray + fan INS = Not significant at 5%. *P< .05.
Z
o
7~ oo
* *P<.01.
Tmilk 0400 h
Meter Tmi l k 1600 h
Tmilk 0400 h
Tmilk 1600 h
Tre 0400 h
1600 h Z < Z
1,000 1.000 .627** .619"*
2,
1.000
1.000 2, t-q
.746** .742**
.303* .557**
1.000 1.000
.520** .739**
.870** .542**
.310" .481"*
.655" * .684**
.428" .456*
.333"* .359**
.223" .226*
.627** .681"*
.875** .894**
.253* .268"
.391" * .301"*
7¢
2, 1.000
2, Z
1.000
2, Z
1.000 1.000 .495** .194 NS1
1.000 1.000
c~
1076
IGONO ET AL.
TABLE 4. Milk production and somatic cell counts of cows in shade and in shade plus fan freestalls during 1984 summer at Columbia, MO. 1
Measurement
Shade + spray + fan
Shade SE
Milk production, kg/d a.m. p.m. Total Somatic e e l l c o u n t ( l O 3) a.m. p.m. a b
.
12.8 a 10.5 a 23.3 a
X
.37 .22 .25
293 a 277 a
SE
13.7 b 11.6 b 25.3 b
23 16
.25 .19 .21
238 b 257 b
18 16
.
' Means within rows having different superscripts differ (P<.05).
1 Study conducted between June 27 and August 15, 1984.
d u r i n g o b s e r v a t i o n s o n d 1 r a n g e d b e t w e e n 23.9 a n d 33.3°C. Cows in b o t h g r o u p s s p e n t a considerable p a r t of t h e day s t a n d i n g r a t h e r t h a n lying d o w n . By standing, cows m a x i m i z e evap o r a t i o n f r o m b o d y surfaces a n d also b e n e f i t f r o m c o n v e c t i o n d u e to w i n d . F o r cows in s h a d e plus s p r a y a n d fan, m u c h of t h e s t a n d i n g in t h e s h a d e was w i t h t h e f o r e l i m b s in t h e stall a n d h i n d l i m b s in t h e alley. In this m a n n e r , cows benefited by exposing the body trunk to spray w a t e r a n d fan s i m u l t a n e o u s l y . O n d 2, a n i m a l s were o n p a s t u r e b e t w e e n 1 1 0 0 a n d 1 2 0 0 h for exercise, b u t b e f o r e t h e y r e t u r n e d , t h e gate b e t w e e n g r o u p s was removed. Ambient temperature declined from 32.2°C at 1 2 0 0 h to 17.2°C at 2 4 0 0 h w i t h a O m e a n of 26.2 C. O f all cows (19), o n l y .6 h were s p e n t u n d e r s h a d e o n l y . T h e r e m a i n d e r
were u n d e r t h e s p r a y fan s y s t e m as i n d i c a t e d . Cows p r e f e r r e d t h e t h e r m o r e g u l a t o r y b e n e f i t s o f s p r a y plus fan. However, a f t e r 2 0 0 0 h, w h e n s p r a y a n d fan a u t o m a t i c a l l y t u r n e d off, s o m e cows f r o m s h a d e g r o u p w e n t b a c k to t h e i r s h a d e freestall area a n d s p e n t t h e r e m a i n d e r o f t h e n i g h t lying o n t h e o p e n l o t b e h i n d t h e f e e d b u n k . T h e b e h a v i o r a l p a t t e r n o n d 3 was similar t o d 2. Despite t h e p r e l i m i n a r y n a t u r e of t h e s e b e h a v i o r a l studies, t h e e v i d e n c e was t h a t given choice o f s h a d e versus s h a d e plus s p r a y plus fan freestalls, cows w o u l d c h o o s e s h a d e plus s p r a y plus fan. F e e d i n t a k e , milk yield, a n d e c o n o m i c analysis o f t h e p e r f o r m a n c e o f s p r a y a n d fan treatm e n t is s h o w n in T a b l e 7. Cows in s h a d e plus s p r a y a n d f a n ate m o r e feed a n d p r o d u c e d 2 kg m o r e m i l k c o m p a r e d w i t h cows in shade. It is
TABLE 5. Effect of shade and shade plus spray with fan on plasma growth hormone and prolactin of Holstein cows during summer 1984.1
Measurement
Plasma growth hormone, ng/ml Plasma prolactin, ng/ml
Shade + spray + fan (n=12)
Shade (n=12)
4.6 a 59.9 a
SE
~,
SE
.21 1.79
5.7 b 44.9 b
.31 .94
a'bMeans within rows having different superscripts differ (P<.05). 1 Study conducted between June 27 and August 15, 1984. Journal of Dairy Science Vol. 70, No. 5, 1987
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ENVIRONMENTAL SHADE, SPRAY, AND FAN EFFECTS
TABLE 6. Preference of lactating cows for spray plus fan versus shade during summer heat between I i 0 0 and 2400 h during summer 1984. Groups Day Date (1984) No, cows prefer Shade Shade+ 2 Avg. hours per cow Shade Shade+
Restricted 1 8/21 9 10
Choice
Choice
2 8/22
3 8/23
19 19
8 7.8
19 19
.6 6.9
.4 9.0
1Shade over free stalls, alley, and feed bunk. Shade+ = Shade + spray + fan. Spray over alley and rear of feed bunk with fan (air ducts) over rear of feed bunk and with fan (air ducts) over each freestall and feed bunk. 3 Average hours per cow; standing with head in freestall to benefit from fan with rear in freestall alley or in feed bunk area between 1100 and 2400 h. 4 Observations made every 30 min except time of feeding and milking.
TABLE 7. Feed intake, milk yield, and estimated economic analysis of productive performance of cows in shade and shade plus spray and fan freestalls during summer 1984 in Columbia, MO.
Shade
Shade + spray + fan
Difference
Feed intake, kg/d (silage and grain mixture as fed)
32.8
35.1
+2.3
Milk yield, kg/d a.m. p.m. Total
12.7 10.6 23.3
13.7 11.6 25.3
+1.0 +1.0 +2.0
$2.70
$2.89
Economic analysis Input variables Feed intake, $/kg per cow per d, 8.2¢ Water intake, 1 $/L per cow per d, .05¢ Spray water, ~ $/L per cow per d, .05¢ Fan (2 hp, 1 fan), 3 est. kWh per cow per d Total input costs Income from milk, 29.5¢/kg per d Profit, S/cow per d 4
6¢
3¢ $.11 $.10
;2176
$3.13
$37
$6.88
$7.47
$.59 $.22
1Water intake for shade = 133 L/cow per d. Shade + spray + fan = 53 L/cow per d. 2 Spray water = 217 L/cow per d and does not include costs of shade, pipes, and installation labor. 3 Fan (two 1 hp units) operated for 6C/kwh an average of 10 h/d. 4 Other benefits of body weight gain or lack of weight loss due to stress and reproductive efficiency are not considered here. Journal of Dairy Science Vol. 70, No. 5, 1987
1078
IGONO ET AL.
a p p a r e n t , t h e r e f o r e , t h a t t h e s p r a y plus fan t r e a t m e n t , b y m i n i m i z i n g t h e e x t e n t a n d durat i o n of h e a t stress, lessened t h e t h e r m a l inhibit i o n of f e e d i n t a k e t o allow f o r h i g h e r e n e r g y c o n s u m p t i o n a n d m e t a b o l i s m n e c e s s a r y t o sustain high p r o d u c t i v e p e r f o r m a n c e . A conservative e c o n o m i c analysis using local prices s h o w e d a n e t i n c o m e o f 2 2 ¢ / c o w per d for cows in s h a d e plus s p r a y a n d fan over cows in shade. This w o u l d b e a p p r o x i m a t e l y $ 2 2 / d a y per 1 0 0 cows f o r this 56-d s u m m e r h e a t period. T h e costs o f e x t r a feed i n t a k e , s p r a y water, a n d fan e l e c t r i c i t y were d e d u c t e d f r o m i n c o m e , leaving 2 2 ¢ / c o w as n e t profit. However, effects o f c o m f o r t a n d a n y o t h e r a n i m a l physiological b e n e f i t s d u e to l o w e r e d b o d y t e m p e r a t u r e were n o t measured. In s u m m a r y , m i l k t e m p e r a t u r e , especially in t h e claw piece, offers a n o p p o r t u n i t y t o assess t h e i m p a c t o f climate o f dairy cows plus it m a y b e useful in d e t e c t i o n o f mastitis (13) a n d estrus (18, 19). However, t h e possibility t h a t h e a t stress m a y o b s c u r e t h e e s t r u s - i n d u c e d rise in Tmilk d u r i n g s u m m e r n e e d s i n v e s t i g a t i o n a n d clarification, b e c a u s e t h e r m a l e n v i r o n m e n t was n o t i n t e g r a t e d in t h e i n t e r p r e t a t i o n o f t h e d a t a o f Maatje a n d R o s s i n g (19). Overall, s p r a y plus fan u n d e r s h a d e p r o v e d to b e a l o w cost management practice that improved thermal balance, lessened physiological changes, a n d increased m i l k yields, r e s u l t i n g in a greater profit margin for milk production. ACKNOWLEDGMENTS
T h e assistance o f W. A. H a i n e n a n d F o r e m o s t Dairy F a r m S t a f f w i t h a n i m a l m a n a g e m e n t a n d t e c h n i c a l assistance o f Carl H o u c h i n s w i t h i n s t r u m e n t s is a p p r e c i a t e d . REFERENCES
1 Ansell, R. H. 1983. Extreme heat stress in dairy cattle and its alleviation. A case report. Pages 205-306 in Environmental aspects of housing for animal production. J. A. Clark, ed. Butterworths, London. 2 Bane, A., and E. Rajahkowski. 1961. The bovine estrous cycle. Cornell Vet. 51 : 77. 3 Bauman, D. E., J. H. Eisemann, and W. B. Currie. 1982. Hormonal effects on partitioning of nutrients for tissue growth: role of growth hormone and prolactin. Fed. Proc. 41:2538. 4 Becker, B. A., M. A. Bober, F. D. EI-Nouty, and H. D. Johnson. 1985. Prolactin and its involvement in fluid regulation in the bovine. Comp. Biochem. 81A:93--98. Journal of Dairy Science Vol. 70, No. 5, 1987
5 Bodoh, C. W., C. J. Tyler, L. H. Schultz, and G. F. Shook. 1972. Thyroid activities of Holstein cows selected for average or high average milk production. J. Dairy Sci. 55:682. 6 Bond, T. E., C. F. Kelly, S. R. Morrison, and N. Pereira. 1957. Solar, atmospheric, and'terrestrial radiation received by shaded and unshaded animals. Trans. Am. Soc. Agric. Eng. 10:622. 7 Brody, S., A. C. Ragsdale, H. J. Thompson, and D. M. Worstell. 1954. The effect of wind on milk production, feed and water consumption and body weight in dairy cattle. Missouri Agric. Exp. Stn. Res. Bull. 545. 8 Clabaugh, G. A., G. M. Jones, R. E. Pearson, C. W. Heald, and W. E. Vinson. 1981. The effect of DHI somatic cell counts upon milk production. J. Dairy Sci. 64:148. 9 Friend, R. J., and R. C. Littell. 1981. SAS for linear models. SAS Inst. Inc., Cary, NC. 10 Fuquay, J. W., A. B. Zook, J. w. Daniel, W. H. Brown, and W. E. Poe. 1979. Modifications in freestall housing for dairy cows during the summer. J. Dairy Sci. 62:577. 11 Gangwar, P. C., C. Branton, and D. L. Evans. 1965. Reproductive and physiological responses of Holstein heifers to controlled and natural climatic conditions. J. Dairy Sci. 48:222. 12 Hart, I. C., J. A. Bines, and S. V. Morant. 1979. Endocrine control of energy metabolism in the cow: correlations of hormones and metabolites in high- and low-yielding cows for stages of lactation. J. Dairy Sci. 62:270. 13 Igono, M. O., B. J. Steevens, M. D. Shanklin, and H. D. Johnson. 1985. Spray cooling effects on milk production, milk and rectal temperature of cows during a moderate temperate summer season. J. Dairy Sci. 68:979. 14 Igono, M. O., H. D. Johnson, B. J. Steevens, and M. D. Shanklin. 1985. Environmental modifications for cows. Ph.D. thesis, Univ. Missouri, Columbia. 15 Ingraham, R. H., R. W. Stanley, and W. C. Wagner. 1979. Seasonal effects of tropical climate on shaded and nonshaded cows as measured by rectal temperature, adrenal cortex hormones, thyroid hormone and milk production. Am. J. Vet. Res. 40 : 1792. 16 Johnson, H. D., O. DeDios, and A. C. Lippincott. 1976. Environmental stress, TRH, and lactation effects on plasma growth hormone of cattle. Pages 5 5 5 - 5 6 2 in Nuclear techniques in animal production and health. Int. At. Energy Ag., Vienna, Austria. 17 Kibler, H. H., and S. Brody. 1954. Influence of radiation intensity on evaporative cooling, heat production, and cardiorespiratory activities in Jersey, Holstein, and Brahman cows. Missouri Agric. Exp. Sm. Res. Bull. 574. 18 Lira, M., R. G. Rodewald, and S. L. Sphar. 1975. Relation of estrus to temperatures of ear canal, rectum, and milk in dairy cattle. J. Dairy Sci. 58 (Suppl. 1):770. (Abstr.) 19 Maatje, K., and W. Rossing. 1976. Detecting estrus by measuring milk temperatures of dairy cows during milking. Livest. Prod. Sci. 3:85.
E N V I R O N M E N T A L SHADE, SPRAY, AND FAN EFFECTS 20 Miller, G, D., J. B. Frye, Jr., B. J. Burch, Jr., P. J. Henderson, a n d L. L. Rusoff. 1951. The effect of sprinkling on the respiratory rate, b o d y temperature, grazing performance and milk production of dairy cattle. J. A n i m . Sci. 10:961. 21 Mills, D. E., and D. Robertshaw. 1981. Responses of plasma prolactin to changes in ambient temperature and h u m i d i t y in man. J. Clin. Endocr. Metab. 52:279. 22 M o h a m m e d , M. E., and H. D. Johnson. 1985. Effect of growth h o r m o n e on milk yields and related physiological functions of Holstein cows exposed to heat stress. J. Dairy Sci. 68:1123. 23 Paape, M. J., W. D. Schultze, R. H. Miller, and J. W. Smith. 1973. Thermal stress and circulating e n y t h r o c y t e s , leucocytes and milk somatic cells. J. Dairy Sci. 56:84.
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24 Ragab, M. T., M. A. Ghany, and A. A. Asker. 1953. Effect of shading and sprinkling on cattle and buffaloes in Egypt. Ind. J. Vet. Sci. Anita. Husb. 23:205. 25 Roman-Ponce, H., W. W. Thatcher, D. E. Buffington, C. J. Wilcox, and H. H. Van Horn. 1977. Physiological and production responses of dairy cattle to a shade structure in a subtropical environment. J. Dairy Sci. 60:424. 26 Wegner, T. N., J. D. Shuh, F. E. Nelson, and G. H. Stott. 1976. Effect of stress on blood leucocyte and milk somatic cell counts in dairy cows. J. Dairy Sci. 59:949. 27 Zartman, D. L., D. M. Halford, L. A. Tierney, and M. Y. Hussain. 1983. Reproductive characteristics of Holstein heifers fitted with intravaginal temperature transmitters. Theriogenology 19:541.