SCVMJ, XIII (2) 2008
367
SUITABILITY OF OSTRICH EGGS TO HATCHABILITY
Hegab, I.M., Mohammad, M.A.; Fares, I.M. Maha, M.T.; and
Ashraf, M.M.K.
Suez Canal University, Faculty of Veterinary Medicine
Department of Hygiene, Zoonoses and Animal Behaviour and Management
ABSTRACT
This study was undertaken to investigate some factors affecting ostrich
eggs hatching. The mean percentage of egg weight loss (EWL) increased
significantly (P ≤ 0.01) in the large size eggs than that in the small and
medium sized ones. The number of large pores /cm2 increased significantly (P
≤ 0.01) in the large sized eggs. There was a significant positive correlation (P
≤ 0.05) between the number of large pores and the egg weight loss. A
significant positive correlation was found between the egg size and egg weight
loss (P ≤ 0.01). Shell thickness did not differ significantly in different egg
sizes. Hatchability Percentage in the large, medium and small sized eggs was
78.95, 65.00 and 35.00 % respectively. The highest hatchability (P ≤ 0.05) was
achieved when the shell thickness was less than 1.7 mm (75.00 ± 8.57) which
coincided with the significant increase (P ≤ 0.01) in the percentage of egg
weight loss (12.84 ± 0.66) in the same group. The lowest hatchability and egg
weight loss were recorded when shell thickness was more than 1.9 mm. A
highly significant negative correlation (P ≤ 0.01) existed between the shell
thickness and hatchability. There was a significant negative correlation
between the shell thickness and egg weight loss. The lowest hatchability 33.30
± 8.21 (P ≤ 0.01) was found in eggs with large pore count ≤ 7 /cm 2 this came
parallel with a significant decrease in EWL (8.46 ± 0.65) in the same group.
The highest hatchability and egg weight loss were achieved when large pore
count /cm2 was >10. There was a significant positive correlation between egg
weight loss and the number of large pores. There was a highly significant
positive correlation between the number of large pores and hatchability.
INTRODUCTION
Although ostriches have been
domesticated for more than 100 years,
the bulk of a scanty literature describing artificial incubation practices
368
for ostrich eggs centers around popular reports. Scientific investigations
into the conditions required for the
artificial incubation of ostrich eggs has
been very poor, a situation that has
hampered the development of the industry worldwide (Deeming, et al., 1993).
Hatching success of ostrich
eggs in artificial incubators is considerably below than that found in wild
ostriches (Hurxthal, 1979; Bertram
and Burger, 1981), this suggests that
the hatchability of artificially incubated ostrich eggs can be improved by
identifying and altering factors inherent to eggs or associated with the current incubation practices that preclude
maximum hatchability. However, these factors affecting egg hatchability
were the length of the pre-incubation
storage time, egg size, shell thickness
and porosity (Fasenko, et al. 1992).
The aim of the current study is
to examine various factors controlling
egg hatchability as egg size and the
length of pre-incubation storage on
incubation egg weight loss, hatchability, and chick weight at hatch. In addition, the relationships between eggshell thickness and the number of eggshell pores on egg weight loss and hatchability were also examined.
MATERIALS & METHODS
This study was done on three
different farms at Ismailia Governate,
Egypt. The first one was the farm of
Faculty of Agriculture, Suez Canal
Hegab et al.,
University. The second was El-Horria
for poultry and ostrich industry and
the third one was Military farm
located in EL-Kassasin town during
the period from March 2005 to August
2006 and was accomplished on ostrich
farms (black neck breed).
I- Measurements
1- Egg incubation
Eggs were transferred to the
incubation department where they identified and stored. Eggs were incubated at 35.8-36.1˚C and about 20%
RH (15-25%). Turning of eggs were
done each two hours automatically
throughout the incubation period which was typically around 40 days (the
time at which internal pipping took
place.
2- Hatching
When the eggs exhibited evidence of internal pipping they were
transferred to hatcher maintained at
36˚C and 30% RH. Eggs that did not
hatch by the day 43 were removed
from the hatcher. Temperature and RH
were maintained acc. to Gonzalez et
al., (1999).
3- Samples
Egg shells and hatching shards from hatched eggs, as well as materials from manually opened eggs that
did not hatch were marked and individually stored in plastic bags. Shell
samples were collected as 5 squares as
follows; one from the air cell, 2 from
each side of the equator, and 2 from
the other end. 
SCVMJ, XIII (2) 2008
4- Egg Weight Loss during Incubation
Eggs were categorized into
Sm
>
≥
Egg weight loss (EWL) during
incubation was determined according
to Gonzalez et al., (1999), by the
following formula:
EWL (%) = (egg weight at day 1
egg weight at day 40)/egg weight
day 1) ×100. Egg weight on day 1 was
determined at the time of setting eggs
in incubator according to Gonzalez et
al., (1999).
The number of large Pores per
Cm2 of shell surface area (LP), egg
shell thickness (THICK), EWL, hatchability% (HATCH), and chick weight
at hatching (CWT) was determined for
different groups of eggs.
- Each selected site of the
shell was stained with Methylene blue
dye 3% to facilitate accurate counting
of large pores through using a dissecting microscope.
- A Slip clutch micrometer was
used to measure shell thickness to the
nearest 0.01 mm.
- Chick weights were determined at hatching using an electronic
pan balance.
5- Statistical analysis:
369
Because only 59 eggs were
available for this study, we conducted
a series of independent statistical
analyses for each of the four treatment
categories (egg shell porosity, egg
shell thickness, egg size, and storage
length groups) as they independently
affected selected variables.
Consideration of these four categories
in a factorial arrangement of treatments (3 3 3 2) would be prohibitive given the small sample size.
Differences in means from treatment
categories (i.e., low, intermediate, or
high) of LP or THICK on EWL and
HATCH were assessed by one-way
ANOVA using a completely randomized design (CRD) (Steele and Torrie,
1980). Where appropriate, category
means were partitioned by L.S.D Test.
Pearson correlation coefficients and
their probabilities of significance (Pvalues) were calculated between the
following variables: LP with EWL, LP
with HATCH, THICK with EWL, and
THICK with HATCH. Differences in
the three egg size treatment categories
(small, medium, and large) on mean
LP, THICK, EWL, HATCH, and
CWT were also detected by one-way
ANOVA using a CRD and, where
appropriate, category means were
again separated by L.S.D.
370
Hegab et al.,
RESULTS & DISCUSSION
Table (1): Means of egg weight loss (EWL), large pores, chick weight
(CWT), and HATCH % in different sizes of ostrich eggs.
Egg
size
Small
No.
of
eggs
20
Medium
20
Large
19
L.S.D0.01
-
(EWL)
%
(Thick)/mm
(LP)/cm2
(CWT)/g
HATCH
(%)
9.00
±
0.69a
10.40
±
0.55a
13.48
±
0.81b
1.81
±
0.03
1.86
±
0.03
1.85
±
0.02
5.68
±
0.39a
8.08
±
0.3b
10.51
±
0.73c
755.0
±
10.57a
825.0
±
17.08b
955.0
±
11.18c
35.00
2.67
-
1.96
55.32
-
65.00
78.95
*Means in each column with different superscripts within the same column are highly
significant at (P ≤ 0.01).
The mean percentage of egg
weight loss increased significantly (P
≤ 0.01) in the large sized eggs (13.48
+ 0.81) than that in the small and medium sized ones (Table, 1). Besides, the
number of large pores / cm2 increased
significantly (P ≤ 0.01) in the large
sized eggs. Moreover, there was a
significant positive correlation (P ≤
0.05) between the number of large
pores and the egg weight loss along
with another one between the egg size
and egg weight loss (P ≤ 0.01) (table,
3). These results may not only confirm
the relationship between the number
of large pores and egg weight loss but
also clarify the increase of egg weight
loss in the large sized eggs. This increase in EWL may be attributed to the
increase in number of large pores/cm2
in large than medium or small sized
eggs. Large pores act as diffusion paths for transportation of gasses between the embryo and the environment.
Also, it allows evaporation of water
from the egg to the surrounding atmosphere due to the pressure difference
between the inside and the outside of
the egg. The amount of water lost during the course of incubation is usually
known as the egg weight loss.
SCVMJ, XIII (2) 2008
371
Chick weight (g) increased significantly (P ≤ 0.01) in the large-sized
eggs (955 ± 11.18) than medium and
small-sized ones. In addition, there was
a highly significant positive correlation (P ≤ 0.01) between the egg size
and chick weight (table, 3). Larger
chick, without a doubt, in the larger
egg will require additional number of
pores to compensate the gaseous dem-
ands for respiration which may explain the increased large pore count/cm2
in large size eggs. The late explanation
is in consistence with Gonzalez, et al.,
(1999) and Hassan, et al., (2005) who
reported that the relationship between
egg size and chick weight exists among ostrich species, as heavier chicks
were associated with larger eggs.
Table (2): Correlation coefficient (r) between variables.
Variables
Large pore count X Hatchability
Shell thickness X Hatchability
Shell thickness X Egg weight loss
** Highly significant at (P ≤ 0.01).
(r)
0.9998**
-0.84**
-0.34*
* Significant at (P ≤ 0.05).
Concerning hatchability, hatchability (%) in the large, medium and small sized eggs were 78.95,
65.00 and 35.00 % respectively (table,
1). In fact, poor egg weight loss may
give the reason for the lowest hatchability in the small sized egg because
it is usually associated with enhanced
embryonic mortalities Ar (1996).
Therefore, we should conclude
that the best egg to incubate is that egg
higher than 1350 gm which posses higher number of pores allowing better
egg weight loss and respiration for the
embryo.
Table (3): Correlation coefficient (r) between variables.
Variables
Egg size X EWL
Egg size X Chick weight
Number of large pore X Egg weight loss
**Highly significant at (P ≤ 0.01). * Significant at (P ≤ 0.05).
(r)
0.44**
0.59**
0.33*
372
Table (4):
Hegab et al.,
Mean percentages of egg weight loss and hatchability with
variations in the shell thickness/mm.
(Thick)/mm
No. of
examined eggs
EWL%
HATCH%
≤1.7
23
12.84±0.66a
75.00±8.57a
>1.7 , ≤1.9
20
9.23±0.34b
60.71±5.87b
>1.9
16
7.62±0.66b
46.44±6.47c
-
1.68
9.82
L.S.D0.01
Means with different superscripts are significant at (P ≤ 0.05).
The highest hatchability (P ≤
0.05) was achieved when the shell
thickness was less than 1.7 mm (75.00
± 8.57) which coincides with the significant increase (P ≤ 0.05) in the percentage of egg weight loss (12.84 ±
0.66) in the same group (table, 4).
Similarly, the lowest hatchability and egg weight loss were recorded when shell thickness was more
than 1.9mm. Moreover, a highly significant negative correlation (P ≤ 0.01)
existed between the shell thickness
and hatchability (-0.84) with a significant negative correlation (-0.34) between the shell thickness and egg
weight loss (table, 2). These results are
in agreement with Gonzalez, et al.,
(1999) who found that there was a
negative relationship between shell
thickness and egg weight loss in the
first 40 days of incubation and between shell thickness and hatchability.
As a matter of fact, the more increase
in shell thickness, the longer the diffusion paths which in turn will resist
the water vapor passage through the
egg shell. This will inevitably lower
the egg weight loss which reflects
negatively on hatchability as embryos
became weak, edematous, and unable
to break through the shell. Also, it
reflects the poor ability of egg shell to
exchange vital gasses between the embryo and the surrounding environment. Consequently, embryos have
died due to suffocation.
SCVMJ, XIII (2) 2008
373
Table (5): Mean percentage of egg weight loss and hatchability with
variation in the numbers of large pores.
LP/cm2
No. of
examined eggs
EWL%
HATCH%
≤7
19
8.46±0.65a
33.30±8.21a
> 7 , ≤10
18
10.82±0.52b
57.14±9.53b
> 10
22
13.89±0.67c
71.42±7.71c
-
1.72
12.45
L.S.D0.01
Means with different superscripts are significant at (P ≤ 0.05).
The lowest hatchability 33.30
± 8.21 (P ≤ 0.05) was found in eggs
with large pore count ≥ 7 /cm2 with
highly significant decrease in EWL
(8.46 ± 0.65) within the same group
(table, 5). Meanwhile, the highest hatchability and egg weight loss were achieved when large pore count /cm2
was >10. Furthermore, there was a
significant positive correlation (table,
3) between egg weight loss and large
pore count (0.33) and a highly significant positive correlation (table, 2) between large pores and hatchability
(0.99). These results may be due to the
fact that large pores act as paths allowing evaporation of water from the
egg to the surrounding atmosphere.
So, the higher the number of pores, the
higher the amount of water evaporated
from the egg. Accordingly, lower pore
count result in excess water to be
retained in the egg or low egg weight
loss this leads to smaller airspace
within the egg which may complicate
the internal pipping causing consequent inhalation of liquids into the
airways of the chick making it difficult
to begin aerial respiration Sahan, et
al., (2003) and Ar and Mover (1994).
Definitely, large pores are considered
the lung of the egg which permits
exchange of gasses (supply of O2 and
removal of Co2 from the embryo). So,
lowered hatchability in eggs with large
pore count ≤ 7/cm2 may indicate that
there is inadequate gaseous exchange
between the embryo and the outer
environment.
374
REFERENCES
Ar, A. and Mover, H. (1994): Oxygen tension in developing embryos:
system inefficiency or system requirement? In: Ar, A. (1996). Requirements
for successful artificial incubation of
ostrich eggs. Improving our understanding in ratites in a farming environment, ratite conference, Oxfordshire,
U.K, p.131-144., England.
Ar, A. (1996): Requirements for successful artificial incubation of ostrich
eggs. In: Improving our understanding
in ratites in a farming environment,
ratite conference, Oxfordshire, U.K, P.
131-144.
Bertram, B.C.R. and. Burger, A. E.
(1981): Aspects of incubation in
ostriches. Ostrich 52:36–43.
Deeming, D.C.; Ayres, L. and Ayres,
F.J. (1993): Observations on the commercial production of ostrich (Struthio
camelus) eggs in the United Kingdom:
incubation. Veterinary Record, 132: P.
602-607.
Fasenko, G. M.; F. E. Robinson; R.
T. Hardin; and J. L. Wilson, (1992):
Research note: Variability in pre-incubation embryonic development in domestic fowl. 2. Effects of duration of
egg storage period. . In: Gonzalez, A.;
Hegab et al.,
Satterlee, D.G.; Moharer, F. and Cadd,
G.G. (1999). Factors affecting ostrich
egg hatchability. Poultry Science, 78:
P. 1257-1262.
Gonzalez, A.; Satterlee, D.G.; Moharer, F. and Cadd, G.G. (1999): Factors affecting ostrich egg hatchability.
Poultry Science, 78: P. 1257-1262.
Hassan, S.M.; Siam, A.A.; Mady, M.E.
and Cartwright, A.L.(2005): Egg storage period and weight effects on hatchability of ostrich (Struthio camelus)
eggs. Poult Sci. Dec; 84(12): P. 19081912. (Abstract).
Hurxthal, L. M., (1979): Breeding behaviour of the Ostrich (Struthio camelus
massaicus) Neumann in Nairobi Park.
Ph.D. thesis, Nairobi University, Nairobi, Kenya.
Sahan, U¨.; Altan, O¨.; Iipek, A. and
Yilmaz, B. (2003): Effects of some egg
characteristics on the mass loss and
hatchability of ostrich (Struthio camelus) eggs British Poultry Science
Volume 44, Number 3 (July 2003), p.
380–385.
Steel, R.G.D. and J. H. Torrie, (1980):
Principles and Procedures of Statistics.
Abiometric Approach (2nd ed.), McGrawHill Co., New York, NY.
‫‪SCVMJ, XIII (2) 2008‬‬
‫‪375‬‬
‫الملخص العربى‬
‫مدى مالئمة بيض النعام لعلملية الفقس‬
‫إبراهيم محمد فارس‪ ,‬مها محمد ثابت‪ ,‬أشرف محمود خليل‪ ,‬إبراهيم مجدي حجاب‪ ,‬محمد عبد المحسن محمد‬
‫قسم الصحة واألمراض المشتركة وسلوكيات ورعاية الحيوان‪ -‬كلية الطب البيطري‪ -‬جامعة قناة السويس‬
‫أجريت هذه الدراسة إللقاء الضوء على بعض العوامل المؤثرة علي نسبة الفقس في بيض النعام‬
‫ب َتح ّري مدى مالئمة األنماط المختلفة لبيض النعام للفقس ‪.‬‬
‫‪ ‬زادت نسبة الفقس معنويا في البيض ذو الحجم الكبير (‪ )0483.±18.0‬عنه فى البيض ذو‬
‫الحجم الصغير والمتوسط‪.‬‬
‫‪ ‬كانت هناك عالقة معنوية طردية بين عدد الثغور الكبيرة وبين النقص فى وزن البيض نتيجة‬
‫فقد نسبة من المياه‪.‬‬
‫‪‬‬
‫وجدت عالقة طردية بين معدل النقص في وزن البيض وبين حجمه‪.‬‬
‫‪‬‬
‫كانت نسبة الفقس فى البيض الكبير والمتوسط و الصغير الحجم‬
‫‪- 07811 - 5.887‬‬
‫‪ %47811‬على التوالي‪.‬‬
‫‪‬‬
‫أعلى نسبة فقس تم الحصول عليها عندما كان سمك قشرة البيض أقل من ‪ 015‬ملل (‪.875‬‬
‫‪ )57811±‬والتي تتمشى مع الزيادة المعنوية في نقص وزن البيض ‪ )088.3±1800‬بنفس‬
‫المجموعة‪.‬‬
‫‪‬‬
‫سجل أقل معدل فقس وكذلك نقس وزن البيض عندما كان سمك القشرة أكبر من ‪018‬ملل‪.‬‬
‫‪‬‬
‫كانت هناك عالقة عكسية معنوية بين معدل الفقس وسمك القشرة فى البيض وكذا كنت هناك‬
‫عالقة عكسية معنوية بين سمك قشرة البيض ومعدل النقص في وزن البيض‪.‬‬
‫‪‬‬
‫سجل أقل نسبة فقس (‪ )44841±.880‬في البيض ذو األعداد الكبيرة من الثغور) ≥‪/5‬سم‪)8‬‬
‫والتي تتوازى مع النقص المعنوي في وزن البيض (‪ ).803±1807‬بنفس المجموعة‪.‬‬
‫‪‬‬
‫سجل أكبر نسبة فقس عندما كان عدد الثغور الكبيرة فى القشرة (≥‪ /01‬سم‪.)8‬‬
‫‪‬‬
‫كانت هناك عالقة طردية معنوية بين النقص فى وزن البيض وعدد الثغور الكبيرة فى القشرة‪.‬‬
‫‪‬‬
‫كانت هناك عالقة طردية معنوية بين معدل الفقس وعدد الثغور الكبيرة في القشرة‪.‬‬