heat stress basics...heat stress basics cows experience heat stress when effective ambient...
TRANSCRIPT
12/23/2013
1
Katie Ballard and Rick GrantWilliam H. Miner Agricultural Research Institute
Chazy, NY
An Evaluation of CowKühlerZEvaporative Cooling System for
Heat Stress Abatement in High Producing Dairy Cows
Heat stress basics
Cows experience heat stress when effective ambient temperature exceeds upper limit of TNZ
12/23/2013
2
Heat stress basics
THI of 68 -threshold for milk loss for cows producing >77 lb/d of milk (Zimbelman et al., 2009)
Cows producing >100 lb/d?
Heat stress basics
Cows become more sensitive to thermal stress as milk production increases due to greater metabolic heat output
12/23/2013
3
Heat production by dairy cow (Smith, 2000)
Human metabolism: 1 100-watt light bulb
Lactating cow: 16 100-watt bulbs
Cows give off 4,500 BTU/hour Similar to 1,500-watt hair dryer at high setting running for
one hour
Cow response to heat stress
Reduced activity
Increased body temperature >102.5oF
Panting >80 breaths/minute
Reduced DMI, 10-15+%
Reduced milk, 10-20+%
As body temperature rises, cow consumes less feed to produce less metabolic heat
(Rhoads et al., 2009)
12/23/2013
4
Heat stress and behavioral responses (Tapki and Sahin, 2006)
As air temp increases from 78 to 104oF Eating: decreases 46% Ruminating: decreases 22% Standing: increases 34% Drinking: increases 30% Locomotion: decreases 19%
Higher producing cows (>70 lb/d) more sensitive than low producing cows Especially for lying/standing
Lying and standing related to body temperature (Hillman et al., 2005)
Cows stand when body temperature reaches ~102oF; they lie down when it drops below this temperature.
Body temperature mediates cow’s standing and lying response to varying conditions of heat stress.
The quickest way to get a cow to lie down is to cool her body temperature.
12/23/2013
5
Lying decreases with higher temperature (Arnold, 1980)
16
18
20
22
24
26
28
45 55 65 75
% cows lying
Mea
n te
mpe
ratu
re (
o C)
(Grant, 2005)Resting time (h)
Milk
yie
ld (
lb/d
)
60
7080
90
100
110
7 10 13 17
y = 49.2 + 3.7 xr2 = 0.31
~3.7 lb/dmore milk foreach extra hour
2 to 3.5 lb/cow
Increased resting time with greater DIM, milk yield (Bach et al., 2010)
12/23/2013
6
Heat stress, lying, and lameness (Cook et al., 2007)
As THI increased from 56 to 75: Lying time decreased from 10.9 to 7.9 h/d Standing in alley increased from 2.6 to 4.5
h/d Drinking increased from 0.3 to 0.5 h/d
Lameness score/claw lesions increased and were associated with greater standing time, sporadic eating, slug feeding
Lameness peaked ~2 months after temperatures peaked
Economic consequences of heat stress
Economic loss with minimal abatement (DeVries, 2012)
$600/cow/yr for Florida and Texas Annual hours of THI>70 were 49 and 36%
$72/cow/year for Wisconsin Annual hours of THI>70 were 9%
Large differences by region of US in heat stress severity Estimated 2:1 return on investment in New
York State (St-Pierre, 2001)
12/23/2013
7
CowKühlerZ Evaporative Cooling System
Unique nozzle system delivers precise spray pattern designed to optimize evaporative cooling while minimizing water use.
System allows for effective cooling over stalls as well as feed bunk.
Key questions…
Primary: How does CowKühlerZ system compare with minimal cooling (fans only over stalls)?
Primary: How do lying and rumination activity respond to heat abatement and stall cooling?
Secondary: Can we measure a short-term milk response?
12/23/2013
8
Pen 1“Minimal” heat abatement: -fans over stalls
Pen 2Heat abatement treatments: -fans over stalls-sprinklers & fans over feeding area
3’ 48’ 45’ 40’ 53’
Feed Alley
curtainsDoor
Door
• 4 fans, centered over stalls • 52-in diameter blades• ~8 ft from floor• Fans spaced ~ 40 - 48 ft apart • Avg. wind speed: 6 mph
12/23/2013
9
Located over feeding area, extends entire length of pen
9’10” from pen floor, 3’3” wide
• 5 fans over feeding area• 52” diameter• 10’ 3” from floor• Spaced 40’ apart • Avg. wind speed – 7 mph
• 4 fans, centered over stalls • 52” diameter blades• Same spacing as Pen 1• Avg. wind speed – 6 mph
12/23/2013
10
7’ above alley floor Soaker heads
(Edstrom C440S) spaced 6’ apart
Total 31 soaker heads in Pen 2
Low setting - 78°F; 2 min/15 min int.
High setting - 90°F; 3 min/9 min int.
7’ high
Attached to existing fans over stalls and feedbunk
Low setting - 72°F; 1 min/3 min int.
High setting - 90°F; 2 min/3 min int.
12/23/2013
11
Quasi-experimental◦ Not able to control extraneous influences ◦ Randomization of treatments not feasible◦ Comparing experimental treatments (Pen 2) against
control or baseline cooling (Pen 1) Study Period◦ August 6 – September 23, 2013◦ Rotation through treatments: 1-week periods
25 cows selected/pen Balanced for parity,
DIM, milk yield All cows received rbST
Item Pen 1 (Control)
Pen 2(Treatments)
n 25 25Parity 2.2±0.9 2.5±1.1Days in milk 175±37 158±112Milk (lb/d) 111±11 111±6
12/23/2013
12
• Aug. 6-12; Sep. 3-9Edstrom Soakers/Fans at Feedbunk + Stall Fans
• Aug. 13-19; Sep. 10-16CowKühlerZ/Fans at Feedbunkand Stalls
• Aug. 20-26; Sep. 17-23Fans only at Feedbunk and CowKühlerZ/Fans at Stalls
• Aug. 27-Sep. 3Edstrom Soakers/Fans at
Feedbunk and CowKühlerZ/Fans at Stalls
A
B
C
D
Temp/Humidity Water Usage Milk Production
Lying time Activity Rumination
12/23/2013
13
Pen 1 Pen 2
405060708090
100
Temp (F) RH %
405060708090
100
Temp (F) RH %
4045505560657075808590
THI
Pen - 1 Pen - 2
THI - 68
12/23/2013
14
12/23/2013
15
12/23/2013
16
Heat stress and acidosis
5
5.2
5.4
5.6
5.8
6
6.2
6.4
6.6R
um
en p
H
Cool Hot HR HG CHR HHR CHG HHG
Cool = 64oF, 50% RH; Hot = 85oF, 85% RHHR = 65% Roughage HG = 35% Roughage Mishra et al. (1970)
12/23/2013
17
12/23/2013
18
Edstrom Soakers
Cow KuhlerZ Stalls Only
Edstrom KuhlerZ Cow KuhlerZ
8/9/2013 8/22/2013 9/1/2013 9/11/2013Rumination TimePen 1 319.9 330.9 308.6 276.1SE 16.7 20.8 14.8 22.6Pen 2 341.0 388.5 356.9 374.8SE 31.6 30.5 27.8 27.4Activity Time 8/9/2013 8/22/2013 9/1/2013 9/11/2013Pen 1 426.6 472.7 458.8 420.3SE 16.5 20.8 24.9 22.0Pen 2 404.2 422.8 401.9 402.9SE 15.8 20.5 19.2 19.4Standing Bouts 8/9/2013 8/22/2013 9/1/2013 9/11/2013Pen 1 12.4 12.6 12.0 12.1SE 0.8 0.8 0.8 0.8Pen 2 11.4 11.4 10.3 13.0SE 1.0 0.9 0.9 1.1Lying Time 8/9/2013 8/22/2013 9/1/2013 9/11/2013Pen 1 689.6 639.0 628.0 589.7SE 21.3 27.9 25.0 31.4Pen 2 698.5 626.2 604.9 615.6SE 30.0 35.4 35.2 36.3Water Usage (gallons) 170 50 220 30
320
690
427341
699
404
200
300
400
500
600
700
800
Rumination Lying Activity
Min
utes
/d
Pen 1 Pen 2
12/23/2013
19
331
639
473
389
626
423
200
300
400
500
600
700
Rumination Lying Activity
Min
utes
/d
Pen 1 Pen 2
309
628
459
357
605
402
200
300
400
500
600
700
Rumination Lying Activity
Min
utes
/d
Pen 1 Pen 2
12/23/2013
20
276
590
420375
616
403
200
300
400
500
600
700
Rumination Lying Activity
Min
utes
/d
Pen 1 Pen 2
DM% of sawdust bedding collected from stalls after two consecutive days of water useagewas similar to bedding in Pen 1◦ 84.9% DM for CowKühlerZ system◦ 86.2% DM for Fans Only
Need to evaluate bedding DM% during longer-term heat stress when system runs longer.
12/23/2013
21
Study design Time of year: mid-summer to early fall. Severe, prolonged heat stress events did not
occur during study. Additional studies needed to evaluate system
during extended heat events. Need to be cautious not to over-interpret and
infer results . . .
Enhanced cooling during periods of heat stress improved lying and reduced activity within pen
Enhanced cooling appeared to increase milk yield Enhanced cooling improved rumination Most notable during 4th heat stress period,
CowKühlerZ System provided benefits in◦ greater stall lying time◦ more rumination◦ more milk yield◦ used less water than soaker system during heat events
even though there was lower activation temp
12/23/2013
22