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This is to certify that the

dissertation entitled

EFFECT OF ACUTE HEAT STRESS ON WHITE LEGHORN HENS WITH
OR WITHOUT ACTIVE SHELL DEPOSITION AND SOME ATTEMPTS
TO OVERCOME THE DETRIMENTAL EFFECT OF HEAT STRESS
ON EGG SHELL QUALITY

presented by

ADEL ZAKI SOLIMAN

has been accepted towards fulfillment
of the requirements for

Ph.D. degree in Animal §cience

 

 

    

Major - rofessor

Date 2- 20 — E

\0

MS U i: an Affirmative Action/Equal Opportunity Institution 0- 12771

PLACE IN RETURN BOX to remove this checkout from your record.
TO AVOID FINES return on or before date due.

      

DATEVHDQE DATE DUE DATE DUE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

msu Is An Affirmative ActtorvKuaI Opportunity Institution

EFFECT OF ACUTE HEAT STRESS ON WHITE LEGHORN HENS WITH OR
WITHOUT ACTIVE SHELL DEPOSITION AND SOME ATTEMPTS TO
OVERCOME THE DETRIMENTAL EFFECT OF HEAT STRESS
ON EGG SHELL QUALITY

BY

Adel Zaki Soliman

A DISSERTATION

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

DOCTOR OF PHILOSOPHY
Department of Animal Science

1989

(.904 350!

ABSTRACT

EFFECT OF ACUTE HEAT STRESS ON WHITE LEGHORN HENS WITH OR
WITHOUT ACTIVE SHELL DEPOSITION AND SOME ATTEMPTS TO
OVERCOME THE DETRIMENTAL EFFECT OF HEAT STRESS
ON EGG SHELL QUALITY

BY
Adel Zaki Soliman

This study was conducted with Single Comb White Leghorn
(SCWL) laying hens to establish a procedure to evaluate the
effect of acute heat stress on shell quality without
endangering the hens. This research also included attempts
to overcome the deterimental effect of heat stress on egg
shell quality.

SCWL hens kept at 21°C were stressed at 35°C for 1, 2,
4, and 6 hours. Control hens were in the cabinet at ambient
temperature (23°C) for the same length of time. Hens were
either 46 (young) or 61 (old) weeks of age. Eggs were
collected for 3 days before each hen was in the cabinet and
for 3 days afterward. The difference between before and
after values for % shell of egg weight, weight of shell, and

2 of the shell were determined for each hen. Heat at

Ca/mm
35°C for 4 hours caused lower shell quality on the first day
following the stay in the heat chamber than those from hens
stressed for l or 2 hours, while shells laid on the second

and third day were equivalent to values before heat stress.

Adel Zaki Soliman

At least 4 hours of 35°C, acute heat stress, were required
to reduce shell quality significantly. Heat-stressed hens
with an egg in the uterus laid eggs prematurely, or laid
lesser quality shells. This was noted when the water was
not available during egg shell formation. The minimum
decline in the shell quality was observed when both feed and
water were available during the stay in the chamber (during
egg shell deposition). Blood PC02 and HCO3- significantly
(P g .01) declined in heat stressed hens.

There was no improvement in egg shell quality due to the use
of analgesic drugs such as aspirin (in feed or water) or
acetaminophen (in water). Vitamin C had no significant
effect on preventing the rise in body temperature or the.
decline in shell quality due to the acute heat stress. The
inclusion in the water of high concentration of KCl and

CaCl2 increased the incidence of shell defects.

ACKNOWLEDGEMENT

The author wishes to express his deep personal
gratitude and sincere appreciation to his major professor,
Dr. Donald Polin, for his help, constructive suggestions and
continuous encouragement during the accomplishment of the
practical part of this study, and to his valuable criticism
during writing the thesis. Appreciation is expressed to
Drs. Maurice Bennink, Cal J. Flegal and Mel Yokoyama for
serving as members of the guidance committee and for the
valuable information that I learned from them.

I am also deeply greatful to my wife Zeinab for her
support and encouragement during this study.

I wish to express my deep thanks to the staff members
and technicians of the department of Animal Science, Faculty
of Agriculture, Michigan State University for their co-
operation and help during the laboratory work.

Finally, the author heartly wishes to express his
indebtedness to his parents, especially his mother, for her

understanding and loving care.

iv

1.

2.

TABLE OF CONTENTS

Page
INTRODUCTION ................................... 1
REVIEW OF LITERATURE ............................. 2
2.1 Egg Formation ............... . ................. 2
2.1.1 The Structure and the role of
oviduct ........... . ..... . ............. .. 2
2.1.2 Structure and Composition of the
egg sell ................................. 2
2.2 Some of the factors that influence
egg shell quality ............................. 4
2.2.1 The various techniques and devices that
are used to evaluate shell quality . ...... 4
2.2.2 Nutrition ................................ 5
2.2.2.1 Effect of minerals on the hardness
of hen's egg shells .............. 5
2.2.2.2 Effect of calcium source on
egg shell strength ............... 9
2.2.2.3 Effect of Vitamin D ............. 10
2.2.2.4 Importance of time 3f feed intake . 11
2.2.2.5 Effect of drugs and hormones ..... 13
2.2.3 Effect of disease ............ . .......... 14
2.2.4 Effect of physiology of the bird ......... 14
2.2.4.1 Interval between oviposition ..... 14
2.2.4.2 Effect of acid base balance ...... 15
2.2.4.3 Frightening of chickens or
foreign objects in uterine tissue. 15
2.2.5 Effect of age of the birds ............... 16
2.2.6 Effect of the management . ................ 17
2.2.7 The effect of heat stress ................ 17
2.2.7.1 Effect of heat stress on feed
intake and shell quality ......... l7

2. 2. 7. 2 Effect of heat stress on egg
shell quality ....... .. ........ 20
2. 2. 7. 3 Effect of heat stress on physiology
of the birds and shell quality ... 22
2.2.7.3.1 The effect on pulse rate, blood
pressure, body temperature
and oxygen consumption ........ 22
2.2.7.3.2 The effect of heat on the
blood and acid-base balance .. 23
2.2.7.3.3 Effect of heat stress on the

hormones and metabolism ...... 25
2.2.7.3.4 Effect of heat on heat
tolerance ................... 27
2.2.8 Alleviating thermal stress in poultry .. 28
2.2.8.1 Dietary manipulation ........... 28
2.2.8.2 Water treatment for heat stress. 31
2.2.8.3 Using other measures ....... .... 33
3. Experimentation .................................... 34
3.1 The birds ...................................... 34
3.2 Lighting program .............................. 34
3.3 Hen room ...................................... 34
3.4 Environmental chamber ......................... 35
3.5 Egg quality parameters ......................... 35
3.6 Blood analysis . ............................... 36
3.7 Body temperature ............................. 37
3.8 Composition of the diet ........................ 38
3.9 Statistical analysis .......................... 43
4. Results .......................................... 44

4.1 Effect of heat (35°C) or no heat treatments
for l, 2, 4, and 6 hours on egg quality using

SCWL hens 61 weeks of age ...................... 44
4.1.1 The effect on the change (gm) in egg

weight .................................. 44
4.1.2 The effect on the change (gm) in

shell weight : ...... ............ ........ 50
4.1.3 The effect on the change in % shell ...... 56

vi

4.1.4 The effect on the change in mg Ca/mm2 ... 62

Effect of heat (35°C) or no heat treatments

for 6 hours at the time between 0800 and 1600 hr
(without active shell deposition) on the change in
egg quality on the lst day following the stay in

the chamber using SCWL hens 46 weeks of age ... 69

4.2.1 The effect on the change (gm) in

egg weight .............................. 69
4.2.2 The effect on the change (gm) in

shell weight ............................. 69
4.2.3 The effect on the change in % shell ..... 72
4.2.4 The effect on the change in Ca/mm2 ....... 72
4.2.5 The effect on the feed intake ............ 72

4.2.6 The effect on the change in body
temperature ............................. 73

Effect of heat (35°C) or no heat for 6 hours

at the time between 0800 and 1600 hr (without

shell deposition) and during egg shell formation
(between 1600 and 2300 hr) on the change in egg
quality for the lst egg following the stay in

the chamber using SCWL hens 46 weeks of age ... 74

4.3.1 The effect on the change (gm) in
egg weight .............................. 74

4.3.2 The effect on the change (gm) in
shell weight ............................ 74

4.3.3 The effect on the change in % shell ...... 76

4.3.4 The effect on the change in mg Ca/mm2 .... 77

4.3.5 The effect on the feed intake ........... 78

4.3.6 The effect on the change in body
temperature .......... . .................. 78

Effect of heat (35°C) or no heat for 4 or 6
hours (during egg shell formation) on egg
quality using SCWL hens 46 weeks of age . ....... 79

4.4.1 The effect on the change (gm) in egg
weight .................................. 79

vii

4.4.2 The effect on the change (gm) in

shell weight .............................. 80
4.4.3 The effect on the change in % shell ...... 80
4.4.4 The effect on the change (mg) Ca/mm2 ..... 80
4.4.5 The effect on the feed intake . ........... 82

4.4.6 The effect on the change in body
temperature ............. . ............... 82

Effect of feed and/or water under heat (35°C)
or no heat for 4 hours during egg shell
formation on egg quality using SCWL hens

46 weeks of age ................................ 84
4.5.1 The effect on the change (gm) in egg

weight ............... . .................. 84
4.5.2 The effect on the change (gm) in

shell weight .............................. 84
4.5.3 The effect on the change in % shell ...... 87
4.5.4 The effect on the change in mg Ca/mm2 .... 90
4.5.5 The effect on shell-less eggs ......... ... 93
4.5.6 The effect on the feed intake ........... 94

4.5.7 The effect on the change in body
temperature .................. ... ........ 97

Effect of using some drugs and chemicals in the

food to alleviate the effect of 4 hours of heat
stress (35°C) on egg quality using SCWL hens

61 weeks of age actively forming egg shell ..... 101

4.6.1 The effect on the change (gm) in egg
weight ...................... . ........... 101

4.6.2 The effect on the change (gm) in
shell weight. ............................. 101

4.6.3 The effect on the change in % shell ...... 101
4.6.4 The effect on producing shell-less eggs .. 103
4.6.5 The effect on the feed intake ..... ...... 103

4.6.6 The effect on the change in body
temperature ............................. 103

viii

4.7

Effect of using aspirin and potassium
bicarbonate to alleviate the effect of heat
stress (35°C) for 4 hours during egg shell
formation on egg quality using SCWL

61 weeks of age ............................... 103
4.7.1 The effect on the egg quality ........... 105
4.7.2 The effect on feed intake ............... 105

4.7.3 The effect on change in body temperature . 105

4.7.4 The effect on the blood parameters

(pH, PC02, and HCO3 ) ................... 107
The difference between the effect of heat
stress (35°C) for 4 hours during egg shell
formation or no heat at that time on the blood
parameters ................................... 107
4.8.1 The effect on the blood pH .............. 107
4.8.2 The effect on blood PCO2 ................ 108
4.8.3 The effect on blood Hco3' ............... '108

Effect on egg quality when using KCl, CaClz,
aspirin, acetaminophen, or buffer solution

in the drinking water to alleviate the effect

of 4 hours of heat stress (35°C) during egg

shell formation of SCWL hens 61 weeks of age ... 108

4.9.1 The effect on the change (gm) in egg

weight .................................. 109
4.9.2 The effect on the change (gm) in

shell weight .............. . ............... 109
4.9.3 The effect on the change in % shell ...... 109

4.9.4 The effect on production of shell-less
eggs ................ . ................... 111

4.9.5 The effect on the consumption of feed,
water and the drugs ..................... 111

4.9.6 The effect on the change in body
temperature .. ........................... 111

Effect of using potassium chloride, carbonated
water with Vitamin C, and acetaminophen with
Vitamin C on egg quality using SCWL hens of 61

weeks of age ..... .......... .... .......... ..... 113

ix

4.10.1 The effect on the change in egg quality . 113

4.10.2 The effect on the intake of feed, water
and chemicals .......................... 115

4.10.3 The effect on the change in body

temperature ............................ 115
5. Discussion ......... ................................ 117
6. Summary and Conclusion ............................ 124
BIBLIOGRAPHY ......................................... 127
Appendix ............................................. 139

LIST OF TABLES

TABLE Page
l.a The percentage composition of the diet

fed to the hens used in the experiments

from 2 to 10 .. ...... ... ..... .......... ..... 38
1.b Treatments used in an attempt to alleviate

the effect of heat for 4 hours during egg
shell formation (Experiment 10) ........... 43

2.a Effect of heat or no heat treatments for
l, 2, 4, and 6 hours on the change in egg
weight using SCWL hens 61 weeks of age .... 45

2.b Effect of heat or no heat treatments and

the hours of exposure to these treatments

on the change in egg weight .............. 47
2.c Effect of heat or no heat treatments and

the days following the stay in chamber on the
change in egg weight ...................... 47

3.a Effect of heat or no heat treatments for
l, 2, 4, and 6 hours on the change in
shell weight ............................... 51

3.b Effect of heat or no heat treatments and
the hours of exposure to these treatments
on the change in shell weight ............ 53

3.c Effect of heat or no heat treatments and
the days following the stay in chamber on
change in shell weight .................... 53

4.a Effect of heat or no heat treatments for
1, 2, 4, and 6 hours on the change in
%She11 ....0.0.000.........OOOOOOOOOOOOOOOO 57

4.b Effect of heat or no heat treatments and
the hours of exposure to these treatments
on the change in % shell ................. 59

xi

10 (A to D)

11

12

Effect of heat or no heat treatments and
the days following the stay in chamber on
change in % shell ................ ..... ..... 59

Effect of heat or no heat treatments for

l, 2, 4, and 6 hours on the change in Ca/mm

of the egg shell using SCWL hens 61 weeks

of age .......................... ........... 64

Effect of heat or no heat treatments and
the hours of exposure to hese treatments
on the change in mg Ca/mm of egg shell .... 66

Effect of heat or no heat treatments and
the days following She stay in chamber on
the change in Ca/mm of egg shell .. ........ 66

The correlation between egg shell quality
parameters used in experiment 1 ............ 69

Regression analysis of hours in heat

chamber and the change in egg parameters

for heat or no heat treatments on the

first egg following the treatments in

experiment 1 ........................ . ..... 70

Effect of heat or no heat treatments for 6

hours at the time between 0800 and 1600 hr
(without egg shell deposition) on change in

egg quality on the first day following the

stay in the chamber using SCWL hens 46 weeks

of age . ........ ........ ...... .............. 71

The correlation between egg shell quality
parameters in experiment 2 ......... .. ..... 72

The relationship between heat or no heat
treatment for 6 hours at the time between

0800 and 1600 hr (without egg shell formation)
and both of feed consumption and the change in
body temperature due to these treatments .. 73

Effect of heat or no heat for 6 hours at

(No SF) time vs. (SF) time on the change

in egg weight, shell weight, % shell and

Ca/mm on the lst day following the stay

in the chamber using SCWL hens 46 weeks

of age .......... .......... .......... ...... 75

The correlation between egg shell quality
parameters used in experiment 3 ........ .... 77

Effect of heat or no heat during egg shell
formation and during (No SF) time for 6 hours

xii

13 (A to D)

14

15.1

15.2.a

15.2.b

15.2.c

15.2.d

15.3.a

15.3.b

15.3.c

15.3.d

15.4.a

15.4.b

15.4.c

on both of feed consumption and the change in
body temperature ......... . .............. .. 79

Effect of heat or no heat for 4 and 6 hours
during egg shell formation on the change in
egg weight, shell weight, % shell and Ca/mm
on the lst day following the stay in the

chamber ..... ............................... 81

2

Effect of heat or no heat for 4 and 6 hours
during egg shell formation on the feed

intake and the change in body temperature

of SCWL hens 46 weeks of age ..... . ......... 83

Effect of providing feed and/or water during
heat stress or no heat for 4 hours at the

time egg shell formation is occurring on

the change in egg weight using SCWL hens

46 weeks of age ......... . ..... ....... ..... 85

The change in shell weight (the effect of
the temperature, feed and water) ... ....... 85

The change in shell weight (the effect of
water and feed) ....... .................... .86

The change in shell weight (the effect of
the temperature and water) ...... . ......... 86

The change in shell weight (the effect of
the temperature and feed) ...... .... ....... 86

The change in % shell due to the effect of
the temperature, feed and water ....... .... 88

The change in % shell due to the effect of
water and feed ............................ 89

The change in % shell due to the effect of
the temperature and water ...... ........... 89

The change in % shell due to the effect of
the temperature and feed .......... . ....... 89

The change in Ca/mmzdue to the effect of the
temperature, feed and water . ...... ........ 91

The change in Ca/mm2 due to the effect of the
water and feed .. ......... ................. 92

The change in Ca/mm2 due to the effect of
the temperature and water ........... ...... 92

xiii

15.4.d

16

17

18.a

18.b

18.c

18.d

19.a

19.b

19.c

19.d

20.1

20.2

The change in Ca/mm2 due to the effect of
the temperature and feed ...... ... ......... 92

The correlation between egg shell quality
parameters used in experiment 5 ........... 93

Effect of feed and/or water under heat or

no heat for 4 hours (during egg shell

formation) on the production of shell-less

eggs ...... ' ................................ 93

The effect of feed and/or water under heat

or no heat for 4 hours during egg shell
formation on the feed intake 24 hours

after the hens were in the chamber (the

effect of the temperature, feed and water) .. 95

The feed intake due to the effect of
water and feed .................... .. ....... 96

The feed intake due to the effect of the
temperature and water ..................... 96

The feed intake due to the effect of the
temperature and feed ...................... 96

The effect of allowing or not allowing of feed
and/or water, heat or no heat for 4 hours,
during the hens' stay in a chamber when they

are actively depositing shells, on the change

in body temperature due to the effect of the
Chamber’s temperature, or the provision of

water and feed ............................ 98

The change in body temperature due to the
effect of the water and feed .......... ..... 100

The change in body temperature due to the
effect of the temperature and water ....... 100

The change in body temperature due to the
effect of the temperature and feed ......... 100

The effect of using vitamin C, aspirin,
potassium bicarbonate and sodium bicarbonate

in the feed to alleviate the effect of 4

hours of heat stress during egg shell

formation on egg quality using SCWL

hens 61 weeks of age . ........ . ....... ..... 102

The effect of vitamin C, aspirin, potassium

bicarbonate and sodium bicarbonate on
feed intake and the change in body

xiv

21.1

21.2

21.3

22

23.1

23.2

24.1

24.2

temperature due to heat stress for 4 hours
during egg shell formation ..... ...... ..... 104

The effect of using aspirin, and potassium
bicarbonate in the feed to alleviate 4

hours of heat stress during egg shell

formation on egg quality using SCWL hens

61 weeks of age ........ ............ .. ...... 106

The effect of feeding aspirin or potassium
bicarbonate on feed intake and the change

in body temperature due to 4 hours of

heat stress during egg shell formation ..... 106

The effect of aspirin or potassium

bicarbonate on the blood pH, blood PCO

and blood HCO of hens, actively depositing
shell, stresséd for 4 hours during egg

shell formation .. ..... .................... 110

Effect of heat stress for 4 hours on blood
pH, FCC and HCO during egg shell formation
in SCWL hens 61 weeks of age .............. 108

The effect of using some drugs in the water

to alleviate the effect of heat stress for

4 hours during egg shell formation on egg
quality (experiment 9) ... ....... .......... 110

The relationship between the drugs and both

of the feed intake, water intake, drug

intake and the change in the body

temperature due to heat stress for

4 hours . ............ ..... ...... ........... 112

The effect of using an oral dose of potassium
chloride, carbonated water with vitamin C,

or acetaminophen with vitamin C before

heat stress in addition to that in the

water during heat stress to alleviate the effect
of 4 hours of heat stress during egg shell
formation in SCWL hens 61 weeks of age ..... 114

The effect of potassium chloride, carbonated
water with vitamin C, and acetaminophen with
vitamin C on feed intake, water intake,

chemical intake, and the change in body
temperature due to 4 hours of heat stress

at the time of egg shell formation ......... 116

XV

Figure

LIST OF FIGURES

Page
Effect of heat or no heat treatments for
l, 2, 4 and 6 hours on the change in egg
weight on the lst day following the stay
in the chamber ............................ 46

Effect of heat for l, 2, 4 and 6 hours on the
change in egg weight on the lst day following
the stay in the chamber ................... 46

Effect of no heat treatments for 1, 2, 4

and 6 hours on the change in egg weight

on the lst day following the stay in

the chamber ................ . .............. 49

Effect of heat or no heat treatments for

l, 2, 4 and 6 hours on the change in shell
weight on the lst day following the stay

in the chamber ............................ 52

Effect of heat stress for 1, 2, 4 and 6
hours on the change in shell weight on the
lst day following the stay in the chamber... 54

Effect of no heat treatments for 1, 2, 4

and 6 hours on the change in shell weight

on the lst day following the stay in the

chamber .................................... 55

Effect of heat or no heat treatments for 1,

2, 4 and 6 hours on the change in % shell

on the lst day following the stay in the

chamber ....................... .. ..... ..... 58

Effect of heat stress for l, 2, 4 and 6 hours
on the change in % shell on the lst day
following the stay in the chamber .......... 60

Effect of no.heat treatments for 1, 2, 4 and

6 hours on the change in % shell on the
lst day following the stay in the chamber .. 61

xvi

10

11

12

Effect of heat or no heat treatments for 1, 2,
4 and 6 hours on the change in mg Ca/mm ... 65

Effect of heat stress for l, 2, 4 and 6 hours
on the change in mg Ca/mm on the lst day
following the stay in the chamber .......... 67

Effect of no heat treatments fo 1, 2, 4 and 6

hours on the change in mg Ca/mm on the lst
day following the stay in the chamber ...... 68

xvii

1. Introduction

 

As domestic egg production becomes more mechanized,
increasing numbers of shells get broken as eggs move from
the hen to consumer.

Egg shell breakage is related to shell quality, or
shell strength, which refers to the ability of egg shells to
withstand externally applied forces without cracking or
breaking.

Hamilton (1982) reported that shell breakage is
estimated to cost Candian egg producers about $10 million
annually and United States producers about $100 million. In
addition to the economic losses, there is the loss of a high
quality foodstuff for humans. During summer, heat waves
cause hens to lay egg with lesser quality shells, thereby
increasing egg breakage. This work was conducted with
Single Comb White Leghorn (SCWL) laying hens to establish a
procedure to evaluate the effect of acute heat stress on
shell quality without endangering the hens. This research
also included attempts to overcome the detrimental effect of

heat stress on egg shell quality.

2. Review of Literature

 

2.1 Egg Formation
2.1.1 The Structure and the Role of the Oviduct

The fowl oviduct consists of five regions, (1) the
infundibulum or funnel, which receives the ovum (yolk) when it
is ovulated; (2) the magnum or albumen secreting region (also
water and salts are added to the albumen); (3) the isthmus, in
which the shell membranes are formed; (4) the shell gland, or
uterus, where the shell is formed around the membranes and
pigment (due to the secretion of porphyrins) added to the
shell and (5) the vagina, which takes no part in the formation
of the egg but may be involved in the expulsion of the egg.
The duration of time for which the egg stays in the
infundibulum, magnum, and isthmus for chickens are 1/4 - 1/2
hr., 2-3 hr., and about 1 1/4 hr., respectively. The average
stay of the ovum in the shell gland is 20-26 hr. (Fig.1)

(Sturkie, 1986).

2.1.2 Structure and Composition of the Egg Shell
There are three components of fowl egg shells. They are
(from the inside to the outside: (a) two proteinaceous
membranes that are rich in cystine and contain hydroxyproline
and hydroxylysine, (b) the true shell, and (c) a proteinaceous
cuticle (Fig. 2). The true or calcified shell consists of the
mammillary and the pallisade or spongy layer. The true shell

is composed of 2% organic material (a series of layers of

2

Immature mum Monty

Ruptured In MLI'I

[nature mum fr-llt‘cle

\oi‘t
\\I\

Flo-ginning ol albumen
wrrotmu locum or
magnum

t

     
    
     

Infumlt'nu'um m
'unm-l ut oviduct

End oftsthmus and
bcgtnning ot uterus

End at magnum
and beginmn: of
isthmus

End of uterus and
houmning at (arms

Opening of
O\ iducr into cloaca

l-‘igu're 1. Reproductive tract of the laying hen
(Sturkie, 1986).

Organic cuttcuts

Surface crystalline layer
Fig. 2
A cross secttbn of the
shell membranes and
the shell ole hen’s
egg. The various lay-
ers are shown in dia-
gram form.

(Sinmons, 1985)

Palisade lever wlth
growth ttnee (dotted)

 

 

 

 

 

 

Conic lever Wltl't memrnllee

 

'OutermembreneI‘

lnmmmfibnfi '- :—-—-_._.—

o—c—o—o—od

4

protein plus acid mucopolysaccharide on which calcification
takes place). And the remainder (98%) is mostly crystalline
calcium carbonate in the form of calcite with small
quantities of magnesium, phosphate, citrate, and traces of
sodium and potassium. The beginning of true shell formation

occurs in the isthmus (Sturkie, 1986).

2.2 Some of the Factors That Influence Egg Shell Quality

 

2.2.1 The Various Techniques and Devices That Are Used to
Evaluate Shell Quality

 

 

McNally (1965) used shell weight and the number of
cracked eggs to evaluate shell quality. True shell
expressed as % of egg weight, shell thickness and specific
gravity of eggs also were used (De Andrade et al., 1976).
Also breaking strength, shell deformation (Belyavin and
Boorman, 1980) and shell calcium (Atteh and Leeson, 1983)
have been used. Meyer et al. (1973) reported that scanning
electron micrographs revealed that most of the changes
responsible for differences in shell breaking strength
apparently take place in the palisade layer, while the
mammillary layer remains approximately constant. Also they
found a poor correlation between breaking strength and total
shell thickness. They suggested that breaking strength is a
superior measure of egg shell quality because it takes into
consideration both the thickness and the concentration of
the palisade layer around the crystalline mammillary portion
of the egg shell. However egg shell thickness, egg shell

weight and egg specific gravity were found to be correlated

5
with crack incidence (Anderson et al., 1970; McNally, 1965;

Wells, 1967).

Belyavin and Boorman (1980) studied the relationship
between the cuticle layer and shell quality. They found
that the cuticle made a significant contribution to shell
thickness and removal of it reduced shell strength when
measured directly. Blake et al. (1985) found that
percentage of amino acids in the dried membrane (outer shell
membrane) was significantly less for old hens (75 weeks)
that laid eggs of lower specific gravity as compared to
those of younger hens (43 weeks). They suggested using
shell membrane as a determinant of shell quality. Castaldo
and Maurice (1988) provided that there is a relationship
between phospholipid content of the chicken shell gland and
egg shell strength. They indicated that weak egg shells
produced towards the end of lay were laid by hens whose
shell gland contained less phosphatidylcholine and a lower

ratio of phosphatidylcholine: phosphatidyl-ethanolamine.

2.2.2 Nutrition

 

2.2.2.1 Effect of Minerals on the Hardness of Hen’s Egg
Shells:

Much of the egg shell quality research has emphasized
the role of calcium, since approximately 98% of the shell is
composed of calcium carbonate. Dietary phosphorous has
become a focus of attention lately, and as a result, the

nutritional strategy has shifted to include optimizing both

6

dietary calcium and phosphorus relative to the age and
strain of the bird (Klingensmith and Hester, 1983).

Hurwitz (1978) indicated that a low dietary intake of
calcium leads to a reduction in the thickness of the shell.
The magnitude of this reduction is not proportional to the
reduced dietary level, resulting in use of medullary bone
calcium. Ousterhout (1981) suggested that egg shell quality
may be improved by dietary manipulations of calcium levels,
but this effect may be temporary (Hamilton and Cipera,
1981). Ousterhout (1981) reported that when protein was
decreased by 1% while calcium was increased by 5% at 12 week
intervals, the rate of the decline in shell quality with
increasing age was slower than if a diet with average -
protein (16.5%) and calcium (3.5%) was used.

Atteh and Leeson (1983) studied the effect of
increasing dietary magnesium level from 0.17 to 0.77% and
calcium level from 3 to 4.2% for laying hens during 70
weeks. They indicated that increasing dietary magnesium
level had no significant effect on calcium retention,
although there was a significant (P < 0.01) reduction in the
percentage of magnesium retained. Also they found that egg
shell calcium content was significantly (P < 0.01) reduced
and shell magnesium significantly (P < 0.05) increased in
response to increase in dietary magnesium content. Hurwitz
and Bar (1965) reported increased calcium absorption during
shell formation. Alcock and MacIntyre (1962) explained the

relationship between calcium and magnesium by reporting that

7

the presence of a high concentrations of calcium competing
for the same absorptive site with magnesium may be
responsible for the decreased trend in magnesium retention
noted as dietary calcium level increased. Holder and Huntly
(1978) studied the influence of added manganese, magnesium,
zinc, and calcium level (in diet) on egg shell quality.

They used laying hens (23 weeks old), which were fed
practical basal diets with calcium 2.5 or 3.5%, each alone
or with magnesium 1000 mg/kg added as MgCO3, or manganese 65
mg/kg as MnSO4, or zinc 130 mg/kg as ZnO. They found that
more Ca in the diet increased shell thickness but not
significantly. They also indicated that with added Mn,
shell thickness was greater than without added Mn and
significantly greater than with added Mg or Zn. Leach and
Gross (1983) observed that manganese deficiency in the
laying hen resulted in decreased egg shell thickness. They
noted that the chemical analysis of the organic matrix of
the eggs shells showed a decrease in hexosamine and
hexuronic acid content consistent with the known role of
manganese in polysaccharide synthesis.

Klingensmith and Hester (1983) investigated the
relationship among available levels of dietary phosphorus
(0.2, 0.3, and 0.4%) and the production of soft-shell (SS)
and shell-less (SL) eggs in White Leghorns of a commercial
strain. They found that egg specific gravity was
significantly higher among hens consuming the 0.2% available

phosphorus diet when compared to hens consuming the 0.3 or

8
0.4% available phosphorus diets. Also they indicated that

the level of available phosphorus in this study did not
significantly affect the production of SS or SL eggs.

Costello and Odom (1984) determined percent mineral
ash, sodium (Na) and potassium (K) in tibia bone and egg
shells of SCWL laying hens. They found significant negative
correlations (P < 0.05) between percent bone ash and percent
egg-shell ash for both mineral electrolytes. This indicated
that Na and K in tibia bone can be used in egg shell
formation. Sauveur and Mongin (1971) indicated that
potassium is one of the ions involved in the electrolyte
exchange which takes place between the egg and the shell
gland tissue during shell formation.

There was a lower concentration of plasma calcium and
magnesium in hens which just laid either soft-shell (SS),
shell-less (SL) eggs or hard-shell (HS) eggs when compared
to hens with SS/SL or HS eggs in their uteri. And the
concentration of plasma phosphate was higher in birds that
laid SS/SL eggs than in birds that laid HS eggs (Hester et
al., 1980). Parsons and Combs (1981) reported that the
concentrations of ionized calcium peak (5.67 mg%) 4 hr.
after oviposition, then decrease significantly during the
period of shell calcification (4.85 mg%). There was no
detectable difference in total (ionized plus un-ionized)
plasma calcium at the comparable periods. Feeding a

calcium-deficient diet to laying hens causes a significant

9
decrease in plasma ionized calcium concentrations (Taylor et

al., 1962).

2.2.2.2 Effect of Calcium Source on Egg Shell Strength

 

Egg shells from the hens fed the diets containing
oyster shell, pulverized egg shell and limestone grit were
significantly better than egg shells from hens fed diets
containing pulverized or ground limestone as the calcium
source (March and Amin, 1981; Meyer et al., 1973).

When no shell was being formed, only about 40% of the
dietary calcium was being absorbed; then, this rate
gradually increased to 72.4% during the late stages of egg
shell formation (Hurwitz, 1970). Roland (1972) observed
that the lowest serum calcium levels occurred during the
early morning hours (4:00 A.M. & 8:00 A.M.) in hens
receiving pulverized limestone. These results indicate that
hens do not have the ability to resorb sufficient bone
calcium to maintain high blood calcium levels, and that
dietary calcium is absorbed at a faster rate during active
egg shell deposition. Therefore, blood calcium levels can
be maintained during the early morning hours due to the
presence of calcium carbonate particles in the intestine
(Meyer et al., 1973). Also, Kuhi et a1. (1977) indicated
that the larger particles allow a release of calcium to the
gut at a rate that is optimum for maximum intestinal

absorption during egg shell formation.

10

2.2.2.3 Effect of Vitamin D3

Vitamin D3 is hydroxylated in the liver to 25-hydroxy
vitamin D3 (25-OH-D3) which is further hydroxylated in the
kidney to the active form 1, 25-dihydroxyvitamin D3 (1,
25(OH)2D3). It is involved in the synthesis of vitamin D-
dependent calcium-binding protein for the calcium transport
system in intestine (Christakos et al., 1979) and in avian
shell gland (Bar and Hurwitz, 1975).

The high level (600 1.0.) of 25-hydroxy cholecalciferol
in combination with oyster shell or limestone (for 4 weeks),
or feeding la-OH-D3 (Sug/kg diet) to laying hens for 22
weeks resulted in significantly improved shell breaking
strength and tibial calcification (the hens were 62, 74, or
40 weeks of age) (McLoughlin and Soares, 1976; Soares et
al., 1988). Soars et a1. (1988) also reported that hens
producing eggs with superior egg shell quality have a higher
concentration of circulating l, 25 (OH)2-D3 than hens
producing poor quality egg shells. However, there was no
improvement in shell quality (egg shell calcification or
shell strength) by injection of vitamin D3 in hens 72 and 50
weeks of age fed a 7.9% Ca diet or when the birds fed
gelatin capsules containing 1,000 IU of 25-OH-D3 each day
for three days (Potts and Washburn, 1977; McLoughlin and
Soares, 1976). Castillo et a1. (1979) did not find a

relationship between the plasma 1, 25-(OH)2-D and the

3
changes in medullary bone during the egg-laying cycle.

11
2.2.2.4 Importance of Time of Feed Intake

 

Since hens stop eating food at night when the lights go
out, and this occurs during the early stages of shell
calcification, Simkiss (1961) and Taylor (1970) believed
that crop and the skeletal system can supply additional
calcium during the calcification process. Roland et a1.
(1973) found that much more calcium was metered from the
crop during the early hours of the night than the late
hours, and most of the calcium was used by midnight. They
suggested that the crop was not able to provide a constant
source of calcium to the small intestine for the shell
calcification process.

The role of bone calcium in shell calcification was
studied by Lennards and Roland (1981). This study was to
determine if hens could store enough calcium in their bones
to maintain shell quality when fed a 2 or 3 day supply of
calcium in 1 day, followed by a calcium deficient diet the
next 1 or 2 days. They found that egg specific gravity
decreased on the day following consumption of the 0.4%
calcium diet regardless of whether they consumed diets
containing a 6.4% calcium or 9.4% calcium the day before.
They concluded that hens could not maintain shell
calcification for even one day with only skeletal calcium,
even though there is enough calcium in the skeletal system
to calcify several eggs.

Farmer et a1. (1983) studied the importance of time of

calcium intake on shell quality in broiler hens using three

12
groups of breeders. The control group was fed a diet
containing 3.1% calcium. The other two groups were
restricted to the same diet except that the diet contained
only 0.4% calcium and the hens were intubated with 3 gm of
calcium at 0800 or 1600 hr daily. All hens received the
same total amount of calcium. The results of this
experiment indicated that the broiler hens given most of
their calcium at 0800 hr could not maintain egg specific
gravity at levels comparable to that of the controls.
However, hens intubated at 1600 hr showed no drop in shell
weight or specific gravity. Thus, the most important time
for the hens to receive calcium was during the afternoon
when shell calcification was ongoing. Farmer and Roland
(1982) indicated that for hens to receive maximum benefit
from calcium supplementation they not only need calcium but
also feed with calcium. They found that hens fed a low
(0.08%) calcium diet and intubated with calcium (about 3.5
gm calcium) at 1700 hr. had significantly higher specific
gravity than hens deprived of all feed for 24 hr. and
intubated with the same asmount of calcium at the same time.
Farmer and Roland (1982) also suggested that hens cannot
absorb calcium efficiently from the digestive tract or
mobilize skeletal calcium in the absence of the other
nutrients. This is because they found that the hens fed the
low calcium diet had significantly better shells than fasted
hens. And the increase in shell weight and specific gravity

was much greater than could be accounted for by the calcium

13

in the 0.08% calcium diet. On the same subject, Junqueira
et a1. (1984) found that hens fed 0.4% total phosphorus in
the afternoon produced eggs with higher specific gravity as
compared with hens fed 1.4% total phosphorus during the
entire experiment. They concluded that dietary phosphorus
level has an influence on eggshell quality when the hens is

forming the egg shell.

2.2.2.5 Effect of Drugs and Hormones

 

Reserpine, in the diet, in all but one case (Wilkinson,
1961) was reported not to affect the egg shell thickness of
chickens (Robertson et a1, 1964; Robertson and Francis, 1965
and Heywang, 1965) or turkeys (Casey et al., 1963).

Aspirin at 0.1 or 0.2 percent in diet of laying
chickens had no significant effect on egg shell thickness
(Thomas et al., 1966).

Feeding chlortetracycline or oxytetracycline (Eoff et
al., 1962) or penicillin (Gabuten and Shaffner, 1954)
increased % shell and egg specific gravity or decreased the
percentage of cracked eggs. 2

Sulfanilamide decreased shell quality (Becker and
Bearse, 1962).

Feeding dry thyroid to chickens increased egg shell
weight (Asmundson and Pinsky, 1935). Feeding thyroprotein
(iodinated casein) increased egg shell quality (Savage et
al., 1952). Although Berg and Bearse (1948) did not find a

significant effect on egg shell thickness due to the

l4
iodinated casein. Thiouracil, an antithyroid product, has
been reported to decrease egg shell thickness (Berg and
Bearse, 1948). Subsequently, Berg and Bearse (1951) and
Hunt and Attken (1962) did not observe a significant effect
on egg shell thickness or egg specific gravity when they
used thiouracil. Feeding thyroxin (0.02% of the diet) or
stilbesterol (0.2 mg/hen/day), resulted in an increase in
egg specific gravity (Gabuten and Shaffner, 1954). These
authors found that testosterone propionate (0.2 mg/hen/day)
decreased the egg specific gravity. Polin and Sturkie
(1957) indicated that parathyroidectomy resulted in the

production of soft-shelled or shell-less eggs.

2.2.3 Effect of Disease

 

New Castle, infectious bronchitis and chronic
respiratory disease reduced egg shell thickness (Quinn et

a1, 1956, Crinion, 1969 and Carson et al., 1954).

2.2.4 Effect of Physiology of the Bird

 

2.2.4.1 Interval between Oviposition

The amount of shell deposited is a linear function of
time in the shell gland after plumping (Burmester et al.,
1939). The length of time in the shell gland can influence
the amount of shell deposited and, consequently, the shell
strength. Ephedrin sulfate delayed oviposition of a chicken
consistently laying shell-less eggs and allowed deposition

of egg shell calcium (Polin and Sturkie, 1955). However,

15

when ephedrine was injected into normal hens, egg shell
weight was decreased (Sturkie et al., 1954). Choi et a1.
(1981) have shown that the longer the interval between eggs
the more shell is deposited on the egg. This influence is
more noticeable if management, feeding, and lighting are
disrupted and if an egg is held in the uterus too long so
that the next egg in the clutch does not get sufficient

shell (Siegel et al., 1978).

2.2.4.2 Effect of Acid Base Balance

 

Winget and Smith (1959) showed that an increase of H+
ion concentration favours calcium liberation from the
vitelline-calcium complex. Winget et a1. (1958) indicated
that it is likely that calcium drawn from the blood by the
uterus is found in ionic form and that its immediate and
local course is calcium complexed with proteins. Hodges
(1965) found that a relatively low uterine pH makes the
dissociation of protein-Ca complex easier. Taylor and
Hertelendy (1961) showed that a pH increase from 7.55 to

7.87 decreases blood ionic calcium by 20%.

2.2.4.3 Frightening of Chickens or Foreign Objects in
Uterine Tissue

 

 

Frightening of chickens has resulted in a decreased
shell thickness (Stiles and Dawson, 1961). Also foreign
objects, such as a thread, placed in the uterine tissue

results in SL eggs (Jaap and Muir, 1968).

16
2.2.5 Effect of Age of the Birds

 

Peterson (1965) has proposed that the amount of Ca the
hen absorbs and retains and the skeletal Ca available for
shell calcification decrease with age. The studies by
Roland et a1. (1975) and Roland (1980) indicated that the
decline in shell strength with age was not due to a decline
in the ability to absorb or mobilize Ca, but was due to an
increase in egg size with progressing age without a
concomitant increase in shell weight (Ousterhout, 1981).
Also Roland et a1. (1975) and Roland (1980) showed that the
amount of shell deposited did not decrease but remained
reasonably constant or slightly increased with age. Roland
(1979) found that an egg that had the greater increase in
size with increasing age had the greater decline in shell
quality. This was (Roland et al., 1978) due to an increase
in egg weight at a faster rate than the increase in shell
weight, which resulted in a decrease in the amount of shell
to cover the egg. 1

However, Mehner and Torges (1967) indicated that egg
breaking strength can be improved after a laying pause in
old hens.

Ousterhout (1981) observed that a reduction in the
dietary protein level of aging hens can result in a

decreased egg size without increasing shell strength.

17
2.2.6 Effect of the Management

 

Hamilton et a1. (1979) reported that although factors
such as genetic potential, diet, temperature, and age of the
flock may be fixed, management can be an important factor to
the extent of shell breakage. They found that as the number
of hens in a cage is increased, the chance that the egg will
be damaged before it reaches the collection belt is
increased. Also, they indicated that disruption of laying
hens can result in breakage of an egg shell in the uterus.
Yannakopoulos and Morris (1979) found an improvement in
shell strength, when an ahemeral light cycle (28 hours) was

used at a time near the end of lay.

2.2.7 The Effect of Heat Stress

 

2.2.7.1 Effect of Heat Stress on Feed Intake and Shel
Quality

Mueller (1959) studied the effect of environmental

 

temperature (85°F or 30°C) on feed intake, calcium balance,
and serum calcium levels and to find out if differences in
these characteristics explain the effect of environment on
shell thickness. He used S.C.W. Leghorns (from 174 to 450
days of age). The results of his experiment indicated that
high environmental temperature reduces shell thickness,
blood calcium levels and feed intake. The lower calcium
intakes at high temperature were offset by better calcium
retention so that all the birds retained some quantity of
calcium. Also the correlation between calcium intake and

shell thickness was small and insignificant. This indicates

18
that hens with high and low calcium intakes produced eggs of

about same shell thickness.

Mueller also found a negative correlation between serum
calcium level and shell thickness. This indicated that hens
having high serum calcium levels produced eggs with thinner
shells than hens having low serum calcium levels. He
concluded that it is unlikely that the reduction in shell
thickness at high temperature was caused by the concomitant
reduction in calcium intake or serum calcium levels. He
also indicated that the positive correlation between calcium
intake and serum calcium levels may be due to increased
calcium absorption in the digestive tract when the calcium
intake increases. Campos et a1. (1960) studied the effect
of heat stress on egg quality. They found a reduction in
shell thickness and also a marked reduction in feed
consumption from heat stress. De Andrade et al. (1976)
subjected two groups of S. C. W. Leghorn pullets to either a
21 or 32°C environmental temperature. The birds were fed
either a typical corn-soy laying diet (15% protein, 2.8% Ca,
0.57% avail. P, 2,915 Cal. M.E./gm plus vitamins and
minerals) or a High Nutrient Density (HND) diet (20% more of
all nutrients except energy which was increased only 10%).
They found that food consumption, egg weight, specific
gravity of eggs, shell thickness, and % shell decreased from
heat stress. The use of (HND) diet partially alleviated the
effects of heat stress on egg weight but there was no

significant improvement in specific gravity due to the

19

significant increase in egg weight with the (HND) diet.

This was supported by Hurwitz and Griminger (1962) who
reported that egg specific gravity was affected by change in
egg weight and will therefore fail to reveal true changes in
shell quality when changes in egg weight take place. De
Andrade et a1. (1976) observed that there was an increase in
shell thickness observed with HND diet under heat stress;
yet it was inferior to the control diet at 21°C. However,
De Andrade et a1. (1977) found that High Nutrient Density
diet did not improve specific gravity, % shell or shell
thickness under heat stress. They added that the calcium
consumption was increased in all environments by feeding
(HND) diet. Vasquez and Teeter (1986) used the force
feeding (70, 85, 100 and 115% of thermoneutral (24°C) ad
lib. consumption. This was to study the effect of heat
stress (35°C) on egg quality. They indicated that heat
stress depressed egg weight (3.2%), shell weight (7.4%),
shell thickness (9.3%) and specific gravity (1%).

Increasing feed consumption of heat-stressed layers by force
feeding increased egg weight (2.6%), shell weight (0.4%),
shell thickness (0.7%) and specific gravity (0.2%). They
also observed that there was a linear increase of hen
mortality with intake. These authors also noticed that
increasing feed consumption of the heat stressed hens
enabled partial recovery of egg quality. There was a
beneficial effect from adding fat to the diet of broilers

during heat stress, as a means of reducing the

20
Specific Dynamic Action (SDA) of the diet (Dale and Fuller,

1980). The latter authors indicated that with constant high
temperature stress, the situation is so severe as to
override completely any beneficial effect due to the reduced
SDA of the diet. Pastro et a1. (1969) found that the body

temperature increased in lysine deficiency.

2.2.7.2 Effect of Heat Stress on Egg Shell Quality

 

Campos et a1. (1960) studied the effect of heat stress
(100°F or 37°C) for 24 hours using a fast rise (4°F or
2.2°C/hr) and a slow rise (5°F for 2.8°C/24 hrs) in air
temperature on Rhode Island Reds, W. Leghorns and New
Hampshires (8 to 15 months.of age). They found that the
rate at which temperature rises above 70-80°F influences the
quality of eggs laid and the amount of feed consumed, but
not egg production. They also reported that the rate of
temperature change alone did not exert marked adverse effect
on egg size or albumin quality, since in other tests
employing fast (3.5°C/hr.) rises in temperature to 37.5°C
for a duration of only 6 hours, no effect was observed.

They also indicated that, of the egg characters considered
in their experiment, shell thickness was found to be more
sensitive to rises in ambient temperature than egg
production. The degree of reduction was greatly influenced
by the prevailing temperature when shell deposition was
taking place. Also, they noticed a marked reduction in feed

consumption with fast rises in temperature when compared to

21

that in case of slow rises. Miller and Sunde (1975) showed
that the increase in the environmental temperature decreased
rigidity of the egg shell, egg weight and feed consumption,
but egg production was not markedly affected over an
extended period of time (up to 90 days). They indicated
that constant high temperature (32°C) resulted in lower
shell deformation (0.018 vs. 0.023 mm) than acyclic (over 10
hours) hot temperature (26-38°C). Arima et a1. (1976)
studied the effect of weekly constant environmental
temperatures on egg shell quality using hens of two age
groups. They found that neither 14 months old nor young 8
months old hens showed a marked change in egg weight at
environmental temperatures up to 32.5°C. However, egg
weight decreased to about the same degree in both age groups
subjected to 35.0°C. They also found that egg shell
strength gradually decreased when the environmental
temperature in both age groups was increased to 29.5°C and
higher. The decline in shell strength was more severe in
older than in younger hens.

Wolfenson et al. (1979) subjected mature laying hens
(10 to 15 months of age) to ambient temperature (34 to 40°C)
sufficient to maintain body temperature of 43°C for periods
of 6 to 7 hrs during the day (from 10.00 to 16.00 hr) or the
night (from 20.00 to 03.00 hr). There was no reduction in
total daily food consumption. The effect of heat stress

during the day was mostly on egg shell quality. The heat

22

stress at night caused a significant decrease in egg
production.

Laying hens exposed to a 24 hr linear temperature cycle
ranging from 26.7 to 35°C had a significantly lowered egg
shell breaking strength and a significantly thinner shell
than the hens exposed to the temperature cycles of 21.1 to
35°C or 15.6 to 35°C (Deaton et al., 1981). White Leghorn
hens 21, 25, and 33 weeks of age had decreased feed
consumption, egg production (except for the hens 21 weeks of
age), egg weight, and egg shell thickness from 35°C stress
(after a 3-day test period) (Tanor et al., 1984). Increases
in energy and calcium intake partially helped to maintain
normal egg production, egg weight, and egg shell

deformation.

2.2.7.3 Effect of Heat Stress on Physiology of the
Birds and Shell Quality

 

 

2.2.7.3.1 The Effect on Pulse RateL7Blood Pressure,
Body Temperature and Oxygen Consumption

Thornton (1962) observed that an increase in
environmental temperature to 35°C brought about a rise in
body temperature of both control hens and those given 44 mg
ascorbic acid/kg diet. Body temperature increased more in
control hens than in hens fed vitamin C. Thornton also
found that the control and ascorbic acid supplemented hens
exhibited an initial decrease in body temperature when the
ambient temperature was increased followed by the increase

in body temperature. Also, there was a marked reduction in

23
oxygen uptake (in case of the decreased body temperature) by

each group followed by a higher oxygen uptake as the body
temperature increased. S. C. W. Leghorn hens moved from
21°C to 35°C and from 5°C to 35°C environmental

temperatures had slowly decreasing pulse rate and blood
pressure, and increasing respiratory rate, body temperature,
and oxygen consumption; the latter decreased later in the
exposure period (Harrison and Biellier, 1969). Also, oxygen
consumption was significantly reduced at 35.0°C for l3-month
old 8. C. W. Leghorn hens, but not for 15 and 18-month old
birds. Pullets subjected to an abrupt change in temperature
from 21 to 35°C laid eggs with lower specific gravity of
eggs (with no change in egg weight) within the first day of
exposure to 35°C (Harrison and Biellier, 1969). Panting
caused the birds to develop a respiratory alkalosis
compensated for by renal excretion of calcium bases. This
change in calcium metabolism was the reason for the rapid
change in specific gravity. All parameters approached a
plateau or acclimated functional level within 12 to 24 hours
following exposure of the hens to the increase in ambient

temperature.

2.2.7.3.2 The Effect of Heat on the Blood and
Acid-Base Balance

 

 

Adult male turkeys subjected to 32.2 or 37.8°C had
blood tests at 0, l, 7, 14, 21 and 28 days of stress (Parker
and Boone, 1971). There was a low red blood cell count due

to hemodilution beginning at 14 days of 37.8°C stress. But

24
not until 28 days at 32.2°C did hemodilution occur.

Hemodilution occurred on day 14 for the 37.8°C treatment,
and it continued throughout the remainder of the study.
Blood pH was the same for both heat treatments. Most of the
changes in criteria became constant during the 37.8°C stress
at between 14 and 21 days. Acclimatization to the heat
occurred generally between 7 and 14 days. Stress at 37.8°C
(for 21 or 28 days) proved to have long lasting deleterious
effects. Kohne and Jones (1975a) studied the effect of the
acute hyperthermia of 49°C for 165 minutes on PCOZ, pH and
plasma electrolytes in non-laying female turkeys to avoid
the effect of egg shell deposition on the blood parameters
measured. The pH and PCO2 of the turkeys did not change
significantly during the first 60 minutes of the
experimental period, but as the ambient temperature reached
43°C, the venous blood pH increased significantly (from 7.40
to 7.69) and the PC02 decreased significantly (from 54.5 to
16.3 mmHg). Also,there was a significant decrease in plasma
sodium, total calcium, magnesium and inorganic phosphorus
from the 43°C heat, while plasma potassium was significantly
increased. In another study, Kohne and Jones (1975b)
exposed turkey hens to stepwise increases in ambient
temperature from 21 to 25 to 30 to 35°C at two week
intervals. They studied the effect of heat stress on venous
blood pH, PC02 and plasma electrolytes during the second
week after each increase in ambient temperature. There was

a significant decrease in plasma sodium and a significant

25
increase in plasma potassium as the ambient temperature rose

to 30°C. Also, there was a significant increase in PC02
from 52.9 mmHg at 21°C to 62.5 mmHg at 25°C and then
declined at a significant rate to 56.2 mmHg at 30°C and 53.7
mmHg at 35°C. There was no significant difference in venous
pH. The shell thickness or egg size was not significantly
correlated to any of the plasma electrolytes measured.

The relationship between PC02 and egg shell quality was
studied by Mongin (1968) who indicated that the thinning of
egg shells in hot weather was due to hyperventilation of the
lungs with a resultant loss of C02. Mongin and Lacassagne
(1966) reported that hyperventilation due to high
temperature causes the bird to lower its blood carbon
dioxide tension and thus its blood bicarbonate level.
Gutowska and Mitchell (1945) indicated that the bicarbonate
ions are the source of shell carbonate. Hodges and Lorcher

(1967) found that when 14

C bicarbonate ions were injected
into the blood there was relatively little labelling of the

shell.

2.2.7.3.3 Effect of Heat Stress on the Hormones
and Metabolism

 

High temperature decreased thyroxin production in
laying hens (Bell and Freeman, 1971). The reduction in egg
weight under heat stress may be due to a reduction in
calcium metabolizing hormones because of a negative effect

on the pituitary and/or hypothalamus (Miller and Sunde,

26
1975). Less follicle stimulating hormone may account for a

decreased ovum weight that results in lower egg weight.

Edens (1976) showed that injection of a 5% Na+ solution
was followed by a significantly greater increase in body
temperature during exposure to 45°C than in controls (using
3-week old chickens) at the same temperature. Edens also
reported that corticosterone may have a function in survival
during heat exposure. One of the crucial functions of
corticosterone is the maintenance of phosphorus and calcium
concentrations in the blood, thus protecting against
cardiovascular failure. Adult roosters exposed to 42.2°C
survived longer than controls when they were fed thiouracil
(inhibitor of thyroid hormone synthesis) and less than the
controls when they received thyroxine (Fox, 1980).

Goto et a1. (1979) studied the effect of heat stress
(32°C) on the concentration of carbonic anhydrase which is
one of the key factors that is involved in egg shell
formation. Concentrations of carbonic anhydrase in uteri
and kidney tissue of hens were significantly increased from
0.33 and 1.85 to 0.43 and 2.31 Eu/mg after high temperature
(32°C) exposure (Goto et al., 1979). The activity of this
key enzyme in shell formation was significantly decreased
from 1.00 to 0.61 Eu/mg in whole blood. They indicated that
the concentration of carbonic anhydrase of the uteri of hens
that laid normal shell eggs was significantly higher than

that of hens laying eggs with highly pimpled shells. Also,

27

egg shell thickness was significantly decreased as the

pimpling of egg shell was increased.

2.2.7.3.4 Effect of Heat on Heat Tolerance

 

Randall and Hiestand (1939) and Randall (1943) found
that panting depended on rectal temperature,whether the bird
was heated from outside, or internally, indicating that the
stimulation of the panting center was central, and did not
depend on skin temperature. Hutchinson and Sykes (1953)
used 3 cocks and 3 hens to study the effect of hot
environment on acclimatization of the fowls. They found
that twenty-four daily exposures for 4 hr., or for shorter
periods, significantly improved heat tolerance at 37.2°C.
According to Arieli et a1. (1979) metabolic and insulative
modifications are involved in seasonal acclimatization which
is slow and gradual in the fowl. Arieli et al. reported in
1980 that at 32°C the adjustment potentials of vasomotor
function and metabolic rate are exhausted in hens.

Vasomotor function reached a maximal value and the metabolic
rate its minimum. They suggested that 32°C probably
represents an upper limit for homeothermy in the hen. Sykes
(1983a, b) exposed some birds for up to 4 hrs daily to an
ambient temperature that brought about a steep rise in body
temperature. Unacclimatized birds showed a rise of 4°C in 1
hour; whereas, those fully acclimatized showed a rise of

only 1.5°C in 4 hours.

28
2.2.8 Alleviating Thermal Stress in Poultry

2.2.8.1 Dietary Manipulation

 

De Andrade et a1. (1977) studied the effect of elevated
temperatures of 21 and 31°C constant and 26.7-35.6°C cyclic
on egg production and shell quality. The hens in each
environment were fed either a typical corn-soy laying diet
or High Nutrient Density (HND) diet that contained 25% more
of all nutrients except energy which was increased 10%.
During heat stress, the HND diet increased egg production
and egg size in comparison to the typical diet but not egg
specific gravity, shell thickness or % shell.

Vitamin C may be one of the nutrients that should be
added to poultry diets for hens subjected to high
environmental temperature. Hunt and Aitken (1962a)
indicated that blood ascorbic acid (AA) was significantly
depressed in Leghorn hens maintained at 35°C, when compared
to hens maintained at 21°C. Also, there was a significant
decline in plasma AA 4 hours after heat stress at 42°C and
AA levels returned to preheat values within 24 hours (Nathan
et al., 1976). In contrast, Kechik and Sykes (1978)
observed a significant increase in plasma AA in fowls
exposed to 36°C for three hours.

Thornton (1960) found that dietary ascorbic acid at 44
mg/kg diet) was effective in maintaining shell thickness
during periods of increased environmental temperatures when
the calcium level was 2.5 or 3.0% in the diet. Thornton and

Deeb (1961) showed that iodinated casein in the diet was

29

accompanied by increased blood AA and that the addition of
thiouracil to the diet decreased vitamin C blood level.
Apparently, the metabolic rate of the chicken is associated
with its ability to synthesize ascorbic acid. Thornton
(1962) reported that 44 mg ascorbic acid/kg diet had no
effect on the body temperatures of laying hens maintained in
a moderate environment (24.4 to 26.1°C). Elevating the
ambient temperature to 37.8°C resulted in significantly
lower body temperatures in AA-supplemented hens as compared
to controls. Lyle and Moreng (1968) found that ascorbic
acid supplementation significantly limited the increase in
body temperature of Leghorns exposed to 29°C for one week.
There were no significant differences in the cloacal
temperatures of chicks 4 weeks of age supplemented with 1000
ppm ascorbic acid, when compared with nonsupplemented chicks
maintained at 22°C or acutely exposed to 43°C, according to
Pardue et a1. (1985).

Ahmad et a1. (1967) studied the effect of adding AA at
44 mg/kg diet on progressive heat stress using 13, 15 and 18
months old S. C. W. Leghorns. AA did not maintain egg shell
thickness of the 13-month old hens. The lS-month old hens
being fed ascorbic acid maintained shell thickness at 29.4°C
but not at 35.0°C. There was an adverse effect on shell
thickness due to supplementation of ascorbic acid in the
diet of hens 18 months of age. Only in the 18-month old
hens was there a significant reduction in body temperature

(42.09°C for control vs. 41.79°C for treated group) due to

30

AA suplementation. Shell deformation or percentage of
cracked eggs from 10 or 13 months old hens was not
influenced using 100 or 500 mg AA/kg diet at 32.2 or 33.3°C
environmental temperature (Isnak and Sykes, 1974). Oluyemi
and Adebanjo (1979) studied the effect of AA at 50, 100, 150
and 200 mg/kg diet on egg shell quality of 30- and 62-weeks
old hens held at 22.8 to 36.9°C. The shell thickness of the
younger birds was depressed from feeding AA. This trend
appeared to be reversed in the older hens in which AA was
beneficial at dietary concentrations of 100, 150 or 200
mg/kg.

Deetz and Ringrose (1976) found that heat stress
increased potassium excretion from the body. They suggested
that 0.4% potassium in the diet is adequate for meeting
potassium requirements at temperatures of 26.7, 32.2 and
37.8°C. They recommended that 0.6% dietary potassium may be
a more suitable level for assurance against a potassium
imbalance at elevated temperature.

Blood pH of 7.40 was greater in panting birds kept at
32°C than in heat-stressed nonpanting (7.28) birds or those
kept at 24°C (7.28) (Teeter et al., 1985). ‘Adding 0.3 or 1%
ammonium chloride to diets decreased blood pH (P < .01) to
7.19. Also, adding calcium chloride (0.5, 1%) to a mixture

of 1% NH Cl plus 0.5% NaHCO3 lowered the dietary Na:C1

4
ratios. The blood pH of panting birds declined linearly

with lowered dietary Na:Cl ratio, but not to the extent of

the 1% NH4C1 level.

31
Rossoff (1974) indicated that acetaminophen (N-acetyl-

p-aminophenol) increased growth rate and feed utilization in
chickens. Acetaminophen is analgesic, antipyretic and is
the active metabolite of phenacetin. It was used at levels
of 0.5 gm/kg of feed for cockerels and 2.0 gm/kg of feed for
hens. Oluyemi and Adebanjo (1979) studied the effect of
aspirin (acetylsalicylic acid) on egg shell quality from
hens kept at 22.8 or 36.9°C environmental temperature.
Aspirin at 0.15 and 0.20% of diet gave better shell
thickness (mm) for eggs from young hens (30 weeks old) than
levels of 0.05 and 0.10%. There was no significant effect
due to aspirin on shell thickness when fed to old hens (62
weeks of age). Gilbert et a1. (1982) indicated that daily
ingestion of up to 400 mg aspirin for 3 weeks, or 750 mg
aspirin for 2 weeks had no effect on egg production,

oviposition time or bird behavior.

2.2.8.2 Water Treatment for Heat Stress

 

Balnave and Scott (1986) studied the effect of adding
mineral salts to drinking water on egg quality. They added
the following minerals to municipal town water: NaCl(250

mg/l), KCl (40 mg/l), CaCl (120 mg/l), hydrated MgSO (300

2
(200 mg/l) and NaNO

4

mg/l), anhydrous CuSO (350 mg/l). The

4 3
minerals were added to the drinking water over a 6-week
period during which birds were allowed free access to food
and water. The inclusion in the water of low concentrations

of all the mineral salts substantially increased the

32

incidence of shell defects particularly those supplements
with chloride ion. The increase in shell defects was not
associated with the pH of the water. In all cases water
consumption was reduced by between 10 and 20% as compared to
intake by birds receiving no added minerals. Also, the
effect was not related to a decreased feed intake. They
suggested that the adverse shell effects noted from the NaCl
and KCl supplements may be due to the increased intake of
chloride. Balnave and Yoselewitz (1987) also noted a
significant linear increase in egg-shell defects by 60 week-
old laying hens given increasing concentrations of NaCl in
drinking water (up to 600 mg/l).

The addition of 1000 ppm AA to the drinking water of
cockerels, 4 weeks of age, for 4 hours resulted in a
significant increase in plasma AA (Pardue et al., 1984).

Market-age broilers were given Banamine at 0, 1.32,
5.26, and 10.52 mg/l as a treatment for heat stress (35°C
for 8 hours) (Oliver and Birrenkott, 1982). Banamine is a
nonsteroidal anti-inflammatory drug thought to interfere
with prostaglandin production at the level of cyclo-
oxygenase (Ferreira, 1979). There was no effect of Banamine
on peripheral venous prostaglandin F level. However,
Banamine at 10.52 mg/l resulted in less survival time than
the level of 5.26 mg/l, 242 vs 337 minutes, respectively.
The authors presumed that Banamine may be exerting an effect

through its analgesic activity.

33
2.2.8.3 Using Other Measures

Oluyemi and Adebanjo (1979) tried to combat thermal
stress (22.8 to 36.9°C) in 30 and 62-week old laying hens
with the following treatments: 1) control; 2) forced
ventilation at the rate of 9 cfm/layer; 3) drinking water at
0°C between 1200 to 1800 hr; 4) dunking in cold water (0°C)
at 1300 to 1400 hr; 5) dunking in water at 4°C at 1300 to
1400 hr; 6) feeding only at night time, 1800 to 0600 hr
under artificial lighting (10 lux); 7) feeding confined to
day time (0600 to 1800 hr), with artificial lighting (10
lux). Egg size of older hens was significantly (p < .05)
heavier with night feeding whereas the younger layers laid
at a higher rate but produced lighter eggs. The shells of
the older birds were thicker with night feeding and drinking

cold water (0°C) than with any other treatment.

3. Experimentation

 

A total of 256 Single Comb White Leghorn (SCWL) hens
forty six and sixty one weeks of age were used in this
study. The objectives of the experiments were mainly:

1. To find the minimum time of exposure to heat stress that
can result in an obvious reduction in shell quality; 2. To
study the effect of heat stress (35°C) on egg shell quality
during egg shell formation, and to study the importance of
allowing feed and/or water during that time. 3. To overcome
the effect of heat stress on egg shell quality during the
time of egg shell formation. In the last part of the study,
the lighting program was modified so that the light was on
from 12 midnight to 4 p.m. This was done by changing one
hour every two days. The shift in time was done to change
the time of egg shell formation (night time for hens) to
match the regular day time.

The experiments were conducted at the Department of
Animal Science, Michigan State University. The hens came
from a commercial flock of SCWL hens kept at the Poultry
Teaching and Research Center. The birds were kept in single
cages of wire floored batteries in a room kept at 21°C. In

this room, birds were supplied with feed and water ad

34

35

libitum, and artificial light was on a schedule of 16:8,
(light:dark) hours.

An environmental chamber with room for six hens in
single cages was used to study the effect of heat stress on
egg shell quality. Air was provided from an external source
and dispersed through the chamber by a fan. Artificial
light was provided so that the hens could see the feed
and/or the water during the experiment. In some experiments
no feed and water were supplied during the time the hens
were in the heat chamber. An electric heater was used to
provide the required heat. It took 30 to 60 minutes for the
temperature to reach 35°C. When this temperature was
attained, the birds started panting and continued panting to
the end of the experiment. The hens and treatments were
randomly distributed within the environmental chamber to
reduce possible position influences.

Three eggs were collected from each hen before and
after each treatment to measure egg quality (egg weight;
shell weight; % shell of egg weight; mg calcium per unit
surface area, Ca/mm2 (Carter, 1975)). The change in egg
quality (due to the treatment) was measured by the
difference between the average measurements of egg quality
for the three eggs before treatment vs the measurements on
each of the three eggs immediately following the treatment.
For example, if the average of the egg weight for the three
eggs before treatment was 60 grams and the egg weight for

the first day following the stay in the chamber was 58

36
grams. The change in egg weight due to the treatment will

be (58-60) - 2 grams. Eggs were collected and weighed
daily. After weighing the eggs and removing their contents,
the shells were carefully washed, dried, and weighed.
Percent shell (weight of dried shell plus membranes/total
egg weight x 100) was determined. For some experiments a

model 158 Corning Blood Gas System was used for determining

the pH, PCO2 (partial pressure of carbon dioxide) and HCO3

(bicarbonate) activities of whole blood immediately after

each sample was drawn from the wing vein of each bird.

3.1 Experiment 1

 

This experiment was designed to study the effect of
acute heat stress (35°C) for 1, 2, 4, and 6 hours on egg
quality. SCWL hens, approximately 61 weeks of age, were
used after one month of acclimatization at 21°C. During
this period, the birds were fed a commercial laying diet
(14.0% crude protein, 3.2% calcium and total phosphorus of
0.55%). They received 15 hours artificial light per day.
Following the acclimatization period, a total of 12 birds
for each treatment were subjected to 35°C for 1, 2, or 6
hrs., and 24 birds for 4 hours. Another group of hens was
used as a control in the environmental chamber for each of
the same lengths of time at the chamber temperature (23°C).
During the experiment in the environmental chamber, only
water was available. After being used in the heat chamber,

the hens were kept at 21°C for two weeks, at least, before

37

being used again. This two week period was to avoid
acclimatization to the heat. Wolfenson et al. (1979)
reported that one week after exposure to 34 to 40°C for 6 to
7 hours was enough for recovery from the high temperature

exposures .

3.2. Experiment 2

 

The experiment was designed to study the effect of heat
stress (35°C) on the first egg following the exposure of
young hens 46 weeks of age to 6 hours of heat stress during
the day time (without active shell deposition). During the
acclimatization period (about a month), the birds were fed a
laying diet which was formulated to ensure an adequate
intake of all nutrients, recommended by N. R. C. (1984)
(Table l.a).

There was a period of recovery from heat stress for 3
to 4 weeks before hens were used again in the heat chamber.
In this experiment the temperature of 35°C was reached in 30
minutes. A total of 12 hens were heat-stressed, and 12 were
in the chamber without heat. Ambient temperature was about
23°C. During the stay in the chamber only water was
available. Egg quality was measured as described in
eXperiment 1. Also in this experiment, feed consumption was
determined for each hen over the next 24 hours after leaving
the chamber. Body temperature was taken for each bird as
they were placed into the chamber and when they were

removed. Body temperature was read directly from a

38

thermometer inserted into the rectum to a depth of six
centimeters and held in place for two minutes prior to a

reading (Harrison and Biellier, 1969).

Table l.a The percentage composition of the diet fed to the
hens used in the experiments from 2 to 10.

 

 

Ingredients %
Ground yellow corn 63.5
Soyabean meal (44%) 23.36
Corn 011 2.27
Dicalcium phosphate 1.19
Ground limestone 9.00
Iodized salt 0.366
Vitamin and mineral mix (1) 0.250
DL Methionine 0.072
Total 100.00

Calculated values

 

crude protein, % 15.87
calcium, % 3.75
available phosphorus, % 0.35
metabolizable energy, K cal/gm 2.848
lysine, % 0.836
ether extract (fat), % 4.87
methionine + cystine, % 0.61

<Supplies per kg diet)

(1) Vitamin A, 11,013 IU; vit D 3304 ICU; vit E, 16.5 IU;

3'
vit K1, 2.2 mg; vit 82' 5.5 mg; pantothenic acid, 16.5

mg; Niacin, 55.1 mg; choline chloride, 330.0 mg; vit

0.014 mg; biotin, 0.06 mg; vit B 1.10 mg; vit B

312' 1' 6'
1.65 mg; folic acid, 0.55 mg; Mn, 75 mg; Se, 0.1 mg; Zn,

75 mg; Fe, 37.5 mg; Cu, 0.75 mg; I, 0.75 mg.

39

3.3 Experiment 3

 

The purpose of this experiment was to study the effect of
35°C for 6 hours on egg quality of hens stressed at the time
of egg shell formation and when there was no egg shell
formation. The photoperiod was from 0700 to 2300 hr. The
effect of heat stress on egg quality during the time of active
shell deposition was studied during the hours of 1600 to 2300.
The effect of heat stress on egg quality from hens without
active shell deposition was studied at the time between 0800
and 1600 hr. During the stay in the chamber only water was
available. Feed comsumption and body temperature were

determined.

3.4 Experiment 4

Heat for 4 or 6 hours or a stay in the chamber without
heat was applied (during the time of egg shell formation) to
forty eight hens in 2 x 2 factorial design. During the time
the hens were in the chamber only water was available. Body
temperature was determined just before and after hens were in
the chamber. Feed intake was determined 24 hours after the

hens were in the chamber.

3.5 Experiment 5

 

This experiment was designed to study the effect of feed
and/or water, heat or no heat during egg shell formation. A
total of 12 birds for each treatment was used. Four hours

exposure time in the chamber was used. Hens were palpated

40

for an egg in the uterus, and only those with an egg were used

in this experiment.

3.6 Experiment 6

 

SCWL hens approximately 61 weeks of age were used after a
30-day period of acclimatization to 21°C. They were used to
study the effect of drugs and chemicals to alleviate the
effect of 35°C heat for 4 hours during egg shell formation.
Feed consumption, body temperature, water intake and drug
consumed were determined as well as egg quality. Only birds
actively depositing shells were used in the heat chamber. At
least 3 to 4 weeks were allowed after heat stress before birds
were used in another experiment.

Six treatments were used in this experiment consisting of
a control diet, (table 1), which was supplemented with vitamin
C at 50 or 150 mg/kg; aspirin, 0.2%; potassium bicarbonate,
0.9% or sodium bicarbonate, 0.75% (by proportionate
displacement of all ingredients). Hens were fed the
experimental diets for at least 3 days before they were placed
into the environmental chamber and stressed at 35°C.’ During
the heat stress, only water was available. Egg weight,shell
weight and % shell were measured. Also body temperature
before and after treatment and feed consumption over the next

24 hours for each hen were also determined.

3.7 Experiment 7
In this experiment, three of the last six treatments were

duplicated. These treatments were: the control diet, aspirin

41

at 0.2%, and potassium bicarbonate at 0.9%. Shell thickness
was added to the previous egg quality measurements. Blood
samples from the brachial vein were taken at the end of the 4
hours in the heat chamber, using a heparinized syringe
(Corning Medical, Corning Glass Works, Medfield, Massachusetts
and HCO - activities of whole blood

2 3

were determined. In addition, body temperature of each hen

02052, USA). The pH, PCO

was taken at the time of the blood sample.

3.8 Experiment 8

 

This experiment was designed to compare the blood pH,

PCO and HCO - of hens stressed at 35°C compared to the blood

2’ 3
of hens in the chamber at 21°C. Twelve hens were used for
heat study and 10 hens for the no heat study. The blood

samples were taken only from a bird with an egg in the uterus.

During heat stress only water was available.

3.9 Experiment 9

 

This experiment was carried out (during the time of egg
shell formation) to determine if the effect of heat stress
could be counteracted by drugs and minerals in the water. In
this experiment one of the following compounds was added to
tap water (control): 1.6 gm KCl/l (or 0.839 gm K/l); 8.30 gm
CaClZ/l (or 2.996 gm Ca/l); 1.083 gm aspirin/l; 0.267 gm
acetaminophen/1, and 4.81 pH buffer solution. The buffer
solution was made of 1.2 gm KOH/l and citric acid in deionized

water. It contained 0.833 gm K/l of water. A pH meter, Model

42
825 (Fisher Scientific) was used to adjust the pH of the

buffer solution. Aspirin was provided as sodium acetyl-
salicylate (Miles Inc., Elkhart, IN 46515 USA). Acetaminophen
is product of Mead Johnson Nutritionals, A Bristol Myers
Company, Evansville, IN 47721 U.S.A. The following
measurements were taken: egg weight, shell weight, % shell,
body temperature, feed intake/day. Also water and drug intake
during the heat treatment were measured. There was no feed

available during the heat of 35°C for 4 hours.

3.10 Experiment 10

 

In this experiment, five different treatments were used
during heat (35°C) at the time of egg shell formation for four
hours (Table l.b). Each hen was given orally 2 equal doses of
each of KCl and acetaminophen. The first dose was given
orally in a volume of 5 ml distilled water about 2 hours
before hens went into the environmental chamber. The second
dose was given in the water allowed during heat stress. A
dose of 5 mg Vitamin C/hen was given orally two-hours before
providing carbonated water during heat stress, or in addition
to the oral dose of the acetaminophen. Carbonated water was
provided in the commercial form for human consumption which
contains corn syrup. In this experiment both water and feed
were available during heat stress. ‘Feed consumption, water
intake, drug intake, body temperature, egg weight, shell

weight, and % shell were determined in this experiment.

43

Table l.b Treatments used in an attempt to alleviate the effect of heat
at 35°C for 4 hrs. during egg shell formation.

 

 

Treatment Compounds that gm/hen gm/l water allowed
number are used (2 hrs before) (during heat stress)
1 None in ‘ 0 0
tap water
(control)
2 KCl (level 1) 0.286 KCl 1.907 KCl
(or 0.15 K) (or 0.999 K)
3 KCl (level 2) 0.572 KCl 3.814 KCl
(or 0.30 K) (or l.998 K)
4 carbonated carbonated water carbonated water
water + vit C + 5 mg vit C
5 acetaminophen 0.096 acetamino- 0.640 acetamino-
+ vit C phen + 5 mg vit C phen

 

Statistical Analysis

 

Data collected (for each treatment in each of the three
stages) were subjected to analysis of variance and simple
linear regression using the Stat View 512+ program by Brain
Power Inc., 24009 Ventura Boulevard Calabases, CA 91302 for
the Macintosh computer. Means were further subjected to
Fishers (Protected) least significant difference (FPlsd).
Analysis of covariance was used for some data, according to

Steel and Torrie (1980).

4 . RESULTS

4.1. Experiment 1. Effect of heat (35°C) or no heat
treatments for 1,2,4, and 6 hrs on egg quality using
SCWL hens 61 weeks of age

 

4.1.1. The Effect on the Change (gm) in Egg Weight

 

Hens held in the heat chamber at ambient temperature
for 1, 2, 4, or 6 hours laid eggs averaging 0.32 gm more
than the 3 eggs they laid before going into the chamber. On
the other hand, the hens stressed at 35°C for l, 2, 4 or 6
hours laid eggs that averaged 0.218 gm less than the three
each hen laid before being heat stressed (Table 2.a). There
was no consistent trend for egg weight to decline with
increasing hours of heat (Fig. l). The loss in egg weight
was as great after 1 hour of heat stress as that after 6
hours. Furthermore, the eggs laid by hens stressed for 4
hours actually weighed more than their controls, or those
laid by hens in the chamber for 4 hours but not heat
stressed (Fig. l). The average gain or loss in egg weight
for the hens in the chamber at various times, whether heat
stressed or not, is provided in tables 2.a, b, and c. No
definite trend for a loss of egg weight associated with
acute heat stress is noted. Linear regression analysis
(Table 6) showed that there was no significant reduction in
egg weight with increasing hours of the exposure to the heat

(Fig. 2) or no heat (Fig. 3) on the lst day following the

44

45

Table 2.a. Effect of heat or no heat treatments for l, 2, 4, and 6 hrs. on
the change (gm) in egg weight using SCWL hens 6) weeks of

 

 

age.

hrs. in chamber and No heat Heat (35°C) Overall

days following the No. of AV. of No. of AV. of No. of AV. of

stay in the chamber hens change hens change hens change
lhr.
day I 11 0.394 11 -l.42 22 -0.513
day 2 8 0.031 10 -l.0)2 18 -0.548
day 3 10 2.325 )0 -0.714 20 0.806
2hrs.
day l 9 -0.422 8 -0.951 )7 -0.671
day 2 10 0.345 It 1.077 2] 0.729
day 3 )0 -0.36 8 0.571 18 0.054
4hrs.
day I 22 0.15 20 0.23 42 0.188
day 2 16 0.467 22 0.465 38 0.466
day 3 22 -0.288 21 0.073 43 -0.lll
6hrs.
day l 9 0.854 10 -l.374 l9 -0.3l8
day 2 12 -0.08 10 -0.333 22 -0.l95
day 3 9 1.407 9 -0.886 )8 0.261

overall average

of change 148 0.322 150 -0.218 298 0.05

 

 

(1) Change - The egg weight for a hen on the lst (or 2nd or 3rd) day
following the stay in chamber - Average of 3 eggs weights for the same
hen before being in the chamber.

46

RIO-’80

I-qut :|-

 

 

 

I Control I Huntsman

 

 

 

Figure 1: Effect of heat or no heat treatments for 1,2,4 and 6 hrs on the
change (gm) in egg weight on the lst day following the stay in
the chamber

47

Table 2.b. Effect of heat or no heat treatments and the hours of exposure
to these treatments on the change (gm) in egg weight

 

 

hrs. in chamber No heat Heat (35°C) Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
1hr. 29 0.96 31 -1.061 60 -0.084
2 hrs. 29 -0.l36 27 0.326 56 0.087
4 hrs. 60 0.074 63 0.26 123 0.169
6 hrs. 30 0.646 29 -0.863 59 -0.096
overall AV.
of change 148 0.322 150 -0.218 298 0.05

 

Table 2.c. Effect of heat or no heat treatments and the days following the
stay in chamber on the change (gm) in egg weight.

 

 

No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change

day 1 51 0.226 49 -0.66 100 -0.208
day 2 46 0.222 53 0.163 0.19
day 3 51 0.509 48 -0.187 0.172
Overall AV.
of change 148 0.322 150 -0.218 298 0.05

 

Chg Egg Vt-g

48

g I .2211: - 1.233, R-squrod: 6.83153
8 L A i i A .

 

' V W 1

 

 

0000 0CD

 

 

 

9‘0 OOOfikm 00

0‘4

Figure 2: Effect of heat stress (35°C) for 1,2,4 and 6 hrs on
the change (gm) in egg weight on the lst day following
the stay in the chamber -

Che £99 “-9

49

g I .149; - .156, W: 3.8093

 

 

 

 

 

 

 

 

 

6 a g a

1 9 .
41 0 0
21 a e e g .

9 0 9. o

n t5 ‘ -
- - O U U

‘ 8
-2+ ,. Q 8 .

1 g 8 .
-4« C)
‘64 O 1
'8 T e. . . r . . e . r

.3 1 2 4 6

Han 11 Chamber:

Figure 3: Effect of no heat treatments for 1,2,4 and 6 hrs on the
change (gm) in egg weight on the lst day following the
stay in the chamber

50

stay in the chamber. Covariance analysis showed that there
was no difference in the change in egg weight between heat
or no heat treatments at the various times on the lst day

following the treatment.

4.1.2. The Effect on the Change (gm) in Shell Weight
Average change in shell weight is shown in Table 3.a,
b, and c. There was a reduction of 0.131 gm in shell weight
due to heat stress (35°C) regardless of the hours of the
exposure to that heat or the days following the stay in the
chamber. There was a reduction of only 0.014 gm in shell
weight due to no heat treatments (Table 3.b). Four hours
heat stress caused the maximum reduction in shell weight (-
0.172 gm) and the reduction due to 4 hrs and 6 hrs heat
stress was about the same (-0.l72 vs. -0.l46 gm) (Table
3.6). Most of the reduction in shell weight was on the lst
day following the stay in the chamber (regardless of the
hours in the chamber or the temperature) (Table 3.c). There
was a reduction in shell weight of 0.198 gm on the lst day
following the stay in the chamber vs. a reduction of 0.046
or an increase of 0.026 gm on the second and the third day,
respectively. There was an obvious trend for shell weight
to decline with increasing hours of heat (Fig. 4). Maximum
reduction in shell weight was on the lst day following heat
stress for 6 hours (0.486 gm). And there was a reduction of
only 0.141 gm due to the stay in the chamber for 6 hours but

without heat stress (Table 3.a). Linear regression analysis

51

Table 3.a. Effect of heat or no heat treatments for 1, 2, 4, and 6 hrs.
on the change (gm) in shell weight using SCWL hens 61 weeks

 

 

of age.
hrs. in chamber and No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change
lhr.
day 1 11 -0.105 11 -0.206 22 -0.156
day 2 8 -0.17 10 -0.016 18 -0.084
day 3 10 0.086 10 0.045 20 0.065
2 hrs.
day l 9 -0.044 8 -0.181 17 -0.109
day 2 10 -0.|29 11 -0.065 21 -0.095
day 3 10 —0.144 8 -0.068 18 -0.11
4 hrs.
day 1 22 -0.064 20 -0.351 42 -0.20
day 2 16 0.129 22 -0.197 38 -0.06
day 3 22 0.091 21 0.026 43 0.059
6 hrs.
day 1 9 -0.141 10 -0.486 19 -0.323
day 2 12 0.018 10 0.101 22 0.055
day 3 9 -0.042 9 0.123 18 0.041
overall AV.

of change 148 -0.014 150 -O.l31 298 -0.073

 

MQI’SO

Oidza—M: .—

 

Figure 4:

52

 

 

LI Control I mama ' I

Effect of heat or no heat treatments for 1,2,4 and 6 hrs
on the change (gm) ixldrfllweight on the lst day following
the stay in the chamber '

Table 3.b. Effect of heat or no heat treatments and the hours of exposure

to these treatments on the change (gm) in shell weight.

 

 

hrs. in chamber No heat Heat (35°C) Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
1 hr. 29 f0.057 31 -0.064 60 -0.061
2 hrs. 29 -0.108 27 -0.10 56 -0.104
4 hrs. 60 0.045 63 -0.172 123 -0.066
6 hrs. 30 0.0016 29 -O.146 59 -0.071
overall AV.
of change 148 -0.014 150 -0.131 298 -0.073

 

Table 3.c. Effect of heat or no heat treatments and the days following the
stay in chamber on the change (gm) in shell weight.

 

 

No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change

day 1 51 -0.083 49 -0.318 100 -0.198
day 2 46 -0.0080 53 -0.079 99 -0.046
day 3 51 0.05 48 0.0014 99 0.026
overall AV.
of change 148 -0.014 150 -0.131 298 -0.073

 

54

 

 

 

 

 

cmsmn Vt-g
I
9'

000 ooq

 

 

 

41 .
‘1251 1
“I .51 L
-‘ on V I ‘ V 77 Y fl 7 T I
.3 1 2 6
Hours mm:

‘Figure 5: Effect of heat stress (35°C) for 1,2,4 and 6 hrs on the
change (gm)in shell weight on the lst day following the
stay in the chamber

CM 81%“ Vt-g

55

Control has 1. but chamber at ambient 1m

 

 

 

 

 

 

.6‘ O a . .
AI 0 O [
2. O o B
o 8 0 .5 ’
-2, o T o
341 g; r C) 1? C) .
{64 (D ‘3 C) :
'31 .
.. a V g Y g r 9
5 Hows Ir‘ICMnbor: 2 4 6

Figure 6: Effect of no heat treatments for 1,2,4 and 6 hrs on the
change (gm)in.shenpweight on the lst day following the
stay in the chamber

56

(Table 6) showed that there was a borderline significant

(P = .05) reduction in shell weight with increasing hours of
heat (Fig. 5) but there was no effect due to the hours when
there was no heat (Fig. 6 and Table 6). Covariance analysis
showed that there was a highly significant (P < .01)
reduction in shell weight between heat or no heat treatments
at the various times on the lst day following the treatment.
Table 3.c showed that there was a reduction of 0.318 gm in
shell weight due to heat stress compared to a reduction of
only 0.083 gm due to no heat treatments on the lst egg
following the stay in the chamber. Covariance analysis also
showed that there was no significant difference between the
effect of heat or no heat treatments at the various times on
the shell weight in case of the second or third egg
following the stay in the chamber. This indicates that the
effect of 35°C heat stress (for periods up to 6 hours) on

the shell weight lasts for only one day.

4.1.3. The Effect on the Change in % Shell

The average value of change in % shell are shown in
tables 4.a, b, and c. There was a reduction of 0.197% in %
shell for hens held in the chamber with heat (35°C) for 1,
2, 4 or 6 hours but there was a reduction of only 0.121%
when there was no heat (Table 4.a). The % shell results
supported the previous results for shell weight in that most
of the effect was on the lst egg following the stay in the

chamber (Table 4.c). Regardless of the hours in the

57

Table 4.a. Effect of heat or no heat treatments for 1, 2, 4, and 6 hrs. on
the change (gm) in Z shell using SCWL hens 61 weeks of age.

 

 

hrs. in chamber and No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change
1hr.
day 1 11 -0.238 11 -0.023 22 -0.13
day 2 8 -0.296 10 0.112 18 -0.069
day 3 10 -0.229 10 0.223 20 -0.0030
2 hrs.
day 1 9 0.0033 8 -0.16 17 -0.074
day 2 10 -0.26 11 -0.265 21 -O.262
day 3 10 -0.191 8 -0.196 18 -O.193
4 hrs.
day 1 22 -0.135 20 -0.679 42 -0.394
day 2 16 -0.229 22 -0.46 38 -0.363
day 3 22 0.148 21 -0.0090 43 0.071
6hrs.
day 1 9 -0.349 10 -O.604 19 -0.483
day 2 12 0.045 10 0.207 22 0.119
day 3 9 -0.027 9 0.116 18 0.044
overall AV.
of change 148 -0.121 150 -0.197 298 -0.159

 

F'C’Ill-akfi g.

0.1:

-0.3 :1
'0J‘“
'0511
-015v
-CL7"

 

Figure 7:

 

58

 

 

 

' I Control I mam

 

 

 

Effect of heat or no heat treatments for 1,2,4 and 6 hrs
on the change in Z shell on the lst day following the
stay in the chamber

59

Table 4.b. Effect of heat or no heat treatments and the hours of exposure

to these treatments on the change in Z shell.

 

 

hrs. in chamber No heat Heat (35°C) Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
1 hr. 29 -0.251 31 0.10 60 -0.07
2 hrs. 29 -0.154 27 -0.213 56 -0.183
4 hrs. 60 -0.056 63 -0.379 123 -0.222
6 hrs. 30 -0.095 29 -0.101 59 -0.098
overall AV.
of change 148 -0.121 150 -O.197 298 -O.159

 

Table 4.c. Effect of heat or no heat treatments and the days following the
stay in chamber on the change in Z shell.

 

 

No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change
day 1 51 -0.17 49 -0.432 100 -0.299
day 2 46 -0.176 53 -0.185 99 -0.181
day 3 51 -0.023 48 0.031 99 0.0033
overall AV.
of change 148 -0.121 150 -0.197 298 -0.159

 

60

g I ~24): + .109, W: .138

 

 

 

 

 

 

-21 I
-25. L
1
-31 o ,
a: - . e f Y 1 - - v
s 1 2 4 6

Figure 8: Effect of heat stress (35°C) for 1,2,4 and 6 hrs on the
change in Z shell on the lst day following the stay in
the chamber ,

61

 

 

 

 

 

 

2 n
1:51 o 0 ,
1< 1
. O
3 ~51 o 0 >
=: 0 EL—— #4; ’3
1% 'a51 . E; .
a - ° *
‘; o 1
4.54] .
‘24 0 .
-2.s‘ , r e 4 s - a . s . . .
.3 1 2 4 6

Figure 9: Effect of no heat treatments for 1,2,4 and 6 hrs on the
change in Z shell on the lst day following the stay in
the chamber

62

chamber, there was a reduction of 0.299% in shell percentage
in case of the lst egg following the stay in the chamber and
a reduction of only 0.181% or almost no change in case of
the second or the third egg following the stay in the
chamber (Table 4.C). The trend for % shell to decline with
increasing hours of stay in the chamber was not clear for
the overall average of all the 3 days together (Table 4.b);
but the effect of hours of the exposure to heat was definite
on the lst day (Fig. 7). There was a reduction of 0.679 and
0.604% shell for 4 and 6 hours, respectively, and there was
a reduction of only 0.023 and 0.16% shell for 1 and 2 hours
heat stress, respectively (Table 4.a). Linear regression
analysis (Table 6) indicated that there was a highly
significant reduction in % shell with increasing hours of
heat (Fig. 8) but there was no effect in case of no heat
(Fig. 9). Covariance analysis indicated that there was a
significant reduction in % shell in case of heat when
compared to no heat treatments at various times on the lst
day following the stay in the chamber. There was no
difference between heat or no heat treatments on the % shell
on the second or third day following the stay in the
chamber.

4.1.4. The Effect on the Change in mg Came2

 

The average change in mg Ca/mm2 for the hens in the
chamber at various times, whether heat stressed or not, is

provided in table 5.a, b and c. Hens held in the heat

63

chamber at ambient temperature for l, 2, 4, or 6 hours laid
eggs averaging 0.0054 mg Ca/mm2 less than the 3 eggs they
laid before going into the chamber. However, the hens
stressed at 35°C for l, 2, 4 or 6 hours laid eggs that
averaged 0.0069 less than the three each hen laid before
being heat stressed (Table 5.a.). There was a significant
decline in Ca/mm2 starting with 4 hours of heat stress (Fig.
10). The results of the change in mg Ca/mm2 supported the
results of both shell weight and % shell in that the effect
of heat stress was obvious only on the lst day following the
treatment (Fig. 11) and there was no effect from staying in
the chamber without the heat treatments (Fig. 12). The

2 of the shell was 0.022 and 0.021 mg

decline in mg Ca/mm
Ca/mm2 for 4 and 6 hours exposure to heat stress (35°C) vs.
a reduction of 0.0065 and 0.0068 mg Ca/mm2 for l and 2
hours exposure to the same temperature (Table 5.a).

The overall results of this experiment showed that:
1) four or six hours exposure to heat stress for only one
day was enough to reduce the egg shell quality significantly
for one day (lst day following the treatment), 2) there was
no significant effect on egg weight due to this experiment,

3) there was a high correlation between egg shell quality

parameters (shell weight, % shell and Ca/mmz) (Table 5.d).

64

Table 5.a. Effect of heat or no hgat treatments for 1, 2, 4, and 6 hrs. on
the change in mg Ca/mm of the egg shell using SCWL hens 61
weeks of age.

 

 

hrs. in chamber and No heat Heat (35°C) Overall
days following the No. AV. of No. AV. of No. of AV. of
stay in the chamber hens change hens change hens change
lhr.
day 1 11 -0.0074 11 -0.0065 22 -0.0070
day 2 8 -0.016 10 0.0008 18 -0.0069
day 3 10 -0.0034 10 0.0040 20 0.0003
2 hrs.
day 1 9 -0.0004 8 ~0.0068 17 ~0.0034
day 2 10 -0.0083 11 -0.0075 21 -0.0079
day 3 10 —0.0076 8 -0.0076 18 ~0.0076
. 4 hrs.
day 1 22 -0.0043 20 -0.022 42 -0.013
day 2 16 ~0.007O 22 ~0.011 38 -0.0092
day 3 22 -0.0055 21 0.0025 43 -0.0027
6 hrs.
day 1 9 —0.011 10 -0.021 19 -0.016
day 2 12 0.0017 10 0.0069 22 0.0040
day 3 9 0.0010 9 0.0089 18 0.0094
overall AV.
of change 148 -0.0054 150 -0.0069 298 -0.0062

 

can I a -r:

O. a-‘-

W.‘

MI I

65

 

 

-0.025 4-

 

LI Control I batsman

 

Figure 10: Effect of heat or no heat treatments for 1,2,4 and 6 hrs
on the change in mg Ca/mm on the lst day following the
stay in the chamber

66

Table 5.b. Effect of heat (35°C) or no heat treatments and the ho rs of
exposure to these treatments on the change in mg Ca/mm of egg

 

 

shell.
hrs. in chamber No heat Heat (35°C) Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
1 hr. 29 -0.0085 31 -0.0008 60 -0.0045
2 hrs. 29 -0.0056 27 -0.0073 56 -0.0064
4 hrs. 60 -0.0055 63 -0.011 123 -0.0082
6 hrs. 30 -0.0022 29 -0.0047 59 -0.0034
overall AV.
of change 148 -0.0054 150 -0.0069 298 -0.0062

 

Table 5.c. Effect of heat or no heat treatments and Ehe days following the
stay in chamber on the change in mg Ca/mm of egg shell

 

 

No heat Heat (35°C) Overall
days following the No. of AV. of No. of AV. of No. of AV. of
stay in the chamber hens change hens change hens change

day 1 51 -0.0054 49 -0.016 100 -0.011
day 2 46 -0.0067 53 -0.0046 99 -0.0056
day 3 51 —0.0044 48 -0.0002 99 -0.0023

overall AV.
of change 148 -0.0054 150 -0.0069 298 -0.0062

 

CththwnZ

67

g I -6.166£-3x + 8.339793, W: .107

 

 

 

 

 

m 4
M< 0 1
1 1
.021 O 1
1
8 e n ‘
01 5 1
' 024 O ‘ 1
1 (D C)
-.04« b
4051 ' .
egg. ,
-0' T r T V v T r I ' 9 T V I v
.5 l 2 4 6
How: it Chm:

Figure 11: Effect of heat stress (35°C) for 1,2,4 and 6 hrs.on the
change in mg Ca/mm2 on the lst day following the stay in
the'chamber

68

9 II -9.343E-4x - 3.01ZE-3, Ram: 3.23353

 

 

 

 

 

 

.06J l
.041 0 o .
.02« V 0 1
1 O 0 O
3 °—— “ 4e
1 V
g... 3 i o ,
‘ o
'0‘“ .
1
70‘] o 1
303 . 4r - ' f7 .~ T . 4 .— f
a 1 2 4 6
Hulslncannr:

Figure 12: Effect of no heat treatments for 1,2,4 and 6 hrs on the
change in mg Ca/mm2 on the lst day follOwing the stay in
the chamber

 

 

69

Table 5.d. The correlation between egg shell quality
parameters used in experiment 1.

Chg. % shell wt. Chg. Ca/mm2 Chg. shell wt.

 

Chg % shell Wt. l
Chg Ca/mm2 .949 l
Chg Shell Wt. .747 .839 l

 

4.2. Experiment 2. Effect of heat (35°C) or no heat
treatments for 6 hrs at the time between 0800 and 1600
hr (without active shell deposition) on the change in
egg quality on the lst day following the stay in the
chamber using SCWL hens 46 weeks of age

 

4.2.1. The Effect on the Change (gm) in EggfiWeight

 

The average change in egg weight is shown in Table 7.
There was a reduction of 2.043 gm in egg weight in case of
heat stress and 0.866 gm in case of no heat. The reduction

in egg weight due to heat was not significant.

4.2.2. The Effect on the Change (gm) in Shell Weight
There was almost no change (+0.03) in shell weight
(Table 7) due to no heat for 6 hours, but the shell weight
of the lst egg following the heat stress (35°C) was 0.283 gm
less than average value of the the 3 eggs laid before being
heat stressed. The reduction in shell weight due to heat

stress was significant (P < .05).

70

. . 1 .

Table 6. Regre551on analy31s of hours( ) in heat chamber and the change
in egg parameters for heat or no heat treatments on the first
egg following the treatments in experiment 1.

 

 

Egg parameters Regressibn equation Correlation Significance
coefficient level (p)

1. Egg weight

a. with heat y = 0.221x - 1.233 0.083 0.572

b. without heat y = 0.149x - 0.156 0.062 0.665

2. Shell weight

 

 

a. with heat y = -0.097x - 0.066 0.269 0.062
b. without heat y = -0.007x - 0.065 0.026 0.857
3. Z Shell

a. with heat y = -0.24x + 0.189 0.371 0.009
b. without heat y = -0.032x - 0.088 0.056 0.695
4. Ca/mm2

a. with heat y = -0.006x + 0.00008 0.327 0.022
b. without heat y = -0.0009x - 0.003 0.057 0.692
(1)

Hours = 1, 2, 4, and 6 hours.

71

Table 7. Effect of heat (35°C) or no heat treatments for 6 hrs. at the
time between 0800 and 1600 hr. (without egg shell deposition) on
the change in egg quality on the first day following the stay in
the chamber using SCWL hens 46 weeks of age.

 

 

Egg quality No heat (9 hens) Heat (35°C) (10 hens)
Parameters Average of change Average of change

1. egg weight (gm) -0.aaea -2.0438

2. shell weight (gm) 0.03a -0.283b

3. z shell 0.184a --0.20a

4. mg Ca/mm2 0.0051a —0.007ea

 

a, b values followed by different letters in the same row are
significantly different (P.S .05).

72
4.2.3. The Effect on the Change in % Shell

The values for the change in % shell are shown in Table
7. The reduction in % shell (-0.20%) due to heat stress was
not significant when compared to the change in % shell in

case of no heat (+0.184%).

4.2.4. The Effect on the Change in Ca/mm2
The change in mg Ca/mmzof the egg shell (Table 7) was
not significant between heat (-0.0076 mg Ca/mmz) and no heat
(+ 0.0051 mg Ca/mmz). There was a high correlation between

egg shell quality parameters (Table 8).

Table 8 . The correlation between egg shell quality
parameters in experiment 2.

Chg. % shell wt. Chg. Ca/mm2 Chg. Shell wt.

 

Chg. % shell Wt. l
Chg. Ca/mm2 .969 1
Chg. Shell Wt.(g) .982 .98 l

 

4.2.5. The Effect on the Feed Intake
The amount of feed intake (Table 9) 24 hours following
the heat stress (35°C) for 6 hours (74 gm) did not differ
significantly than the amount of feed intake 24 hours

following the stay in the chamber without heat (85 gm).

73
4.2.6. The Effect on the Change in Body Temperature

 

There was a significant increase in body temperature
due to heat stress (+0.79°C) when compared to no heat

treatment (+0.ll°C) (Table 9).

Table 9. The relationship between heat (35°C) or no heat
treatment for 6 hours at the time between 0800
and 1600 hr (without egg shell formation) and
both of feed consumption and the change in body
temperature due to these treatments.

 

Heat No Heat
(10 hens.) (9 hens.)
Feed Intake (gm) 18 hours a a
following the stay in chamber 74 85
Change in body temp. (°C) a b
due to the stay in the chamber +0.79 +0.11

 

a, b values in the same row differently superscripted are

significantly different (P g .05).

The overall results of this experiment showed that the
effect of heat stress (35°C) for 6 hours at day time, when
shell deposition was not occuring, in case of young hens (46
weeks of age) was significantly effecting only the shell
weight of many factors analyzed. This effect may be due to
the significant increase in body temperature rather than the

difference in feed intake at that time.

74

4.3. Experiment 3. Effect of heat (35°C) or no heat for 6
hrs at the time between 0800 and 1600 hr (without
shell deposition) and during egg shell formation
(between 1600 and 2300 hr) on the change in egg
quality for the lst egg following the stay in the
chamber using SCWL hens 46 weeks of age

 

4.3.1. The Effect on the Change (gm) in Egg Weight
There was a reduction of 1.408 gm in egg weight for the

treatments when there was no shell formation (No SF) due to
stay in the chamber for 6 hours and there was a reduction of
only 0.255 gm for the treatments during egg shell formation
(SF). Regardless of heat or no heat treatments, the
difference between those values was significant. Regardless
of the time of the stay in the chamber, heat treatments
caused a reduction of 1.197 gm in egg weight vs. a reduction
of only 0.27 gm for no heat treatments (Table 10). The
difference between the last two values was not significant.
LSD analysis (Table A.l.a Appendix) showed that there was no
significant difference between the change in egg weight due
to heat (-l.899 gm) and no heat (-0.863 gm) at (No SF) time.
Also there was no difference between the values of the
change in egg weight due to the temperature during egg shell

formation time (Table 10.A).

4.3.2. The Effect on the Change (gm) in Shell Weight
Table 10.8 shows that the egg shell for the first egg
laid after being in the chamber decreased 0.683 gm due to
the heat stress but it decreased only 0.317 gm due to the
stay in the chamber for 6 hours without heat. The

difference between those two values was significant. There

75

 

 

Table 10. Effect of heat (35°C) or no heat for 6 hrs. at (No SF) time

(SF) time on

A. The change in egg weight (gm) on the lst day following the
stay in the chamber using SCWL hens 46 weeks of age.

treatments (No SF) time (SF) time overall

No. AV. of No. of AV. of No. of AV. of

hens change hens change hens change
No heat 9 -0.863: 8 0.397: 17 -0.273
Heat 10 -1.899 13 -0.656 23 -1.197a
Overall AV. a b
of change 19 -1.408 21 -0.255 40 -0.803

. The change in shell weight (gm)
No heat 9 0.038a 8 -0.70gb 17 -0.317:
Heat 10 -0.283 13 -0.99 23 -O.683
Overall AV. a b
of change 19 -O.135 21 -0.882 40 '0.527
C. The change in Z shell
No heat 9 0.181: 8 -I.259: 17 -0.496:
Heat 10 '0.142 13 -1.577 23 “0.953
Overall AV. a b
of change 19 0.011 21 -1.456 40 -O.759
D. The change in mg Ca/mm2

No heat 9 0.0051: 8 -0.04bb 17 -0.0163
Heat 10 -0.0076 13 -0.051 23 -0.0328
Overall AV. a b
of change 19 -0.0016 21 -0.047 40 -0.025

 

a, b values followed by different letters in the same column or row are

significantly different (P.S .05). Values followed by different letters

in the overall average column or row are significantly different (P.S

.05).

76
was a highly significant reduction in shell weight (-0.882

gm) due to the stay in the chamber during egg shell
formation when compared to the stay in the chamber at (NO
SE) time (-0.135 gm). LSD analysis (Table A.l.b) showed
there was no significant differences between the values for
heat and no heat at (SF) or at (No SF) time. But there was
a significant reduction in shell weight due to the stay in
the chamber during egg shell formation regardless of the

temperature.

4.3.3. The Effect on the Change in % Shell

 

The values for % shell were -0.953% for heat and -
0.496% for no heat. The difference between these values was
not significant. There was a highly significant reduction
of 1.456% shell for (SF) time treatment when compared to an
increase of 0.011% shell for (No SF) time treatment (Table
10.c). LSD analysis (Table A.l.c.) indicated that the
values of % shell (-l.259 and -l.577%) obtained from the
treatments during egg shell formation for no heat and for
heat treatments, respectively, were significantly different
from those (0.181 and -0.142%) obtained from the stay in the
chamber during (No SF) time. And there was no difference
between the values due to the temperature during (No SF)
time (0.181 vs. -0.l42%) or at the time of egg shell

deposition (-1.259 vs -l.577%) (Table 10.c).

77

4.3.4. The Effect on the Change in mgCa/mm2

 

The change in mg Ca/mm2 is presented in Table 10.0.
The reduction (-0.032 mg Ca/mmz) in mg Ca/mm2 of the egg
shell due to heat treatments was not significantly different
from that (-0.016 mg Ca/mmz) for no heat treatments. There
was a highly significant reduction in % shell (-0.047%) due
to the treatments during egg shell formation when compared
to that (-0.0016%) during (No SF) time. LSD analysis (Table
A.l.d) showed that there was a significant reduction in
Ca/mm2 for the values obtained from hens in the chamber for
6 hours during egg shell formation (with or without heat)
when compared to those values obtained from the (No SF) time
treatments (Table 10.D). The high correlation between egg
shell quality parameters was supported also by this

experiment (Table 11).

Table 11. The correlation between egg shell quality
parameters used in experiment 3.

2

Chg. % shell wt. Chg. Ca/mm Chg. Shell wt.

 

Chg. % shell Wt. 1
Chg. Ca/mm2 .995 l
Chg. Shell Wt.(g) .956 .975 l

 

78
4.3.5. The Effect on the Feed Intake

There was a significant reduction (p = 0.03) in feed
intake due to both of heat stress (69.1 vs. 79.6 gm) and
(SF) time treatments (68.5 vs. 79.1 gm) when compared to no
heat or (No SF) time treatments (Table 12). LSD analysis
(Table A.l.e) showed that there was no significant reduction
in feed intake due to heat at (No SF) time (74 vs 85 gm) but
there was a significant reduction in feed intake due to (SF)
time treatments (68.5 vs. 79.1 gm) when compared to no heat

and (No SF) time treatments.

4.3.6. The Effect on the Change in Body Temperature
Heat stress caused a highly significant increase

(0.76°C) in body temperature when compared to no heat
treatments (-0.15°C) Table 12. During egg shell formation,
the body temperature increased 0.28°C after the stay in the
chamber for 6 hours. The increase in body temperature after
(No SF) time treatments was 0.47°C. There was no
significant difference between these values (0.28 and
0.47°C). LSD analysis (Table A.l.f) showed that the change
in body temperature at (No SF) or (SF) time due to heat was
significantly different than that for no heat treatments
(Table 12). There was no significant difference in the
change in body temperature between (No SF) time and (SF)
time treatments when there was heat (35°C) (0.79 vs. 0.73°C)
or when there was no heat (-0.45°C vs. 0.11°C) during the

stay in the chamber.

79

Table 12. Effect of heat (35°C) or no heat during egg shell formation
and during (No SF) time for 6 hours on both of feed
consumption and the change in body temperature.

 

Feed Intake (gm) 18 hours The change (°C) in body
following the stay in the temperature
chamber

(No SF) time (SF) time overall (No SF) time (SF) time overall

 

AV. AV.
No heat 858 73ab 79.6a 0.11a -0.45a -0.158
(9 hens) (8 hens) (17 hens) (9 hens) (8 hens) (l7 hens)
Heat 74‘” 66bc 69.1b 0.79b 0.73b 0.76b
(10 hens) (13 hens) (23 hens) (10 hens) (13 hens) (23 hens)
Overall
AV. of a b a a
change 79.] 68.5 73.6 0.47 0.28 0.37

(19 hens) (21 hens) (4O hens) (19 hens) (21 hens) (40 hens)

 

a,b,c values followed by different letters within the same
parameters (Feed intake or body temperature) are
significantly different (P g .05). Values followed by
different letters in the overall average row or column
within the same parameters are sigificantly different (P g

.05).

4.4. Experiment 4. Effect of heat (35°C) or no heat for 4
or 6 hours (during egg shell formation) on egg quality
using SCWL hens 46 weeks of age

4.4.1. The Effect on the Change (gm) in Egg_Weight
Heat stress did not reduce egg weight significantly,
but 6 hours of stay in the chamber, regardless of the

temperature, caused significantly less egg weight than did

the 4 hours stay (Table l3.A). The average values of the

80
change were 0.081 and 0.857 gm for heat and no heat,

respectively. The reduction in egg weight due to 6 hours
was 0.255 gm and there was an increase in egg weight of
1.187 gm due to 4 hours stay in the chamber. The value of
the change in egg weight due to the stay in the chamber for
6 hours was less than the value obtained after 4 hours in
the heat chamber. These values averages 0.397 and -0.656 gm
for no heat and heat treatments respectively, for 6 hours
and 1.224 and 1.146 gm for no heat and heat treatments

respectively for 4 hours.

4.4.2. The Effect on the Change (gm) in Shell Weight
The reduction in shell weight due to heat stress
(-0.807 gm) or due to 6 hours stay in the chamber,
regardless of the temperature (-0.805 gm), was not
significant when compared to no heat (~0.629 gm) or 4 hours

stay in the chamber (-0.64l gm) (Table 13.3).

4.4.3. The Effect on the Change in % Shell_
There was no significant difference between the values
of the change in % shell due to the hours of the stay in the

chamber or due to the temperature (Table l3.C).

4.4.4.. The Effect on the Change (mg) Ca/mm2 of the Shell
The results of the Ca/mm2 were similar to those for

shell weight and % shell in that there was no differences

81

Table 13. Effect of heat (35°C) or no heat for 4 and 6 hrs. (during egg
shell formation) on
A. The change in egg weight (gm) on the lst day following the
stay in the chamber using SCWL hens 46 weeks of age.

 

 

treatments 4 hours 6 hours overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No heat 10 1.224 8 0.397 18 0.857
Heat 9 1.146 13 -0.656 22 0.08]
Overall AV.
of change 19 1.187 21 -0.255 40 0.43

B. The change in shell weight (gm)

No heat 10 -0.566 8 -O.707 18 -0.629
Heat 9 -0.723 13 -0.865 22 -0.807

Overall AV.
of change 19 -0.641 21 -0.805 40 -0.727

C. The change in Z shell

No heat 10 -1.092 8 -1.128 18 -1.108
Heat 9 -1.282- 13 -1.577 22 -1.456
Overall AV.

of change 19 -1.182 21 -1.406 40 -1.30

D. The change in mg Ca/mm2

No heat 10 -0.034 8 -0.04 18 -0.037
Heat 9 -0.04 13 -0.051 22 -0.047
Overall AV.

of change 19 -0.037 21 -0.047 40 -0.042

 

N.B: The significant difference in the change in egg weight between 6
hours and 4 hours stay in the chamber was due to significant
difference only between (no heat 4 hours) and (heat 6 hours)
treatments.

82
between the values due to the temperature or the time of the

stay in the heat chamber (Table l3.D).

4.4.5. The Effect on the Feed Intake
Table 14 shows that there was a reduction in feed
intake (24 hours following the stay in the chamber) due to
hours of the stay in the chamber (68.5 gm for 6 hours vs.
72.89 gm for 4 hours) and due to the temperature (69.0 gm
for heat vs. 72.6 gm for no heat). The difference between

these values was not significant.

4.4.6. The Effect on the Change in Body Tempgrature

The difference between the change in body temperature
for 4 hours and 6 hours stay in the chamber, regardless of
the temperature, was not significant (0.27°C for 4 hours vs.
0.28°C for 6 hours). There was a highly significant
increase in body temperature (0.72°C) due to heat stress
when compared to no heat (-0.26°C) (Table 14).

There was a reduction in body temperature of 0.11 and

0.45°C for 4 hours and 6 hours stay in the chamber without
heat. The increase in body temperature due to heat stress

was about the same for both 4 hours and 6 hours exposure to
35°C heat stress (0.70 vs. 0.73°C).

The overall results of this experiment indicates that
both 4 and 6 hours stay in the chamber during egg shell
formation have about the same effect on egg shell quality.

The reduction in shell quality due to stay in the chamber

83

with heat or without heat for same hours was about the same.
This study also showed that both of 4 and 6 hours to heat
stress caused a reduction in shell quality when compared to
the three eggs each hen laid before being heat stressed.
This reduction in shell quality appears to be due to the
absence of feed during the stay in the chamber (during egg
shell formation).

Table 14. Effect of heat (35°C) or no heat for 4 and 6 hours (during

egg shell formation) on the feed intake and the change in
body temperature of SCWL hens 46 weeks of age.

 

Feed Intake (gm) The change (°C) in body
20 hrs 18 hours temperature
after after

chamber chamber

 

4 hours 6 hours overall 4 hours 6 hours overall
AV. AV.
No heat 72 73 72.6 -0.11a -0.45a -0.268
(10 hens) (8 hens) (18 hens) (10 hens) (8 hens) (18 hens)
Heat 73.9 65.6 69.0 0.70b 0.73b 0.72”
(9 hens) (13 hens) (22 hens) (9 hens) (13 hens) (22 hens)
Overall
AV. of a
change 72.89 68.5 70.6 0.27 0.283 0.28

(19 hens) (21 hens) (40 hens) (19 hens) (21 hens) (40 hens)

 

a, b values followed by different letters are significantly
different (P g .05). Values followed by different letters
in the overall average row or column are significantly
different (P g .05).

N. B. l) The overall average of feed intake/hen/day in hens
room before hens go to the heat chamber was 107 gm.

84

2) There was no significant difference between the
values of feed intake due to temperature and hours
of stay in the chamber.

4.5. Experiment 5. Effect of feed and/or water under heat
(35°C) or no heat for 4 hours during egg shell
formation on egg quality using SCWL hens 46 weeks of
age

 

4.5.1. The Effect on the Change (gm) in Egg Weight
The average values of the change in egg weight are
shown in Table 15.1. Almost all the values increased after
the stay in the chamber except for no water and no feed
treatment under heat stress (-0.123 gm). There was no
significant difference in the change in egg weight due to
water (+ water or no water), feed (+feed or no feed) or due

to the temperature (+ heat or no heat).

4.5.2. The Effect on the Chapge (gm) in Shell Weight
Egg shell weight for the first egg laid following the

stay in the chamber with heat (35°C) for 4 hours was 0.709
gm less than the three each hen laid before being heat
stressed (Table 15.2.c). There was a reduction of 0.484 gm
in shell weight of hens kept in the chamber with no heat
(Table 15.2.c). The difference between these values (-0.709
and -0.484 gm) was significant. The feed did not have a
significant effect on egg shell weight (Table 15.2.d).
There was a reduction of 0.602 gm in shell weight when the
feed was not available during the stay in the chamber and a
reduction of 0.568 gm when the feed was available. The

difference between the values of the change in shell weight

85

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eaonm ma unwfios Hagan new unwfios wwm aw owcmno ecu mo moemwum> mo mammamc< "m.z

 

 

 

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bwm.01 go q_n.o: q. mmq.01 o. m©m.01 m. -m.on a. mwcmso mo
.>< Hanuo>o
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mmb.©l _m .mm.on N mac.on m mno.ou c ~n¢.on 3 none: oz
Auoums new comm .musumuoaamu can no bomwwo osHv
unwwoa dance a“ Aawv owcmno was .m.~.m_ manna
mmw.o go mw_._ a. Ncq.o o_ wmo.o m. oo_._ m. wwamnu mo
.>< Hgmum>o
Nmm.o mm cu... m mmo.o n oq_._ m ¢-._ 0. nouns +
man.o _m oo~._ m wqm.o a mm_.0l o 05¢.o m noun: oz
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uo .>< «0 oz mo .>< mo .oz mo .>< mo .oz we .>< mo .oz «0 .>< mo .oz
Hzmuo>o new: new: oz boom new: oz nueoaumoue
comm + comm oz
owe mo mxooz on mew; 430m wean: unwflms wwo am Aawv owcmno one ._
"so wcfluusooo ma :ofiumEHOH Hausa wwo mafia
och on .mp5 4 new one; o: no Aoammv mmouum new: wcfiusu umum3 uo\pcm comm wcwpw>0ua mo boowwm .m. manna

86

Table 15.2.b. The change (gm) in shell weight
(The effect of water and feed)

 

 

treatments No feed + Feed Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 15 -0.553 16 -0.794 31 -0.677
+ Water 19 -O.641 14 -0.309 33 -0.50
Overall AV.
of change 34 -0.602 30 -0.568 64 -0.586

 

Table 15.2.c. The change (gm) in shell weight
(The effect of the temperature and water)

 

 

treatments 'No heat + Heat Overall
No.of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 18 -0.561 13 -0.839 31 -0.677
+ Water 17 -0.403 16 -0.602 33 -0.50
Overall AV. '
of change 35 -0.484 29 -0.709 64 -0.586

 

Table 15. 2.d. The change (gm) in shell weight
(The effect of the temperature and feed)

 

 

treatments No heat Heat Overall
So-of . AV. of No. of AV. of No. of AV. of
tens change hens change hens change
No feed 19 -O.522 15 -0.703 34 -0.602
+ Feed 16 -0.439 14 -0.714 30 -0.568
Overall AV.

of change 35 -0.484 29 -0.709 64 -0.586

 

87

when the water was not available during the stay in the
chamber (-0.677) and when the water was available (—0.50)
was significant. When the water was available, there was a
significant difference in the change in shell weight between
(No Feed) and (+Feed) treatments (-0.64 vs. -0.309 gm) but
when the water was not available it did not make any
difference in the change in shell weight whether the food
was available or not (-0.794 vs. -0.553 gm) (Table 15.2.b).
The minimum reduction in shell weight (-0.17 gm) was when
both of the water and feed were available and there was no
heat stress. The maximum reduction in shell weight (-0.981
gm) was when the water was not available during heat stress

(35°C) and the feed was available.

4.5.3. The Effect on the Change in % Shell
There was a significant reduction due to heat

treatments when compared to no heat treatments (-1.l97 vs.
-0.881% shell) (Table 15.3.d). Regardless of the effect of
water or the temperature on % shell, the feed did not have a
significant effect on the change in % shell (-l.088% for no
feed vs. -0.952% shell for feed treatments) (Table 15.3.d).
When the water was not available during the stay in the
chamber for 4 hours, there was a significant reduction of
1.14 % shell when compared to the change in % shell for hens
provided with water (-0.915%). As detected for the change
in shell weights, when water was available there was a

significant difference between the values of the change in %

88

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«No._1 «0 _o~._n q. qm~.ol 0. mm_._1 m. moo._l m. mwcmno «0

.>< Hamuo>o

m_m.o| mm mow.01 n mom.01 m ~m~._l m Nmo._l o. noun: +

q_._1 _m amm._n m abo._l a wmo._l b wom.0: a umuma oz
owcmno new: mwcmso new: owcmnu new: owcmno new: mwcmzu new:
wo .>< «0 oz mo .>< wo .oz mo .>< «0 .oz mo .>< «0 .oz «0 .>< mo .oz

Hzmuo>o new: new: oz new: new: oz mucmsumous

comm + comm oz
nouns can comm .ouaumnmanu gnu mo boowmo one On one fizmam N :H owcmco may .m.m.m_ memH

89
Table 15.3.b. The change in Z shell due to the effect of
water and feed

 

 

treatments No feed + Feed Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 15 -0.968 16 -1.301 31 -1.14
+ Water 19 -1.182 14 -0.553 33 -0.915

Overall AV.
of change 34 -1.088 30 -0.952 64 -1.024

 

 

Table 15.3.c. The change in Z shell due to the effect of the
temperature and water

 

 

treatments No heat Heat Overall
No“.of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 18 -0.988 13 -1.349 31 -1.14
+ Water 17 -0.767 16 -1.072 33 -O.915

Overall AV.
of change 35 -0.881 29 -1.l97 64 -1.024

 

Table 15. 3.d. The change in Z shell due to the effect of the
- temperature and feed)

 

 

treatment No heat Heat Overall
No.0f AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No feed 19 -1.005 15 -1.193 34 -1.088
+ Feed 16 éO.734 14 -1.201 30 -0.952
Overall AV.

of change 35 -0.881 29 -1.197 64 -1.024

 

90

shell when feed was present (-0.553) as Compared to when
feed was not provided (-l.182) (Table 15.3.b). The minimum
reduction of % shell (-0.303%) was when both feed and water
were allowed when there was no heat during the hen’s stay in
the chamber (Table 15.3.a). The maximum reduction (-l.599%
shell) was when there was no water but feed was provided

during heat stress (Table 15.3.a).

4.5.4. The Effect on the Chagge in mgCa/mm2 of the Shell

 

The results of mg Ca/mm2 supported the results of the
other shell quality parameters. Heat treatments reduced the
amount of Ca/mm2 of the shell significantly when compared to
no heat treatments (-0.038 vs. -0.027 mg Ca/mmz) (Table
15.4.c). The presence of feed, regardless of allowable
water or the temperature of the chamber did not have an

2 (-0.034 vs. -0.030 mg

effect on the change in mg Ca/mm
Ca/mmz, Table 15.4.b). Absence of water during the hen’s
stay in the chamber caused a significant reduction in the

2 of the shell (-0.036 mg) when compared to

amount of Ca/mm
when there was water (-0.029 mg) (Table 15.4.b). In the

absence of water during the stay in the chamber, providing
feed or not did not make significant difference on the mg

2 (-0.042 vs. -0.03 mg Ca/mmz) (Table 15.4.b).

Ca/mm
The high correlation between egg shell parameters also

was confirmed in this experiment (Table 16).

 

91

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aw caonm we zzmnm wo EE\mo we em mmcmno ecu mo mocmwum> mo mammfimc< "m.z

 

 

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Nmo.ou so mmo.on a. mmo.01 o_ wmo.on m. .mo.01 m. owamno mo
.>< Hamuo>o
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cmo.01 _m mmo.01 n cmo.¢n m mmo.01 o mmo.Ol m nouns oz
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no .>« «0 oz mo .>< mo .oz «0 .>< mo .oz mo .>< mo .oz wo .>< mo .oz
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comm + comm oz

 

Home: new comm .ousumumasmu was no bomwwo may ob mac NEE\mo we :« mwcm:u CLH m.q.m_ wanna

92
Table 15.4.b. The change in mg Ca/mm2 due to the effect of the water

 

 

 

and feed.
treatments No feed + Feed Overall
No. of AV. of No. of AV. of No. of AV. of
hens Change hens Change hens change
No water 15 -0.03 ' 16 -0.042 31 -0.036
+ Water 19 -0.037 14 -0.017 33 -0.029
Overall AV.
of change 34 -0.034 30 -0.03 64 -0.032

 

Table 15.4.c. The Change in mg Ca/mm2 due to the effect of the
temperature and water.

 

 

treatments No Heat Heat Overall
Nowof AV. of No. of AV. of No. of AV. of
hens Change hens Change hens change
No water 18 -0.03 13 -0.044 31 -0.036
+ Water 17 -0.024 16 -0.034 33 -0.029
Overall AV.
of change 35 -0.027 29 -0.038 64 -0.032

 

 

Table 15.4.d. The Change in mg Ca/mm2 due to the effect of
the temperature and feed.

 

 

treatments No heat Heat Overall
so.o£ AV. of No. of AV. of No. of AV. of
hens Change hens change hens change

No Feed 19 -0.031 15 -0.038 34 -0.034

+ Feed 16 -0.023 14 -0.039 30 -0.03

Ovefall AV.
of change 35 -0.027 29 -0.038 64 -0.032

 

 

93

Table 16. The correlation between egg shell quality
parameters used in experiment 5.

Chg. % shell wt. Chg. Ca/mm2 Chg. shell wt.

 

Chg % shell Wt. l
Chg Ca/mm2 .989 l
Chg Shell Wt.(gm) .906 .954 l

 

4.5.5. The Effect on Shell-less Eggs (SL eggs)

 

Hens under heat stress produced shell-less eggs only
when the water was not available (Table 17). Maximum number
of the shell-less eggs was when both water and feed were not
available during the heat stress (50% of the total eggs)

(Table 17).

Table 17. Effect of feed and/or water under heat (35°C) or no heat for
4 hours (during egg shell formation) on the production of
shell-less eggs.

 

 

 

No heat Heat
No water + water No water + water
No. Z of No. Z of No. Z of No. Z of
of SL total of SL total of SL total of SL total
3883 9883 9883 9883 9883 9883 9885 9883
-Feed 0 0/9 (OZ) 0 0/10 (OZ) 6 6/12 (SOZ) 0 0/9 (OZ)

+Feed O 0/9 (OZ) 0 0/7 (OZ) 3 3/10 (30Z) 0 0/7 (OZ)

 

94

4.5.6. The Effect on Feed Intake

The values of feed intake 24 hours following the stay
in the chamber are shown in Table 18.a, b, c, and d. There
was no difference in the feed intake due to the temperature
(83.83 gm for heat vs. 87.23 gm for no heat) (Table 18.d).
There was a highly significant difference in the feed intake
due to the presence of the feed during the stay in the
chamber. The hens consumed more feed (100.2 gm) when there
was feed than when there was no feed during the stay in the
chamber (72.9 gm) (Table 18.b). When water was not
available during the stay in the chamber the hens ate less
food than when the water was available. The difference
between the amounts of feed intake was highly significant
(82.7 gm for no water vs. 88.5 gm for + water treatment)
(Table 18.b).

Feed allowed during the stay in the chamber (with or
without water) caused hens to consume significantly more
food than when there was no feed available. When feed was
not available during the stay in the chamber providing water
did not make a difference in the subsequent feed intake
(72.8 gm for no water vs. 72.9 for + water treatment) (Table
18.b). But when the feed was available during the time the
hens were in the chamber, they consumed more feed in case of
existence of the water than in its absence (109.6 vs. 92

gm).

 

 

 

95

 

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cmmm + cmmm oz

 

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Hamnm wwm mewuscv .mp5 s new ummc o: no AvammV ummn umpcs umuma uo\pcm Ummm mo nommwm may .m. manmy

96

 

 

 

 

 

 

 

 

 

Table 18.b. The feed Intake due to the effect of water and feed.
treatments No feed + Feed Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 15 72.8 16 92.0 31 82.7
+ Water 19 72.9 14 109.6 33 88.5
Overall AV.
of Change 34 72.9 30 100.2 64 85.7
Table 18.c The feed intake due to the effect of the temperature and water ‘
treatments No heat Heat Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 18 85.9 13 78.3 31 82.7
+ Water 17 88.7 16 88.3 33 88.5
Overall AV.
of change 35 87.2 29 83.8 64 85.7
Table 18.d. The feed intake due to the effect of the temperature
and feed.
treatments No heat Heat Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No feed 19 71.8 15 74. 34 72.9
+ Feed 16 105.6 14 94.1 30 100.2
Overall AV.
of change 35 87.2 29 83.8 64 85.7

 

97

When the feed was not available during the stay in the
chamber, there was no effect due to the temperature on the
subsequent feed intake (71.8 gm for no heat vs. 74.2 gm for
heat). But when the feed was available, the hens consumed
significantly more feed afterwards in case of no heat vs.
heat stress (105.6 gm for no heat vs. 94.1 gm for heat

treatment) (Table 18.d).

4.5.7. The Effect on the Change in Body Temperature

The Change in body temperature due to 4 hours stay in
the chamber during egg shell formation is presented in
Tables l9.a, b, c, and d. There was a highly significant
increase in body temperature due to heat (1.134°C) when
compared to no heat treatment (-0.037°C) (Table l9.c).

Regardless of the effect of water and ambient
temperature, there was no difference between the change in
body temperature as influenced by the presence or absence of
feed (0.60 vs. 0.40°C) (Table 19.b). There was a highly
significant increase in body temperature when the water was
not available during the stay in heat chamber (0.723°C) when
compared to when the water was available (0.279°C) (Table
l9.c). When the feed was available during the stay in the
chamber, water reduced the increase in body temperature
significantly (0.286°C) as compared to the lack of water
(0.875°C) (Table 19.b). There was no difference in the
change in body temperature between any of the other values

in Table 19.b.

 

98

 

 

 

 

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99

When water was not available during the stay in the
chamber, heat caused a significant increase (1.554°C) in
body temperature when compared to when the hens were not
heat stressed (0.122°C). Also significantly increasing body
temperature due to heat stress was when water was not
available (1.554°C) when compared to when no water was
available (0.794°C) (Table l9.c). Hens not stressed with
35°C in the chamber did not show a change in body
temperature whether or not water was present (0.122°C vs.
-0.206°C) (Table l9.c). This experiment revealed the
importance of having both water and feed available during
heat stress, especially during the time of egg shell
formation. The results of this experiment also give an
explanation for the reduction in shell quality obtained from
the treatments during egg shell formation without heat
stress when the feed was not available at that time. This
conclusion is based on the fact that the best egg shell
quality was when both of water and feed were available
during the stay in the chamber. There was a negative
correlation (-0.50) between the Change in shell weight and
the change in body temperature. This means that the
increase in body temperature is one of the factors that
cause a reduction in shell weight during heat stress,
regardless of the effect of other factors such as feed or

water.

 

 

 

 

 

 

 

 

 

100
Table 19.b. The change in body temperature due to the effect of the
water and feed.
treatments No feed + Feed Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 15 0.56. 16 0.875 31 0.723
+ Water 19 0.274 14 0.286 33 0.279
Overall AV.
of change 34 0.40 30 0.60 64 0.494
Table 19.c. The change in body temperature due to
The effect of the temperature and water.
treatments No heat Heat Overall
No. of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No water 18 0.122 13 1.554 31 0.723
+ Water 17 -0.206 16 0.794 33 0.279
Overall AV.
of Change 35 -0.037 29 1.134 64 0.494
Table 19.d. The change in body temperature due to the effect of
the temperature and feed.
treatments No heat Heat Overall
No of AV. of No. of AV. of No. of AV. of
hens change hens change hens change
No feed 19 -0.058 15 0.98 34 0.40
+ Feed 16 -0.013 14 1.30 30 0.60
Overall AV.
of change 35 -0.037 29 1.134

64 0.494

 

 

 

101

4.6. Experiment 6. Effect of using some drugs and
chemicals in the food to alleviate the effect of 4
hours of heat stress (35°C) on egg quality using SCWL
hens 61 weeks of age actively forming egg shell

 

4.6.1. The Effect on the Chagge (gm) in Egg Weight
With the exception of giving the layers a diet
containing 0.2% Aspirin, all the treatments caused a slight
increase in egg weight. There was no significant difference
in the change in egg weight due to the treatments. It was
obvious that the heat stress (35°C) for 4 hours during egg

shell formation does not affect the egg weight.

4.6.2. The Effect on the Change (gm) in Shell Weight
The Shell weight was not improved by any of the
treatments (Table 20.1). The controls had a reduction in
shell weight of 0.72 g. The minimum non-significant
reduction in shell weight was for Vit C 50 mg/Kg diet (-0.52
gm). The maximum reduction was for KHCO3 fed at 0.9% of the
diet (-0.96 gm). There was no significant difference among

any of the values due to the treatments. Heat stress

reduced the shell weight in all cases.

4.6.3. The Effect on the Chagge in % Shell
There was no significant difference among any of the
values for one of the treatments to alleviate the reduction
in % shell. All the values of % shell for the lst egg
following the heat stress were less than the average of the

three eggs each hen laid before being heat stressed.

 

102

Table 20.1. The effect of using vitamin C, aspirin, potassium bicarbonate
and sodium bicarbonate in the feed to alleviate the effect of
4 hours of heat stress (35°C) during egg shell formation on
egg quality using SCWL hens 61 weeks of age.

 

Treatments No. of Shell-less eggs AV. of the change in
eggs No. of Z of the eggs with shells
eggs total eggs egg wt-g shell wt-g Z shell

 

Control 6 2 33 2.64 -0.72 -1.53
Vit C - 50mg/

kg diet 6 3 50 0.55 -0.52 -O.93
Vit C - 150mg/

kg diet 7 4 57 2.22 -0.70 -1.45
Aspirin 0.2Z

of the diet 7 1 14 -O.11 -0.94 -1.44
KHCO - 0.9Z

of tee diet 6 l 17 1.57 -0.96 -l.63
NaHCO3 " 0.762

of the diet 6 3 50 0.64 -0.56 -1.00
Overall

average 38 14 37 1.17 -0.78 -1.38

 

 

N.B: There was no significant differences (P > .05) between the values of
the Change in egg shell quality parameters (egg wt., shell wt., or Z
shell) due to the treatments.

 

103
4.6.4. The Effect on ProducingiShell-less Eggs

Many of the hens produced shell-less eggs in this
experiment (Table 20.1). The minimum number of shell-less

eggs was produced by hens fed KHCO3 and Aspirin. The most

 

shell-less eggs were laid by hens given Vit C at 150 mg/kg

diet (Table 20.1).

 

4.6.5. The Effect on Feed Intake ,
Hens fed the commercial diet at all times consumed 69.5 [

gm feed per bird during the 24 hours after 4 hours of heat 3
1

stress. In comparison those fed the diet containing KHCO3

ate 64.6 gm, while those fed a diet with NaHCO ate 79.3

3
gm/bird. There was no significant difference in feed intake

from these treatments (Table 20.2).

4.6.6. The Effect on the Change in Body Temperature
The maximum increase in body temperature from 35°C heat
stress was for hens given for vit C at 50 mg/kg diet
treatment (0.53°C) and the minimum increase (0.l3°C) was for
150 mg vit C/kg diet treatment (Table 20.2). There was no
significant effect due to the treatments on the change in

body temperature.

4.7. Experiment 7. Effect of using aspirin and potassium
bicarbonate to alleviate the effect of heat stress
(35°C) for 4 hours during egg shell formation on egg
quality using SCWL 61 weeks of age

 

Because aspirin and potassium bicarbonate in the

previous experiment gave the lowest number of shell-less

104

Table 20.2. The effect of vitamin C, aspirin, potassium bicarbonate and
sodium bicarbonate on feed intake and the change in body
temperature due to heat stress (35°C) for 4 hrs. during egg
shell formation using SCWL hens 61 weeks of age.

 

 

Treatments No. of Feed intake (gm) The change in body
hens laid 20 hrs. following the temperature (°C)
eggs with stay in the chamber
shells

Control 4 69.5 0.38

 

Vit C - 50mg/
kg diet 3 75.7 0.53

Vit c - 150mg/
kg diet 3 79 0.13

 

Aspirin 0.2Z

of the diet 6 78 0.30
KHCO - 0.9Z
of tee diet 5 64.6 0.32

NaHCO - 0.762
of diet 3 79.3 0.40

 

 

N.B: There was no significant difference (P > .05) between the values of
feed intake or the change in body temperature due to the treatments.

105

eggs, these treatments were repeated to determine if the

results could be duplicated.

4.7.1. The Effect on the Egg Quality

 

None of the egg quality parameters was improved by

feeding aspirin or KHCO (Table 21.1). Heat stress did not

3

have a negative effect on egg weight except for control hens

 

(-0.929 gm egg weight). There were no significant

differences between the values for each parameter. Heat

 

stress (35°C) for 4 hours during egg shell formation reduced
egg shell quality (including shell thickness) for the lst
egg following the heat stress when compared to the average
of the three eggs laid prior to heat stress. Aspirin or

potassium bicarbonate in the diet did not prevent shell-less

eggs.

4.7.2. The Effect on Feed Intake

 

 

The amounts of feed consumed 24 hours following 4 hours
of heat stress (35°C) are shown in Table 21.2. The hens in
the control group consumed 56 gm whereas the hens fed KHCO3

in their diet consumed 69 gm. There was no significant

difference in feed intake among the treatment groups.

4.7.3. The Effect on the Change in Body Temperature
The least increase in the body temperature was detected

in control hens (0.48°C); whereas the most increase was for

106

Table 21.1. The effect of using Aspirin and Potassium bicarbonate in the
feed to alleviate 4 hours of heat stress (35°C) during egg
shell formation on egg quality using SCWL hens 61 weeks of

 

 

age.
Egg quality Control Aspirin 0.2Z KHCO 0.9Z
parameters of the diet of tge diet
No. of eggs with shells 8 6 8
AV. of the change in
egg weight (gm) -0.93 0.66 1.01
shell weight (gm) -0.87 -0.90 -0.61
Z shell -1.26 -1.48 -1.07
Shell thickness (mm) -4.66 -5.08 -3.45
No. of shell-less eggs 2 3 4

Z of shell-less egg
of the total eggs 20 33 33

 

Table 21.2. The effect of feeding aspirin or potassium bicarbonate on
feed intake and the Change in body temperature due to 4 hours
of heat stress (35°C) during egg shell formation using SCWL
hens 61 weeks of age.

 

 

Treatments No. of Feed intake (gm) The change in body
hens laid 20 hrs. following the temperature (°C)
eggs with stay in the Chamber
shells

Control 8 56 0.48

Aspirin 0.2Z 6 61 0.92

KHCO3 0.9Z 8 69 0.79

 

N.B: There was no significant difference (P > .05) between the values of
the change in egg quality parameters, feed intake or the change in
body temperature due to the treatments.

107

hens fed aspirin (0.92°C). There was no significant

differences between any of the values due to the treatments.

4.7.4. The Effect on the Blood Parameters (pH, PCOq and
HCO ) ‘

——-3—-

The results of the blood parameters, summarized in
Table 21.3, reveal that the highest value of blood pH (7.4)
was for hens fed KHCO3 in their diet, and the minimum value
(7.376) was for the control group. Blood pressure of the
blood carbon dioxide (PC02) ranged between 37.3 mm Hg for
aspirin treatment and 40.35 mm Hg for control group. The
concentration of blood bicarbonate ions (HC03-) ranged
between 20.85 for aspirin group and 22.38 for control group.
There was no significant difference between any of the

values for each of the blood parameters due to the

treatments.

4.8. Experiment 8. The difference between the effect of
heat stress (35°C) for 4 hours during egg shell
formation or no heat at that time on the blood
parameters (pH, PC02 and HCO3 ) of SCWL hens 61 weeks
of age. .

 

4.8.1. The Effect on the Blood pH
The pH was not significantly affected by 35°C for 4
hours during egg shell formation. The values were 7.35 for
hens at ambient temperature (about 21°C) vs. 7.37 for those

heat stressed for 4 hours (Table 22).

 

 

108
4.8.2. The Effect on Blood PCO2

 

The blood PCO2 activity in the hens kept in the chamber

 

at 21°C was 54.18 mm Hg as compared to the significantly
(P < .01) lower value of 40.89 mm Hg at the end of 4 hours

exposure to 35°C (Table 22).

4.8.3. The Effect on Blood Hcog'

 

Heat stress (35°C) for 4 hours during egg shell

formation decreased blood HCO3- significantly (P g 0.01) to

22.3 to 28.58 in hens at 21°C (Table 22). 3

Table 22. Effect of heat stress (35°C) for 4 hours on blood pH, P00
and HCO during egg shell formation in SCWL hens 61 weeks of

 

3

age
Group Count pH PCO2 (mm Hg) HC03_ (m mol/l)
Control (at 21°c) 10 7.35a 54.18a 28.58a
Heat (35°c) 12 7.373 40.89b 22.32b

 

a, b values in the same column differently supercripted are

significantly different (P g .01).

4.9. Experiment 9. Effect on egg quality when using some
drugs and minerals in the drinking water to alleviate
the effect of 4 hours of heat stress (35°C) during egg
shell formation of SCWL hens 61 weeks of age.

In this experiment, a small number of hens (4 hens)

were used to just give an idea about how the hens will

109
respond to the chemicals which were used and the effect of

these chemicals on egg shell quality during heat stress.

4.9.1. The Effect on the Change (gm) in Egg Weight
Egg weight was not affected by treatment. The results
of the change in egg weight in this experiment confirm those
of most of the previous experiments in that heat stress
(35°C) up to 6 hours does not affect egg weight. The
average egg weight was 1.23 to 3.28 gm higher of the treated
groups as compared to the 3.19 gm higher weight of the

control eggs (Table 23.1).

4.9.2. The Effect on the Change (gm) in Shell Weight
Hens treated with potassium chloride, calcium chloride,
aspirin, acetaminohen, or a buffer solution laid eggs with
less shell as a result of heat stress; their shell weights
were -0.15 to -l.34 gm less than the shells laid just prior
to heat stress. Hens not treated laid eggs with shells
weighing -l.15 gm than prior to heat stress. There was no
indications that any of the treatments acted to lessen the

effect of heat stress on shell weight (Table 23.1).

4.9.3. The Effect on the Change in % Shell
The % shell was not improved by any of the treatments
in drinking water and the effect of heat stress was to

reduce the % shell for the first egg following the heat

 

 

110

Table 21.3. The effect of aspirin or potassium bicarbonate on the blood
pH, blood P00 and blood HCO of hens, actively depositing
shell, stressed for 4 hrs. a 35°C during egg shell
formation.

 

 

Treatments No. of Blood pH Blood PCO Blood HCO
. 3
hens laid (mm Hg)
eggs with
shells
Control 8 7.38 40.35 22.38
Aspirin 0.2Z 6 7.38 37.30 20.85
KHCO3 0.9Z 8 7.40 37.71 21.99

 

N.B: There was no significant difference (P > .05) between the values of

blood pH, P002 or blood bicarbonate due to the treatments.

 

Table 23.1. The effect of using some drugs in the water to alleviate the
effect of heat stress (35°C) for 4 hrs. during egg shell
formation on egg quality using SCWL hens 61 weeks of age.

 

Treatments No. of AV. of the change in Shell-less eggs
eggs with No. of Z of the
shells egg wt-g shell wt-g Z shell eggs total eggs

 

Control 4 3.19 -1.15 -2.23 0 OZ
KCl - 1.6gm/l 4 1.23 -1.15 -1.93 0 OZ
CaCl2 -

8.3gm/l 1 2.06 -0.64 -1.41 3 75Z
Aspirin -

1.083gm/l 3 3.28 -0.15 -0.65 0 OZ
Acetaminophen -

0.267gm/l 3 1.49 -1.10 -2.05 1 25Z
Buffer

solution -

4.81 pH 3 1.92 -l.34 -2.34 0 OZ

 

N.B: There appeared to be no differences among the values of the change
in each of egg quality parameters (egg wt., shell wt., or Z shell)
due to the treatments.

111

stress when compared to 3 eggs laid just before heat stress

(Table 23.1).

4.9.4. The Effect on the Production of Shell-less Eggs

 

Calcium chloride at 8.3 gm/l caused 75% of the eggs
laid to be shell-less. One of the 4 hens treated with
acetaminophen laid a shell-less eggs and all of the other
hens laid eggs with shells although they weighed less

(except for aspirin) (Table 23.1).

4.9.5. The Effect on the Consumption of Feed! Water and
the Drugs

 

 

Feed intake/hen ranged between 61.5 gm for buffer
solution treatment and 83.5 gm for aspirin group as compared
to 64.3 gm for controls. Water intake during the period of
heat stress (4 hours) ranged between 44 ml for CaCl2 group
and 267.3 ml for acetaminophen group as compared to 194 ml
for controls that were heat-stressed. There appeared to be
no differences among the values for both of feed intake and
water intake. In this experiment the consumption per hen
was 168.3 mg K, 132 mg Ca, 249.7 mg aspirin, 71.4 mg
acetaminophen and 113 mg K in case of KCl, CaClz, aspirin,
acetaminophen and buffer solution treatments, respectively

(Table 23.2).

4.9.6. The Effect on the Change in Body Temperature

 

Mean change in body temperature is shown in Table 23.2.

All the values were higher after the heat stress than before

112

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113

heat stress except for the control group in which there was
almost no change (-0.08°C), and the acetaminophen group in
which the body temperature decreased (-0.43°C). There was
no indication that any of the treatments acted to keep body

temperature from rising.

4.10. Experiment 10. Effect of using some drugs and
minerals in the water during heat stress (35°C) for 4
hours in addition to an oral dose 2 hours before hens
were placed into the environmental chamber on egg
quality using SCWL hens 61 weeks of age

 

4.10.1. The Effect on the Change in Egg Quality

 

None of the treatments in this experiment prevented
heat stress from reducing the egg quality parameters (egg
weight, shell weight or % shell) (Table 24.1). Some of the
values for egg weight increased after heat stress; whereas
those of eggs from hens treated with KCl (Level 1) or
carbonated water + vit C decreased about -0.50 gm. Changes
in shell weight ranged between -0.55 gm for the control
group and -l.44 gm for hens given carbonated water with vit
C. The change in % shell was between -0.94% for KCl (Level
2) treatment and -2.20% for carbonated water with vit C.
There was no significant difference (P > .05) between the
values of any of these egg quality parameters due to
treatments. The highest number of shell-less eggs (50%) was
observed with birds receiving the KCl (Level 2) treatments

(Table 24.1).

 

114

Table 24.1. The effect of using an oral dose of potassium chloride,
carbonated water with vitamin C, or acetaminophen with
vitamin C before heat stress in addition to that in the water
during heat stress (35°C) to alleviate the effect of 4 hrs.
of heat stress during egg shell formation in SCWL hens 61
weeks of age.

 

 

Treatments No. of AV. of the change in Shell-less eggs
eggs with No. of Z of the
shells egg wt-g shell wt-g Z shell eggs total eggs

Control 13 1.51 -0.55 -1.03 1 7.14

KCl

(0.3 gm/hen) 10 -0.45 -0.94 -1.41 1 9.09

KCl

(0.6 gm/hen) 5 0.07 -0.59 -0.94 5 50.00

Carbonated

water + Vit C 2 -0.50 -1.44 -2.20 2 50.00

Acetaminophen

+ Vit C 4 0.82 -0.63 -1.12 2 33.33

 

115
4.10.2. The Effect on the intake of Feed, Water and

Chemicals

 

Because both feed and water were available during the
stay in the chamber, the maximum amount of feed consumed was
90.6 gm (for KCl Level 2 group), and the minimum amount was
55.5 gm (carbonated water with vit C) (Table 24.2). Each
hen consumed 222.5 ml water that contained acetaminophen
during the 4 hours of heat stress. Those provided
carbonated water with vit C drank only 60.0 ml/hen. The
controls drank 203 ml during that time. In this experiment
each hen consumed a total of 325.3 mg K, 603.2 mg K and
238.5 mg acetaminophen for KCl (Level 1), KCl (Level 2) and

acetaminophen groups, respectively.

4.10.3. The Effect on the Change in Body Temperature
Controls had an increase in body temperature of 0.52°C
due to heat stress (Table 24.2). The hens treated with
various chemicals in the drinking water had increases in
body temperature of 0.23°C, for birds that consumed KCl
(level 1), up to a maximum increase of 1.0°C for birds that
consumed the carbonated water during the heat stress (Table
24.2). According to an ANOVA, no significant differences
(P > .05) were detected for body temperatures due to any of

the treatments (Table 24.2).

 

 

 

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5. Discussion

 

The primary effect of acute heat stress on egg quality

was to reduce shell weight and other measures involving

 

shell. Egg weight was not significantly reduced. Wolfenson

et al. (1979) reported that the exposure to heat stress (34

 

to 40°C) for 6 to 7 hours for only one day lowered shell
weight (P < .05). The results of experiment 1 in this study
showed that the exposure to 35°C for only 4 hours for just
one day caused a significant reduction in egg shell quality
as measured by shell weight, % shell and mg Ca/mm2 of the
shell. Furthermore, these results indicated, for the first
time, that exposure of the hens to 35°C for 1 hour or 2
hours did not cause an effect on egg shell quality.

Harrison and Biellier (1969) found that there was a decrease
in egg shell quality (specific gravity) within the first day
of exposure to 35°C but there was no change in egg weight.

The results of our experiments confirm this. On the other

 

hand, Vasquez and Teeter (1986) showed that heat stress
(35°C) depressed both shell weight and egg weight. The
reduction in shell quality due to heat stress was in
agreement with that obtained by De Andrade et al. (1976 and
1977) who observed that % shell and other shell quality

parameters such as specific gravity and shell thickness

117

118

decreased at the end of three weeks exposure to 32°C. The
results of this experiment supported the results obtained by
Wolfenson et a1. (1979) in that shell quality which was
decreased due to heat stress on the day after heating
reverted to that of controls on the second and third day
after the heat treatment.

The effect of heat stress (35°C) on the egg quality of

 

hens 46 weeks of age (experiment 2) was also detected in
hens 61 weeks of age; both laid eggs with less shell weight
from heat stress for 6 hours, while their egg weight was not ‘5
affected by that stress. Heat stress (35°C) for 6 hours

during (No SF) time, when hens were not actively depositing

shell, did not affect food intake over the next 24 hours.

 

Wolfenson et a1. (1979) had reported that there was no
significant reduction in total daily feed consumption due to
heat stress (34 to 40°C) for 6 to 7 hours. The effect of
heat stress on egg shell weight was not mainly due to the
reduction in feed intake but due to other changes in the
body, as an example a rise in body temperature.

The significant increase in body temperature due to
heat stress confirmed the earlier studies of Thornton
(1962). Laying hens are more susceptible to any stress,
i.e., no feed or the increase in the environmental
temperature, during the time of egg shell formation than
when there is no egg shell formation. As a result of the
absence of feed during the hen’s stay in the chamber there

was a significant reduction in total daily feed consumption

119
if the hen is actively depositing shell. This did not

occur with hens stressed with heat and not actively
depositing shell. The reduction in feed intake at the time
of shell deposition, even when there was no heat, indicated
the importance of offering the feed during that time. This
observation indicated that the reduction in shell quality of
egg obtained from (SE) time experiments was not only due to
heat stress but also the absence of feed at that time.

Those not heat stressed also showed the reduction in shell
quality from the absence of feed. The importance of the
time of feed intake was indicated by Farmer et a1. (1983)
who concluded that the most important time for the hens to
receive calcium was during the afternoon when shell
calcification is initiated. Also, Former and Roland (1982)
indicated that not only the calcium was important at the
time of egg shell calcification but also the other nutrients
(the whole feed) were also needed. The reduction in body
temperature at the time of egg shell formation when there
was no heat (Exp. 3) may be related to less ability in
regulating the body temperature during egg shell formation,
or to a lower metabolism from a sleep induced effect.

In addition to the importance of the feed at the time
of egg shell deposition, water was also important at that
time, regardless of the environmental temperature, to obtain
the best egg shell quality. Oluyemi and Adebanjo (1979)
observed that the shells of the old hens (62 weeks old) kept

in an environmental temperature of 22.8 to 36.9°C were

 

 

120

improved with the offering of cold water (0°C); or feeding
the hens during the time of egg shell formation. The study
of Oluyemi and Adebanjo was different than the present
study. In this study, various combinations of feed and
water were used in a 2 x 2 x 2 factorial at the time of egg
shell formation with 4 hours of heat stress (35°C). The

best egg shell quality was obtained when both the water and

 

feed were available at the time of egg shell formation with

heat or without heat. The worst egg shell quality was when

 

the water was not present and the feed was present during
heat stress. This may be due to heat that is produced from
the feed in addition to the heat stress. It was observed
that hens during their stay in the chamber with heat (35°C)
consumed about 22 gm feed during the 4 hours. Water was
effective in reducing the increase in body temperature due
to heat and its existence improved feed intake. Both water
and feed were required for optimum shell quality.

There was no improvement in egg shell quality due to
the use of analgesic drugs such as aspirin (in feed or
water) or acetaminophen (in water). Oluyemi and Adebanjo
(1979) showed that aspirin at 0.15 and 0.2% of the diet with
environmental temperature of 22.8 to 36.9°C over a period of
5 weeks did not improve shell quality (shell thickness) in
case of old hens (62 weeks old). In this experiment, 0.2%
aspirin in the diet for at least 3 days before 4 hours of
35°C heat stress was not effective. The use of bicarbonate

ions (as NaHCO or KHCO3) at 0.55% of the diet was also not

3

 

121

effective in improving shell quality. The concentration of
Na and K was 0.21 and 0.35% of the diets. Possibly,
bicarbonate ions or these minerals were not effective in
alleviating the effect of heat stress on egg shell quality
because feed was absent during heat stress. The presence of
whole feed during egg shell formation is important. Ahmed
et al. (1967) observed that the lS-month old hens being fed
vitamin C (44 mg/kg diet) could not maintain shell thickness
at 35°C. They also observed, and substantiated by our
experiments that vitamin C had no significant effect on
preventing a rise in body temperature due to heat.

Balnave and Scott (1986) reported that inclusion in the
water of low concentrations of KCl (40 mg/l) and-CaCl2 (120
mg/l) substantially increased the incidence of shell
defects. In this study, the inclusion in the water of high

concentration of KCl (1.6 gm/l) and CaCl (8.3 gm/l) also

2
increased the incidence of shell defects. For example,
CaCl2 treatment gave the highest number of shell-less eggs.
Balnave and Scott (1986) indicated that this effect may be
due to the chloride ion and that the increase in shell
defects was not associated with the pH of the water.
Carbonated water did not have an effect on egg shell
quality, and that may be due to the loss of CO2 from the
carbonated water during heat stress. Acetaminophen did not
prevent the heat stress effect in these experiments, this

may be because treatment was not long enough to give it a

chance to be effective during the time of heat stress.

 

 

 

122

The effect of heat stress on blood bicarbonate ions
PCO2 was indicated by Mongin and Lacassagne (1966) who
observed that the hyperventilation due to high temperature
caused the hen to lower its blood carbon dioxide tension and
thus its blood bicarbonate level. Gutowska and Mitchell
(1945) indicated that the bicarbonate ions are the source of
shell carbonate. The reduction in PC02 due to heat stress
was observed also by Kohne and Jones (1975a) who studied the
effect of acute hyperthermia (49°C for 165 minutes) on blood
PC02 and pH using nonlaying female turkeys. They found that
the venous blood pH and PCO2 did not change significantly
during the first 60 minutes of the experimental period, and
not until the ambient temperature reached 43°C. The venous
pH increased significantly (from 7.4 to 7.69) and the PC02
decreased significantly (from 54.5 to 16.3 mm Hg) during the
experimental period. In this experiment the temperature was

only 35°C and this temperature did not reduce the PCO to

2
the degree which was observed by Kohne and Jones (1975a).
The significant reduction in blood HCO3 ions may be one of
the factors that caused the reduction in egg shell quality
due to heat stress (even when both of feed and water were
available during the treatments) when compared to no heat
treatments.

The overall conclusion of all experiments indicates
that egg shell quality can be improved during the hot

environmental temperature by somehow keeping the body

temperature of the hen and its blood bicarbonate ions

123

without change. In addition, offering feed and cold water
together especially at the time of egg shell formation may

help maintain egg shell quality.

 

6. SUMMARY AND CONCLUSION

During summer, increased temperature causes hens to lay

egg with lesser quality shells, thereby increasing egg

breakage. This study was conducted with SCWL laying hens to

establish a procedure to evaluate the effect of acute heat

stress on shell quality without endangering the hens. This

research also included attempts to overcome the detrimental

effect of heat stress on egg shell quality.

The results of the study could be summarized as

follows:

1.

Four or six hours exposure to heat stress (35°C) for only
one day was enough to reduce egg shell quality (shell
weight, % shell, and Ca/mm2 of shell) significantly for
only one day (lst day following the treatment).
Generally, egg weight was not affected by heat stress in
this study. There was a high correlation between shell

quality parameters.

. The effect of heat stress (35°C) for 6 hours when shell

deposition was not occurring, in case of young hen (46
weeks of age) was significantly effected only the shell
weight of many factors analyzed. This effect may be due
to the significant increase in body temperature rather

than the difference in feed intake at that time.

124

 

 

125

3. There was a significant reduction in shell weight due to
the stay in the chamber (with or without heat) when feed
was not available during egg shell deposition.

4. Minimum reduction in shell weight due to heat stress
(-0.45 gm) was observed when both of feed and water were
available during heat stress. There was a reduction of
0.98 gm shell weight for (+ Feed No water) treatment due
to heat stress.

5. Supplementing the diet with vitamin C at 50 or 150 mg/kg;
aspirin, 0.2%; potassium bicarbonate, 0.9% or sodium
bicarbonate, 0.75% did not prevent heat stress (35°C)
effect on egg shell quality.

6. Blood PC02 and HCO3_ significantly (P g .01) declined in
heat stressed hens.

7. The inclusion in the water (per liter) of 1.6 gm KCl;
8.30 gm CaClz, 1.083 gm aspirin (as sodium acetyl
salicylate), 0.267 gm acetaminophen, or 4.81 pH buffer
solution did not improve egg shell quality.

8. The high doses of KCl (0.3 or 0.6 gm/hen) or
acetaminophen (0.239 gm with 5mg vitamin C/hen) did not
prevent the effect of heat stress on egg shell quality.
Also carbonated water with 5mg vitamin C/hen did not have
a positive effect on egg shell quality.

The overall conclusion of this study indicates that egg
shell quality can be improved during the hot environmental
temperature by somehow keeping the body temperature of the

hen and its blood bicarbonate ions static as the same as

 

126

before heat stress. In addition, offering feed and cold
water together especially at the time of egg shell formation

may help maintain egg shell quality.

 

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APPENDIX

APPENDIX

Table A.1. LSD analysis of the change in
a. egg weight due to 6 hours exposure to heat stress (35°C)
at day time and during egg shell formation (night time).

 

 

4 3 2 1 AV. Change Treat No.
0.397 -0.656 -O.863 -1.899 in egg wt.
(1.913) (2.068) (2.0197) 0.397 4
1.053 1.260 +2.296
(1.846) (1.791) -0.656 3
0.207 1.243
(1.956) -O.863 2
1.036
-1.899 1

 

Table A.l.b. LSD analysis of the change in shell weight

 

2 1 4 3 AV. Change Treat No.
0.03 -0.283 -0.707 -0.99 in shell wt.

 

(0.403) (0.426) (0.380)

0.313 +0.737 +1.02 0.03 2
(0.416) (0.369)

+0.424 +0.707 -O.283 ‘ 1
(0.394)

0.283 -0.707 4

-0.99 3

 

Note: treat 1 a heat at day time
treat 2 = no heat at day time
treat 3 - heat at night time
treat 4 - no heat at night time
+ = significant (p < 0.05)
( ) = LSD value at 52 level of significant

139

140

 

 

 

 

 

Table A.l.c. LSD analysis of the change in Z shell
2 1 4 AV. Change Treat No.
0.181 -0.142 -1.259 -1.577 in z shell wt. ‘
(0.694) (0.734) (0.655)
0.323 +1.44 +1.758 0.181 2
(0.717) (0.636)
+1.117 +1.435 -0.142 1
(0.679)
0.318 -1.259 4
-1.577 3
Table A.l.d. LSD analysis of the change in mg Ca/mm2
2 1 4 3 AV. Change Treat No.
0.0051 -0.0076 —0.040 —0.051 in Ca/mm
(0.0219) (0.0231) (0.0206)
0.0127 +0.0451 +0.0561 0.0051 2
(0.0226) (0.0200)
+0.0324 +0.0434 -0.0076 _ 1
(0.0191)
0.011 -0.04 4
-0.051 3

 

141

 

 

Table A.l.e. LSD analysis of the feed intake (gm) within 24 hours
following the stay in the chamber.
2 1 4 3 AV. of Feed. Treat No.
85.22 73.6 73.25 65.62 Intake on 24hrs.
following the stay
in the chamber
(0.328) (0.347) (0.310)
+11.62 +11.97 +19.60 85.22 2
(0.339) (0.300)
*0.35 +7.98 73.6 1
(0.321)
+7.63 73.25 4
65.62 3

 

Table A.l.f. LSD analysis of the change (°C) in body temperature

 

 

1 3 2 4 AV. Change Treat No.
0.79 0.73 0.11 -0.45 in body temp.

(0.266) (0.290) (0.299)

0.06 +0.68 +1.24 0.79 1
(0.273) (0.284)

+0.62 +1.18 0.73 3
(0.307)

+0.56 0.11 2

 

142

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table A.2. Analysis of variance (3 factors) of the change
in a. egg weight due to providing feed and/or water
during heat stress (35°C) or no-heat for 4 hours at
the time egg shell formation is occurring.
Source: (11: mascara: may”: PM: Puts:
V414? (A) 1 .679 .679 .135 .7146
lhnd(3) 1 9lfllllh6 9MNIIIF6 1ifllfllr6 .9999
AB 1 «4301 l4.701 .955 .5377
Fuggwwhlb(t) 1 .123 .125 .024 .3764
AC 1 12595 215!) £fl4v .4765
BC 1 744 7J4 L421 .2355
ABC 1 .164 .164 .055 .9575
fiwnr 56 25LA74 5026 -

 

Table A.2.b.

Analysis of variance of the change in shell weight. '

 

 

 

 

 

 

 

 

Sara: 4!: mum: Momma: Hm: Puts:
9mm 1 .78: ' .733 4.491 0807
1hnd(0) 1 .004 .034 .209 .6499
AB 1 1301 L301 7306 .0067
1mm (0) 1 .911 .91 1 5357 .0219
AC 1 .01 01 .059 .9101
an 1 .061 .061 .114 .5432
ABC 1 13125-4 131256-11 OWE-4 .9775
Error 96 9.193 .164

 

 

 

 

 

 

 

 

 

143

Table A.2.c. Analysis of variance of the change in Z shell.
Sana: . of : : Hut:
1294' 1294 5691
.515 515 392
775 1
1226 1
9691
A61 1
4 4

     
    
 

  

-12 59

Table A.2.d. Analysis of variance of the change in.mg Ca/mmz.

8am: Mo! ° : ° P
1 11936-8

          

40555-5

L24€flb5
75HIF4
2255559

Table A.2.e.

144

Analysis of variance of the feed intake (gm)

within 24 hours following the stay in the

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

chamber.

W04: 11!: snowmen: Measure: Hem: Pvehe:
Voter (A) 1 1352.759 1352.759 9.035 1004
Feed (9) 1 11513.996 11513.996 76m 13-4
AB 1 1401554 ' 14015H4 ‘9361 .0034
M (c) 1 364.599 364.599 2.435 .1124_§_ ,
AC 1 140 140 .955 .3377
90 1 959155 939355 561 .0214

, 491: 1 202946 202046 1355 P .2494

Error 56 9394.296 149.719

1
1

Table A.2.f. Analysis of variance of the change (°C) in body

 

 

 

 

 

 

 

 

temperature. 4

Source: 41: mum: Menage": Med: Puts:
Voter (A) 1 4573 4573 15.292 3m-4
Feed (9) 1 .254 .254 .951 .3602
49 ' 1 .293 .293 .979 .3267
1mm (0) 1 23.423 23.423 7932 1 .154
AC 1 .593 .593 1 .949 .1693
a: 1 .232 232 .776 .3923
m 1 .16 .16 .536 .4673
Error 56 16.746 299

 

 

 

 

 

 

 

 

 

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