1. Analysis of heat stress in
dairy cattle
Adnan Al-Kanaan
Department of Animal Breeding
Organic Agriculture-Witzenhausen
Kassel University
30-10-2012
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2. • Heat stress : The magnitude of the force external to the body which tend to displace its system
from their resting or ground state
• Thermoneutral zone( TNZ) is the range of ambient temperature within which metabolic rate is
at a minimum, and within which temperature regulation is achieved by non-evaporative
physical processes alone (Yousef, 1985)
• .
Background 2

3. Background 3
Temperature-humidity
index
(THI): index
developed to
assess discomfort
related to high
ambient
temperature and
relative humidity
Temperature-humidity index (THI)
DANGER
1-Dry blub temperature
2-Wet bulb temperature
3-Relative Humidity
4-Dew point
Temperature
THI > 72
THI > 68

4. Data
 Physiological traits:
1. Rectal body temperature (thermometer)
2. Respiration rate( account flank movements)
3. Pulse rate ( cow tail)
4. Surface body temperature (infrared thermo graphic camera)
• Total upper cow body area
• Shoulders and back area
• Line from back to shoulders
• Withers area
Ambient temperature C◦, relative humidity %
and dew point temperature measured by
digital meteorological logger instilling in the
cows barns
Temperature Humidity Index (THI)
THI = (1.8 × Tdb + 32) - (0.55- 0.0055 x RH) x (1.8 × Tdb - 26) (NRC, 1971)
 Production traits: Milk yield (test-day), protein (%), milk fat (%), milk fat (kg), urea, somatic cell score SCS, days in milk (lactation stage)
 Reproduction traits: Days open, conception rate, age at first conception & calving, dry period, calving interval and Dystocia
 Health status traits: Mastitis, acidosis, ketosis, laminas and abortion
 Non-genetic factors: Parity, age, year, season, lactation stage, production system, farm, cattle breed
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The study began in March-2012 in three farms located in Frankenhausen, Malsfeld and Thüringen

5. Results: Means and distributions 5
Variable N Mean Std Dev Sum Minimum Maximum
Body Temperature 1176 38.29218 0.45639 45032 36.30 40.50
Pulse rate 727 76.88721 8.35859 55897 57.00 102.00
Respiration rate 763 30.45675 9.41944 23239 15.00 72.00
upper cow body 347 28.26548 4.25562 9808 14.03 37.53
shoulders and back area 347 27.89205 4.41785 9679 13.74 37.18
line (shoulders to back) 347 27.84078 4.47136 9661 12.27 36.83
withers area 347 27.88009 4.46392 9674 12.75 36.33
15 17.5 20 22.5 25 27.5 30 32.5 35 37.5
25
20
15
10
5
0
Percent
25
20
15
10
5
0
Percent
upper 13.75 16.25 18.75 21.25 23.75 26.25 28.75 31.25 33.75 36.25
shoulders
13.75 16.25 18.75 21.25 23.75 26.25 28.75 31.25 33.75 36.25
25
20
15
10
5
0
Percent
withers
12.5 15 17.5 20 22.5 25 27.5 30 32.5 35 37.5
25
20
15
10
5
0
Percent
line
Rectal Body temperature
N=1176
Pulse rate
N=727
Respiration rate
N=763
Upper cow body
N=347
Shoulders and back
N=347
Line: from tail to neck
N=347
Withers: cycle in
withers area
N=347

6. Results: Correlations 6

7. Strategies 7
• Preparing the data for analysis
• Basic data
• Physiological data
• Production data
• Fertility data
• Health data
• Weather data - Overview
• Weather data (THI) – Physiological traits
Production traits
Reproduction traits
Health traits
• Genetic analysis
• Heritability : Rectal body temperature
Pulse rate
Resperation rate
Surface body temperature
• Genetic correlations: Physiological traits & Production traits
Reproduction traits
Health traits
• Variance components

8. Thank you
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