Heat stress basics...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

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