UNIVERSITI PUTRA MALAYSIA
THE EFFECT OF SEX-LINKED DWARF (DW), NAKED NECK (Na)
AND FRIZZLE (F) GENES ON VARIOUS TRAITS IN LAYING HENS
UNDER TROPICAL CONDITIONS
ZULKIFLI BIN HJ. IDRUS
FPV 1991 4
THE EFFECT OF SEX-LINKED DWARF (dw) , NAKED NECK (Na)
AND FRIZZLE (l) GENES ON VARIOUS TRAITS IN LAYING HENS
UNDER TROPICAL CONDITIONS
By
ZULKIFLI BIN HJ. IDRUS
Thesis S�itted in Part ial Fulfill.ent of the Requireaents
for the Degree of Master of Science in the Faculty of
Veterinary Medicine and Ani.al Science,
Universiti Pertanian Malaysia
April 1991
ACKNOWLEDGEMENTS
My most sincere grat itude is extended to the following :
Prof .
Dr .
Yukio
Yamada ,
my
supervisor ,
invaluable advice , guidance , assistance
of making this s t udy
Dr .
Wan
and
for
all
his
encouragement
possibl e .
Khadi j ah
Embong
of
the Department of Genetics
and Cel lular Biology , University of Malaya for
allowing me
to
use her data for my study .
Assoc .
Prof .
Dr .
Prof . Dr . Kassim Hamid , Dr . I shak
M . K . Vidyadaran
and
Yahaya ,
Dr . Dahlan Ismail
Assoc .
for
their
suggestions and comments .
Assoc . Prof . Dr . Tengku Azmi Tengku Ibrahim,
of the
Faculty
Deputy
Dean
of Veterinary Medicine and Animal Science
for
his const ant encouragement .
Miss Nor Arizah Masiron
and
Mr . Zailan Mat Ali for their
assistance in the analysis of the data.
My
mother ,
Puan
Haj j ah
Zaiton
Mohd .
Shari f f ,
encouragement and moral support are beyond words .
ii
whose
TABLE OF CONTENTS
Page
ii
ACKNOWLEDGEMENTS
LIST OF TABLES
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LIST OF FIGURES
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LIST OF ABBREVIATIONS
ABSTRACT
ABSTRAK
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xiii
CHAPTER
I
II
INTRODUCTION
1
LITERATURE REVIEW
4
Recessive Sex - Linked Dwarf ism
Gene (dw)
Ef f ec t on Body Weight
and Growth
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Ef f ect on Egg Production
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Ef f ec t on Body Conformat ion
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Eff ect on Mortality and
Susceptibi li ty to Speci f ic
Diseases
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Autosomal Incomplete Dominant Naked
Neck Gene (Na)
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Effect on Body Weight
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Ef f ect on Egg Production
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Traits
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Ef f ect on Feed Consumption
and Ef ficiency
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Effect on Body Conformation
Traits
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Ef f ec t on Mortality
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Interpretation of Associated
Ef fects
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Autosomal Incomplete Dominant
Frizzle Gene Cl>
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Ef fect on Production
Trai ts
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I II
MATERIALS AND METHODS
Experimenta l S tock
Management
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Housing
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Feeding
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Vaccination
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Climate
Traits S tudied
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Body Weight
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Body Conformation
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Individual Feed
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Consumption
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Egg Production
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Egg Weight
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Feed Ef f iciency
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Egg Quality
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statistical Analysis
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RESULTS
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Body Weight
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Body Conformat ion Traits
Egg Quality Tra i ts
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Shell Thickness
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Shell Weight
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Yolk Weight
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Yolk Height
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Shell Breaking Strength
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Albumen Height
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Individual Feed Consumption
Egg Production
Egg Weigh t
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Feed Ef f iciency
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Principal Component Analysis
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DISCUSSION
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Body Weight
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Feed Consumption
Egg Production
Egg Weight
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Feed Ef f iciency
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Principal Component Analysis
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v
VI
SUMMARY
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BIBLIOGRAPHY
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APPENDICES
VITA
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LIST OF TABLES
Table
1.
Page
Ef f ect of dw on Response to Speci f ic
Diseases and on Immune Response
2.
Breeding Plan of Experimental Stock
3.
Traits Studied and Time of Recording
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5.
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Test
of Sign i f icance Between Genotypes
f or Body Weight and Body Conformat ion
Traits (Model I ) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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Means and Standard Deviations of
Weight and Body Conformat ion Traits
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Test of Signif icance Between Genotypes
f or Egg Quality Traits at 60 and 76
Weeks (Model I)
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Means and Standard Devi ations
Quality Tra i t s at 60 Weeks
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Means and S t andard De!viations
Quality Traits at 76 Weeks
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Egg
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Means and Standard Deviations of Feed
Consumption at Various Laying Periods (g)
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Test of Significance Between Genotypes
for Egg Product i on at Various Laying
Periods (Model I)
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Means and S t andard Deviations
Egg Product ion at Various Laying
Periods (number)
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Test of Signi f icance Between Genotypes
f or Egg Weight at Various Laying
Periods (Model I)
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Tes t of Signi f icance Between Genotypes
f or Feed Consumpt ion at Various Laying
Periods (Model I )
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Table
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Test of Signif i cance Between Genotypes
for Feed Ef f iciency at Various Laying
Periods (Model I)
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Heans and S t andard Deviations of
Feed Eff iciency at Various Laying
Periods ( feed/egg mass)
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Eigenvectors of the
Principal Components
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Second
First and
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Summary of Analysis of Variance for Body
Weight and Body Conformation Trait s
(Model I I ) ............... . ............................................... ..
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Summary of Analysis of Variance for Egg
Quality Traits at 60 Weeks (Model I I )
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Summary of Analysis o f Variance f or Egg
Quality Traits at 16 Weeks (Model I I ) ..............
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Summary of Analysis of Variance f or Feed
Consumption at Various Laying Periods
(Model I I )
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Summary of Analysis of Variance for Egg
Product ion at Various Laying Periods
(Model� I I ) .. . ...... . ........ . .... . ........ . . . .. . ........ . ........ . ..
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Summary of Analysis of Variance for Egg
Weight at Various Laying Periods
(Model I I )
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Summary of Analys i s of Variance for Feed
Eff iciency at Various Laying Periods
(Model I I ) ....................................................................
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LIST OF FIGURES
Figure
1.
Page
Principal Component Chart of the Firs t
and Second Components Based o n 1 6 Traits
of Various Genotypes
2.
Mean Body Weight of Various Genotypes
3.
Mean Shank Length of Various Genotypes
91
4.
Mean Breast Depth of Various Genotypes
92
5.
Mean Tibial Length of Various Genotypes
6.
Mean Keel Length of Various Genotypes
7.
Mean Breast Width of Various Genotypes
8.
Mean Shell Thickness o f Various Genotypes
at 60 and 16 Weeks
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Mean Yolk Weight of Various Genotypes
at 60 and 76 weeks
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Mean Yolk Height o f Various Genotypes
at 60 and 76 Weeks
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Mean Shel l Breaking S trength of
Genotypes at 60 and 76 Weeks
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of Various Genotypes
Mean Shel l Weight
at 60 and 76 Weeks
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Various
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Mean Albumen Height of Various
Genotypes at 60 and 76 Weeks
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Mean Feed Consumption of Various
Genotypes
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Mean Egg Production of Various Genotypes
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Mean Egg Weight of Various Genotypes
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Mean Feed Efficiency of Various
Genotypes
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LIST OF ABBREVIATIONS
dw
Dwarf gene
Na
Naked neck gene
NaNa
Homozygous naked neck layers
Nana
Heterozygous naked neck l ayers
!@!!A
Normal layers
r
Frizzle gene
Dw- f f nana
Normal
Dw- f f Nana
Naked neck
Dw- Ff nana
Frizzled
Dw- Ff Nana
Frizzled naked neck
dw- f f nana
Dwarf
dw- f f Nana
Dwarf naked neck
dw- Ff nana
Dwarf f rizzled
dw- Ff Nana
Dwarf f rizzl ed naked neck
PRIN 1
Principal component 1
PRIN 2
Principal component 2
x
Abst ract of thesis submit ted to the Senat e of Unive rsiti
Pertanian Malaysia in partial fulfil lment of the requirements
for the degree o f Master o f Science .
THE EFFECT OF SEX-LINKED DWARF (dw) , NAKED NECK (Na) AND
FRIZZLE (r) GENES ON VARIOUS TRAITS IN LAYING HENS
UNDER TROPICAL CONDITIONS
By
ZULKIFLI BIN HJ. IDRUS
APRIL, 1991
Supervisor
Prof . Dr . Yukio Yamada
Faculty
Veterinary Medicine and Animal Science
A
s tudy was carried out to investigate the ef f ec t o f
the
s ex-linked dwarf (dw) , naked neck (Na) and f rizzle (l) genes on
various quantitative t raits in l ayers and also to identify
appropriate
genotypes under t ropical conditions .
The
the
experi-
mental s tock comprised of non-dwarf non-f rizzled non-naked neck
or
normal
(Dw- f f nana) , naked neck
(Dw- Ff nana) ,
(dw- f f nana) ,
(dw- Ff nana)
f rizzled
naked
(Dw- f f Nana) ,
neck
(Dw- Ff Nana) ,
dwarf naked neck (dw- f f Nana) , dwarf
and
dwarf
f rizzled
f rizzled
naked
neck
dwarf
f rizzled
(dw- Ff Nana)
genotypes .
The
weight ,
dw was observed to cause a prof ound reduction in
body
However ,
ef ficiency .
the
conformation ,
dw
reduced
egg production
f eed
intake
and
and
egg
weight .
improved
The dw also had detrimental ef f ect on several
quality t raits .
xi
body
f eed
egg
Body
af f ected
weight
by
increased
and body conformation measurements
the
in
Dw- f f Nana
Na ,
both
while
dwarf
f eed
and
intake
non-dwarf
was
were
signif icant ly
populations .
hens were observed to have bet ter
egg
The
product i on
and egg weight . Shel l quality t raits were f ound to improve
to the Na .
not
due
However , among the dwarf population , the Na had
an
adverse e f f ect on f eed e f f iciency .
Except for an increase in yolk weight and a decl ine in
production ,
On
the [ had no maj or e f f ect on quantitative
the other hand , the e f f ect of the Na and r
egg
traits .
combination
on
various traits was f ound to be comparable with the .inf luence of
Na .
Genotypes
with
dw
could be improved
through
long
term
select ion , whi le the Dw- f f Nana birds appear to be superior in
t e rms of egg production and egg weigh t but f eed the
value
attained
was inferior compared to
e f f ic iency
genotypes
with
dW ,
principal
component
except dw- f f Nana .
The
f i rs t principal component of the
analysis where the contribution of each trait was equally high ,
indicated
dw .
an obvious d i f f e rence between genotypes with Dw
and
However , in the second principal component , where only the
contribution
of
she l l thickness and shell
breaking
were
high , a reverse observat ion was made . Genotypes
were
observed to be separated f rom the others when
s trength
wi th
they
projected into the axis of the second principal component .
xii
Na
were
Abst ra k thesis yang d ikemukakan kepada S enat Universi t i
Pertani an
Malaysia sebagai memenuhi
sebahagian
daripada
keperluan i j azah Master Sains .
IESAN GEN'-GO KERDIL (dw) , LEDER TIDAl BERBULU (N'a)
DAN BULU TERBALII (�.> IE ATAS PELBAGAI CIRI-CIRI
AYAN PEN'ELUR DI BAVAD lEADAU' TROPIIA
Oleh
ZULKIFLI BIN' DJ. IDRUS
Apri l , 1991
Penyelia
Prof. Dr. Yukio Yamada
Fakul t i
Kedoktoran Veterinar dan Sains Peternakan
Suatu kaj i an telah d i j alankan untuk menyelidik kesan-kesan
gen-gen
kerdil
terba l i k
<t)
kuantitatif
(dw) ,
l eher t idak
serta kombinasinya ke
pada
genotip-genotip
ayam
yang
penelur
berbulu
atas
dan
sesuai di bawah
terbalik
bukan
l eher
t idak
dan
berbagai
j uga
bulu
ciri-ciri
untuk
keadaan
eksperimen terdiri daripada genotip-genot ip
bulu
(Na)
mengenali
tropika .
Stok
bukan kerdil bukan
berbulu
atau
normal
( Dw- ff nana) , Ieher t idak berbulu ( Dw- f f Nana) , bulu terbal i k
( Dw- Ff nana) , bulu terbalik leher tidak berbulu
(Dw- Ff Nana)
kerdil (dw- f f nana ) , kerd i l l eher t idak berbulu (dw- f f Nana) ,
kerdi l
bulu terbalik
l eher tidak berbulu
Pengurangan
(dw- Ff nana) dan kerd i l
bulu
t erbalik
(dw- Ff Nana) .
yang
j elas
berlaku
pada
berat
konformasi badan , pengeluaran telur dan berat telur
xii i
badan ,
disebabkan
oleh
dw .
Walau
makanan
kerdil
dan
bagaimanapun ,
dw
mengurangkan
meningkatkan kecekapan
pertukaran
pengambilan
makanan .
j uga menunj ukkan kesan t idak memuaskan kepada
Gen
beberapa
ciri-ciri kualiti t elur yang dikaj i .
Ukuran berat badan dan konformasi badan t idak
dipengaruhi
oleh Na , manakala pengambilan makanan didapa t i bertambah dengan
bererti
di dalam kedua-dua populas i kerdil dan
bukan
kerdil .
Ayam-ayam penelur Dw- f f Nana menunj ukkan pengeluaran telur dan
berat
t elur
yang
genot ip-genotip
meningkat
lebih
yang
tinggi
lain .
j ika
Kual i t i
dibandingkan
dengan
cengkerang ,
didapa t i
disebabkan oleh Na . Bagi nilai kecekapan
pertukaran
makanan , Na menunj ukkan kesan yang kurang memuaskan di kalangan
populasi kerdil .
Selain
pengurangan
daripada peningkatan pad a berat kuning
produksi
telur ,
r
t id ak
menunjukkan
pent ing pada ciri-ciri kuant i tatif . Manakala , kesan
Na
dan
r
ke at as
berbagai-bagai
telur
ciri
didapat i
dan
pengaruh
kombinasi
menyerupai
pengaruh Na .
Genotip-genotip
melalui
pemilihan
yang
mengandungi dw
j angkamasa panj ang .
boleh
Ayam-ayam
ditingkatkan
Dw- f f Nana
menunjukkan prestasi yang memuaskan dari segi penghasilan t elur
dan
berat t elur tetapi kecekapan pertukaran makanannya
kurang
memuaskan
berbanding
dengan
mempunyai dW , kecuali dw- f f Nana .
xiv
genotip-genotip
adalah
yang
Komponen
komponen ,
di
prinsipal
pertama
bagi
anali s a
mana sumbangan set i ap ciri adalah
prinsipal
t inggi
dan
serupa , menunjukkan perbezaan yang j elas di antara genotip yang
mempunyai
Dw
prinsipal
kedua , di mana hanya sumbangan ketebalan
telur
dan
dan dw .
daya
Wal au bagaimanapun , di
pemecahan
didapa t i .
Genotip-genotip
mempunyai
Na , terletak lebih t inggi
menunj ukkan
diproj ekkan
cengkerang
s ahaj a
yang
apabila
komponen
cengkerang
keputusan
lain
berlawanan
dalam
kepada
daripada
komponen
yang
xv
yang
genotip-genotip
prinsipal
bahawa Na mempunyai kesan pos i t i f ke atas
cengkerang .
t inggi ,
kedua ,
kua l i t i
CHAPTER I
INTRODUCTION
Livestock
the
and cash crop product ion play a maj or
rural and socioeconomic development of
f arming
role
Poultry
Malaysia .
const i tutes a maj or l ivestock activi ty
in
Peninsular
Malaysia . In 1990 , Malaysi a produced 3 9 0 , 000 tons poultry
and
4.4
bil lion eggs (Wang , 1 9 9 1 ) .
poult ry
science
development
Malaysian
broi ler
of
farms ,
hori zontal
and
management) .
exported
There
(breeding
product ion
was
local
feedmi l l s ,
etc .
establ ished
egg
the
made
a
in
s igni f icant
poult ry
Malaysian
impact
indus t ry .
meat
on
The
the
present
poul try industry encompasses of breeding , layer
suppl iers
adopted
have
Advances
ar. e
veterinary
several
drugs
large
and
- hatching , f eedmill ing ,
marketing
and
one
Total domestic requirement for poultry
attained
in
the early 80's
and
in
where
systems
egg
operation all into
and
equipment
companies
and vertical integration
in
1990
are
broi ler
system
of
meat
and
Malaysia
thirty-six million ringgi t worth of poultry meat
and
eggs to Singapore (Wang , 1 9 9 1 ) .
In
poult ry
pure
the
production
breeds .
enhance
early
Late r ,
days , breeding
pract i ces
were conf ined towards the
breeders
crossed
in
improvement
d i f ferent
produc tion . Changes through successful
con t r ibuted
to the availabi l i ty of new synthe t i c
have brought dramati c changes in
commercial
breeds
breeding
l ines
poultry production .
1
of
to
have
which
2
The
was
introduction of commercial hybrids in Southeast
initiated
in the
1 960 ' s (Arboleda , 1988) . The
Asia
extensive
use of exotic hybrids f rom USA , Australia and Europe , is one of
the
main
catalysts
Malaysian
poult ry
domesticated
1990) ,
in
the
for
the
indust ry.
establishment
Although
of
chickens
the Asian region about 2000
Asia
is s till low . This is in
p resent
were
B.C.
production e f f iciency of broilers
Southeast
the
(Crawford ,
layers
and
spite
of
humid
The
probable constrain is the prevailing
climate which is a disadvantage f or optimum
in
high-tech
management sys tem , adequate f eed .and st ringent disease
measures .
f irst
control
hot
and
production .
Bray and Gessel ( 1 9 61 ) , Payne (1966) , Mowbray and Sykes ( 1 971 ) ,
Wilson
that
et al . ( 1 9 7 2 ) , and Davis et al . ( 1 9 7 2 , 1 9 73 ) f
both
egg
production
and
egg
weight
reported
declined
at
breeders and geneticists are working towards
the
temperatures above 300C .
Poult ry
search
for
genotypes that produce optimum
production
under
adverse thermal environment . The e f f ects of several maj or genes
on
anatomical
and physiological t raits could be
utilized
to
improve the performance of l aying hens in t ropical climate . The
maj ors
genes
(Panandam,
of
1 985 ;
interest
Mathur ,
are
sex-linked
dwarf
1985 ;
Khadi j ah ,
1988) ,
incomplete dominant naked neck gene , Na ,
Bordas
and
Mathur ,
1985 ;
dominant
1 988 ;
Mera t , 1 984 ; Rauen et al .
Khadij ah , 1988) and
f rizzle
Mathur
and
the
(Bordas
198 6 ;
gene ,
autosomal
et al . , 1980 ;
Panandam,
autosomal
1 990) .
Previous
1985 ;
incomplete
gene , r, (Horst , 1987 ; Haaren-Kiso
Horst ,
dw ,
studies
et al . ,
on
the
3
inf luence
results
of
incorporating Na and
dw
indicated
encouraging
on productive adaptability of laying hens in
t ropical
clima t e .
Thus , the utilization of maj or genes , namely , dW , N�
[
in
the st ructure of t ropical poultry breeding ,
has
and
great
potential . The obj ectives of the present study include :
1.
To
inves tigate
the e f f ect of the dW , Na and
their combinations
2.
[
and
on various t raits in l ayers .
To identify suitable genotypes for optimum production
under t ropical conditions .
CHAPTER II
LITERATURE REVIEW
Recessive Sex - Linked Dwarfism Gene (dw)
Body
of
size in the domestic fowl varies greatly , f rom
the Jersey Giant cock ( 6 . 0 kg) to that of the Dutch
cock
at
0 . 6 kg . Some maj or s ingle genes ei ther
that
bantam
autosomal
or
sex-linked were f ound to have a maj o r e f f ects on skeletal s i z e ,
muscle
mass , ski n , f eathers and f a t deposi tion although
there
are several other contributing f actors .
There are at least two sex-linked genes which retards body
growth in f owl s . The recessive sex-l inked dwarf i sm gene
particular
wide
interest to poultry breeders and geneticists
since i t has great potential in the development
e f f icient
egg and meat producing s t rains . According
( 1 9 90) , this
of
is
world
of
more
to
Somes
gene has greater dwarf ing e f f ect than other
discovered
genes
(dominant
sex-linked
dwarf ism,
of
type
�
and
autosomal dwarfism, adw) .
Effect on Body Weight and Growth
A
on
number of workers observed t hat
body weight
1 95 3 , 1 9 5 9 ;
of birds early
in
the i r lives
Raj ara tnam e t al . , 1969 ;
( 1 9 5 9 ) and Baron ( 19 7 1 ) observed
the dw has
that
no
( Hut t ,
1949 ,
Selvaraj ah , 1970) .
Hut t
body weight a t two
four weeks of age , respectively were reduced due to the
4
ef f ect
and
e f f ect
5
of
dw .
On
showed
the
other hand. Delpech
(cited f rom Merat. 1 9 6 9 )
that w i t h an approximately s imilar body weight to
that
of dwarf chicks. the dwarf chick at hatching had a heavier yolk
sac
of about 1 0 . 2% inst ead of 7 . 1% of the whole
This
body
weight .
suggests that reduct ion of tissue growth in dwarf
occurred
s ince
embryonic li f e . Thus. the dwarf ing
chicks
e f f ect
is
manif es ted prog ressively according to age .
There are conflicting reports on the relative reduction of
body weight. a t tributable to dw at a given age . It was observed
that
the
would
size of the adult bird where the
determine
the
relative
reduction
dw
is
introduced
of
body
weight .
Mohammadian and Jaap ( 1 97 2 ) reported the back crossing of dwarf
bi rds f rom Leghorn s t rain to a White Rock type s t rain caused
reduct i on of body weight at
eight weeks of 3 7 . 1% in the
a
f irst
generat ion and of 1 9 . 2% in the third .
Effect on Egg Production Traits
The
phenomenon
Merat
Quisenberry
( 1 97 3 ) ,
l ight ,
type
the dw
ef fect
on
laying
rate
Bernier and Arscott ( 1 960) , Magruder and
contradicting .
(1969) ,
of
( 1 969) ,
( 1 97 2 ) ,
Quisenberry
Summers
(1972) ,
and
Bradley
Pol kinghorne
Coune
( 1971 ) �
and
Lowe
Doran and Quisenberry ( 1 974) and others who worked
heavy
s tocks
and medium (birds weighing up to 2 . 5
f ound
a decl ine in laying
rate
of
is
on
kg)
l ayer
about
10% .
However , Merat e t al . ( 19 8 8 ) reported dwarf layers bene f i t more
in terms of l ay ing rate , f rom ahemeral light cycles compared to
normal l ayers .
6
dw in meat type s t rains does not
On the other hand ,
pro­
duce detriment al e f f ect in laying rat e . However , Prod ' homme and
Merat
( 1969) ,
Yamada
e t ale
unchanged
( 1 990)
stocks
Sherwood
( 1971 ) ,
Ricard
and
Cochez
( 1972) ,
( 1972 ) , and Reddy and Siegel ( 1977 ) reported
or
improved
showed
that
laying
rate .
More
recently ,
egg number is decreased
in
Merat
layer
and more in the Leghorn light type than in the
an
type
medium­
sized type but not in the meat-type strain .
The con t radicting ef f ects of dw on layer and broiler types
were
investigated by several workers . Jaap and
Clancy
(cited
f rom Panandam , 1985) report ed that meat type pullets have
.large
rapid
growing
at
a
high
between
percentage
ovary
of
and oviduct function ,
abnormal
eggs
more
laying
rate . On the contrary , the
same
of
results
(double-yolked ,
shelless and soft-shelled eggs) and consequently a
of
a
rate than the oviduct is able to f orm eggs. The lack
synchronization
in
f ollicles . Thus , yolk is produced
many
depression
workers
reported
layer type stocks are more compatible with normal laying
rate ,
as the number of large f ollicles is lower .
According
( 1 91 3 ) ,
to Jaap and Mohammadian ( 1969) , van
Middlekoop
Guillaume ( 1916 ) , Silber and Merat (cited f rom
Merat ,
1984) and Merat ( 1984) , the e f f ect of dw on yolk formation
may
be
al .
due to the decline of growth , whilst van Tienhoven
( 1966) suggested that the low level of
blood
thyroid hormones in the
s t ream of dwarf birds could be the explanation
abnormal yolk formation .
et
for
the
7
S i ze
is one of the most influencing f actors for the
sale
of eggs (Africa and Paul t z , 1968) . Due to a high preference
by
consumers , the incorporation of
dw
of
larger
eggs
in
the
laying
strain which is associated with smaller s i zed eggs
has
been a major setback . A number of workers
(Hut t , 1959 ; Bernier
and
1969 ;
Arscott ,
1 960 ; French and Nordskog ,
Magruder
and
Dorminey
et al . , 1974 ; Khoo and Beh , 1 977 ; Hors t and
1 97 9 ;
Coune ,
1969 ;
Sadj adi et al . , 1 983 ;
have
reported
Raap ,
1970 ;
Merat ,
1969;
Selvara j ah ,
Panandam, 198 5 ;
197 1 ;
Petersen ,
Khad i j ah ,
a reduction of egg weight due to
dW ,
1988)
in
range of 3% to 1 4% compared to normal layers. The reduction
egg
size
body
could be explained by the high
correlation
egg size in relat ion to body size as compared to normal
(Selvaraj ah
et a l . , 1970 ; Bernier and Arscott , 1 97 1 ;
of
between
weight and egg weight (Gui llaume , 1976 ) . However , it
f ound that dwarf layers are more eff icient in terms of
the
was
average
layers
Khan
et
al . , 1 98 3 ) .
Dwarf gene has both benef icial and
qua l i ty .
egg
( 1970)
reported
al though
Selvaraj ah ( 1970 , 197 1 ) and Selvaraj ah
dw has no mod i fying e f f ect
on
egg
et al.
qual i ty ,
Raap ( 1970) , Ricard and Cochez ( 1972 ) and Si lber
Merat (ci t ed f rom Merat , 1984) , observed
eggs
detrimental e f f ects on
and
reduction of
cracked
in bat tery cages , regardless of s i z e among dwarf
layers.
Bernier
and Arscott ( 1960) , Gleichauf ( 1973 ) , Panandam
( 1985 )
and Khadi j ah ( 1988) reported dwarf birds laid eggs with thinner
she l l and lower breaking strength . Carter ( 1975 ) suggested that
the
reduct ion of cracked eggs
was probably
due to lower body
8
weight of dwarf hens , thus the weight exer ted on the cage f loor
was
reduced resul ting in less mechanical pressure on the
eggs .
egg
laid
Other contributing f actors are lesser height of drop
as the shanks of dwarf hens are shorter and
probably
of
the
qui t e temperament of the dwarf bi rds (Merat , 1990) .
The inf luence of the dw on the quality of the egg contents
showed
some contradict ions . Kerat ( 1970 , 1 9 7 2 )
reported
that
the dwarf birds produced eggs with an increased albumen height ,
whi l e Panandam ( 1 9 8 5 ) and Khadi j ah ( 1 98 8 ) reported the reverse.
The
in
con t rasting f indings were probably due to the
d i f ferences
cl imatic environment . Dwarf layers also produced eggs
reduced
yolk
and albumen weight (Benhof f
and
with
Renden ,
1 983 ;
Panandam , 1 9 8 5 ; Khad i j ah , 1 988) .
Effect on Feed Consuaption and Efficiency
The
reducing
e f f ect of the dw on f eed
intake
has
widely reported {Butt , 1 9 5 9 : Bernier and Arscott , 1 966 ;
been
S elva­
raj ah et al . , 1970 ; Quisenberry , 1972 ; Marks , 1 98 0 ; Alihussain ,
1 9 8 3 ; Panandam, 1985 ; Khadij ah , 1988} .
that
the
immediately
e f f ect
after
of
the
dw
hatching ,
on
f eed
reducing
Marks
{1980}
intake
the
was
f irst
reported
observed
day
f eed
consumption by 20% and the subsequent four to f ive days by 44% .
The
reduction
in f eed intake will occur at,all
dwarf birds (Quisenberry , 1 9 7 2 ) .
ages
of
the
9
the
Feed consti tutes 70% of the cost of eggs . It i s
therefore
ultimate aim of poul t ry geneticist to
genotypes
which
have
iden t i f y
a superior f eed ut i l i za ti on . Several workers
reported the potential of dwarfs for a bet ter f eed
particularly
in the t ropics
have
eff iciency ,
(Mukherj ee et al . , 1 980i
Hors t ,
1 988) . Dwarf bi rds showed a better f eed e f f iciency in terms
f eed per dozen of eggs ratio (Bernier and Arscott , 1 9 6 0 ,
1 97 2 ;
and
1966 ,
Arscott and Bernier , 1968 ; Chamber et al . , 1974 ;
Pi loski ,
1975)
and
( Prod ' homme and Merat , 1 969 ;
f eed
mass
per
egg
S t rain
mass
ratio
Quisenberry et al . , 1969 ;
French
and
Nordskog , 1 97 1 , 1 9 7 3 ) within the range of 82 . 1%
and
63 . 7%
to
of
82% f rom the f eed uti l i zation
of
to
96 . 2%
normal
hens
respectively . Weaver ( 1974) , based on f ield data (col lected
in
the USA) reported feed cost expressed in lb per chick produced ,
showed a gain of 33 % with dw meat type st rains .
The probable explanation for the improved f eed uti l ization
of dwarfs is likely due to low maintenance requi rement (due
small
for
body size) which enable more nut rients to
egg
Arscott ,
product ion (French and Nordskog ,
1972) .
However ,
Hut t ( 1 9 5 9 )
1973 ;
reported
be
allocated
Bernier
that
related
to
normals .
The
contradicting
to cl ima t ic f actors . Under a hot
f indings
and
dwarfs
require higher maintenance due to the i r l arger body surf ace
compared
to
as
probably
environment ,
energy
requi rement for heat conservation is not crucial and vice versa
under a moderate temperature . Despite the fact that dwarf s con­
sumed signif icantly lesser f eed compared to normals but due
reduced
egg weight and laying rate , several workers
to
indicated