ABSTRACT
Master of Science
,
Animal Science
(Genetics and Breeding)
PA LANG HSU
A STUDY OF THE INHERITANCE OF A DWARF ISOLATE IN ruE
œICKEN AND ITS EFFECT ON PERFORMANCE
A dwarf chicken was isolated in 1963 from a population of meat
chickens.
From this bird a population of dwarfs was developed.
The
inheritance of this dwarf and the performance of dwarf birds and their
crosses were studied.
The dwarf condition was due ta
which has been designated dIJ'I.
a sex-linked
recessive
gene
Results from various matings indicate
that dzJ" is an aUele at the dwarf
(dw)
locus.
It is diffarent fran
With respect to ~ the results were inconclusive
and dominant to dW.
as ta whether dJJ'I was the sàme or a different allele.
In
addition
~o(
reducing
body
size,
preliminary evidence ~
,"
suggested that the
~
reduced egg production but not egg size.
There
"
was no effect
of cbJ" on fertility,
hatchability or mortality
during
the growing period, but wi th respect to _adul t mortali ty J. the si tuation
was not conclusive.
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Maitrise en Science
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PA LANG HSU
Zootechnie
ETUDE DE L'HEREDITE ET DES EFFECTS DU NANISME ŒlEZ
LA POULE
En 1963, une poulette naine a été isolée d'une population de
poulets h chair et une race naine en fut développée, dSht on a étudié
l'hérédité, les
p~rformances
et la croissance.
Ce nanisme est dû à un gène lié au sexe récessif designé
awm
qui est un allèle du locus dW, dont il est différent mais sur lequel
il domine.
En ce qui concerne, ~, il n'est pas possible de définir
si ~ est sur le même allèle ~u sur un allèle différent.
Des résultats préliminaires suggèrent que, en plus de réduire
la taille corporelle, ~ diminue la production des oeufs mais non
leur gtlJsseur.
Le gène dùf' n'a' pas d'effet sur la fertilité,
l'intensité de ponte, ou la mortalité pendant la période de croissance,
mais on ne peut tirer aucune conclusion en ce qui concerne la
mortalité chez l'adulte.
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A STUDY OF THE INHERITANCE OF, A 'oWARF ISOLATE IN
nœ
QUCIŒN AND ITS
by
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Pa Lang Hsu
A thesis subnitted to the Facul ty of Gradua'te Studies and Research
pf McGill Univ~rsity in partial fuI filment of the requirElllents
for completion of the degree of Master of Science
Departœent of Animal Science,
Macdonald Campus' of McGill tJniversity,
Montreal, Quebec, CANADA.
August 1973
,
----,.,---'
Pa Lang Hsu
1974
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Suggested short title:
A DWARF ISOLATE
~ CHICIŒN
HSU
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ACKNOWLEDGEMENTS
The author wishes to express hfs gratitude to Dr. R. B. Buckland for his
guid~nce~
encouragement and assistance throughout this
.~~.
\
The aUyhor is particularly grateful to Dr. R. O. Hawes for
"
"his helpful advice in the initial stage of the project.
The author wishes to thank Drs. M. ·Fanous and J. E. Moxley
-
for
1
their~nterest
and advice in the statistical analysis.
The author
wishes to thank Mr. R. Benison for technical
"
,
assistance.
The author is deeply indebted to his wife, Chren-Ru, for her
patience, understanding and encouragement.
r
The author gratefully acknowledges the financial support for
this project.provided by the Quebec Agriculture Research Council.
The help of.Mrs. K. Marsh in the typing of this manuscript is
also appreciated.
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TABLE OF CONTENTS
Page
ACKNOWLEIXiEMENTS.
iv
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LIST OF TABLES.
ix
LIST OF FIGURES .
xi
Chapter
1.
II.
INTRODUCTION
1
REVIEW OF RElATED LITERATURE
3
II.1.
INHERITANCE OF BODY SIZE.
3
II.1.1.
Inheritance of dwarfism in mamma1s
3
II.1.1.1.
II. 1 .1 .2.
II.1.1.3.
5
J
I~1.2.
11.2.
cS
Autosomal recessive •
Autosomal dominant . • . •
Sex-linked recessive (dw locus)
PHYSIOLOGICAL AND BIOCHEMICAL ACTION OF DWARFING
GENES . . . . •
II.2.1.
Mammals.
II.2.1.1.
II.2.1.2.
. 11.2.2 .
•
4
Inheritance of dwarfism in birds . . . •
11.1.2.1.
11.1.2.2.
II.1.2.3.
(
Autosoma1 recessive .
Autosana1 dominant. .
Sex-linked recessive.
4
•
•
Autosomal recessive .
Autosomal dominant.
IV.
5
6
6
7
10
10 ___
12
Birds. • .
12
II.2.2.1.
12
13
Autosomal recessive .
11.2 .2 .2. Autosanal dominant. . . c.
II.2.2.3. Sex-linked recessive • . •
III.
5
13
SPECIFIC STATEMENT OF PROBLEM.
16
MATERIALS AND METHODS.
17
v
17
0
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Chapter
IV. 1.
GENERAL
IV. 1.1.
o/IV. 1. 2.
IV. 1. 3.
IV.2.
Page
17
Artificial insemination.
Incuba tion •.
..•..
Housing and feeding of experimental birds.
17
17
17
STUD1ES ON THE INHERITANCE OF THE DWARF ISOLATE .•
18
IV. 2 .1.
Reciprocal ma tings of the Macdonald dwarf
isolate with non-dwa'rf Leghorn (dt..J~ • •
IV.2.l.I.
IV. 2.1. 2.
IV.2.1.3.
IV. 2 .1.4.
IV.2.1. S.
IV.2.2.
Matings
males
dwarf
quent
IV.2.2.4.
IV.2.3.
IV.2.3.4.
IV.3.
Stocks. . .'. . • . . . • .
Matings and incubation . .
Determination of body weights
and shank lengths • . • • •
Statistical analysis of body
weight and shank length data.
Reciprocal matings between the Macdonald
dwarf isolate and the Old English Game
Bantam. and between the SCWL and the Old
English Game Bant~. • • • • • •
IV. 2. 3.1.
IV.2.3.2.
IV.2.3.3.
Stocks. . . . . . . . . . .
Matings and incubation.
Determination of body weight
and shank length. • . • • • •
Statistical analysis of body
weight and shank length data.
STIJDIES ON THE PERFORMANCE OF nIE MACDONALD DWARF
ISOIATE AND 1TS CROSSES • • • • • •
D
IV.3.1.
IV.3.2.
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19
20
20
h
of the Macdonald dwarf isolate
with the sex-linked recessive
Leghorn females (~-) and subseF2 and backcr~ss • . . . . •
IV. 2.2.1.
IV.2.2.2.
IV.2.2.3.
,
Stoaks. . . . . .' . . . . • . •
and incubation. . . . •
Determination of body weight
and shank length. • . . . . •
Determination of sexual
dimorphism. . . . . . . . . •
Statistical analysis of body
weight and shank length data.
M~tings
18
Body weight and shank length
Egg production • . • • • • • •
....
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22-
22
23
23
23
24
24
24
2S
2S
26~
26
26
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Chapter
Fertility. . . . . .
Hatchabili ty . . . .
Mortality. . . . . .
Statistical ana1ysis of the performance
data
IV.3.3.
IV.3.4.
IV.3.5.
IV.3.6.
V.
26
27
27
28
EXPERIMENTAL RESULTS •
V.1.
v . 2.
29
RECIPROCAL MATINGS BETWEEN THE MACDONALD DWARF
ISOLATE AND lliE. NON-DWARF LEGHORN. • • • • •
29
MATINGS OF THE MACDONALD DWARF ISOLATE MALES WITH
SEX-LINKED RECESSIVE LEGHORN FEMALES (dw-) .
31
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V. 3.
V. 4.
RECIPROCÀL MATINGS BETWEEN THE MACDONALD DWARF
ISOLATE AND THE OLD ENGLISH GAME BANTAM, AND
BETWEEN THE SINGLE COMB WHn'E LEGHORN AND THE
OLD ENGLISH GAME BANTAM. . • • • • •
33
THE EFFECTS OF MACDONALD DWARF ISOLATE ON
PERFORMANCE. • • • • • • • •
35
V.4.1.
V.4.2.
V.4.3.
V.4.4.
V.4.5.
VI.
Body weight and shank 1ength
Egg production
Fertility. .
Hatchabi l i ty
Mortality.
35
35
36
36
37
DISCUSSION.
38
VI.l.
INHERITANCE OF THE MACDONALD DWARF ISOLATE.
38
VI.l.l.
VI.l.2.
38
General. . . • . . . . • . . . . • •
The genetic relationship of the Macdonald
dwarf isolate to the known alleles at
the dw locus • . . . . . . • . . . .
VI. 1.2.1.
VI.l.2.2.
VI. 2.
The relationship of
, to dw • • • • • •
The relationship of
to ~. • . . • •
Body weight and shank length
VI. 2 .1.1.
VI. 2 .1.. 2.
Hatching. • •
Post hatching
vii
42
the dJJ"
• • • •
42
the dJJ"
. . • •
44
THE EFFECfS OF THE MACDONALD DWARF ISOUTE ON
PERFO~CE • • • • • • • • • • • • •
VI.2.1.
e.
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46
46
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Chapter
Page
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Egg production
VI.2
VI.2.3. \ Fertility . .
VI. 2. 4. Hatchability •
VI .2-.5. Viability. . .
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VII.
VIII.
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SUMMARY AND CONCLUSIONS.
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LITERATURE ClTED .
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49
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LIST OF TABLES
{]
Table
1.
2.
3.
4.
S.
Page
Deviation of each hatch from the overall mean of body
weights and shank lengths at various ages of the ofîspring
from the D x D, 0 x L, L x D and L x L mating types •.
54
Mean body weight and shank length of the offspring from
D x 0, 0 x L, L x 0 and L x L mating types. . . . : . .
55
Mean body weight and shank Iength of the offspring from
D x 0, D X L, L x 0 and L x L mafing types after adjusting
for egg weight and hatch effect ~ . .
. . . . .
56
Mean squares of the analysis of variance on the adjusted
body weight and shank length data of the offspring ~m
D x 0, D x L, L x 0 and Lx L mating types . . . . . '\,~ . .
57
Degree of sexual dimorphism at 12 weeks of age of offspring
from 0 x 0, 0 x L, L x D and L x L rnating types . . . . . .
58
Mean squares of analysis of variance of the sex dimorphism
6.
da ta. . . . . . . . . .
. . . " . . . . . . .
59
7.
Mean adult body weights and shank lengths of Macdonald
Dwarf Isolate (MDI), 21-week body weights and shank Iengths
of the FI of MOI males x Sex-linked Recessive Dwarf (SRD)
females, mean adult body weights and shank lengths of SRD
and~ormal Single Comb White Leghorns (SCWL) and the results
of c~arisons between the FI and other birds of each sex. 60
8.
Mean body weights and shank Iengths of the F2 generation of
. . . . . . • . . . . . . . . .
61
Mean body weights and shank lengths of the offspring from
the backcross of the FI (MDI x SRD) to the MDI males • . . .
62
the MDI x SRD . .
9.
10.
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Comparisons of body weight~ and of shank lengths at 12
weeks of age between the backcross of the FI femalés (MDI x
SRD) to the MDI males and those of pure line MDI. . • . • • 63
Comparisons of the body weights and of the shank lengths at
21 weeks of age of the FI and F2 generations of the MDI x
SRD . • • • • • • • . • • • • • • • • • • • • • • • • • • •
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Table
Page
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Mean body weig~ts and shank lengths of the chicks from
B x L, L x B, B x 0 and 0 x B mating types... • .
65
Comparisons of body weights and of shank lengths at ,12
weeks of age of fhe Bantam with those of the related birds.
66
~4.
Average body weights and shank 1engths of the chicks from
the OB x 0 and LB x 0 ma ting types. . . . . •
w
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67..
15.
Comparisons of body weights and of shank lengths of the ,:
progeny from the DB x D, LB x D and D x 0 mating types.
68
12.
l:h
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16.
417.
18.
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Mean percent egg" production and egg weight for the pullet~.J
from 0 x D, D x L, H x 6> and H x L matings at various ages. 69
Mean squares of analysis of variance of the percent.egg
production at 12 months of age and egg weight at 49 weeks'
of àge. . .
........ . . . . . . . . . . . .
70
Mean percent .fertility for 14-day duration post
insemination and number of hens . . . • . .~. . . . .
71
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Ana1ysis of variance of the ferti1~ty data . •
20.
Effect of mating type on the hatchabilityof the offspring
and the TIl.ltl ber 0 f hens.
•.•...•••••.•.
73
Analysi~ ~f ~ance for the effect oilSmating type on
hatchahl 11 t~. . • . . • . . . . . . . .'. . •
74
21.
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.,.
22.
The percent mortality of ~lie offspring from the D x D,
D x L, L x D and 1.. x L matings frOm hatch to 12 weeks of
age . . . •
............. .
75
The 1aying holA;e mortality of the pullets from D x--D,
D x L, H x D and H x L matings from 23 weeks to S6 weeks
of age. . . . . . . . . . . . . . . . .
76
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LIST OF F'IGURES
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Figure
Page
1 .. The distribution of body weights ât 12 weeks of age of
the F2 males ~rom FI males (awmdw) and females (~-) .
2.
3.
4.
5.
"-
The distribu~ion of shank lengths at 12 weeks of age of
the .F2 males f~m FI males (dJJ'ldw) and,;temales (c:iJJ1l-) , •
, I f
79
The distribution of shank lengths at 12 weeks of age of
the F2- females from FI males C~dw) and females (~-)
80
The distribution of body weights at 12 weeks of age of
male offspring produced by OB x 0 (~awB x ~-) mating
Il
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82
The distribution of shank lengths at 12 weeks of age of·
the female offspring produced by DB Qjt 0 (dzJT'awB x dJ"-)
mating type • . . . . • • . . '.
. • . . • •
o
/
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The distributiQn tf body weights at "12 weeks of age of the
female offspring produced by DB x 0 (~~ x ~-) mating
type.. . . . . . . . .
8.
..
')
The distribution of shank lengths at 12 weeks of age of
the male offspring produced by DB x D (awm~ x dJJ'l-)
mating type . . . . .
7.
78
The distribution of body weights at 12 weeks of age of
the F2 females frorn FI males (awmdW) and females (~-)
type. . . . . . .
6.
77
84
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1. INTRODUCTION
Genetic dwarfing has been an important syndrome in'medical
practice and in sorne aspects of the an1mal industry.
In the domestic
(:
fowl, genetic dwarfing has been speculated as a possible tool to
reduce body size of breeding populations and thus reduce overall
production costs.
Discovery of a new dwarfing mutant in chickens
;-:: which has no deleterious side effects could have a large impact on
. the poultry industry.
A dwarf is defined as an individual much below the normal
t
size of its species or bréèd.
Reducing body size could either be
achieved by selection for small body size or by using a major gene
which reduces body size substantially.
In 1963 Dr. R. O. Hawes at the Macdonald Campus of McGill
University found a dwarf among a population of meat-type chickens.
From this isolate a.population of dwarfs was formed and has been
maintained to date.
Preliminary observations on the pedigree data
seemed to suggest that this dwarf was due to an auto sana 1 dominant
gene.
Thus the original purpose of this study was to explore the
physiological action of this autosamal dominant gene, but the body
weight and.shank length data of the ofrspring produced by reciprocal
1
ma t'ings of dwarf and nonnal birds did not eonfi1'll the hypothesis.
Therefore. furthér study ~n the genetie nature of the dwarfism was
neeessary.
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The work reported in this thesis was designed to determine
the inheritance of this dwarfism and its relation with the dw
locus~
, and to obtain prel iminary information on the effect of the dwarfing
gene on perfomancé·.
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II. REVIEW OF RELATED LITERATURE
II. 1.
INHERITANCE OF BODY SIZE
Body size is a polygenic trait (Hutt, 1964), with the exact
number of genes
af(~cting
body size not yet determined.
with polygenic inheritance. a
differing in size
~ds
cros~
In accord
between two breeds or strains
an Fl generation that 1s usua11y intermediate
in size between the two parent breeds or strains, except that in some
crosses hybrid vigor may resu1t in the FI being equal to or greater
than both the parent breeds.
The F2 generation may exhibit trans-
gressive variation (Hutt, 1964) where the extremes of the population
can be, in the case of body weight, for example, either larger or
smâller than the original parental types.
Body size is,also inf1uenced by modifier genes which can
~~ter
the phenotype produced by a particular gene or group of genes
(J ohanssal' and
Rende!, 1968).
In addition, specifie loci have been identified in a number
of species which result in a reduction in body size or dwarfi-sm to
varying degrees.
The present review i5 centered on specifie genes
1
which have substantial influence in reducing body size •
• t
II. 1. 1.
.
Inheritance of dwarfism in mammals
,~.
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Among the genes which reduce body size in mammals are:
(1) autosomal reeessive genes eausing dwarfism in beef cattle. mice.
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sheep and humans; (2) an autosomal dominant gene causing dwarfism in
humans; (3) a sex-linked recessive gene causing dwarfism in rats.
II. 1. 1. 1.
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Auto soma 1 recessive
Dwarfism caused by an apparent1y autosoma1 recessive gene or
genes has been reported in Hereford (Johnson et aZ., 1950) and Angus
cattle (Baker et al., 1951).
Bone (1963) classified the dwarfism
into brachycephalic, do1ichocephalic, and compressed.
Of the three.
the brachycephalic type is found most frequently in'Hereford and is
ca1led snorter dwarf because of peculiar noises made by breathing
even while at rest.
The snorter calves were not identifiable unti1
about two months old.
The campressed and the do1ichocephalic dwarfs are produced by
the snorter gene in a heterozygous condition (Bone. 1963).
Since not
aIl snorter animaIs are compressed, Bone (1963) suggested that this
,"
rnight be due to the effect of many modifying genes or'variable
\.
penetrance of the snorter gene Or genes.
An
auto~omal
recessive gene causing dwarfism has been reported
in sheep (Landauer and Chang, 1949).
lhe dwarf sheep, in addition ta
having reduced body size, have short and crooled forelegs and have
been given the Greek name Ancon.
Snell (1929) reported an autosOma.l recessive gene that
reduced body weight by 30 percent in mice.
Schaible and Gowen (1961)
also reported,a dwarf gene reducing body weight by 50 percent that
was not allelie ta the dwarf found by Snell (1929).
Midget is another
autosaD'àl':recessive gene reducing body weight by about 30 percent·
4.
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5
(Fow1er and Edwards, 1961), but the al1e1ic re1ationship of the
" midget to the above dwarfs has
no~
yet been detennined.
The pituitary dwarfism in humans is inherited as an autosamal
~
recessive character (Seip et al., 1968).
II. 1. 1. 2.
~
Autosamal dominant
Achondroplasia, a dwarf syndrome in humans, has been reported
to be caused by an autosama1 dominant gene (Rimoin et al., 1970).
However, Langer et al. (1970) reported that five out of the six cases
they examined were female and
"
sugge~ted
that both autosoma1 and sex-
linked inheritance May be invo1ved.
II. 1. 1. 3.
Sex-linked recessive
A sex-linked recessive gene which reduces body weight by
about 50 percent in males and 70 percent in females has been reported
in rats (Lambert and Sciudetti, 1935).
The dwarf, rats cannot be
identified until about two weeks of age, after which there is a
proportionate reduction in skeleta1 size.
fI. 1. 2.
Inheritance of dwarfism ip birds
In the chicken autosanal daninant and recessive, and sexlinked recessive genes that reduce body size have been reported.
II. 1. 2. 1.
Autosomal recessive
A phenotype called crooked-neck dwarf has been reported in
• and Punn, 1956) and'
chickens (Asllundson, '1945), turkeys (Asmundson
Japanese quai! (Sittllan and Craig, 1967; Dadson and Coleman, 1972).
It is lethal in the hClllozygQus condition .... Growth i5 nomal up to
...
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about the eleventh day of incubation, but is retarded thereafter, and
-the embryos'die on the 20th or 2lst day.
These workers aIl concluded
that the crooked-neck dwarf is caused by an autosomal recessive gene
(cm) •
An auto soma 1 recessive gene called chondrodystrophy (ch),
which causes dwarfism, has been reported by Hutt (1949) in the
chicken.
"
A thyrogenic dwarftsm in chickens which is due to an auto soma 1
recessive gene (td) was first reported by Landauer (1929).
1
('
homozygous condition the birds
~e
In the
not only dwarf but usually die
1
before
weeks of age (Upp, 1934).
~our
The few birds that survive are
retarded in growth, and never become sexually mature and have a broad
skull and short legs.
II. 1. 2. 2.
Autosomal dominant
An autosamal incomplete dominant gene (CP) has been reported
in
(Landauer and Dunn, 1930) which is 1etha1 in the hamo-
~hickens
zygous condition, and in
~
the~eterozygous
~
condition reduces the
.
~
length of the three long leg bones by 27 percent in males and 21
percent in females.
II. 1.2. 3.
Sex.linked.recessive"(~
locus)
A sex-linked recessiv~ dwarfism (dW) in chickens .as first
recognized by Hutt (1959) in a population of Single Comb White
Leghorns.
Females ca;tTying
30 percent less at
hanozygous for
lIaturi~y
œ weighed
~ ~n
the hemizygou,s condition weighed
than their nomal sisters, while
1la~S
42 pérc:ent less than their "hCllOzygous wilc:l
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type brothers.
The long leg banes are réduced in 1ength by 24
percent in bOth sexes.
•
Both male and famale dwarfs mature sexuaIly.
Maw (1935) mated reciproca1ly Light Brahmas and Golden
Sebrights and showed in the FI and F2 generations definite evidence
that the bantams carried a dominant sex-linked gene that reduced body
,
size.
Although Hutt (1959) was not sure that this phenotype was
caused by a single' gene, Jaap (1969b)agreed with Maw (1935) and
pro,posed that the Bantam gene of the Sebright Bantam be designated
dwB
and that it was at the dW locus and was dominant to both dw+ and
ù
dW.
However, based on.further data, Jaap (1971) suggested the order
of dominance was dW+~ ~ :ànd dW, that is the
awB
is recessive to
dW+, but dominant to dzù.
II. 2.
PHYSIOLOGICAL AND BIOCHEMICAL ACTION OF DWARFING GENES
Growth can be defined as the replication of DNA and secretion
of protein:
Replication of DNA ev~ntuates because of functiona1
demands, genes, or alteration of the cerebral function with release
of growth-promoting hormones or hormones that modify structure.
Growth retardation which causes dwarfism can be defined accordingly
as a failure of cell multiplication or a failure of RNA synthesis or
protein sy,nthesis.
Thus, one wou1d anticipate that
~der
abnoraal
conditions hormones no longer exert their optimal éffects (Cheek,
1968) •
Investigation of èIIlbryonic growth in two breeds of rabbit
r
r~vealed
that the genetit
cons~itution
acted directly on the ability
"
J
of ceUs to grow and proliferate. '" In the two breeds, with the s.e
1
.~
"
o
,
J
, ,~
"'a' ,(,
~.
{ .
-
- !
,
_/~ ,~\ ~ ~.t:l t~:~t»"';"'~ ;t"~;': ;~),~iY~~~,~:~t:~~
1
8
egg size. differences in size appeared at the stage of cleavage.
Flemish giant
~bryos
',,-
breed.
50
that at
The
c1eaved at a quicker rate than the sma11 Po1ish
~given
-
time there were more ce11s in the embryos
of the giant breed (Gregory and Cast1e. 1931).
The difference in the
,
rate of growth persisted throughout the 1ater
ge~tation
and during
,
the postembryonic
de~elopnent
(Balinsky, "1965).
Patterns of growth vary somewhat from species to species.
Rats continue to grow, a1though at a declining rate. throÙghout 1ife.
In humans there are two periqps of rapid growth (Ganong, 1965), the
\~
first in infancy and the !econd at the time of puberty just before
~
growth stops.
The first period of accelerated growth is partly a
continuation of the fetal growth period.
The second growth is mainly
due to the action of the sex hormones (Ganong, 1965).
In chickens egg size 1imits chick size at hatching~ Embryos
of rapid-growth strains start out more rapidly but slow down as the
1imit
o~
egg size is approached.
After hâtching the chick is freed
from the depressing effect of egg size and again grows at a rapid
rate. with the effect of egg size disappearing entirely by six to"
eight weeks of age t(Jaap, 1970).
i
A broUer chicken completes"i-ts
growth and reaches adult size
,,-',
at about 10 to 11 months of age.
During the first few weeks it grows
at a constant percentage l'ate/ making a «eater gain edth day than it
did the previous day.
growth phase.
This is often cailed the se1f-accelerating
Sooner or Iater each chicken reaches a point whe.re the
gain made each day'is less than that of th~ previous one.
This is
9
called the curve of diminishing retum.
This curve appears to resul t
from the ceiling of adult size ~see Jaap, 1970 for review).
Il
It seems certain that genetic
differen~es i~.
size depend not
'merely upon the rapidity of growth in early stages, but also upon the
time at which initial growth phase terminates.
Cocks are larger than
hens because growth of the skeleton continues in males after it has
slowed down or ceased in f~males (Hutt, 1949).
Byerly et al. (1938)
found that retardation of growth began during the third week in
Silkies.but not until the fifth or sixth week in Silkie x Rhode
-
Island Red hybrids.
The physiological mechanisms of growth promotion have been
1
summarized by Guyton t1966) as
follows~
(1) Increased rate of
protein synthesis in aIl the cells of the body, (2) decreased carbohydrate utilization throughout the body. and (3) increased
mobilization of fats for energy. Growth homone enhances amino aeid
transport through the cell membrane to the interior of the cell.
t
This increased
conc~ntration
to enhance protein synthesis.
of amino acid in the cells is presumed
Thus, according to Guyton (1966) the
major'effects of growth hormone can probably be explained by this
simple action at the cell membrane itself, and aIl its other effects
could be secondary to
this~
Thyroxine is also very important in
growth rate due to ~ts effec~ increasing the rate of glucose
absorption fram the gastrointestinal tract and increasing glucpse
utilization in the cells.
Insulin 1s essentia! for growth of animais,
largely because' of its protein-sparing effect on carbohydrate
metabolism and because,of its direct effect on protein anabolisa.
,
.(
0
t
,
'
10
II. 2. 1.
II. 2. 1.
Mammals
l.~l
recessive
,f.9Ie~_èt al. r960)
suggested that the gene responsible for
snorter dwarfism was condérned with the pituitary.
~ey
pointed out
that dwarfs generally possessed normal amounts of hormones in toe '
hypothalamus, but added that this fact did not necessarily mean that
endocrine function in the dwarf was normal because there were
significant differences between normal and dwarf genotypes with
respect to blood sugar changes after varied dosages of insuline
However, since 1960 conflicting reports have been published.
The
~
snorter gene in Hereford cattle was reported to decrease the growth
honnone secretion from the pituiiary gland (Marlowe, 1964), but Dev
1
and Lasley (1969) reported that dwarfs, carriers of the dwarf gene
~ and normal individuals did not 'differ significantly in their blood
levels of growth hormone.
These latter workers suggested that there
was no severe lack of growth hOnDone release fram the anterior
pituitary gland into the
b~ood
"
of the snorter dwarf, but that dwarfism
in cattle was due either to a failure of the target cells or organs
to respond to the hormone or that the hormone was not biologically
active.
In sheep Bogart and Dyer (1942) reported that the thyroid
gland of dwarf sheep was devoid of colloid and suggested that the
o
,dwarf condition was primarily due to an effect of the ,dwarfing gene
on thyroid activity. However, thyroxine therapy
was not successful
•
1
in a. n1lllber of 181lbs.
,-
.
~
11
Carsner and Rennels (1960) transplanted the anterior lobe of
the pituitary from a normal mouse to a dwarf littermate which resu!ted
in normal growth of the
\
dwarf~
In addition they reported that the
anterior pituitary of dwarf mice lacked the growth hormone-producing
acidophile cells and that administration of growth hormone restored
growth.
Studies of the reproduction of dwarf mice, mainly conducted
by
Bartke (1964, 1965a, 1965b), indicated that dwarf males produce
n9rmal spermatozoa but fail' to produce offspring.
He demonstrated
that both males and females were capable of reproduction after growthhormone, thyroxine and luteotropin treatment.
Baront' et aL. (1969)
()
reported that treatment of the dwarf mouse with growth hormone and
thyroxine resulted in a morphological and functiona1 reconstitution
of the
~une
system.
The pituitary dwarfism in humans appeared to be due to
quantitative lack of growth hormone, because such
•
dwarfs~
9
when
treated with growth hormone, made significant weight gain and
increased in height (Gershberg et aZ., 1964).
However, Laron et al.
(1966) reported an abnorma11y elevated concentration of serum growth
hormone was found in the presence of clinical signs of pituitary
deficiency and suggested that the growth hormone secreted
patients was immuno1ogica1ly simi1ar to
biologica11y inactive.
~rma1
\)
their
hormone but
Thus the dwarfism may be due
effect of the honaone rather than quantitative.
i~
t~
a qualitative
12
II. 2. 1. 2. Autosomal dominant
It has been suggested by Rimoin et aL. (1970) that human
achondrop1asia may be due to a quantitative detrease
endochondria1 ossification.
~n
the rate of
This in conjunction with undisturbed
perostea1 bone formation resu1ts in the short, squat shape of the
tubu1ar bones.
II. 2. 2.
8irds
II. 2. 2. 1.
Il
Autosomal recessive
The physiologica1 mechanism of the action of crooked-neck
gene which results in dwarfism has not been studied up to the present
time in chickens, turkeys or quai1.
The thyrogenic dwarfing gene resu1ts in an en1arged thyroid
of the chicken (Upp, 1934).
The greater part of the gland of
affected 'birds consists entirely of aplastic tissue without any
co11oid.
It was considered that dwarfism resulted from hypo-function
of the thyroid gland, but the treatment of one bird with hamogenized
-thyroid gland was apparently ineffective in a dwarf 2S weeks old
CUpp, 1934).
A mu1tifactorial autoimmune thyroiditis as described br Cole
(1966) in the chicken was éharacterized by changes in the thyroid
gland.
Th..e changes in the phenotype associated with the trait are
consequences of the lack of an adequate &Mount of thyroxine which
resu1ts in obesity, small size, late sexua1 maturity and poor laying
ability (Cole et a~ ... \968).
Daily injections of 1.6 }.Ig 'thyroxine
for 17 da's caused the ovary and oviduct of seven to eight montbs
.Cl
\
..
"
'',l'/''!
\
,\
f
-J 1
13
old females to develop rapidly (van Tienhoven and Cole, 1962).
feeding of iodinated casein at
~
~The
level of 0.11 g per kg of diet
caused prompt (in two or three weeks) induction of egg production in
birds of
re~oductive
II. 2. 2. 2.
age (Cole et al., 1970).
Autosomal dominant
It has beln suggested (Cains, 1941}' that the creeper gelle
might affect the circulatory system of the yolk sac.
.<>
It was a1so
claimed (Loewenthal~~1957) that homozygous embryos contained less
ribonucleic acid.
Using rose comb creeper embryos, Wallace et al.
(1970) have substantiated that homozygous embryos had
-
circulation of the yolk sac and depressed nucleic acid
abnorm~l
L>~"~
meta~~.
They fbund that the DNA content in embryonic and extra-embryonic
~~ssues
was 70 percent of the content in the control tissues.
However, no work had been done on the physiological action of the
"
creeper gene that results in the heterozygous condition of dwarfism.
II. 2. 2. 3.
Sex-linked recessive
The sex-1inked recessive dwarfing gene (dW) has been shown to
•
lower the rate of yolk formation (Jaap, 1969a).
...
However, the
physiological and biochemical interactions responsible for this
retardation of yolk formation rate are not known at the present time.
van Tienhoven et al. (1966) hâve reported droplets in the pituitary
gland of the dwarf chicKen which may represent acclIDulated growth
hormone and have postulated that this dwarflsm was a failure to
release g.rowth hOI1llone into the blood stream.
These workers believed
that the thyroid and the throtropin-producing cells
,r<
•
~r~
not involved
'r
14
in the manifestation of dwarfism, because protamone, an active
throprotein supplement feeding (0.04 percent), did not correct the
dwarfism although there
to six weeks of age.
wa~
a rèsponse with respect to body weight up
However, Bernier and Arscott (1971) reported
the thyroids of dwarf females to be sma11er than those of normal
II
birds at seven to 13 months of age.
These authors ?uggested that it
i"
could not be ascertained from the bioassay that a1terations in the
pituitary-thyroid axis were responsib1e for the thyroid disturbance
in the dwarfs.
Rajaratnam-et ctl.
(l969~
have shown that the dwarf birds were
hypothyroidie; dwarfs fed 0.033 percent protamone in their diet were
1.
significantly heavier at nine weeks of age than the dwarf control.
Mérat and Guillaume (1969) also suggested a hypothyroidism based on:
(1) reduced thyroid size on percent of body weight, (2) a much higher
.
fat percentage, (3) a lower secretion of. thyroxine as estimated by
1,
the goiter-prevention method~/ and (4) a lower metabolic rate.
Dwarf birds have approximately O.SoC lower body temperature
as compared ta the norm~l birds (~ersJ 197~~.
,
~levated
Feeding thyroprotein
the body temperature of these dwarfs to that of the normal
birds (Summers, 1971).
The e1evation of body temperature may be due
to aeceleration of metabolic rate, and the increase of weight gain
reported by Rajaratnam et al. (1969) wou1d appear to be due to
increase pf protein synthesis.
~b~~
Wood et al. (l97lb) observed no
difference in plasma amine acid composition between dwarfs and non<
dwarfs J except that dwarfs have a lower content of serine and
methionine.
Supplemental me thionine of 0.2 g per day improved the
.
,. ,
1
15
weight gain of_ the dwarf progeny by
of age
~
percent at two and four weeks
1971).
(Guil1a~,
Hematological studies conducted by Wood et al. (197la)
,
revea1ed that the dwarf tends to have lower hemoglobin (Hb) concentration than nonnal birds.
The consistently higher Hb concentration
of non-dwarf versus'" the dwarf str~ins cou1d bê a- contributing factor
,
1
-~
to the lower heat expenditure by the dwarfs.
It was c, shown that the
total serum cholesterol level was lower in dwarf than in the normal
birds, and that the dwarf
f~ale
had a higher albumen-to-globulin
ratio than the non-dwarf female (Wood et al., 1971a).
o
_o.
-,
"
\-'
4 l
,
f'
1
1
_L
_ _ _
~_~"""-_"""-_
r..
~
,~
'_'!$.i
....
, , , , ,_ _
'
.;.
,. .
III. SPECIFIe STATEMENT OF PROBLBM
In 1963 a dwarf segrégate was found in a meat line of
chickens.
From this bird a dwarf Itue was develqped.
The present
work was undertaken to:
(1) determine the mode of rriheritance of dwarfing in this line and
.
,
its relation to the dW locus (dw and dW8),
(2) obtain preliminary information on the pérformance of this dwarf
line and-its crosses.
.
,
16
,
.
,
IV. MATERIALS AND MEnlODS'
IV. 1.
GENERAL
\) IV. 1. 1.
Artificlal insemination
Semen was collected by the abdominal massage technique
described by Burrows and
JI'
~inn
(1935 and 1937).
Males were ejaculated
at a maximlDll of once every 48 h and not more than three times a week.
Intra-vaginal inseminations were carried out with 0.05 ml of
undiluted
semen~
except where
to the procedures of
!
~inn
noted~
during the afternoon according
and Burrows (1936).
Females were
inseminated once a week excepjr for one group where rioted.
IV. 1. 2.
Incubation
Eggs were collected
f~an
the second day post-insemination of.
the first insemination, marked with the hen number, dated, and storel
/
at 4°C for n,ot longer than two weeks beforè being incubated.
~
AlI
eggs were pfewarmed to roan temperature" f~ h bëfore being
incuba ted in a Model 252 Jamesway Incuba tor accordiiig to the
rec~ended
procedures.
.
"
IV. 1. 3. Housins and feeding of
experimefttal biTds
AlI adul t birds were h~d in individual cagés and exposed
to artificial light for 14 h daily.
17
-
~
,
.~I
... 4j..'!,/..,J"'H..t*'
~
.l'
~
1
18
The chicks of both sexes described in sèctions IV. 2. 1.,
IV. 2. 2., and IV. 2. 3. were debeaked a t hatch and brooded on the
floor in a negative-pressure, windowless brooder house with infra-red
"
heat lamps according to the recommended procedures.
At the fourth
week the chicks were again debeaked, one wing clipped and ,EPt in
growing pens in the same building.
A commercial çhick starter was
fed to four weeks, at which time a grower' ration was fed for the
remainder of the growing period.
the birds at a11 times.
Water and feed were available to
AIl birds from each hatch were housed
together in an individual pen.
IV. 2.
STUDIES 00 nIE niHERITANCE
OF THE DWARF ISOLATE
"IV. 2. 1.
Reciprocal matings of the
Macdonald dwarf isolate with
non-dwarf Leghorn (dzJf)
IV. 2 •. 1. 1.
Stocks
In 1963 li fanale dwarf isolate was found in \a meat line of
chickens at the Macdonald Campus of McGi11 University by
Dr. R. O. Hawes.
In 1964 she was mated with a peno(YPicall Y nonnal
male from the smne Une and produced several small clticks, of whiçh
onlr one male survived.
In 1965 this male was mated with White
Plymouth Rock females.
Fran this ma ting a 1 ine of dwarf chickens
was formed .whicb bas been maintained as a closed populatiqn to date.
A dwarf population (hereafter referred to a Macdonald dwar(
-.'
,,
.,
H(rl
-,
'
,~;~~;;
'f
"t!
19
isolate or MDI) consisting of 18 malei and 80 females was used in
this study.
The Single Comb White Leghorns (SCWL) used in this study were
of the Ml line which had been maintained at Macdonald Campus of
McGill University for 14 generations and received moderate selection
for large egg size.
IV. 2. 1. 2.
Matings and incubation
For establishing the mode of inheritance of the dwarf isolate,
and studying its effect on body
matings
betwe~n
~ight
\
and shank length, the fo11owing
the dwarf line (0) and the Leghorn line (L) were
conducted:
(1) Dwarf sire x dwarf dam (D x 0)
(2) Dwarf sire x Leghorn dam (D x L)
(3) Leghorn sire x dwarf dam (L
x
D)
(4) Leghorn sire x Leghorn dam (L x L).
The dwar'f and Legho.rn sires tnated with the dwarf dams were
the same as those mated with the Leghorn dams.
If any sire died it
was replaeed with either a full- or half-sibling.
Females were
assigned to males randomly, and the same pairs .were maintained
throughout the study.
Eggs were oo11ected and incubated as described in sections
IV. 1. 1. and IV. 1. 2.
Seven hatches were set.
/
,
,
..
'
•• 1
,: ,~._~. ~' .!'
20
~V.
2. 1. 3.
Determination of body
weight and shank length
Individual body weight and shank 1ength of the breeding
stocks were measured before being assigned to the study.
Individua!
body weight of the offspring was measured at hatch and body weight
",
and shank length were measured at 3, 6, 9, and 12 weeks of age.
Body weight at hatch was measured to the accuracy of 0.1 g on
a Mettler Type K7T balance.
Body weights at 3, 6, 9, and 12 weeks of
age were detennined to the accuracy of 1 g on a Toledo Model 4031
,'-
beam balance.
Shank length was dete11llined to an accuracy ~f 0.1 cm •
with a vernier caliper which was modified for this purpose .....
IV. 2. 1. 4.
,
Determination of sexual
dimorphism
Ta detennine the effect of the dwarf isolate on sexual
dimorphism, progeny were grouped by sex from each sire wi thin each
mating type.
The degree of sexual dimorphism at
t2 weeks of age
was
calculated as fallows:
y ..
=
Yij
= the
1)
where:
(
percent sex differefu:e of progenies from the j th
sire in the i th mating type_
j = l to
mij = the
mtan
s, and i = l to 4. .
o~
the male
progeni~5' produc~d br
the j th sire
in the i th mating type,
...
f ij =- the mean of the
feaale,~genies produced
sire in the i th mating type.
'
br
~he
jth
,
21
The effect of sire and mating type on sexual dimorphiSJll was.
determined by analysls of variance (Steel and Tçrie, 1960) according
to the following model:
u + p.1. + e··
1.J
where:
y ..
IJ
= the
sexual dimorphism in the jth sire family of the i th
ma ting type,
i
=1
to 4, j
=1
u
= the overall mean,
p.1
=
e·.
= the
IJ
to s.
the effect due to the i th mating type,
randam error associated with each sire family and
was assumed to be normally and independently distributed
(NID) •
Further information was obtained fran the multiple range test
, .,,1'
(Kramer. 1956).
fi
"
IV. 2. 1. S.
J
Statistical analysis 'of body
weight and shank length data
Both body weight and shank length of the offspring produced in
(J
the seven sequential
IV. 2. 1. 3.
hatch~s
were measured as described in Section ,
The hatching effects were assumed
to
be consistent for
the offspring of aIl mating types and were adjusted for by the
,
deviation of each hatch from the overall aean at the various ages
(Table 1).
The body weight and shank length. adjusted for hatchina
effect/, were sttbjected to the analysis of covariance for each sex
.
~
separately. using agg weight as an independent variable according to
•
-- the following model:
,
\
t~l~;
~ 1 ~ ''''~:
,
.'
M
:
~
~
~
M
~
~.~: ''':.~-..(w·:: .,;Î,~.. ;;:~ ~~)~~.~.'9k~
!.!:. ,,1
-;
>
.....
.,
~
where:
Y..
1J
= the
22
body weight or shank length of the j th chick in thé
i th mating type,
j
=1
to r, i = 1 to 4.
"
overall mean,'
'p.1
= the
= the
a
= the
coefficient of regression of the body weight or
u
effect due to the i th mating type,
shank length on egg weight,
x··
1J
= the
egg weigh t whi ch ha tched the j th chi ck in the i th
ma ting type,
e..
1J
= the
random error associated wi th the j th observation in
the i th mating type and was assumed to be NID.
IV~ 2. 2.
Matings of the Macdonald dwarf
isolate males with the sex-li~ked
recessive dwarf Leghorn females
(~-) and .subsequent P2 and
backcross
IV. 2. 2. 1.' Stocks
Sex-linked recessive dwarf SCWL females (dr.c1-) were obtained
from Mr. K. W. Barr, Poultry Division, Agriculture
Canada~
with Macdonald dwarf isolate males by natural mating.
and mated
The FI of this
_a ting was used in the present investigation.
The Macdonald dwarf isolate 'in this mating was from the sae
source as that described in IV. 2. 1. 1 •
•
.p
l
J,"
,
'
r
~
23 '
;
IV. 2. 2. 2.
Matings and incubation
The FI were housed at 23 weeks of }ge as described in
IV. 1. 3.
......
Pedigree matings began about one month after the birds
$l,
were sexually mature.
The FI females were randomly assigne? to ,either FI males or
dwarf isolate males.
out the experiment.
(1)
1\
The same mating pairs were maintained throughThe matings were
des~gned
as follows:
sire x FI dam (F 2),
(2} Macdonald dwarf -isolate sire x FI dam (backcross).
Eggs were collected and incubated as described in Sections
IV. 1. 1. and IV. 1. 2.
IV. 2. 2. 3.
Detennination of body
weights and shank lengths
The measurEment of body weight and shank length were as
described in Section IV. 2. 1. 3.
In
addition~
for two out of the
&three hatches the body weight and shank length of the offspring were
also measured at 21 weeks of age.
IV. 2. 2. 4.
,
Statistical analysis of body
weight and shank length data
( The body weight and the
~
sh~ length of the ..male and female
progeny of the F2 population respectively were plotted in histograJis.
The results were tested
fo~
nonaality of distribution using the
KCJIlogorov-Sairnov test as described by Siegel (1956).
segregation was shown in
tb,~_.,histogt11Dl,
If a clear-cut
e.g., the P2 female pl'Ogeny,
this test was not conducted. rather a Chi-square test of heterogeneity
1
1
1
'j
."
'lJ'"
,
.....r.
,(
:..
,
. '1<
>
;
,. r
• to.
,
~4
was used to de'tennine whether or not the proportion of chicks from
heterozygous sires deviated from the expected ratio of 1:1.
When the data consisted of two populations, the difference
between the two groups was tested by the Student's t test according
to'Stee1 and Torie (1960).
When data from different populations
(generations) were used, a test 'of equality of VarianC\ was
before a canparison was 'performed.
IV. 2: 3.
..
do~e
.}
Reciprocal matings between the
Macdonald dwarf iso1ate and the
Old Eng1ish Game Bantam, and
between the SCWL and the Old
English Game Bantam
,
IV. 2. 3. 1.
.-
Stocks
A population of the Old English Game Bantam which had been
'.
kept as a c1o$ed population for more than 10 generations was used •
.*
.<
1
The Macdonald dwarf iso1ate and the SCWL were the same as those
described in IV. 2. 1. 1.
IV. 2. 3. 2.
Matings and incubation
The following matings were made between the bantam line (B),
Macdonald dwarf !ine (0) and' Leghorn tine (L):
(1) Bantam sire x Leghorn dam (8 x L),
(2) Leghorn sire x bantam dam (L x 8)
l
"-
(3) 8antam sire x dwarf dam (B x 0),
(4) Dwarf sire x bant8111 dam (D x B).
Three cockerals, one (LB) from the L x B aating and two (08)
frOID the D x 8 .ating were _ated vith the dwarf isolate feaiales,
',,-
,
..
t"''''..,..
.,1.:
• .!
,~ _~ ,:'~~,
~
,1,'"
~t~~):,
25
i.e., LB x D and DB x D.
Each male was mated to seven fanales using
semen diluted 1:3 in Wilcox diluent (Wilcox, 1958).
Eggs were co1lected and incubated as in Sections IV. 1. 1.
and IV. 1. 2.
IV. 2. 3. 3.
Determination of body
weight and shank length
The body weight and shank length were measured as described
in Section IV. 2. 1. 3.
IV. 2. 3. 4.
li"
Statistical analysis of body
weight and shank length da ta
The body weights and shank 1engths at 12 weeks of age of the
offspring from the reciprocal crosses were compared using the "t"
test according to Steel and Torrie.(1960).
Data of the offspring
from mating B x L were canpared with those of offspring from mating
~
B x B.
The body wei'ght and shank length data of the offspriJ!,g from
the DB x D mating were plotted on histograms.
tested with sexes separated for
~rmality
Kolmogorov-Smirnov test as described by
The resu1ts were
of distribution using the
Siegel(1~S6).
In addition,
the di"fferences in body weight and shank length of the offspring from
the DB x D mating
v~rsus
the LB x D mating; and the offspring from
the D x 0 mating versus OB x 0 were tested for significance by the
)
Student's t test with
the'se~e$
,separated.
,
l"'~ ., '
-'
,
1
o
D
,
.
26
IV. 3.' \ STUDIES ON THE PERFORMANCE O~
\ TIΠMACDONALD DWARF ISOLATE
AND ITS CROSSES
IV. 3. 1.
1
Body weight and shank lensth
The growth of the dwarf iso1ate and the progeny from crossing
with normal birds was determined by measuring the body weight and
shank length as described in IV. 2. 1. 3.
G'
IV. 3. 2.
Egg production
AlI females obtained from the matings of D x D, D x L. H x D
and H x L (H refers to Hungarian White Leghorn males which were used
.>
in place of males of the Ml Leghorn line because at the time the
cross was made no semen cou1d be obtained from the available Ml
males) were housed·in cages at 23 weeks of age.
fi
Egg production for
individual 'pullets was recorded for two one-month periods, one from
6 to 7, 'one from 12 to 13 months of age.
The percent egg production
was calculated for each hen as follows:
~
No. egss laid x 100%.
No. days
At 24, 26, 44 and 49 weeks of age, aIl eggs were co11ected
for a week and weighed to the
~
IV. 3. 3.
.types
acc~pacy
of,O.l g.
Fertility
The fertility of the D x D, 0 x
was determined.
~,
...,
H x 0 and H x L mating
In these matings three D and three L dams were
assigned to one 0 or H ~ire.
Single inseminations on1y were perfoxmed"
,
-e
as described in section IV. 14 1., and eggs were collected for two
:J'
" ,
<.• _~~~••
27
•
weelts
from·~the
second day post first insemination and in,çubated as
described in IV. 1. 2.
AlI eggs were candled and classified as
at seven days of incubation.
fertile~
non-fertile
Eggs classified as non-fertile were
broken and exarnined macroscopically for evidence of embryonic
deve1opment.
The percent ferti1ity during the two-week period for
each hen was calcula ted as f.ollows:
No. fertile eggs x 100%.
No. eggs set
IV. 3.
4:
Hatchability
.
.....
\~
'
After cand1ing, aIl fertile eggs, not including the dead
embryos, were returned to the incubator.
Pèrcent hatchability was
calculated as follows based on the number of chicks that hatched by
the 22nd day of incubation:
h~hed x
No. chicks
No. fertile eggs
IV. 3. S.
•
100%.
,
Mortality
• ,-<1
AlI dead birds were recorded.
The morta1ity for the seven
.,
hatches of offspring from each of the D x' Q, D x L, L x 0 and L x L
mating type, up
~12
weeks of age,
~s ca~cu1ated
as follows:
No. birds died
x 100\.
No. birds from the mati,ng type
.
The age at death
•
~
wa~also
recorded.
Average age (days) at
death was calculated for offspring ,from each of the D x D, D x L,
L x 0 and L x L mating types.
The laying ..house mortality of the"' feule offspring fl"Cllll the
.':.
'
28
,
D X D, D x L, H x D and H X L mating types was recorded during 33
weeks, from 23 to S6 weeks of age.
Due to the small number of observations, no statistical
1
analysis was perfoimed for the mortality data.
"
IV. 3. 6.
Statistical analysis of the,
performance data
.
,
The body weight and shank length data were analyzed as
described in sections IV. 2. 1., IV. 2. 2. and IV. 2. 3.
Egg
•
production. fertility ând hatchability data were analyzed according
to the following
"
whefe:
Y..
1.J
/
Y..
1.J
'.
,,",
=u
~odel:
+
= the
p. + e ..
1.
1.J
measurement of the jth hen (family) in the i th
mating type,
/~
, l'.
;-
'~
j
=1
to r, i
=1
to 4.
U
= the
Pi
= the effect due to i th mating type,
e ..
= random
1.J
,
,
overallf:tRean,
t
error associated with the jth observation in the
i th mating type and was assumed to be NID.
'>.
t.
....
v.
V. 1.
EXPERIMENTAL RESULTS
RECIPROCAL MATINGS BETWEEN 1lIE
MACDONALD DWARF ISOLA.TE AND
THE NON-DWARF LEGHORN
In the reciprocal matings between the dwarf isolate and the
Single Comb White Leghorn (D x Land L x D), and the pure-line
"
matings of the above lines (D x D and Lx L), 352 male and 391'fema1e
progeny grew to 12 weeks of age.
Table 2 shows the unadjusted average body weights and shank
1engths from hatch to 12 weeks of age of the offspring from the four
,
mating types (D x D, P x L, Lx D and Lx L). An ana1ysis of
,
variance indicated that there was a significant effect of hatch on
body weight and shank 1ength from hatch to 12 weeks of age and that
regression of body weight on egg weight was significant from hatch to
12 weeks of age while the regression of shank 1ength on egg weight
•
was significant only at 3 weeks.
"
Thus, body weights and shank lengths were adjusted for the
effect of hatch and egg weight.
The means and thé results of the
~
multiple range test for'adjusted data are presented in Table 3 and
the corresponding analysis of variance performed on the adjusted data
in Table 4.
The ana1ysis of variance (Table 4) on the adjusted data
-
indicated that there was no significant effect of mating tm on male
body weight at hatch.
However, ,at 3,-6, 9, and 12 weeks of age,
29
mating type had a significant effect on body weight with the
offspring from the D x D mating being the lightest and the offspring
from L x L mating ranking second with the
the L x 0 and D x L matings which were
from each other.
~eaviest
~ot
'birds
b~irlg
fran
significantly different
There was no significant difference in shank length
between the offspring from L x L, L x D, and D x L matings at three
and six weeks, respectively, but they were aIl significantly longer
than the shank.of offspring from the D x 0 mating. At 9 and 12 weeks
offspring from the L x L mating had the longest and those from the
D x D mating the shortest shank, with offspring from the reciprocal
matings, L x D and D x L, being intermediate in shank length and not
significantly different from each other.
In females, the analysis of variance of the adjusted data
indicated that there was no effect of mating type on body weight"at
hatch.
At 3, 6, 9, and 12 weeks the effect of mating type was
significant with the difference between aIl mating types being
significant and the ranking of the matings with respect to their body
(
weight was J.. x D > L xL> 0 xL> D .x D.
The effect of mating type
on shank length was significant at 3, 6, 9, and 12 weeks with
offspring from the L x 0 and L x L ma tings having the longest shanks,
offspring,.from the D x 0 and 0 x
1. matings had significantly shorter
shanks than tbat from the above matings while offspr1ng from the
ox
D mating had the shor1;est shank length.
They were significantly
'"
'shorter than those of offspring
from the D x L mating.
The degree of sexual dimorphism at 12 weeks and the results
of the multiple range test are presented in Table S, with \.the
. .
~
31
corresponding analysis of variance in Table 6.
Tables 5 and 6 show
that the only effect of mating type on sexual dimorphism was the
'-
S~g~ificantlY higher ~egree ~f sexual ùimorphism associated with
..
-
offspring from the D x L matillg"" compared to the offspring from the
other three mating types.
v. i.
MATINGS OF TIIE MACDONALD DWARF
ISOUTE MALES WITH SEX-LINIŒD
RECESSIVE LEGHORN ,FEMALES Càv-)'~
The
mat~g
of the Macdonald dwarf isolate males with the sex-
linked recessive dwarf Single
chicks.
C~
White Leghorn females yielded 82
The average body weights and shank lengths of thes~ FI birds
at 21 weeks of age along with those of various control birds are
presented in Table 7.
The Student's t test showed
were signiftcantly lighter in weight
\
CP
<
<
<
the FI males
0.01) but longer in shank
0.01) than the Macdonald dwarf isolate males, the FI males were
significantly lighter in
CP
CP
th~t
weig~t
CP
<
0.01) and shorter in shank
0.01) than the normal SCWL males.
The t test/also showed that
the FI females were significantly smaller (P < 0.01) but longer in
shank (P
<
0.01) thanothe Macdonald dwarf isolate females. the FI
.
females were significantly heavier in weight (P < 0.01) and longer in
shank than the sex-linked recessive dwarf mothers and the FI females
were significantly lighter in weight (P < 0.01) and'shorter in shank
(P
<
,
0.01) -than the normal SCWL femaJes.
Q'
The body weights and shank lengths of the P2
hatch to 21 weeks of age are presented in-Table 8.
from
hat~h
p~ogeny
from
It i5 noted that
to three weeks of age" the .ale progeny did not show any
,
.....
.(
,
"
32
i
significant differences from their sisters, but the difference
l
'
betweèn the males and females increased gradually afterward.
,
~eeks,
At 12
'
the males averaged 34 percent heavier than the females raised
in the same environment.
The distribution of the body weights and
shank lengths of the male and of the fema'~e F2 progeny were shown in
Figures l, 2, 3, and 4, respectively.
The KoLmogorov-Smirnov test
indicated that both the body weight and shank length at 12 weeks of
the males were normally distributed (P
>
0.20), but the body
of the females were not normally distributed (P
< O.05~~
weight~
The shank
1
1
lengths of the females at this age showed two
clear-cu~
distributions,
with one group from 4.8 cm to 6.3 cm and the other fr~ 6.4 cm to
8.0 cm; the numbers of birds in the two groups were 72 and 66
respectively.
The x 2 was 0.28 which indicated a 1:1 ratio (P
<
0.50).
The body weights and shank 1engths of the offspring from the
backcross (the FI female to the Macdonald dwarf isolate
presented in Table 9.
male~)
are
Comparisons of body weight and of shank length
at 12 weeks between the backcross and the pure-line Macdonald dwarf
isolate were made; the results (Table 10) show that the backcross
significantly heavier in weight and longer in shank (P
<
WBS
0.01) than
the Macdonald dwarf isolate in both sexes.
r
/
,
1ah1e Il shows the oomparisons of the body weight and of sha~
length at 21 weeks of age of the FI and P2 generations.
It vas found
that FI males were significantly heavier (P < 0.05) in weight but not
si~~ificantly
longer in shank (P >-0.05) than
~he
P2 males.
However.
the'F I females .were significant1y heavier (P < 0.01) in ,weight and
sborter in shank
,
CP
<
0.01) than the P2 females.
1
33
V. 3.
RECIPROCAL MATINGS BETWEEN THE
MACDONALD DWARF ISOLATE AND TIre
OLD ENGLISH GAME BANTAM, AND
. BETWEEN THE SINGLE CœB WHITE
LEGHORN AND THE OLD ENGLISH
GAME BANTAM
C.,
Table 12 shows the average body weight and shank length at
hatch, 3, 6, 9 and 12 weeks of age of the offspring from the
reciprocal matings between the Macdonald dwarf iso1ate and the 01d
English Game Bantam (D x B and B x "0) and those of the reciproca1
\
matings between SCWL and the Old Eng1ish Game Bantam (L x Band B xL).
The mating B x L yie1ded 40 progeny.
At 12 weeks of age, the
17 males ranged between 640 g and 920 g in weight with an
aver~ge
769 ! 27.23 g, and from 6.7 cm to 8.3 cm in shank 1ength with an
average of 7.8 ! 0.09 cm.
The 23 females ranged from 390 g to 878 g
in weight with'an ,average of 55l ! 20.05 g, and from 5.9 cm to 7.4 cm
J
in shank 1ength wi th an average of 6. 5
~
0.07 cm.
The differences
between mean body weight and mean shank 1ength of the males and of
, '
the females were 218 g and 1.3 cm, respectively.
The mating of L x B yielded on1y five birds.
The two males
weighed 746 g and 765 g and measured 8.0 and 8.1 cm in shank length,
.
respective1y, at 12 weeks of age.
"
..
The three feaales weighed S97 g,
'.
\
628 g and 660 g and measured 7.9, 7.7 and 7.5 cm'in shank length.
respective1y.
The mating of D x B yie1ded six progeny.
two
ma1~s
At 12 weeks of age,
weighed 724 and 557 g and measured 7.0 and 6.3 cm
length. respectively.
i~
shank
The four famales fanged from 457 to 530 g
in weight wi th an average of 487. 7S '!: 17.68 g and from 5.5 to 6.0
CIl
'l
in shank length wi th an average of 5.7 t 0.15
CIl.
",J
D
,
{
'\'
.1 :
"
34
The mating of D x 0 produced only two male offspring.
were 1138 g and 714 g in weight and 9.1 cm and 6.9
in shank length,
respective1y.
Table 13 shows the mean body weights and shank 1engths at 12
weeks of age of the offspring from the above mating types,.
There was
o
'
no significant difference between male offspring from B x L and L x B,
but
differ~nces
were significant in fema1e offspring, both in body
weight (P < 0.05) and in shank length (P < 0.01).
The difference
between male offspring from B x L and the pure-line bantam males
(8 x D) was not significant for body,weight (P
significant in shank
len~th
difference between male
(P
<
0.01).
>
>
0.05) but high1y
There was
n~
significant
from 0 x 8 and B x 0 in either body
offsprin~
weight or shank _length (P
0.05).
Table 14 shows the average body weights at hatch and body
weight and shank 1ength at 3,
6~
9, and 12 weeks of age of the
offspring from the 08 x 0 and LB x 0 mating types.
It was observed
that there was no significant difference at initial stage in growth
between male and female birds, the rapidity of growth of the two
sexes was divided br three weeks.
And at 12 weeks, males from DB x D
mating type were 24 percent heavier in weight, and 12 percent longer
in shank length than their sisters raised in the saae environaent.
The individual body weights and shank lengths of the offspring
frœ DB x D mating type were plotted in Figures S, 6 and 7. 8,
respectively. for males and fema.les.
The Kolaogorov-Sab:nov test
indicated that tlie body weights as weIl as the shank. lengths vere
.
;'f,1f
_~
CD
They
l
,~
•
1.... ','0
n~ru.lly
distributed in 'bcSth sexes respectively CP
>,
0.20).
However,
"
3S
.
examination of these figures, particularly with respect to body weight
,
(Figures Sand 7), indicated a possible binomial distribution with
large part overlapped.
In comparisons of body weights and of shank lengths as shown
in Table 15, the offspring from DB x D and LB x D mating types, both
males and females, were not significantly different in body weight,
but significantly different in shank lengths.
The shank ,length of
male offspring from OB x 0 mating and that of male offspring from
/
o x 0 mating were not significantly different.
V. 4.
-
1RE EFFECfS OF t-{ACOONALO DWARF
ISOLATE ON PERFORMANCE
V. 4. 1.
Body weight and shank length
-,
The body weight and shank length of the chicks carrying the
Macdonald,dwarf isolate gene in relation to non-dwarf birds has been
described in the previous sections (V.' 1., V. 2. and V. 3.).
V. 4. 2.
Egg production
"
~
(1
. The average percerit egg production
pullets from 0 x D, 0
X
&
,
egg weight for the
L, H x 0 and H x L mating types are presented
in Table 16, with the analysis of ,variance ptesented in Table 17.
The results indicated that the percent egg prOduction a~ 12-13 months
of age,was different (P
<
0.05) between the pullets from the four
. mating types. '" 'lhe multiple range test showed that. the egg production
of offspring
trom
the 0 x 0 versus the 0 x L,
H x L mating~ were,not significantly
diff~rent
~d
(P
,
H x 0 versus the
>
0.05), but the .
agi production of the offspring from both-the
H x D and H• x L vere
<
,
,
....
36
significantly superior to those of offspring from 0 x 0 or D x L
mating (P
< 0.05).
The average egg weights,for these pullets at 24, 26, 44 and
49 weeks are tabu1ated in the same table., The analysis of variance
f
for .~e egg weights at 49 weeks of age (Table 17) indicated that
there was a significant difference between offspring from the four
<)
.
matings with respeèt to egg weights.
The multiple range test showed
that the pullets from D x D laid significantly smaller eggs than did
the other pullets from D x L, H x D and H x L matings, which were not
sig~ificantly
v.
4. 3.
different from each other.
Fertility
The percent fertility of the matings D x D, D x L, H x D and
H x Lare presented in Table 18, and the analysis of variance in
Table 19.
The analysis of variance indicated that the effect of
matings was highly significant.
The multiple range test showed that the fertility of H x D
was higher than any other gro1,lps.
'.he fertility of H x D was 94.5 ,
percent which was approximate1y 12, 17, and 20 percent higher than
D x D, D x Land H x L, respecti vely •
Whereas 1 these. three matings
(D X Di D x L and H x L) were not significant1y different in fertility.
V. 4. 4.
Hatchability
The hatchability of the fertile eggs is presented in Table 20,
vith the analysis of variance in Table 21.
indicated tJl,at there vas
e,
DO
The analysis of variance
sianifiçant difference in hatchability "
between mating populations.
_.i"
>
37
v.
4. 5.
Mortality
The percent mortality and average age at death of the
offspring from the D x
D~
D X L, L x D and L x L,matings from hatch up
to 12 weeks of age are presented in Table 22.
The data showed that
the offspring from D x 0 (9.!%) and L x L (9.4%) matings had higher
,
mortality than those from D x L (1.8\) and L x D (2.3%) matings. but
~.
the average age at
dea~h
for offspring from 0 x D (8.1 days) and
L x D (8.0 days) were younger than that for those from D x L (14.5
days) and L x L (16.6 days) matings.
The laying house mortality of the pullets from D x D, D x L,
H x D and H x L ma'Ùngs is presented in Table '23.
,
No analysis of
va~a~~e due to the small number of observations. During
the 33-week period. from 23 to 56 weeks of age, in
none of the 16 pullets from 0 x D mating, two of 19
u
~he
laying cages,
pull~ts fr~
v
,0 x L mating, one of the 21 pullets from H x D, and 7 of the 25
(
t
\
, ,
• t
\."!t.~
VI. DISCUSSION
VI. 1.
INHERITANCE OF THE MACDONALD
DWARF ISOLATE
VI. 1. 1.
General
(
From observation of pedigree data on the dwarf isqlate from
the time of isolation until the beginning of the present investigation, it was hypothesized that the dwarf condition was due to an
autosomal dominant gene.
The original purpose of the present study
was to explore the physiological action of this dominant dwarfing
gene.
However, the l2-week body weight and shank length data of the
birds produced by the D x L, H x D, D x D and H x L mating types did
not confirm this hypothesis.
Therefore, further study was necessary
to establish the modé of inheritance of this dwarfism.
The reciprocal matings between the dwarf isolate (D) and the
normal Single Comb White Leghorn (L) were conducted to determine the
1
inheritance of the dwarfism.
•(L)
The pure-line matings of the (0) and
lines (0 x D, L xL), respectively, were made as controls.
A
.
considerable number of offspring were obtained fram the above matings
in seven sequential hatches.
Body weight and shank length of the
offspring from the four mating types were taken to dete1'lline the
inheri tance of the dwarf condition.
1
Since body size is a polygenic
character QHutt, 1964), a wide variation in the bo~y size of the
progeny vas expected
and thus the average body size of the populations
,
1
38
o
39
was considered.
Moreover, two
of
typ~s
(0) a meat type and
chickens~
;
an egg type, a150 different in egg size, were used in this study.
(L)
Egg size affected the.body weights as probably did body conformation.
The preliminary ana1ysis of variance a150 indicated that there was a
significant effect of hatch.
of hatch and egg weight.
Thus, data were adjusted for the effect
The body weight and
length after
~hank
adjusting were employed to study the inheritance of the dwarf
is01ate.
The results (Table 3) showed that the offspring from D x D
1 mating were significantly smaller than those for
L
x L mating.
offspring from the crosses of these two lines, i.e.,
in male; L x D in female, were
sign~ficantly
D
x
L
and
The
L
x
0
larger than those from
o x .O'mating. These crosses were close to or even larger than those
of the pure line (L) (L x L).
Thus, the_lene(s) causing the dwarf
isolate appeared to be recessive to the wild type in the normal
Leghorn.
The female offspring from the L
X, D
mating were similar in
size to those from L x L ma1:ing; however, the fanale offspring from.
•
n
the 0 x L mating vere significantly smaller than those from L x D or
L
x L matings, therefore, a sex-linked recessive condition for (D)
vas hypothesized.
f
l'
In considering the sex dimorphism, the results obtained fro.
\
.'
>,
• -
r~
. both -the ptltre lines, Le., L x L and
'f) x D
matings were not
Q
significantly different from each other, if the gene causing dwarf!Dg
Il
was autosClDal, ·the sex dimorphism of the offspring frOlR the 0 x L
,
,
mating type should not be diffetent frol those of L x D mating type.
In the present study.
"
~.-~-~~; ~
~ho
sex d!,aorphi. of the offspring fma the
"
. ,1
"".
40
•
L x-O mating type
offspring from L x
v
~s
L
not
or
0
retmr'ted by Hutt (1949).
signi~icantly
x
0
different from that in
mating type which is similar to that
At 12 weeks of age _the sex dimorphism in
the offspring from the 0 x L mating type was'higher than control,
(L x Lor D x 0).
This can
o~ly
be explained by a
sex-lin~~d
recessive dwarfing gene substantially affecting the boqy size
.
existing in the (0) line .
Thus, it was concluded that the dwarf
1
Il
isolate was caused by a single sex-linked recessive gene.
was assigned the designation
awm
The ge~e
~ differentiate it from the ~
(Hutt, 1959) and dLJB (Jaap, 1969b).
Based on this conclusion, the parents and offspring from the
four mating types were classified phenotypically and genotypically as
follows:
SIRE
PROOENY
DAM
MATING
TYPES
Female
Male
Phenotype
Genotype
Phenotype
Genotype
Phenotype
Genotype
Phenotype
Genotype
Dx 0
dwarf
dJJ"dJJ"
dwarf
chJ"-
dwarf
dJJ"dzJ"
dwarf
dJJ"-
Dx L
dwarf
dzJ"aJ'I
nonnal
+.
dJù-
ll:0mal
dJJ"~+
dwarf
aJ"-
Lx 0
normal dJ/dJù+
dwarf
d1J"-
nomal
œ,,+dIJ"
normal
d1ù+-
Lx L
normal , dhJ+dJù+
normal, dJù+-
normal
œ.,,+dJJ+
nomal
'41:'/'è
That the
•
mal~
offspring from 0 x L and L x 0 matings were
heavier than those from L x L ma tings may be because of the
Q
-
"
41
cpnformational differences between
shartk length of these
two parent lines (D, L).
th~
The
were shorter than the shank length of
"
those offspring from L x L mating. This was also the case in the
female
offsp~ing.
of~spring
females from L x D mat~ng were heavier than those
from L x L mating and the females from D x
~ mati~g
were heavier and
,
~.
longer than those from D x D mating.
~
It was also possibie that some
;
.
interactions among autosomal gene(s) or gene products had taken place
in the offspring
fr~
D x Land L x D or the inbred pressure in the
offspring from D x D and L x L mating\ to account for these
discrepancies.
Based on the above conclusions.
the ' observation from 1963
,
until the initiation of the present study May be explained as follows.
The female dwarf isolate obtained in 1963 was a hemizygous dwarf ~-,
the phenotypically normal sire mated with this female dwarf in 1964
must have been heterozygous (dW+~). the progeny thus produced could
be either heterozygous nonnal, dbJ+ciJ.J1I or hanozygous dwarf. dJJ"d1J" in
the male, and hemizygous normal dJù+ - or dwarf. dJJ'l- in the female.
Among the severai small birds only one male, supposedly ~~
survived and sexually matured.
In 1965 this male was mated with
White Plymouth Rock females (dW+-), they produced normal male
(awmdW~ but dwarf female (dJJ"-) offspring.
In the subsequent
generation balf of the male and female offspring would be normal
(dJJ"dW+ 'or dLJ+-) and half dwarf (dJJ"~' or dJJ"-).
for
smal~
Thus, selection
body size must have been performed since then to establish
the dwarf population (d1J"~. ~-).
42
VI. 1. 2.
-.,
The genetic re1ationship of the
Macdonald dwarf isolate to the
known alleles at the dw locus
...
VI. 1. 2. IS
The relationship of the
to dw
~ ~
Hutt (1959) was the first to study in detail a sex-linked
recessive dwarf gene CdzJ) in the danestic fowl.
"
Several workers
(Bernier and Arseott, 1960; Jaap, 1968; Mérat, 1969 and Barr, 1972)
also discovered dwarfs in various strains of chickens and showed that
in each case dwarfism was due to a'- sex-linked recessive gene.
1\
But
the allelic relationship between these dwarfisms has not been studied,
,
,/
(hough it is generally 'assumed they are aIl due to, dW.
An attempt was made to determine whether or not ~, the gene
causing dwarfism in the Macdonald dwarf isolate, was an allele at the
I~
locus.
l~gous
Since alleles are located in cortesponding part of homo-
chromosanes, only one member of a pair can be present in a
given chromosane and only two are preseht in a, cell of a diploid
organism.
Thus, when the two dwarfs CdJl'ldzJ", dùJ-) were mated, the
malé offspring" this produced would be nondr""lf these dwarf genes
"
CàJm, dw) were not allelic to each other, but if allelic, the offspring would be dwarf.
The results showed that the FI of the ~~ x ~-, both male
CdIJ"dùJ) and female
(dJJ'I-).
•
were significantly smaller than normal wild
type SCWL (dL'+dw+ or dL? -) and appeared to be dwarfed.
This suggests
that the cbJ" and dzù were both aIle les at, the dw locus.
The body
weights at 12 weeks of age of the F2 females were not in a
no~l
:~
o
43
distribution, and the shank lengths fall in two separate groups with
the riumbers of birds in these
t~
groups in a 1:1 ratio.
It was
clear that ~ and dw were segregating in the P2 and therefore ~
and dW were two different alleles both loeated at dw locus.
The
,1
Macdonald dwarf isolate
Caum)
seemed to be dominant to dW, because
the b6dy size of the FI birds was closer to that of ~ than to dW
line. and the FI males c~dW) were not significantly dl' ferent in
skeleton from P2 males c~~, awmdW).
These faets an
those
described previously in Section VI. 1.1. led to the co clusion that
the order of the dominance of these genes in the heterozygous males
was dW +, dJJ" and dLJ.
cdJm-)
That the FI females
skeleton than P2 females
two dwarfing genes,
awm
CdJJ"-,
were significantly longer in
dw-)
was due to the segregation of
and dW, in the P2 whieh yielded half of the
females carrying the dJJ- gene,
The females carrying the dW- feU in
"
a group much smaller than those carrying dJJ"-, whièh fonned another
group in Figure 8.
The fact that the shank length of the FI offspring
of the two dwarfs was longer than tha t of both parent lines may be
attributed to the same reasons as explained in Section VI. 1. 1.
The evidence showed that the offspring (dzJ"dzJ", dJJ'I-) from
the backcross of the FI females CciJ"-) J produ'ced by Macdonald dwarf
isolate males (dlJ'IdJJ") x sex-linked recessive dwarf females (dw-). to
the Macdonald dwarf isolate males (~~) at 12 weeks of age_were
heavier in weight and longer in skeleton than those from the pure line
Macdonald dwarf isolate mating in
probably
~u~
sex
respectiv~ly.
This 1s
to differences in background genotypes as discussed in
Section VI. 1. 1.
'.
ea~h
"t
'.
44
\
,'1
>",
VI_. 1. 2. 2.
The relationship of the
dJJ'I to dzJ3
o
There are divided opinions in the Iiterature concerning the
inheritance of the bantam gene (cbJB).
Jull and Quinn (1931)
suggested that a partial dominance of one or more factors for the
small body size (bantam) might exist.
Punne~t
But
and 'Bailey (1914)
c1aimed that large body size was dominant to the small one.
Reciprocal crosses between Sebright Bantam and Light Brahmas
led Maw (1935) to conc1ude that the reduced sKeletal dimension in the
Bantam breed was due to a sex -linked dominant dwarfing gene.
Hùtt
, !
(1959) believed that there might be severai genes affecting body
size on the sex chromosome, at least one of them was responsible for
the normal sex dimorphism.
Jaap (1969b, 1971) proposed that at 1east two dwarfing genes
in the sei ch,romosome reduced body size and that the bantam gene
(~) was an al1ele at the
\
aw
locus.
He reported (Jaap, 1971) that
the order of the dominance in lieterozygous males was düJ+ (wild type
\
nonna1), ahlB, and dw. That is, the bantam gene ciI3 obtained bt Jaap
(1969b) was dominant to ~ but recessive to
aw+.
In the present studt, male offspring from the reciprocal
crosses between the bantam (8) and the Leghorn CL)
(d1J3aw+
from B x L
and dJ.ù+œJ3 from L x 8 mating) did not differ in either body weight or
shank 1ength.
However, fema1e offspring carrying
aJl-
produced by
D'x L mating were significantly smaller than those car.rying dléproduced by L x 8 pating.
Thereiore. a sex-linked' dwarfing gene
seemed to be responsib1e for the bantam and it was assUID~d to be
as reported by Jaap (1969b, 1971).
\
)
1
dJJ3
1
1
l.
/
4S
•
,.
The offspring from the reciprocal crosses between the bantam
,
(8) and the dwarf isolate (0), Le., 8 x 0 and D x B showed no
differences in either body weight or shank lengthj these birds
-appeared to be dwarfed (average shank length was 6.65 cm).
ad"
and
œJ3
Thus, the
appeared to be alleiic to each other at the clJù locus.
When the two males (dJJTlaJ3) produced by the D x B mating were
backcrossed to the pure line (D) females. Le., DB x D. they produced
aJ3drJ71, dJ"aJ",
male offspring,
which were not significantly different
in shank 1ength from the pure 1ine (0), ~~.
In addition, the
body weights and shank lengths of bot,h sexes at 12 weeks of age of
these offspring were normally distributed.
-.
same allele as~.
Thus,
awm might
be the
Hbwever. the histograms (Figures S, 6, 7, 8)
plotted with these data, particularly those with body weight
(Figures Sand 7). were binanial. though large part of them overlapped.
it tended to suggest that the segregation of
taking place.
In which case they
dJJ'l ànd
CdJJ" and œ}3) would
J
had been
he different
alleles at the same locus.
In canparing the offspring produced by DB x D and those
produced by LB x D mating, the male offspring
Cd1J"azJ", a.J3d1J")
produced by DB x D were significantly smaller than those male offspring
(db/cM", awBdzJ") prod~~ed
offspring
<!"I<
CaJ"-,
dLJB -) produced by DB -x D mating were significantly
smaller than those female offspring (dzJ+-,
mating.
It was evident that these
presence and absence of dJJ+ and
•
by LB x D mating, and the female
dJJ"
aJ3-)
produced by LB x D
differen~is were caused by
genes in the two populations •
~~---
{)
46
VI. 2.
1RE EFFECTS OF THE MACDONALD
DWARF ISOLATE ON PERFORMANCE
Body weight and shank length
VI. 2. 1.
VI. 2. 1. 1.
Hatching
Hutt (1959) reported, based on chick weight at hatching, that
dM had no adverse effect on embryonic growth during the three weeks
of incubation.
He compared the hatching weights of the dwarf females
with that of their normal-sized sisters produced by the heterozygous
males mating to normal Leghorn females which laid nonnal-sized eggs.
His conclusion may not be entirely valid because of the large effect
of egg size on chick size at hatching (Bray and Iton, 1962).
Bray
and Iton (1962) studied,. the embryonic growth in five strains of
domestic fowl and demonstrated that the size of egg can be regarded
as temporary environmental influence which almost entirely determined
chick size at hatching.
In the present study, embryonic weights were Dot recorded,
•
1
. '
the embryonic growth o~ the chicks could not be decided; however, in
the comparison of the hatching weights of female chicks produced by
D
x L and L x L mating types, which produced 'dzJ"- and dM+- females,
respectively,
there was no difference in hatching-weight between ~.
and dbJ+- chicks.
~
It would thus appear that in anomal-shed egg,
did not have a detectable effect on hatching weight.
VI. 2. 1. 2.
Post hatching
'\
The po~t hatching growth uP
,0
the broÜer weight is the .ost
important factor in the successful broiler industry.
In the present
••
,-
47
experiment, the effect of'the dwarfing gene. ~, on growth of chicks
after hatching could be detected by comparing the dwarf, ~-, and
nonnal, (iLl-, female offspring from the reciprocal crosses (0 x L and
L x 0).
The difference hetween these offs{>ring from the two ma ting's
was evident at three weeks of age.
From then the dwarfed birds grew
slower than did the normal birds and ended up with smaller body size.
1
It was observed that the ~ did not stop growing ~t a particular age
in the expertmental period but they had a generally slower growth
rate.
This effect on growth is similar to that
.1
repor~ed
for the dW
aUele by Hutt (1959).
The dwarfing gene C~) appeared to be completely recessive
to the wild type, the male and female offspring from
~x
0 mating and
,
the male offspring from 0 x L mating grew as npidly as did those
from. L x L mat ing .
Since body si ze of the adul t dwarf femal'e s was
significantly smaller than that of normal females, the maintenance of
"
these dwarf females would be re1ativel,Y less.
Thus. it was speculated
.
that the dwarfing gene, ~, could be utilized as a genetic tool to
reduce adult body size of the hreeding stock thereby reducing the
overall production cost.
A line of dwarf females developed from this
Macdonald dwarf isolate could he mated to tne wild-type nomal males
which would produce FI hybrid with nomal growth rate. Although
further study is'necessary in this regard, it was hoped'that the
discovery of the ~ at this Campus may yield a valid cOntribution to
the eOUlpeti ti ve poul try industry.,
-The sex-linked recessi,ve dwarfing gene (c:i.1) was also proposed
~
to be used as a genetie tool to
~uce
~
~
Jo
the production costj 'however,
48
in an extensive
stu~y.
Mohamnadian (1971) reported that the dM was
incampletely recessive to wild type in heterozygous males.
VI. 2. 2.
Egg production
Hutt (1959) recorded the ntlllber of eggs laid in the three
months of highest production and reported that in the four sire
families the average number of eggs laid by the dw- females were from
7.9 to 13.3 less than the corresponding figures for their full-sized
.
sisters from the sane sires.
Similar data were reported by Arscott
and Bernier (1968); they found' that the dwarf laid 13 percent less
eggs and needed slightly more protein to reach the plateau of
production than did the nonnal controls (15% and 14\, respectively,
for dwarf and nonnal pullets).
However, the effects of the dJù gene
on egg production are relative to the genetic size, of the line or
"
cross in which it is carried. French and Nordskog (1969) demonstrated
that the}e was no difference in egg production or egg size for the
dwarf x small-sized normal Leghorn cross carrying dJù cOlllpared with
those for the pure-line Leghorn where each had about the same body
weight at 22 weeks.
L~~horn (H)
C!:
In the present experiment the Hungarian Iftù. te '
males replaced Ml SOiL (L), if one asslDlled that the
effects of (fQ .•SDd (L) males on egg production vere the saae, which
is likely, one would see in the reciprocal matings, the pullets,
dJJ"-, produced by D x L mating. had a significantly lower egg
I,r
production than did those dbJ+- produced by H x D aating.
At 12-13
months of age the dMf'- lowered egg production by about 14 percent.
,
1:1
It should be- noted that the Leghorn used in th.e present study vas
significantly larger than the dwarf isolate.
,i'
49
The ~- pullets, produced by the D x L mating, a~ 49 weeks
of age did not differ in egg size fram the ~+- pullets produced by
the H x D mating, although the
aJ"- pullets produced br the D x D
mating-Iaid significantly smaller eggs, this might be due to the
background genotype of the dwarÎ isolate.
Magruder and Coune (1969) reported that the
~-
females at
"
57 weeks of age laid similar-sized eggs as did those corresponding
nonnal females.
Hutt (1959) campared the egg size fran
that of eggs laid by àw+- in relation to body size.
the dwarf
(dW~)
~-
bir,ds to-'
He found that
laid rather larger eggs in relation ta their body
size than normal birds.
The significantly smaller pullets produced .
by 0 x L mating in this study laid eggs which were not
snaller than
,
those laid by the larger pullets
~roduced
by H x D or L x L mating,_ ].
This-shows that ~ may be ~éorporated into è~ercial birds with a
1
minimal effect on egg size.
VI. 2. 3.
Fertility
In order to obtain as many chicks as possible from each
mating, a11 matings, D x D, 0 x L, L x 0 and L x L, were made by
weekly inseminations throughout the experimental period, thus the
'-
fertility data
~ere
not suitable for ooaparison.
males replaced (L) males, each male,
."-
~ither
However, when (H)
(0) or (H), was matèd to
...
t~èe (D) and three (L) females, the fertilities:of 0 x D, D x L,
1
.
H x D and H x L wer~ COIIpared. The percent fertUity of the (0),
fanales was higher than that of the (L) fetuales' when inseminated with
1
the samen fran (H) males.
•
..
However, the percent fertility of (0)
,
,
'" ,
.'
.
,f
, ~". :',!
<
·~r:.i:
50
,
"
females
wa}
not different
frdm
with semen from the (0) males.
that of CL) fanales when inseminated
In males# the (D) males were not
different in fertili ty from. (H) males when both were mated to (L)
females# however, the (0) males had lower fertility than did the (H)
males when both were mated to the (D) females.
Since in these
matings. Le •• D x D, D x L, H x D and H x L, only the D x D mating
resulted in inbreeding, the other three matings would yield better
\
oomparisons between (0) and (H) in regard to fertility.
/
eviden~
that the
~
It was
.r
gene reducing body size did not affect fertility.
This was quite similar to that Hutt (1959) reported on the effect of
Ν on male or female fert'ility.
VI. 2. 4.
Hatchability
The hatchability of the fertile eggs laid by the ~- famales
was not significantly
diffe~ent
from the hatchability of the fertile
eggs laid by the ~+-'Leghqrn female whether the y were b9th
inseminated with dJ'libJ" or dbJ+dbJ+ semen.
hatchability of eggs laid by dIJ'l-
This ~uld suggest that the
females was nonnal.
Hutt (1959)
also suggested that the sex-liriked recessive dwarf was normal in
respe~t
to hatchability.
VI. 2. 5.
Viabili ty
,
~
It was observed that chicks hatched fl'Olll the dwarf eggs when
t~ferred
fran incubator intd the brooder pen at Uday old" vere
.........
cœparatively weak.
This was reflected in the average age at death:
" the offspring fl'Qlll D x 0 and L x D lIatings had a higher mortali ty in
·e
.
r,df
_~~-~.'~_'_'~,~'-;
,
, " !l
,~=~~~.-~~
--""/ _ ' :""".''.:....'-.<.1.:
f
the first week and those fran D x L and L x L matings had higher
mortality later.
This phenanenon could be due to the background
genotypes of parent bre-OOs.
It was c1ear that the dwarfing
gene~
~J had not influenced the morta1ity~ because in a 33-week period in
the laying cage nc1ne of the 16 pullets from D x D and only two of the
,
19 dwarfs produced by 0 x L mating died compareg to 7 out of 2S
pullets produced by H x L mating which died in that period.
During the experimenta1 period there
disease~
i.e.~
laryngotracheitis.
wa~
an infectioys
Most of the birds in the same
shelter died except those of the dwarf population.
Although the
evidence was ambiguous, it was be1ieved that the dwarfed birds might
be more resistant to this disease.
Hutt (1959) has discussed
chick viability.
th~t
This is not -,'surprising tiecause
C
i"
•
,
r
.1
~.
l'" .,
!!li-
?
the d1N gene has no adverse effect on
Meurier (1971) reported that his dwarf (d1N)" in
White, Leghorn was more resistant to Marek' s disease.
•
li>
~
•
1
\
VII.
r
S~RY
AND CONCLUSIONS
In 1963 a female dwarf was found in a meat line of chickens.
In 1964 she was mated wi th a "noxmal" male from the same line and
produced several small chicks. of which only one male survived and
<
sexually matured.
In 1965 this male was mated with a group of
Plymouth Rock females.
ru te
From this mating a line of Q~rf chickens was
X
formed and bas been maintained as a closed populatioJi,,.,to date.
The present investigation was conducted to:
(a) study the
inheritance of this dwarf isolate, (b) study the relationship of the
inheri tance of this dwarf witl1 known alleles (dr.rJ and œ}3) which cause
a reduction in body si ze in the chicken, and (c) ob tain preliminary
infonnation-'On the performance of the dwarf isolate and its crosses.
The dwarf isolate was:
(1) reciprocally mated with the non-
dwarf Leghorn (D x Land L x D); (2) mated with sex-linked recessive
fœtales (dJ-), the female progeny (dJ'l-) vere -mated with both male
progeny (dJ"cJz,,) and with dwarf isolat:e males, respectively, and
..
(3) reciprocally mated with a Bantam breed (D x Band B x D), the
bantam was also mated reciprocally with a non-dwarf Leghorn (8 x L
and L x B) and two males (dJJ"œJ1) from D x B and one (œr8œ.,~ f1'Olll
L x B mating were mat'ed with the dwarf isolate fsales (ciJ"-). f
Body weight of the progeny was measured at hatch, and body
weight and shank length at 3. 6, 9, and 12 weeb of age.
S2
Egg
..., ....
53
production of the pullets was recorded for a mon th at 6-7 months and
at 12-13 months of age, respectively.
Eggs were.collected and
weighed for each hen separately for a week at
of age respectively.
24~
26. 44 and 49 weeks
The fertility for a two-week period and the
hatchability of the fertile eggs were calculated to evaluate the
reproductive perfonnance of the dwarf isolate.
The mortality of the
chi'cks fran hatch to 12 weeks of age and the laying-house mortality
for six months fran 23 to S6 ,eeks of age was recorded to evalua te
the viability of the dwarf isolate and its crosses.
The following conclusions appear justified:
1.
The dwarf isolate is caused by a sex-linked recessive gene and
has
2.
be~~~ted aJ".
The dwarfing gene
CdLf') is an allele at the dlù locus and is
dominant to d1.ù.
3.
The dwarfing gene
CaJ")
appears to be similar to dzJB in its
effect on body weight and shank length, though the evidence is
not conclusive.
,',
4.
The dwarfing gene (aJ71) starts to reduce body weight and shank
length by about three weeks of age.
S
The dwarfing gene (dlJ") lowers egg productiQ,n by about 14 percent
but does not significantly
,~duce
'.:V
egg size. though this latter
effect may depend on background g,enotype.
6..
The dwarfing gene (aJ1') in either sex bas no effect on fertility,
hatchability or mortality.
,
.'
_.--.--_
~~
..
e.
e
TABLE 1
Deviation of each hatch-fram the overa11 mean of body weights and shant' 1engths at various ages
of the offspring from the D x D, D x L, L x 0 and L x L mating types
3
No. of Hat ch
Weight
Biros
Hatch
No.
BW
Weeks
6
SL
Weeks
BW
9
BW
SL
Weeks
12 Weeks
SL
BW
SL
J
Males
.,
/'
1
13
2
34
0.7
0.0
32.7
- 3.0
0.3
0.0
.. 34.8
6.0
0.3
0.1
31.9
8.8
0.0
0.2
3
SS
-0.8
- 7.4
-0.1
4.3
0.0
1.0
0.3
0.4
-1.5
4.9
-,4 .9
0.1
0.0
-0.1
-0.1
- 0.6
4.0
5.0
-18.1
-31.0
0.2
90
76
31
- 3.5
- 3.3
-10.1
- 4.6
-19.2
-0.1
4
5
-0.1
0.1
-0.1
-0.2
9.4
-76.2
25.1
4.0
-0.1
-0.1
0.1
-0.1
0.1
0.1
0.1
-0.1
0.1
0.0
-0.2
- 1.6
0.8
8.8
37.2
-48.1
19.0
-16.0
0.2
0.0
-0.1
-0.1 "
-0.1
0.1
-0.1
6
7
29
- 7.7
-14.5
0.0
-0.1
-0.1
-0.1
D
38.0
- 4.7
0.1
0.1
;.
Pemales
1
2
3
11
4
5
6
26
69
89
90
50
7
29
<>
1.0
-0.5
-1.0
1.4
0.0
-0.3
-0.6
(
30.1
-, 2.2
- 8.2
3.5
- 1.9
- 9.0
-12.2
0.4
0.0
-0.1
0.0
-0.1
-0.1
-0.1
0.6
-0.1
-0.2
0.0
-0.1
48.1
- 6.1
-13.1
- 4.6
- 6.4
0.7
-0.1
-0.2
-18.5
-23.3
6.0
- 5.2
18.1
19.3
- 2.7
-12.1
-
~
d
. 0
BW = body weight.(g).
SL ... shank length (an).
D ... Macdonald Dwarf Iso1ate.
L = Single Caab White Leghorn.
,~
"
tI1
~
~
.
,-
55
TABLE 2
\
Mean body weight and shank 1ength of the offspring from D x D, D x L,
L x D and L x L mating types
MATING
AGE
Dx D
D x, L
TYPE
Lx D
L x L
(61)
(64)
Male body weight (g)
(57)
•
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
30.4
(146)
43.2
168
435
814
1245
110
316
621
997
33.6
43.0
142
390
766
1,203
155-
1171
3.9
5.7
7.4
3.6
5.6
4.0
5.9
7.2
9.0
9.0
7.8
9.3
(73)
(95)
401
736
Male shank length (cm)
3 weeks
6 weeks
9 weeks
12 weeks
3.1
4.7
6.0
7.5
Female body weight (g)
(50)
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
30.9
104
285
530
804
(146)
41.9
147
362
622
888
32.9
42.7
136
152
368
668
970·
378
645
923
3.6
5.4
7.0
8.0
3.9
5.6
7.2
8.4
Female shank 1ength (cm)
3 weeks
3.0
3.6
6 weeks
4.4
9 weeks
12 weeks
5.8
5.1
6.5
6.7
7.5
D = Macdonald Dwarf Iso1ate.
L
=
Single Comb WIll te Leghorn.
D x L = Macdonald dwarf isolate' male x Single Comb White Leghorn
female.
~
( ) = Number of birds.
'
Il
,,
56
TABLE 3
'\
Mean body weight and shank length of the offspring from D x B, D x L,
L x D and L x L mating types after adjusting for egg weight and
hatch effect
MATING
AGE
Dx L
D x D
TYPE
~ x D
L x L
(61)
(64)
Male body weight (g)
(146)
(57)
'..fiat ch
3 weeks
6 weeks
9 weeks
12 weeks
38.8 a
133 c
ISSa
41S a
788 a
364 c
. 684 c
1060 c
12 weeks
ISSa
42S a
81S a
l25S a
1219 a
Male shank length
3 weeks
6 weeks
9 weeks
39.6 a
39.S a
(cm)
. 3.80 a
5.63 a
7.42 b
8.89 b
b
b
4.94
3.40
6.04 c
7.6S c
3.86 a
a
S.76
a
7.75
3.83 a
5.76 a
7.24 b
b
9.07
9.27 a
Fema1e body weight (g)
(146)
(50)
38.7 a
Hatch
3 weeks
~____
~~~~__~6~w~e~ek~~~,____
139 c
349 c
606 c
876 c
12 weeks
.
~9.
a
ISSa"
402 a
71S a
l012 h
Female shank length (cm)
------------------------------------~------~----------~---3.S1 b
3 weeks
3.78 a
3.81~
3.25~
a --5.50
6 wee~
4.62
5.57
S.03~
9 wee1(s
6.48
7.1S a
5.91 c
7.19 a
r.42 b
~
12 weeks
6.7Sc
8.1S a
8.3S a
\
D = Macdonald ~arf iso1ate.
/
L = Single Comb White Leghor~.
( ) = Number of birds. .
,
Row means with same superscript are not signifi'cantly different at 5%
1eve~: .
1
,
,
•
..
e
-"
e
~
,>
TABLE 4
~ean
.
squares' of the analysls of variance on the ~justed body weight and shank 1ength data of the offspring fram
D x D, D x L, L x D and L x L mating types
r c n __
Sou~e
of
Var1ance
6 Weeks
3 Weeks
df Hatch
Weight
BW
_______
SL
BW
9 Weeks
'SL ____ _
12
BW
SL
191655.63**
16.806**
0.092
5542.160
0.078
13.053**
244492.31**
25.282**
Weeks
BW
SL
Male
cr
p
Between
population
Withln
population
3 6.33(NS)
347
~559.63"
281. 095rj
3.67
1.82**
49826.60**
0 . 04.
1939. <224
6.551*~
426402.31** 20.44**
11583.449
0.139
Fema1e
Between
population
,.....;-
3 8.24(NS)
9453.10**
4.473**
79096.44**
372985.00** 35.718**
,Çj .'
, ;
Within
population
**
*
NS
37S
4.158
244.017
0.043
= Significant at 1% level.
= Significant at st 1eve1.
= Not significantly different
i)
rf
.ço
1489.919
0.108
4035.~9
0.099
o = Macdonald dwarf isolate.
L = Single Comb White Leghorn.
at 5t 1eve1.
7043.375
0.111
VI
-....J
58
TABLE 5
"
Degree of sexual dimorphism at 12 weeks of age of offspring from
D x D, D x L, L x D and L x L mating, types
,
MAT 1 N G - T Y P E
Dx D
l,
Dx L
L x D
L x L
Body weight
17.58b
28.37 a
19.5Sb ,
20.74 b
Shank length
l2.34 b
l6.7Sa
9.84 c
lO.62 c
Row means with same superscript are not
level.
significantlY,differ~nt
at 5%
D = Macdonald Dwarf Isolate.
L = Single Comb White Leghorn.
: ' l
()
l
Q
"
\1
1
59
f
ri
\
TABLE 6
Mean squares of ana1ysis O\f variance of the' sex dimorphism t~
Source of
Variance
df
Body Weight
Shank Length
.
3
237.4457**
112.8518**
Error
r
33
23.2065
Mating type
8.695
* = Significant at 5t level.
**
= Significant
at 1% leve1.
/
,,
..,
1,
t
60
1
" '
TABLE 7
Mean adult body weights and shank lengths of Macdonald Dwarf Isolate
(MDI), 21-week·body weights and shank lengths of the FI of MDI males
x Sex-linked Recessive Dwarf (SRD) females, mean adult body weights
and shank lengths of SRD and Nonnal Single Comb White Leghorns (SCWL)
and the results of comparispns between the FI and other birds of eac~
sex'
Line
MDI
MDI
SCWL
SE
*
**
Body Weight
! SE Cg)
Sex
No. of
Birds
M
20
2142
M
47
1863 + 48.1
M
7
F
49
1653:t
26.96**
6.9 + 0.05**
F
35
1323
60.3
7.4 ~ 0.12
F
37
F
20
+
168.9*
2578 + 2J.7.8**
+
981 ! . 53.24**
185Ù
+
43.06**
= Standard deviation of the mean.
= Significantly
cr
•
different at 5% 1evel.
= SignificantJy different at 1% level .
• t..
Shank Length
+ SE (cm)
8.3
+
0.06**
8.9
+
0.09
10.3 '! 0.09**
5.7 ! 0.05**
8.6 ± 0.06**
'>
61
e
TABLE 8
Mean body weights and shank 1engths of the F2 generation of the
M.DI x SRD
Age
Body Weight (g)
:!: S.E.
Shank Length (cm)
~ S.E.
Male
(108) ,
Hatch
3 weeks
6 weeks
9 weeks
33
140
384
731
12 ~eeks
15 weeks'
18 weeks
21 weeks
1053
1386
1563
1637
+ 0.27
± 2.08
+ 4.80
+ 8.39
+
+
12.52
20.88
+ 27.91
± 30.86
3.60 +- 0.02
5.24 + 0.03
. 6.97 + 0.04
8.13
8.91
9.05
9.12
+ 0.09
+
0.07
+
0.07
± 0.12
-
,."
,
Hatch
3 weeks
6 weeks
9 weeks
12
lS
18
21
weeks
weeks
weeks
weeks
Fema1e
(98)
32 +- 0.25
126 +- , 1.65
+ 4.69
316 534 ± 8.91
696 + 12.60
813 +- 17.22
983 ± 83.38
1004 ± 26.63
f,
3.43 t 0.02
4.72 + 0.03
5.83 ± 0.05
6.54
6.37
6.48
6.49
0.13
-± 0.10
+
+
+
-
0.10
0.12
= Standard deviation of the mean.
= Macdonald dwarf isolate.
= Sex-linked recessive dwarf.
() = Number of birds.
S.E.
MDI
SRD
"'\,
\
\
62
TABLE 9
Mean body weights and shank 1engths of the offsPZ:ing from the
backcros,s of the FI (MDI x SRD) to the MDI males
Body Weight (g)
± S.E.
Age
Shank Length (cm)
! S.E.
\
Male
\
(71)
37
+
-
0.50
3 weeks
148
+
3.42
3.56
6 weeks
473
+
8.52
5.20 ! 0.04
9 weeks
789
,-
+
13.61
7.0! ! 0.06
12 weeks
1166
+
22.75
8.47
Hatch
+
+
0.04
0.13
Fema1e
(98)
"
35 !: - 0.38
Hat ch
3 weeks
130
-+
2.19
3.35 ! 0.03
6 weeks
349
+
5.28
4.79 !: 0.04
650
+
9.24
6.33 + 0.05
893. ! 14.50
7.83 :!: 0.15
9 weeks
-----~-
12 weeks
S.E.
MDI
SRD
( )
-
= Standard deviation of the mean.
= Mac40nald dwarf isolate.
= Sex~linked recessive dwarf.
= Number
of birds.
i'
,J
63
TABLE la
'!'
1
'/.
omparisons of body weights and of shank 1engths at 12 weeks of age
between t~ backcross of the FI fema1es CMDI x SRD) to the MDI
males and thosé of pure 1ine MDI
Sex
No. of
Birds
Body Weight (g)
! S.E.
Shank. Length (cm)
~ S.E.
Back cross
M
71
1166 + 22.75
8.45 + 0.13
Dwarf iso1ate
M
57
997
Difference
t
7.49 +- 0.05
13.06
'169.61**
0.98**
Back cross
F
98
893 +- 14.50"
7.83
Dwarf isolate
F
50
804 + 13.61
6.69 +- 0.06
Difference
1
l'
--
89.34**
"
:t
0.15
1.14** .
...
The differences were tested by the Student's t test.
**
MDI
= Significant at the 1% level.
.
= Macdonald dwarf isolate.
SRD~
Sex-linked recessive dwarf.
....
'-...
a
64
'e
,
,',
TABLE 11
Comparisons of the body weights and of the shank lengths at 21 weeks
of age of the Pl and P2 generations of the MDI x SRD
,
Sex
of
8irds "
NO'
J
M
,47
M
,108
Body Weight Cg)
! S.E.
Difference
Shank Length (cm)
~
S.E.
:!: 48.1
8.91 + 0.09
1637 :!: 30.8
9.12 +- 0.12
1863
... 0. 21(ns)
f26*
F
35
1323
! 60.30
7.42 +
- 0.12
F
98
1004 :!: 26.63
6.48 ± 0.12
Difference
317.8**
0.82**
= Standard deviation of the mean.
MDI = Macdonald dwarf isolate.
SRD = Sex-linked recessive dwarf.
* = Significant at 5\ level.
** = Significant at 1\ level.
S.E.
ns - Not significant at 5\ level.
i
r
65
TABLE 12
Mean body weights and shank l~ngths of the chicks from B x L, L x B,
B x D and D x 8 mating types
AGE
MATING
Lx B
Bx L
T Y PE
Bx D
D
x B
Male body weight (g)
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
(17)
41.3
128.5
297.2
541.6
769.2
(2)
21.2
103.5
259.0
505.5
755.5
•
(2)
31.1
127.5
330.0
645.0
926.0
(2)
17.9
71.5
217.5
406.6
640.5
Male shank 1ength (cm)
3
6
9
12
weeks
weeks
weeks
weeks
3.73
5.25
6.67
7.81
3.45
5.15
6.75
8.05
3.45
5.10
6.90
8.00
4.85
5.50
6.65
Fema1e body weight Cg)
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
(23)
39.8
110.4
251.5
432.1
551.1
(4)
19.7
,87.0
232.5
433.5
628.0
(0)
(4)
18.9
71.0
186.0
339.2
487.8
IJ
Female shank length (an)
\
3 week~
6 weeks
9 weeks
12 weeks
3.31
4.67
5.85
6.53
3.20
4.80
6.63
8.70
2.60
3.78
5.05
5.70
B = English Game Bant~.
L = Single Comb White Leghorn.
( ) = Number of birds.
" D = Macdonald Dwarf Iso1ate.
.>
1
1
•
66
TABLE 13
v
Canparisons of lx>dy weights and of shank lengths at 12 weeks of age
..
of the Bantam with those of the related birds
Sex
No. of
Birds
Bx L
M
17
L x B
M
2
Body Weight (g)
! S.E.
769.24 +
755.50
Difference
27.23
7.81 + 0.09
6.78
8.05 + 0.04
13.74 (ns)
-
-0.14 (ns)
B
M
2
9640.50 +
83.50
6.65 + 0.25
B x D
M
2
926.00 +- 212.00
8.00 + 1.10
D
"
x
,-
Difference
-285 (ns)
-1.35 (ns)
Bx L
F
23
551. 09 +
-
20.05
6.53 + 0.07
Lx B
F
3
628.00 +-
15:08
7.70 + 0.01
Difference
;
+
-
Shank Length (cm)
:t S.E.
"
-76.91*
-1.18**
B JY L
M
17
769.24 ~
27.23
7.81 + 0.09
Bx B
M
12
708.00 +-
29.25
6.28 + 0.08
Difference
S.E.
**
*
ns
S
L
= Standard deviation of the Mean.
= Significant at 1\ level.
= Significant at 5% level.
= Not signif~cant at st 1evel.
61.24 (ns)
-
0,.53**
/
= English Game Bantam.
= Single Canb White Leghorn.
o = Macdona,ld Dwarf Isolate.
o
1
67
TABLE
!4//)
Average body weights and shank lengt~ of the chicks from the DB x D
and LB x D mating types
MAT l N G
AGE
p-
TYPE
l
LB x D
DB x D
Male body weight (g)
.
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
(93)
27.2
107.7
282.1
521.9
840,.1
.~
(48)
25.6
102.0
275.2
524.1
839.7
Male shank length\ (cm)"
3
6
9
12
weeks
weeks
weeks
weeks
Hatch
3 weeks
6 weeks
9 weeks
12 weeks
3.1
}
Fem~
weeks
weeks
weeks
weeks
4.6
6.1
7.4
!
3.1
4.7
6.4
7.7
body weight (g)
(91)
27.7
97.5
236.4
417.0
635~S
-"
3
6
9
12
~
(50)
25.6
94.0
242.9
437.8
666.8
Female shank length (cm)
3.0
4.2
5.5
6.5
DB = Offspring produced by D x B mating.
D • ~acdQnald Dwarf Isolate.
B = English Game Bantam.
L = Single Comb White Leghorn.
( )= Number of birds.
3.0
4.4
5.8
6.8
•
68
TABLE 15
Comparisons of body weights and of shank lengths bf the progeny fram
the DB x D, LB x 0 and 0 x 0 rnating types
Sex
No. [of
Birds
DB x 0
M
93
840.09 + 12.6
LB x 0
M
48
839.18 ! 12.1
Shank Length (an)
! S.E.
Body Weight (g)
! S.E.
<,
7.74
1.91 (ns)
Difference
r
DB x D
F
91
LB x D
+
0.06
-0.39**
635.53 + 14.6
6.45,:!: 0.07
~~ +- 11.5
6.84 ! 0.06
-3~~s),
Difference
7.35 + 0.05
-0.38**
~
\
Dx D
M
57
DB x D
M
32
\
\
7.49 ! '0.05
7.35 ± 0.05
0.14(ns)
Difference
Il
S.E. = Standard devîa~ion of the rnean.
** = Significant at 1\ level.
* ~ Signif~cant at st level.
ns = Not significant at 5% level.
D x D =rMacdonald dwarf isolate 0401) sire x MDI dam.
DB = Offspringjproduced by MDI sire x Bantam dam.
DB x D = D~ sii-e x MDI dam.
LB = Offspring producea by normal SingleoComb White Leghorn (SCWL)
sire x Bantam (B) dam.
'l'
-..
T-----
.?
e
-
~,
~
< o·
~
"
6
...
'----- G
E
<Ii
'<~
TABLE 16
,.,
Mean'percent egg production and egg weight for the pulIets from D x D, D x L, H x D and H x L
t
matings at various ages
~ULLET
LINES
~EGG
PERÇENT EGG PRODUCTION
6-7 Monthsnt
12-13 Months
24
Weeks nt
26
Weeks nt
WEIGHf (g)
44
Weeks nt
Weeks
49
1
Q
74.8 (12)
69.S b (12)
35.1 (12)
35.5 (10)
47.0 (14)
Dx L
83.1 (12)
71.4 b, CÎ4)
41.6 (13)
45.0
(8)
55.8 (16)
Hx D
86.6 (J2)
, 8s.3 a (12)
41.1 (10)
44.6 (14)
S6.6 (19)
56.6 a• (17)
H
85.3 (12)
58.1
58.2 a (15)
.x
•
0
L
../
.
~. "~
( )= Nuœber
?f
-,
55.4a (14)
'
83.3 a (15)
\1
Column means with saœe s~rscripts are pot
analysj.s 01 variance was done.
D =Macdonald Dwarf Iso1ate.
_L .. Single Comb Mù. te Leghorn.
Ji .. Hungarian White Leghorn.
nt = No
~
48.S b (12)
ox D
4S.-t
(7)
signifi~ant1y
"47.6
(8)
(17)
J
different at st 1eve1 .
'"
hens.
'1
,
....
0\
10 }
D
~
,..
(1
'It
o
70
r
.
t
(
•...
TA8LE 17,
'.
,
Hean squares of ana1ysis of variance of the percent egg'production at
.' 12 months of age and egg weight at 49 weeks of age
.
.,'
'1
S04rce of
Variance
df
Percent Egg
Production
Egg Weight
Mat:i.ng type
3
913.696'*
226.625**
Error
~.
~
"
311.278
54
24.03
. /
~.
,
** = Significant a't 1\ leve1.
,>
* = Significailt
at 5% level.
,
..,
"
"'di
;"
....
>.
;,
f·
.
'.
...
,
'
1 •
,\
4
.
.....
'''t.
.:
"
.-.....
.i
,
-e
L,
,
;"
..
~
•
--1
.
1
"
",
..
,J
,
\
l(,
'\"
' 1
•
"
,
\
,...
1
/'
~
,
'~
.
..,A
.
p
'
,
..
,
"
1
b,
,
r
,0 ,
1',
"\.
'"
.., \~ . ....
'
'
')
'.
2.
,c
~
'.
-, . ; -,
.
6 Il
.. 1• •
'
"
.,
•
..
..
'.
\
•
1
f,
"b
J
"
,
e
."
'
.
-,
,.
o -
e·
'"
'\.
'f"
t
"
$
.
"
\,
.,'
TABLE 18
.
ft
Mean percent fertility fOE 14-day duration post insemination and number'of hens
,
"
MATING
ox
.f
""
Percent,ferti1ity'
~
0 '-I..~'
H
..
e2.66 ! 4.0gb
x 0
94.51 ! 3". 23'a
(J
1;
T YP E
v'
H x L
D,x L
'"
73.22 ! J.74 b
77.60 : 5:0gb
"
o
~ber of he~ns
'15
g
9
10
/.
Row'means with same superscript are not significànt1y different at 5% leve1.
f·
_D
z
Macdonald Dwarf Isolate.
~
c
L = Single Camb White Leghorn.
...~
H = Hungarian
-1}
S
White Leghorn.
"
/'
J
"
.
"'-J
~
.
•
o
'1"'
~
0'
.
-.
'
'!.
e
.
.,
•
1'v
)
'"
,
-'
ô
r
TABLE
-r/.
19
'.
Analysis of variance of the fertility data
~
,
Source of
Variance
df
ss .
Total
41
91~~. 7856
.'
6'
---
Matings
Error
-.-
....
3
2345.7551
781.9183
38
6787.0307
l78.606Q
,l
~
,:::
PrÇ>babiÎi ty
c... ~\;
~
",
4.38
<
0.01
0
..
1
,
"-l
N
'~
6
~
~
...----
F
MS
'-
,
~
..",
~
~
e'.
.
'
e
"
.?
-':'
~
~
.,
f
,
.
•
1
1
. /
~
!!
TABLE 20
.,
Effect of mating type on the hatchability of the offspxing and the number of hens
,
..
,
,
z
~
MAT 1 N G
Dx L
Dx D
T YP E
'" L x D ,
L x L
•
'il
85:0 !
Percent hatchabilîty
Number of hens
~
96~5
9.57
6-
87.~!
6
6
~
8.54
90.3 ± 6.24
6
,.
D = MaeâÔnald Dwarf Isolate.
~
! 2.29
L = Normal Single Canb White Leghorn.'
"
r~
..:---~
~
t;
.,.
"=
"
'-1
Vl
'e
e-·
-->.-
(~,\
,
--.
"
TABLE 21
""
Analysis of variance for the effect of mating type on hatchabi1ity
-P
~
Source of
Variance
_.-
df
ss
23
6693.29
3
439.38
146.459
20
46253.92
312.696
>
MS
F
PrC?bability
\
--
Total
Mat.ing type
Errol'
0.46-83
>
0.05
.;>
"'-l
~
~
':.>
75
TABLE 22
The percent mortality of the offspring from the 0 x D. 0 x L. L x
and L x L matings from hatch to 12 weeks of age
p
.;
MATING
No. of birds
i
Percent dl.ed
.
Age at death
",
mean days
D x 0
DxL
113
J
TYPE
LxD
L x L
331
131
171
9.7
1.8
2.3
6.4
8.1
14.5
8.0
'16.6
~
p = Macdonald Dwarf Isolate.
L
= Single Canb
White Leghorn.
1
-
., ,
.. 4 ",'
"
"
. .-,
, !
.
",
.
,
76
, '\
\ ~ J
"
TABLE 23
The 1aying house morta1ity of the pu11ets from '0 x D, D x L, H x D
and H x L matings from 23 weeks to 56 weeks of age
M A
No. of pullets
Number died
1 N G
T Y P E
Dx D
Dx L
H x D
H x L
16
19
21
25
o
2
1
7
5.0
4.8
28.0
Percent died
L
= Macdonald Dwarf Iso1ate.
= Single Camb~White Leghorn.
H
= Hungarian
D
'r.
,
.
(
White Leghorn .
.
,
,'
,'.
.'
.
.'
•,
Q
77
,.....
.
20
~
N= 156
i= ,1 058.8 G
.
-'
50= 153.44
D
0.083 91
MAX
P>0.20
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•the, female offspring produced by D~x D (~dWP x ~-)
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\
VIII .
.
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....
,lf"I"
1
J
·f
87
1
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2nd. Ed.
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Guyton, A. C. 1966. Texthook of Medical Physio10gy.
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------
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Î
L,
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J~
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~
prog~
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T,
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thl
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è
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;
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