Copyright is owned by the Author of the thesis. Permission is given for a copy to be downloaded by an individual for the purpose of research and private study only. The thesis may not be reproduced elsewhere without the permission of the Author.
THE EFFECT OF A HIGH A}'IBIENT TEMPERATURE ON THE PI{YSIOLOGICAL RESPONSES OF
FRIESIAN AND BRAIIMAN X FRIESIAN CALVES FED ON TWO RATIONS
A thesis presented in partial fulfilment of the requi.rements for Ehe
Degree of Master of Agricultural Science in Animal Science
at
Massey University
PASCAL EDWARD LAMLE|},TBE SA1MA
r978
ll_.
ABSTMCT
Eight Friesian and eight Brahman x Friesian (F1) steer calves were
kept at 17 or 34.5oC in temperature controlled rooms and fed on hay or concentrate diets ln a 2 x 2 x 2 factorial design for eight weeks.
Ttren elght of the calves were used to study the effect of coat clipping at the higher air temperature, and later they were exposed each day to
eight hours of artificial radiant heat load for two weeks.
In each trial voluntary feed and water intake, liveweight gain, rectal temperature and respiration rate were assessed. In addition dietary digestibility and hair coat cover were estimeted in the factorial trial, while radiant heat load and sweating rates were measured ir. the
radiation trial.
Data for feed and water intake, digestibility and f-iveweight gain
are the subject of another thesis (King, 1978).
There were no significant differences bethteen breeds at Ehe cool ambient temperature of l7oC, but at the high air tenperature (34.5oC) both breeds had reduced their voluntary feed intake and had signiflcantly increased their rectal temperatures (P<0.01) and respiration rates
(P<0.005). However, although the F, calves ate more feed at the high ambient temperature than the Friesians, rectal temperatures and
respiration rates of Friesians (40.50oC, 100 counts per -lnute) were higher than those for the F, calves (39.80oC and 93 counts per minute
respectively). Nevertheless, only rectal temPeratures showed
significant (P<0.05) interactions between the effects of breed and air
temperature.
At the high anbient temperature concentrate fed calves consu:ned nore DM and had slightly higher respiration rates but slightly lower rectal temperatures (40.lloC) than hay fed calves (40.20oC); Ft calves
fed this diet had the highest DMI and llveweight gain but lowest rectal temperature (39.63oc).
iii.
Coat cover was related to level of feeding, breed and air
temperature. Generally F1 calves consumed more of the concentrate diet
and had significantly (P<0.05) less coat cover than the Friesians. Hay fed calves had significantly (P<0.01) heavier coats than concentrate fed
caLves. Coat weights were substantially heavier at 17oC (t77 glnz)
than at 34.5oC ambient (150 g/nz), but this difference was not
signiflcant.
Although coat cover was positlvely correlared with body temperature
at the high arnbient temPerature, cl-ipping did not affect the DMI' body
temperature or respiration rate of elther of the genotyPes.
Exposure to radiant heaters resulted in a net gain of radiant heat
by the animals of 130 - 140 kcal/n2 hr; this caused significant
increases (P<0.05) in respiration rate and rectal t.emPerature measured
after 8 hours of exposure to the radiant load. However, Fl calves were
significantly (P<0.05) less stressed by the radiation than the Friesians.
The measured sweating rates of 153 and 60 g/mz hr for F1 and Friesian calves respectively suggest that the most important cause for the genotype
differences in heat tolerance is due to the superior abllity of the F1 to
discharge moisture on to the skin surface for evaporative cooling.
ACKNOWLEDGE},IENTS
The author wishes to express his thanks and gratitude to
Dr C.W. Holmes for hls supervision throughout the experinental work and guidance for the preparation of this nanuscript'
Special appreciation is extended to Professors A.L. Rae and D.s. Flux for their helpful discussions regarding the experimental design and nethods; the staff of the Aninal Physiol-ogy Unit for their assistance in animal care and handling before and during fhe
experimenta| period, Mr A.B. Pleasants for his advice and aid in statistical analysis, and Mr C.T. King for his co-operaflon aldi'ng to
the success of the exPeriment.
I am grateful to the Governments of New ZeaLand and Tanzania for enabling me to undertake this study.
Lastly acknowledgement is made to llrs A.F. Barton for the typing
of this manuscript.
TABLE OF CONTENTS
ABSTMCT
ACKNOWLEDGEMENTS
TABLE OF CONTENTS
LIST OF TABLES
LIST OF FIGURES
LIST OF PLATES
CHAPTER ONE - INTRODUCTION
1.1: Animal production statistics
I.2: Factors influencing animal production efficiency in the troPics
1.2.L: Nutrition L.2.2: Disease
L.2.3: Clinate; direct effect of 1.3: Experimental aims
CHAPTER T't,lO - LITERATURE REVIEI^I
2.Lz Influence of climate on heat transfer in animals 2.L.I: Mechanisms of heat transfer
2.1.1. 1: Radiation
,P-.s=-
t_ l_
iv
I I I
2
z
3
2.1.1.22
2. 1. 1. 3:
2.L.r.4:
2.L.I.1. l: Solar radiation 2.L.L.1.2: Longwave radiation
Convective heat transfer
2.1. I.2.L2 Free convective transfer 2.1.L.2.22 Forced convective transfer
2. 1. I .2.32 Respiratory convective transfer Conductive heat transfer
Evaporative heat transfer
2.L.I.4.1: Cutaneous evaporative heat loss
2.I.L.4.22 Respiratory evaporative heat loss
factors infl-uencing heat transfer
Annbient temPerature
Air hunidity Alr movement
Rain or \tetness Radiation
4 4 4 5
6 6 6 6 7 7 8
2.L.22
8 9 9 9 10 10 11
Page
2.1.3: Animal influence on heat transfer II
2.L.4: Thermal equilibriuur 12
2.22 Thernoregulation in the bovine under hot conditions 13 2.2,I: Temperature sensors of the body 14
2.2.I.12 PeriPheral recePtors 14
2.2.I.22 Deep-bodv thermoreceptors 15 2.2.|.3: Integration of diff..,r(lnt thermorecePtors L6 2.2.2: Thermoregulatory effector mechanisms 17
2.2.2.I: Vasomotor control 17
2.2.2.2: Sweating 19
2.2.2. lz Panting 19
2.2.2.4:Endocrineinfluenceonheatproduction20 2.2.3: Thermoregulatory resPonses to climatic conditions 2l
2.2.3.L2 Autonomic responses 2l
2.2,3. 1. 1 : Sweating 22
2.2.3.I.22 Panting 22
2.2.3.2: Behavioural resPonses 23
2.2.3.2.L: Variation of habitat 23 2.2.3.2.22 Posture changes 23 2.2.3.2.3t Wallowing and saliva spreadlnC 24
2.32
2.2.3.2.42 Activity and operative
responses
2,2.3.2.52 VoluntarY intake Effect of a hot condition on metabolism
2.3.L: Endocrine activity and metabolism
2.3.2: Digestive metabolism 2.3.2.I2 Intake
2.3.2.2: Rumen metabolisrn
2.3.2.32 DigestibilitY
2.3.2.42 Dietary effects on metabolism Nitrogen metabolism
Costs in terms of animal production function
of thermoregulation
The ability of cattle to tolerate hot conditions
2.4.I: Factors influencing heat production 2.4.L.I: Metabolic rate
2.4.L.22 Food intake
2.3.32 2.3.42
L+
24 26 26 28 28 28 28 29 29
30 32 34 34 35
2.4:
2'4.2: Factors infLuencing heat loss 2.4.2.Lt Coat cover
2.4,2.22 Coat tYPe 2.4,2.32 Coat dePth
2.4.2.4: Coat colour and skin pigmentation
2.4.2.52 BodY size and morPhologY 2.4.2.6: Hair follicl-e densitY
2.4.2.72 Sweat gland populati-on and size
2.4.2.82 Sweating abilitY 2.4-2.92 Fat dePosition
2.4 .2. 10 : I'later metabolism
2.52 Heat stress indicators 2.5.L: ResPiration rate 2.5.2: Rectal temperature
2.5.3: Other indicators 2.5.4: Heat stress indices
CHAPTER THREE - EXPERIMENTA.I"IATERIALS DESIGN AND METHODS
3.1: Materials and methods
3.1. I: General information
3.I.2: ExPerimental animals 3. 1.3: Measurements
3. 1.3. l: ResPiration rate 3.1.3.2: Rectal temPerature
. 3.1.3.3: Food and water intake
3.1.3.4: Ambient temperature, black globe
temPerature and air huniditY 3.1.3.5: Variation in air temPerature over
a l2-hour Period
3.1.3.6: 24-hour rectal temperature
3.1.3.7: Hair coat cover 3.1.3.8: Sweating rate
3. 1.3.9: Incident radiation
3. 1.3. 10: Net radiation
3.22 Speeific materials and methods for each trial 3.2.L: Trlal I
Page 35 35 37 38 38 39 40 40
4I
42 42 43 43 44 44 44
46 46 46 47 47 47 47
48
48 48 48 48 48 49 49 49
Page
3.2.I.L2 Trial I-a: Effect of breed, ambient Eemperature and diet on physiological
responses 49
3.2.L.1.1: Feeds and feeding 49 3.2.L,L.2t Allocation of calves into
treatment grouPs 50
3.2.L.2: Trial I-b: Effect of clipping on resPiration rate, food intake and
rectal temPerature 51
3.2.2: Trial II: Effect of radiant heat 10ad on calves of two breeds
3.2.2.L2 Aninals 3.2.2.22 Housing
3.2.2.32 Feeds and feeding
3.3: Statistical design and analysis 3.3.1: Design
3.3.2: Statistical analYsis
CHAPTER FOUR - RESULTS 4.L: Trial I
4. 1.1: Environmental conditions
4.L.2: Treatment effects on rectal temperature and resPiraLion rate
4.1.2.I: Main treatuent effects 4.L.2.2: Interactions
4.1.2.3: Relationship between rectal temperature and respiration rate
4.I.2.42 Relationship between rectal temPerature and food intake
52 52 52 52 52 53 53
4.L.2.52 Relationship between respiration rate and food intake
56 56 57
57 57
59
62
62
4.L.2.62 Rel-ationshiP between and liveweight gain 4.L.2.7 z RelationshiP between
and livewelght gain 4.L.2.82 Hair coat cover
4.1.2.92 24-hour Deasurements
4.1.3: Trlal I-b: Effect of cliPPing and rectal temPerature changes
rectal temperature
66
respiration rate
66 66 67
on respiration rate
67
4.22 Radiation Trial
4.2.1: Environmental conditions 4.2.2: Incident radiant heat load 4.2.3: Net radiant heat load
4.2.4: Effect of radiant heat load on and resPiration rate
Sweating rates of calves under
Jlage 70 70 70 70
rectal temPerature
7L
radiant heat load 73
4.2.52
C}IAPTER FIVE - DISCUSSION 5.1: Trial I-a
5. 1. 1: Main effects
5.1-I.1: Effect of ambient temperacure on temperature and respiration rate
5. 1.1.2: Breed effects
5 . 1. 1. 3: Diet effects 5.L.2: Interactions
5. 1. 2. I : Breed x temperature interactions 5,I.2.22 Temperature x diet interactions 5.L.2.32 Breed x diet interactions
5.1.3: Effect of prolonged heat exPosure 5.L.4: Measurements of heat stress
5.1.5: The effect of air temperature, breed and hair coat weight
5. 1. 5. I : Main effects 5.1.5.1.1:
5. 1.5 .L.22
5 . I. 5. 1.3:
5.I.5.22 Interactions
5. 1.5 .2-Lz 5.1.5.2.22 5.1.5.2.32
74
t4 rectal
74 76 76 76 76 77 79 79 80
81
8l Effect of ambient temPerature on coat weight
Breed effects on coat cover Effect of diet on coat weight
Breed x temPerature interactbns Breed x diet effects
Temperature x diet effects
81 82 82 82 82 83 83
5.22 Clipping trial 84
5.2.I: Effect of clipping on rectal temPerature and
resPiration rate
5.2.2: Breed x clippl-ng interaction effects
84 85
5.3:TrialII;Effectofarriflclalr.adfationonsweatin$
f,ate' rectal temPerature and tespiratlon rate
5.3.1: Effecc of radiant hea! load on sweatlng rate 5.3'2.:Effestofradia{lononrectaltetr}p'eratureand
reePiration rate
5.3.3:EffectofradiationonthediffereatgenotyPes
CIIAPTER. SIX - CONELUSIONS
REFER,ENCES
"APPENDICES
P?se
86 86
88 89
92
94
LIST OF TABLES
Characteristics of eattle favouring heat tolerance Relation between coat score and suseeptibility of heat stress
Nominal composition of the two dieEs Treatment groups for trial I-a
Treatment groupings in clipping trial Radiation experimental design
Analysis of variance model for trial I-a Analysis of variance for randomized blocks
Room environment
Average positional ambient temperatures in hot roou
Individual mean rectal temperature values and treatment effects
Indlvidual mean respiration rate values and treatmenl effects
Changes in rectal temperature and the effects of treatments over the three periods during trial I-a
Changes in respiratory frequency and the effects of treatments over the three periods during trial I-a Correlation coefficients for the relationship between rectal- temperature and respiration rate
Correlation coefficient values between rectal
temperature and DMI (kg/100 kg Lw) and the regression coefficient values
Correlation coefficient and regression coefficient values between respiration rate and DMI (kg/tOO kg Lw)
Corr'elation coefficient and regression coefficient values between rectal temperature and liveweight gain Correlation coefficient and regression coefficient values between respiration rate and liveweight gain Individual hair coat weight (g/^2) at the end of trial I-a
Individual rectal temperature and room environment values during the cliPPing trial
Individual breathing frequency during the cllpping trial Rectal temperature differences between periods
A and B, oC
Respiration rate differences between periods A and B,
count per ninute
Page
I-a 33
r-b II-a II-b III
IV
V
VI
VII VIII
IX
X
XI
XII XIII
XIV
38 50
5l
51 52 54 55 56 57
58 58
60
61
62
63
64
65
65
67 XV
XVI-a
XVI.b XVII
)ffIII-a )WIII-b
XIX-a xrx-b
68 68
69
69
xx
LIST OF TABLES
(continued)
Mean ambient temperature' mean globe temperature and mean relative hunidity values for the radiatlon
Page
trial 70
Incident radiant fluxes in radiation pens, keal/m2 hr 70
Average net radiant exchange at calvest coat, kcal/m2 hr 7I
Mean values for rectal temperatur. oC for the radiation trial
Mean values for respiration rate for the radiation trial- (counts per mi.nute)
Breed influence on radiant heat load
Individual mean sweat rate values (gl^2 hr) measured
simultaneously for each pair, values for rectal
temperature in brackets
Effect of diet and ambient temperature on heat increment coefficients (A TR); TA oC per kg DMI
xxr XXII XXIII-a XXIII-b XXIII-c
XXIV
72
72 73
73
rury 78
LIST OF FIGURES
Figure
2.L4 A diagramatic relationship between heat production and heat loss at different
environmental temperatures
2.2.2.L Zone of vasomotor control
2.2.2.2 Influence of body tenperature and skin teruperature on the thermoregulatory responses
2.2.3 Relationship between level of feeding and
critical temperature
F .Page
4.1.1 The relationship between heat load and metabolism
of B. indieus and B. tauras 34
4.2.7.L Age changes in the population density of sweat
glands in Beef Shorthorn cows up to 6 years old 4I
3.2.I Determination of treatuent groups 50
3.L2 Locations of thermometers in the twelve-hourly
ambient temperature measurements 48
3.13 Calcium chloride capsule 48
3.L4 Site for net radiant transfer measurements 49
3.22 Calf positions in trial I 5l
3.23 Radiation room layout 52
4.L Three-day mean ambient temperature and rectal
temperature showing breed and diet effects -
hot treatment only 56
4.2a Mean values for rectal temperature for trial I-a
showing significant effects 57
4.2b Mean values for respiration rate for Erial I-a
showing significant effects 58
4.3a Mean values for rectal temperature during the
three periods in trial I-a 60
4.3b Mean values for respiration rate during the
three periods in trial I-a 6l
4.3c Relationship between rectal temperature and
respiration rate; trial I-a 59
4.4 Relationship between DMI and rectal temperature
trlaL l-a 62
4,5 Relationship between DMI and respirat,ion rate 64 trial I-a
4.6 Hair coat cover (e/n ) shon'ing significant effects 66
4.7 24 hr ambient teEsperature and rectal temperature 67
4.8 The relationship between the average of rectal
temperatures measured at 8 am and 2 pn and that
measured at 2 hour intervals for a 24 hour perlod 68 13 18
20
25
LIST OF FIGURES
(continued)
Figure Page
4.9 Effect of radi.ation during^the day on:
A. Rectal temperature "C at 4 pm 7L
B. Resplration rate at 4 pn lL
5.0 Mean dail-y rectal temperatures showlng the
effect of prol_onged heat exposure triaL l-a g0
LIST OF PLATES
PLATE NO. P"E
I Area clipped for the estinration of hair coar
cover F. 4g
II A cllpped ealf used in the cl"ipping trlal F. 5l
