Abdou, FH

Ayoub, H

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Heritability estimates of hatching time in the fayoumi chickens

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F. H. ABDOU

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HERITABILITY ESTIMATES OF HATCHING  TIME IN THE FAYOUMI CHICKENS

Ayoub H

Abdou FH

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Genetics Selection Evolution

Heritability estimates of hatching time in the <it>fayoumi </it>chickens

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Heritability estimates of hatching time in the fayoumi

HERITABILITY ESTIMATES OF HATCHING
TIME IN THE FAYOUMI CHICKENS
F. H. ABDOU H. AYOUB*
Animal Production Department,
Faculty of Agric., Shebin El-Kom, Tanta Univ.
* Faculty of Agric., Ain Shams Univ.,
Cairo
SUMMARY
Pedigree Fayoumi eggs were collected from individual sire matings, and were used for heri-
tability estimates of hatching time. The eggs were saved for a period of ten days before setting. It
was noticed that the distribution of hatching time approached normality with a mean of zr days
plus 1.28 hours. Heritability estimates of hatching time were ha = 0.28, ha = 0.8 and
h5+, = o.r8. The correlation between the time of egg storage and hatching time was highly signifi-
cant (0.37). The regression coefficient of hatching time on holding time was 0.25 hatching period
(about one hour) per day of holding. The correlation between egg weight and hatching time
was not significant.
It was noticed also that incubation period was increased by increasing inbreeding coeffi-
cients.
INTRODUCTION
Several factors, both genetical and environmental, have been proved to affect
the required hatching time of the chick embryo (BOHRENet al., ig6i). Consistent
differences in hatching time, as observed among breeds and lines of chickens, sup-
ported the heritable nature of this trait. (MORGANand KOHI,M!Y!R, 1957 ; HASAN
and NORDSKOG, i96! ; and ICIDNOE, 1973).
Several investigators reported that large eggs require a longer incubation time
than smaller ones (WILLIAMS et al., ig5z ; BOHREN et al., ig6i ; HASSAN and
NORDSKOG,ig67), however, CHINOE (rg73) reported that larger eggs tended to hatch
earlier than smaller ones in the R.I.R. male R.LW. female hybrid and vice versa
in the case of the Shaver strain of W.L. HASSAN and NORDSKOG(1967) suggested
that selection for high body weight retarded hatching time more than could be accoun-
ted for by the correlated response in egg size and thus hatching time may have
a genetic basis independent of egg size. Storage period of hatching eggs was also
reported to affect hatching time. Bo!>~N et al. (i96i) and ZAWALSKY (i962) observed
that increased preincubation storage time delayed hatching time. MORGAN and
KoH!,l!!YEx (1957) reported that the expected « hatch-day » range was frequently
more variable within inbred lines than that for the non-inbred purebred and that
for crosses. ,
The aim of this experiment therefore, was to estimate the heritability coefh-
cients of hatching time of Fayoumi chickens. Egg weight and pre-incubation sto-
rage were also investigated in relation to hatching time.
MATERIALS AND METHODS
Individual sire matings of Fayoumi males with females were used for heritability estimates
of hatching time (length of incubation period). Twelve sires and i44 dams were randomly mated
in family pens supplied with trap nests where each family was composed of one sire and twelve
females. The pedigree eggs were collected for a period of ten days and the fresh egg weights were
recorded daily.
The temperature of holding room ranged from 55° to 6ooF. and all eggs were turned daily
until six hours before setting. The eggs were incubated in forced draft machine automatically
maintained at a temperature of I ooof. and wet bulb thermometer reading of 86°F. At the begin-
ning of the 2 ist day of incubation the hatcher was opened every four hours to remove the hatched
chicks which were completely free of their shells. The first four hours were assigned period number
one and the removal of chicks continued through i2 periods (48 hours).
For statistical analysis, the dams used in this experiment had at least 3 offspring per dam,
while the sires used had at least 4 dams per sire. Analysis of variance was based on the model
given by KING and HENDERSON (i954), using an analysis appropriate to unequal subclass numbers.
Variance components were for sire (s), dam (d) and full-sibs (e). In a random mating population
the variance arising from genetic differences between sire (a8) is expected to contain one-fourth
of the additive genetic variance, one-sixteenth of the additive X additive epistatic variance and
a smaller portion of the higher order interaction variances involving only additive effects. The
dam component of variance (aa) is expected to contain one-fourth of the additive genetic variance,
one-fourth of the dominance variance, three-sixteenth of the additive X additive epistatic,
one-sixteenth of the dominance X dominance variance and a smaller fraction of the higher
order interaction variances. Variance from maternal effects will also contribute to the dam
component (LERNER, 1958).
Phenotypic correlations between egg weight and hatching time and between holding days
and hatching time were estimated. The variables to be analyzed then were age of storage (Xl)
in days, egg weight (X2) in grams and hatching time (Y) in periods.
In order to observe the effect of inbreeding on hatching time, eggs were collected from diffe-
rent inbred lines of Fayoumi hens having the coefficients of 6.25, 12.5, 25.0, 37.5 and 50.0 p. 100
plus a control of outbred hens.
RESULTS AND DISCUSSION
Table i shows that the distribution of hatching time approached normality
with a mean of 21 days plus 1.28 hours. Similar results were reported by BOHREN
et al. (196) with a longer mean hatching time by about i.72 hours in W. Leghorns.
This may be due to the small size of local Fayoumi eggs (42.83 grams in the present
experiment) .
Heritability estimates of hatching time were h,’ = 0.28, ha = 0.8 and
ha+g = 0.18. It was clear that higher dam than sire component estimates of heritability
for hatching time were observed. With the statistical model employed and random
mating being assumed, variance arising from non-additive genetic and maternal
effects may be expected to be found in the dam component of variance.
Moreover, the correlation between the age of storage and hatching time was
highly significant (0.37). The coefficient for the regression of hatching time on
holding time (days) was 0.25 hatching period (one hour) + 0.3, d.f = 563,
P < o.ooi. Similar results were reported by Boxx!rr et al. (ig6i).
The correlation between egg weight and hatching time was not significant
(r = 0.5 and buzz = 0.24). Boxx!rr et al. (ig6i) reported a small and not signi-
ficant correlation between these two variables on individual basis while it was
significant between dam means. It had been shown by WILLAMSet al. (1951) that
larger eggs required a longer incubation time than smaller ones. On the contrary,
ICHINOU (1973) found that larger eggs tended to hatch earlier as mentioned in the
introduction. The relationship between egg weight and hatching time in this expe-
riment, is not clear (r = 0.5) and this may be due to the medium size of Fayoumi
eggs. ICHINOE (1973) reported that eggs of medium size showed less difference in
hatching time.
The following multiple regression equation was set up in order to predict the
hatching time (Y), in periods, expected from a given egg weight (X,), in grams,
and holding days (X,) :

The effect of inbreeding on hatching time is shown in table 2. It was noticed
that incubation period was increased by the increase of inbreeding coefficients.
While most of the chicks (at least 50 p. 100) of the control group hatched during the
first three periods, most of the inbred chicks hatched during the first five periods.
Similar results were obtained by MORGAN and KOHLMEYER (1957). This may be
due to slow growth rate of the embryos of inbred chickens.
ReFu pour publication en décembre 1975.
RÉSUMÉ
ESTIMATIONS DE I,’H!RITABILITÉ DE LA DURÉE D’ÉCLOSION
CHEZ LA POULE FAYOUMI
Des oeufs pedigree de la race Fayoumi fécondés par différents pères ont été collectés en vue
d’estimations d’héritabilité de la durée d’incubation. Ces oeufs étaient conservés pendant une
période maximum de 10 jours avant la mise en incubation. Il a été observé que la distribution
de la durée d’incubation était proche de la normalité, avec une valeur moyenne de 21 jours plus
i,z8 heures. Les estimations de l’héritabilité de cette durée étaient h’ = o,z8, Aj = 0,8 et
hâ+8 = o,i8. La corrélation entre la durée de conservation des oeufs avant incubation et la durée
d’incubation était hautement significative (0,3!). Le coefficient de régression de la durée d’incuba-
tion sur la durée de conservation était 0,25 « période d’éclosion (environ i h) par jour de conser-
vation. La corrélation entre le poids des oeufs et la durée d’incubation n’était pas significative.
Il a été observé également que la durée d’incubation augmentait avec le coefficient de con-
sanguinité.
REFERENCES
BOHREN B. B., CRITTENDEN L. B., KING R. T., 196. Hatching time and hatchability in the fowl.
Poultry Sci., 40, 620-633.
HASSAN G. M., NORDSKOG A. W., 1967. Influence of selection for body weight and egg weight on
embryonic growth rate and hatching time. Poultry Sci., 48, I27I
ICHINOE K., 1973. The relationship between hatching time and sex ratio in chicks. Poultry Sci., 52,
1584-1592.
KING S. C., HENDERSON C. R., 1954. Variance components analysis in heritability studies. Poultry
Sci., 88, 147-154.
LERNER 1. M., 958 The genetic basis of selection. New York, N. Y., John Wiley and Sons, Inc.
MORGAN W. C., KOHLMEYER W., Ig57 Relative worth of inbred chicks hatched from extended incu-
bation periods. Poultry Sci., 86, II43.
WILLIAMS C., GODFREY G. F., THOMPSON R. B., I95I. The effect of rapidity of hatching on growth,
egg production, mortality and sex ratios in the domestic fowl. Poultry Sci., 80, 599-606.
ZAwwI,sxY M., 1962. The effect of sex, egg weight and preincubation storage on hatching time and
chick weight. Poultry Sci., 41, 1697.


Heritability estimates of hatching time in the  chickens

The relationship between hatching time and sex ratio in chicks.

Variance components analysis in heritability studies.

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Heritability estimates of hatching time in the fayoumi chickens

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