Heat Stress in Dairy Cattle: Applications and New Frontiers. · Heat Stress in Dairy Cattle:...

Heat Stress in Dairy Cattle: Applications and New Frontiers.

byCN Lee, Ph.D. Dept. of Human Nutrition, Food and An.Sci. College of Tropical Agriculture and Human Resources, University of Hawai’i–Manoa.

Impact of Heat Stress on Cattle.

• July 1995 Heat wave in Iowa 3,750 cattle died, $42.8 million direct losses

• July 1999 Heat wave in Nebraska 5,000 cattle died of heat stress $21­31.0 million is direct losses June 2009, Heat wave in Kansas, 2,000 hd. of beef cattle died.

Feedlot Cattle

Dairy Cattle July 2006, Heat wave in California

Losses estimated to be >$1 billion.

Disruption in gonadotropins Secretion: LH

Affects thyroid hormones therefore disrupt metabolism, heart rate, cellular repair, etc.

Decrease contractions in intestines, blood flow to gut, decrease digestion, etc.

Decrease feed intake

Damages follicular development and growth; adverse effect on Oocytes; can take over 60 days for recovery.

Affects placenta steroids, size and lowers birth weights, early birth

Increased drooling; less saliva production & rumination

Increased CO2 expelling decrease saliva buffering

Increased panting

Acidosis related problems

LuCinda ­ >67,941lbs./ 365 days in 1997. Previous record was 1996 – 63,444#

Record was broken after 12 mo. by another >72,000 lbs./365 days (28gallons/day)

Lynn

One lactating cow can generate 1600

Watts of heat 100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

100 Watt

Energy Exchange

Metabolic Heat Production = Evaporative Heat Loss + Sensible Heat Loss

Sensible Heat Loss

If T environment < Tskin

there will be heat loss

Sensible Heat Loss = Convection + Radiation + Conduction

Evaporative Heat Loss

EHL

Water vapor

Conduction

T ground = 35°C T skin = 35°C

T skin = T ground

No Heat Exchange

Conduction

T ground = 38°C T skin = 35°C

HEAT GAIN

Conduction

T ground = 29°C T skin = 35°C

HEAT LOSS

Convection

FAN

T air = 32°C

T skin = 35°C

HEAT LOSS

Convection

FAN

T air = 37°C

T skin = 35°C

HEAT GAIN

Convection

FAN

T air = 35°C

T skin = 35°C

T skin = T air

No Heat Exchange

Radiation

T roof = 40°C

T skin = 35°C HEAT GAIN

Radiation

T roof = 32°C

T skin = 35°C HEAT LOSS

Cows are not good at sweating

At high environmental temperatures heat loss depends upon evaporation

because heat loss by sensible heat loss becomes small as environmental temperatures approach skin

temperatures

Cows are not good at sweating

Typical sweating rates

Cows: 400 g/m 2 ­h Humans: 1000 g/m 2 ­h Horses: 2000 g/m 2 ­h

Temperature­Humidity Index (THI) RELATIVE HUMIDITY, % 0 F 0 C 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 69.8 21 64 64 64 65 65 65 66 66 66 67 67 67 68 68 68 69 69 69 70 70 71.6 22 65 65 65 66 66 67 67 67 68 68 69 69 69 70 70 70 71 71 72 72 73.4 23 66 66 67 67 67 68 68 69 69 70 70 70 71 71 72 72 73 73 74 74 75.2 T 24 67 67 68 68 69 69 70 70 71 71 72 72 73 73 74 74 75 75 76 76 78.8 E 26 68 68 69 69 70 70 71 71 72 73 73 74 74 75 75 76 76 77 77 78 80.6 M 27 69 69 70 70 71 72 72 73 73 74 75 75 76 76 77 78 78 79 79 80 82.4 P 28 69 70 71 71 72 73 73 74 75 75 76 77 77 78 79 79 80 81 81 82 84.2 E 29 71 71 72 73 73 74 75 75 76 77 78 78 79 80 80 81 82 83 83 84 86.0 R 30 71 72 73 74 74 75 76 77 78 78 79 80 81 81 82 83 84 84 85 86 87.8 A 31 72 73 74 75 76 76 77 78 79 80 81 81 82 83 84 85 86 86 87 88 89.6 T 32 73 74 75 76 77 78 79 79 80 81 82 83 84 85 86 86 87 88 89 90 91.4 U 33 74 75 76 77 78 79 80 81 82 83 84 85 85 86 87 88 89 90 91 92 93.2 R 34 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 96.8 E 36 76 77 78 79 80 81 82 83 85 86 87 88 89 90 91 92 93 94 95 96 98.6 37 77 78 79 80 82 83 84 85 86 87 88 89 90 91 93 94 95 96 97 98 100.4 38 78 79 80 82 83 84 85 86 87 88 90 91 92 93 94 95 97 98 99 100 102.2 39 79 80 81 83 84 85 86 87 89 90 91 92 94 95 96 97 98 100 101 102 104.0 40 80 81 82 84 85 86 88 89 90 91 93 94 95 96 98 99 100 101 103 104 105.8 41 81 82 84 85 86 88 89 90 91 93 94 95 97 98 99 101 101 103 105 106 107.6 42 82 83 85 86 87 89 90 92 93 94 96 97 98 100 101 103 104 105 107 108 109.4 43 83 84 86 87 89 90 91 93 94 96 97 99 100 101 103 104 106 107 109 110

Comfortable Alert Danger Emergency

THI for Cattle

http://www.novalynx.com/reference­heat­index.html

64

66

68

70

72

74

76

78

Dairy 1 Dairy 3 RFP

69.2 lbs

31.5 kg

73.1 lbs

33.2 kg

76.4 lbs

34.7 kg

Dairy 1 – Just shade without misters/sprayers

Dairy 3 – Shade with misters at the feed area

RFP – Free stalls with water spray at the feed area

Daily milk production per cow in 3 related farms (owned by the same family) within the same area from June – October, 2000. California.

http://www.bae.uky.edu/ext/Livestock/Dairy/PDFs/KSU_heatstress.pdf

Shade for dairy cows is a necessity! Structural design is important.

37.8

38.0

38.2

38.4

38.6

38.8

39.0

39.2

11:00 11:30 12:00 12:30 13:00 13:30 14:00 14:30 15:00

Time of Day

Tvag

ina, °C

­ 0.50 °C/hr

0.69 °C/hr ­ 1.02 °C/hr 0.84 °C/hr

Lying in stall Lying in stall

Standing under feed line spray

Standing dry

Standing under feed line spray

Lying vs Standing under water spray

When body temperature reaches 39°C cow stands and seeks cooling

Experimental system to cool cows while lying in stalls

Ultrasonic cow detector

Spray during lying

Activity

Rate of change in Tvagina, °C/hr

Standing: feed line spray Standing: no spray Lying: stall spray Lying: no spray

1.0

0.5

0.0

­0.5

­1.0

95% CI for the Mean

Effect of spray on body temperature

­0.8

­0.6

­0.4

­0.2

0

0.2

0.4

0.6

0.0 0.5 1.0 1.5 2.0 2.5

Airflow, m/s

Ch

an

ge

in

Tre

cta

l,

°C/h

r

NO WET

LOW WET

HIGH WET

Cooling Effect of Wetting and Airflow on Body Temperature

Examples of the cooling system in farm B and C. Farm A only had limited shade for animals.

Farm B

Farm C

Oscillating fans

Koral Kool fans

Farm A

Shade Structures

Oscillating fans

Foggers over mangers and shade

Schaffer Fans and Shade

12600 12800 13000 13200 13400

13600 13800 14000 14200 14400 14600

Dairy A Dairy B Dairy C

Milk Production (Kg. per lactation on mature equivalent)

The Use of Water and Shade over the Feed Manger.

0

10

20

30

40

50

1st 2nd 3rd 4th

%

47.6

41.3 37.5

25.0

Conception rates of cows bred in sequence when 4 straws of semen were thawed at the same time in the sub­tropics without shade over the feed manger.

Breeding sequence

The Use of Shades, Fans and Misters

NOT ALL FANS DO THE JOB OF COOLING

Pen of High Producing Cows (n=25)

Uterine blood flow in the (a) gravid and (b) nongravid horns during standing ( ) or lying ( ) positions on d 226, 248, and 267 of gestation. Data are means ± SE during 23 h for 4 (d 226) or 7 (d 248 and 267) pregnant Holstein cows. Numbers above each bar are the mean uterine blood flows (L/min). **P < 0.01, *P < 0.05, and < 0.10 illustrate differences between the 2 postures within day of gestation

Nishida, T. et al.

JDS 2004. 87:2388­2392

Why is the polar bear in the artic white and the majority of the goats in the desert dark or black in color?

Regression of White Cow Population Farm A (4 ­ 7> lactations)

4 5 6 7 0

5

10

15

20

Y = 19.0 ­ 3.58 X R­Squared = 0.813

Regression of Black Cow Population Farm A (4 ­ 6 lactations)

4 5 6 50

55

60

65

70

75

80

0

2000

4000

6000

8000

10000

12000

White BnW Black

Farm A

Farm B

11806 11511

9907 9593

Milk production (kg) between white, black­white and black cows in Waianae. Cows were a min. of 4 lactations or higher.

90% ~50:50% 90% Farm A – 215/960

Farm B – 690/1350

0

5

10

15

20

White Hair Black Hair

Length of long hair in different color Holstein

0

0.2

0.4

0.6

0.8

1

1.2

1.4

White Hair Black Hair

Color of Holstein

Leng

th in

cms

Weight of hair (ug/cm 2 )

The data suggest that:

a) Black hair was shorter

b) Probably more fine

The combine characteristics allow for greater evaporative cooling.

[these hair measurements were samples taken from the thurl region]

Hair coat color and eye pigmentation

Conducting Heat Stress Studies With Feedlot Cattle, measuring evaporative cooling via sweating, 2004.

The Relationship of Hair Coat Score and Total Weight Gain In Cattle.

Turner and Schleger, 1959.

Hair Coat Score:

1­ extremely short, thin

4 ­ fairly long

7 ­ woolly

1 pt change amounts to 25 pounds

1pt change amounts to 25 pounds.

Measuring solar radiation, uv wave length, core body temperature in relationship to hair coat color and hair length, MS 2005.

How do cows cool themselves in nature in a place where the avg. wind speed exceeds 14mph?

Some water dripping on the side.

The Udder is innervated

Little research has been done on cooling the udder other than when the cows are in the holding pen.

Take Home Lessons: • Heat stress affects milk production, reproduction and immunology in cattle

• Signs of heat stress are: standing, panting/increased respiration and drooling.

• Provide animals protection from solar radiation, modify environment, make adjustment in nutrition, select the right breed, etc.

• Always weigh the economic costs of each program (input vs return).

• No silver bullet for all farms but apply principles correctly to gain best results.

American

Jerseys