2002 Poultry Science Association, Inc.
Variability of Ostrich Egg Production
on a Farm in Northern Italy
R. Rizzi,1 M. Erba, M. G. Giuliani, S. Cerolini, and F. Cerutti
Dipartimento di Scienze e Tecnologie Veterinarie per la Sicurezza Alimentare, Facoltà
di Medicina Veterinaria, Via Celoria, 10- Milano, Italy
Primary Audience: Ostrich Egg Producers, Researchers
SUMMARY
In Italy, ostrich breeding is a growing business, due to consumer demands for alternative meat,
but little information is available on egg production. The purpose of this study was to describe
productive and reproductive performance on an ostrich farm in northern Italy and to identify
factors influencing egg and chick weight. Eggs were collected from five trios (one male per two
females), incubated, and candled at 13, 26, and 38 d. Egg weight was recorded at collection, at
set, and at each candling. Chicks were weighed at hatch. Fertility was 69.7%, whereas hatchability
of egg set and of fertile eggs were 51.5 and 73.9%, respectively. Egg weight was 1,558 and 1,530
g at collection and at set, respectively, and the mean egg weight loss (14.2%) from set to 38 d was
in the normal range for ostriches. There was a positive association between egg weight at collection
and both egg weight during incubation and chick weight. Egg weight at set and at first candling
decreased as storage time increased (−3.5 and −2.9 g/d, respectively). Eggs laid in March were
heavier and had the greatest weight losses. Results show that the main source of variability for
egg weight as well as fertility and hatchability was the trio rather than environmental conditions.
Key words: ostriches, egg hatchability, fertility, egg weight
2002 J. Appl. Poult. Res. 11:332–337
DESCRIPTION OF PROBLEM
In Italy, in recent years ostrich breeding increased for meat and skin production. This interest is due to consumer demands for alternative
meat of high nutritional value and lower fat and
cholesterol contents [1]. Most ostrich farms emphasize producing breeders, because meat production has been less profitable and has been
hampered by inadequate slaughter laws. The situation has changed, however, because breeding
for reproduction is no longer profitable now that
supply has exceeded the demand. In addition,
breeding for meat is supported by other factors
such as a growing domestic demand, increasing
export to the European Union countries, and
1
development of new slaughter laws [2]. However, the characteristics of ostrich farms do not
always satisfy the needs of these birds, and
sometimes technologies are not adequate.
This research was carried out on an ostrich
farm for breeder production in northern Italy.
The objective was to describe productive and
reproductive performances and to compare them
with results collected from farms in other countries. Moreover, factors influencing both egg
weight at collection and during incubation and
chick weight were considered.
MATERIALS AND METHODS
Eggs were collected from five trios (one male
per two females) of purebred Blue-neck os-
To whom correspondence should be addressed: [email protected].
RIZZI ET AL: OSTRICH EGG PRODUCTION
triches (Struthio camelus) on a farm situated in
northern Italy at 187 m above sea level from
March to June 1999. Each trio was maintained
in an outdoor enclosure (0.5 hectare) that had a
covered area. Enclosures were covered with
sand. Each breeder consumed 1 to 1.7 kg/d of
a pelleted diet fed ad libitum and composed as
follows (% as fed): 13% moisture, 18% crude
protein, 2.6% ether extract, 9.5% crude fiber,
12.5% ash, and 0.45% methionine. Moreover,
the birds were allowed access to fresh chopped
(2 to 3 cm) alfalfa.
Eggs were collected and weighed just after
laying, which normally occurred in late afternoon. The laying date and enclosure number
were marked on each egg. After being washed
and disinfected with a Virkon S solution, eggs
were stored at room temperature (15 to 18°C)
with RH between 70 to 75% for a period not
exceeding 12 d. Eggs were set in a 250-egg
capacity Victoria I36 electronic incubator at
36°C and 25 to 35% RH and were turned hourly
throughout the incubation period.
Eggs were candled at 13, 26, and 38 d using
a 150-W candling lamp. At 38 d, eggs were
transferred into a Victoria H24 hatcher set at
36°C and 42 to 45% RH. All eggs were weighed
at collection, setting, and at each candling. At
hatch, chicks were identified by a subcutaneous
microchip and weighed. Egg weight loss from
set to the third candling was determined as follows: egg weight loss (%) = [(egg weightat set −
egg weightDay 38)/egg weightat set] × 100. Chick
weight as a percentage of egg weight at set was
also determined.
Egg weight at set and at each candling, chick
weight at hatch, egg weight loss, and chick
weight percentage were analyzed using the general linear models procedure of SAS software
[3]. The statistical model included the following
factors as sources of variation: trio, laying
month, and, as covariates, egg weight at collection and storage time. Significant differences
among means of each factor were determined
by nonorthogonal contrasts.
RESULTS AND DISCUSSION
In total, 99 eggs were collected and set, but
at collection and set the weight was recorded
for 89 eggs only. Fifty-one chicks hatched, but
one chick died within a few hours and was
333
not weighed. Overall fertility of the 99 eggs
produced was 69.7% (Table 1). This result was
consistent with those found on Australian farms
[4] but was lower than the 78.2 and 73.4%
reported for ostrich eggs imported from Zimbabwe [5] and ostrich farms in Italy [6], respectively. A difference was found among the five
trios, the fertilities being 93.7, 55.5, 90.9, 0,
and 73.7%, respectively.
Hatchabilities of eggs set and fertile eggs
were 51.5 and 73.9%, respectively (Table 1).
Hatchability of eggs set was lower than the
70% expected and reported for artificial incubation of ostrich eggs by Dzoma and Dorrestein
[7]. However, in Italy, a similar hatchability
(55%) had already been reported [6]; in other
trials, hatchability varied from 37.2% [5] to
68.5% [8]. Hatchability varied greatly among
the four trios, with hatchabilities of fertile eggs
being 73.3, 90, 86.7, and 35.7% and hatchabilities of egg set being 68.7, 50, 78.8, and
26.3%, respectively.
In ostriches under farming conditions, fertility is affected by factors such as genotype,
nutrition, climate, laying period, age, behavior,
and mate compatibility [7, 9]. The difference
in fertility among the trios were probably due
to the birds, because environmental conditions
and nutrition did not vary among trios. However, it was not possible to assess the reproductive efficiency of each bird, because birds were
maintained in trios. The performances of Trios
3 and 4, the best and the worst, respectively,
could have been associated with reproductive
disorders in males or females as well as to
mating behavior. The Trio 5 showed the lowest
hatchability (26.3% for eggs set and 35.7% for
fertile eggs), although fertility was 73.7%.
Factors that affect hatchability include incubation parameters (temperature, humidity, and
egg turning), length of egg storage, egg size,
and shell thickness and porosity [6, 7, 10]. Egg
size and porosity may be affected by season,
hen immaturity, nutrition, and genetics [4]. Because incubation conditions were the same for
all eggs, egg size as well as shell quality might
have caused reduced hatchability in Trio 5, as
their eggs were lighter during incubation in
comparison with those from the other trios.
Embryonic mortality from set to hatch was
26.1% and greater losses (14.5%) occurred dur-
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334
TABLE 1. Number of fertile, infertile, and hatched eggs and dead embryos for each trio
Trio
Outcome
1
2
3
4
5
Total
Incubated
Fertile
Infertile
Hatched
Failed to hatch
16
15
1
11
4
18
10
8
9
1
33
30
3
26
4
13
0
13
—
—
19
14
5
5
9
99
69
30
51
18
Dead embryos
1–13 d
14–26 d
26–38 d
At hatch
1
2
1
—
—
—
—
1
—
—
—
4
—
—
—
—
—
4
—
5
1
6
1
10
ing the hatching period (Table 1). Lower embryonic mortality (18.4%) was reported in ostrich eggs from 20 Italian farms [6]. As with
other birds, embryonic mortality of ostriches is
high during the first and last weeks of incubation. This may be caused by many factors, such
as low or high water loss from the egg, egg size,
eggshell porosity, and malposition of the chick.
Deeming [5] reported that microbial contamination influences embryonic mortality and is
related to the farm and management. Unfortunately, in the present study, stage of development of dead embryos was not identified by
egg analysis.
Mean egg weight was 1,558 and 1,530 g at
collection and at set, respectively (Table 2), and
was higher than those reported for eggs imported
to the United Kingdom from Namibia (1,437 g)
[11] and Zimbabwe (1,403 g) [5], respectively.
Eggs collected on farms in the United Kingdom
[11] and Florida [10] weighed 1,464 and 1,473
g, respectively, whereas More [4] reported a
lower egg weight on Australian farms (1,302 g).
Hatched eggs had greater weights at set
(1,566 g) in comparison with unhatched eggs
(1,510 g), but the differences were not significant. This result did not agree with that reported
by Deeming [5], in which the mean egg weight
at set was 1,382 and 1,440 g for hatched and
unhatched eggs, respectively. Deeming [5] also
found that a higher proportion of heavier eggs
did not hatch. As illustrated in Figure 1, we
found unhatched eggs in both light and middle
egg weight classes.
TABLE 2. Descriptive statistics for egg weight, chick weight, egg weight loss, and chick weight as percentage
of egg weight at set
Item
n
Mean ± SD
All eggs
Egg weight at collection, g
Egg weight at set, g
Egg weight at 13 d of incubation, g
Egg weight at 26 d of incubation, g
Egg weight at 38 d of incubation, g
Chick weight at hatch, g
Egg weight loss from set to 38 d, %
Chick weight/egg weight at set, %
89
89
68
62
61
50
61
50
1,558
1,530
1,471
1,407
1,335
966
14.2
61.7
±
±
±
±
±
±
±
±
Hatched eggs
Egg weight at collection, g
Egg weight at set, g
Egg weight at 13 d of incubation, g
Egg weight at 26 d of incubation, g
Egg weight at 38 d of incubation, g
Egg weight loss from set to 38 d, %
46
46
51
51
51
46
1,592
1,566
1,491
1,415
1,345
14.1
±
±
±
±
±
±
CV
Range
167
165
166
166
171
137
3.5
5.3
0.11
0.11
0.11
0.12
0.13
0.14
0.25
0.09
1,180–1,860
1,150–1,840
1,110–1,750
1,030–1,660
940–1,570
690–1,170
7.3–24.4
47.3–75.2
172
173
171
169
173
3.6
0.11
0.11
0.11
0.12
0.13
0.25
1,210–1,860
1,200–1,840
1,110–1,750
1,030–1,660
940–1,570
7.3–24.4
RIZZI ET AL: OSTRICH EGG PRODUCTION
FIGURE 1. Distribution of fertile egg weight at set as
a function of eggs that hatched (gray) and eggs that
did not hatch (white).
Chick weight at hatch in the current study
was 966 g and was higher than those reported
from farms in Florida (947 g) [10] and in Australia (823 g) [12] (Table 2).
The mean egg weight loss during incubation
was 14.1% and ranged between 7.3 and 24.4%,
whereas newly hatched chick weight, expressed
as a percentage of initial egg weight, was 61.8%
(Table 3). Therefore, egg weight losses were
within the values characteristic for domestic
birds [7, 8, 11, 13]. Weight losses were lower for
hatched eggs (14.1) than unhatched eggs (15.1),
which is in agreement with other trials [5, 8].
Results of analysis of variance showed that
egg weight at collection significantly affected
egg weight at set and at first, second, and third
335
candlings, and chick weight at hatch (P < 0.001).
The regression coefficient indicated a positive
relation at 0.98, 0.92, 0.87, 0.86, and 0.56, respectively.
Egg weights only at set and at the first candling were significantly affected by the storage
period (P < 0.001), and, because a negative relationship was found, it decreased as storage time
increased (−3.5 and −2.9 g/d of storage, respectively).
Storage time showed a stronger effect on the
egg weight recorded close to lay, because it only
influenced egg weight at set and at first candling.
Storage time was found to affect hatchability
and egg weight loss, with the longer egg storage
being associated with lower hatchability [10]
and greater egg weight loss [13]. The positive
and slightly significant relation between storage
time and chick weight at hatch (+9.1 g/d, P
< 0.05) was not clear, even though a similar
association has been reported in chickens [14].
Moreover, in previous research, ostrich chicks
hatched from eggs stored for more than 12 d had
higher hatchling condition scores [13]. Storage
time was also positively and significantly associated with chick weight percentage (+0.6%/d, P
< 0.05).
Least square means and standard errors for
each trio are shown in Table 3. Trio was a significant source of variation for egg weights (P
< 0.001) and chick weights (P < 0.05) with
TABLE 3. Effect of trio on egg weight, chick weight, egg weight loss, and chick weight as percentage of egg weight
at set (least squares means ± SE)
TrioA
Measurement
n
1
2
3
5
Egg weight at set, g
89
Egg weight at 13 d of incubation, g
62
Egg weight at 26 d of incubation, g
57
Egg weight at 38 d of incubation, g
56
Chick weight at hatch, g
46
Egg weight loss from set to 38 d, %
56
Chick weight/egg weight at set, %
46
1,534 ± 3
(13)
1,480 ± 7a
(12)
1,410 ± 9a
(10)
1,336 ± 16a
(9)
940 ± 32a
(8)
14.9 ± 1.1a
(9)
60.3 ± 1.9a
(9)
1,535 ± 3
(16)
1,483 ± 7a
(9)
1,417 ± 11a
(9)
1,354 ± 16a
(9)
925 ± 35a
(9)
13.7 ± 1.2a
(9)
59.4 ± 2.1a
(9)
1,537 ± 34
(31)
1,495 ± 5a
(28)
1,432 ± 7a
(28)
1,364 ± 11a
(28)
945 ± 25a
(24)
13.4 ± 0.9a
(28)
60.2 ± 1.5a
(28)
1,532 ± 3
(17)
1,448 ± 6b
(13)
1,354 ± 11b
(10)
1,260 ± 16b
(10)
790 ± 47b
(5)
22.1 ± 1.7
(10)
50.1 ± 2.9b
(10)
Means in a row with different letters are significantly different (P < 0.05).
Numbers of observations are in parentheses.
a,b
A
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336
TABLE 4. Effect of the month of lay on egg weight, chick weight, egg weight loss, and chick weight as percentage
of egg weight at set (least squares means ± SE)
Month
Measurement
March
April
May
1,551 ± 3
(15)
1,487 ± 6
(10)
1,407 ± 10
(8)
1,326 ± 15
(8)
810 ± 42a
(4)
16.1 ± 1.1
(8)
51.6 ± 2.6a
(4)
a
Egg weight at set, g
Egg weight at 13 d of incubation, g
Egg weight at 26 d of incubation, g
Egg weight at 38 d of incubation, g
Chick weight at hatch, g
Egg weight loss from set to 38 d, %
Chick weight/egg weight at set, %
1,529 ± 3b
(17)
1,472 ± 5
(15)
1,403 ± 8
(14)
1,321 ± 12
(13)
921 ± 27b
(11)
14.4 ± 0.8
(13)
59.0 ± 1.7b
(11)
1,526 ± 2b
(57)
1,470 ± 3
(37)
1,399 ± 5
(35)
1,327 ± 8
(36)
970 ± 19b
(31)
14.7 ± 0.6
(36)
61.9 ± 1.2b
(31)
Means in rows with different letter are significantly different (P < 0.05).
a,b
the exception of egg weight at set. Also, trio
influenced egg weight loss (P < 0.001) and chick
weight percentage (P < 0.05). For a farm in the
United Kingdom, Deeming [5] reported differences among trios and found that productivity
and fertility decreased as group size increased.
Because position, climate, and management
were common to all trios, it was likely that trio
affected the variability of egg weight, even if it
was difficult to ascertain paternal or maternal influence.
Trio 5 showed lower incubated egg and chick
weights in comparison with the other trios. We
noted that Trio 5 also showed the lowest egg
hatchability (26.3%), whereas Trio 3 had the
heaviest eggs and the heaviest hatchability
(78.3%). These results agree with previous work
reporting a positive association between egg
weight and hatchability [4, 6, 7]. The greatest
weight loss was found for eggs from Trio 5
(21.9%), suggesting that eggshell porosity and
thickness would account for it. Gonzales et al.
[8] found the egg weight loss was greater in
eggs having low shell thickness (< 1.7 mm) and
high number of large pores per cubic centimeter
of shell surface area (> 10).
Month of lay significantly affected egg
weight at set, chick weight, and chick weight
percentage (P < 0.05). Table 4 shows least
squares means of all measurements for each
month. Eggs laid in March, at the beginning of
the laying period were heaviest and lost the most
weight, whereas chicks hatched from these eggs
weighed the least. In fowl, eggs laid at the beginning of the laying period are small. The higher
weight of ostrich eggs in March could have been
due to the poor climate, as the weather was cold
and wet in northern Italy. However, there is little
information about the effect of month of lay on
egg and chick weight in ostriches, even if lay
season may affect egg production [9] and hatchability [4].
CONCLUSIONS AND APPLICATIONS
1. Fertility and hatchability were within ranges reported for ostrich farms in other countries. Eggs
were heavier in comparison with data from other reports. Egg weight loss during incubation
was in the typical range reported for ostriches.
2. Because hatched and unhatched eggs occurred in all weight classes, egg weight at set may not
be a predictor of a successful hatch.
3. As the pre-incubation storage time increased, egg weight recorded at set and at first candling
decreased. Because storage time was previously found to affect hatchability and egg weight
loss, eggs should be stored for only a short period before incubation.
RIZZI ET AL: OSTRICH EGG PRODUCTION
337
4. The trio was an important source of variability in fertility, hatchability, and egg weight. In this
study, it was not possible to assess male or female influence. Research is needed on genetic
aspects of reproduction and production in ostriches in order to improve performance.
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