ISRAEL JOURNAL OF
VETERINARY MEDICINE
Vol. 56 (4) 2001
NUTRITION RELATED MICROGNATHIA IN
OSTRICHES
B. Perelman1, D.Fucks1, D. Heller2, M. Schonfeld3
1. Be’eri Ostrich farm and Hatchery,
2. Dept of Poultry Sciences and Immunology, and
3. Interdepartmental Equipment Unit, Faculty of Agriculture, Hebrew University, Jerusalem.
Summary
Very uncommon findings characterized by low hatchability, late embryo mortality, leg deformation
and severe micrognathia, were observed in ostrich eggs and new hatched ostrich chicks from one
ostrich breeding farm located in the south of Israel. These problems were not observed in eggs or
chicks originating from other ostrich farms incubated in the same setters and hatchers in the same
hatchery at the same time. The only outstanding difference between the farms was that on the affected
farm the breeding flock of ostriches was fed with a self-prepared feed without a vitamin or mineral
supplement.
Introduction
Commercial ostrich farming has been carried out in Israel for almost 20 years. During this period,
management procedures, nutrition, incubation and hatching conditions have reached very good levels
and today Israel is considered the second largest producer of ostriches in the world after South Africa.
The economic situation of the ostrich industry in 1998, forced some of the farms to try and cut costs
of production to a minimum. Reduction in the cost of production included in some cases reduction in
the quality of the feed provided, such as the use of maintenance feeds during the breeding season or
withdrawal of premixes containing vitamins and microelements.
During the breeding season of 1998, a significant reduction of hatchability was reported by a regional
ostrich hatchery in the Negev area in Israel. Analysis of the data accumulated in the hatchery showed
that most of the reduction observed was related to a significantly lower hatchability in the eggs
originating from one of the ostrich farms incubating eggs at the same time in this hatchery.
Examination of the eggs and piping embryos revealed that many of the dead in shell chicks suffered
from leg deformations and severe micrognathia.
Analysis of the feed provided to the breeding flock as well as determination of the levels of macroand microelements in the yolk and liver of affected embryos were performed in order to try to
determine the possible cause of this unusual and interesting case.
To our best knowledge, this is the first report of nutritional related micrognathia in ostrich chicks
caused by an apparent deficiency in the feed of the parent flock.
Description of the clinical case:
A significantly lower hatchability rate was first observed in a commercial hatchery for ostriches
located in the Southern part of Israel. The commercial hatchery incubates and hatches ostrich eggs
from different ostrich farms and is equipped with modern Pro-Hatch setters and hatchers with accurate
environmental electronic control during the incubation and hatch periods. The incubation lasts 42 days
in temperature of 360C and relative humidity of 30%. The hatchery carries out routine candling and
examination of eggs, and keeps an accurate computerized data follow up and records.
During the breeding season of 1998, eggs originating from one of the ostrich farms (Farm A)
suffered from a significantly lower hatchability rate when compared to ostrich eggs originating from
other ostrich farms (B and C) and incubated in the same setters and hatchers under the same incubation
and hatching conditions.
Examination of piping non-hatched fertile eggs revealed that most of the dead in shell ostrich
embryos originating from Farm A were well developed but more than 30% of the embryos examined
showed bent tarsal bones and severe micrognathia.
All the farms supplying eggs to this commercial hatchery have the same genetic source.
The affected ostrich breeding flock is located in the northern part of the Negev and has a
population of breeding ostriches of about 900 birds in their second year of production. About
50% of the breeding birds are kept as trios in closed pens of 50X50 meters. Water is provided
ad lib. and the farmer provides all their feed on a daily basis. The rest of the breeding flock is
located in two large pens called the "Safari" (about 250 birds each) and kept as a large mixed
flock with males and females under semi-extensive management conditions.
The feed provided to the ostriches in this farm was a mixture of hay, silage and grains
without any vitamin or minerals additions. This mix was calculated to provide a minimum of
16% protein and about 2750 Kcal energy per kg feed.
All the birds in the trio pens received this diet as the only feed, while the birds at the large
enclosure pens received the same feed prepared by the farm but had the chance to eat the
natural vegetation that grew inside the large pen during the first months of the breeding
season (between January and September).
All the other farms in the area received during the same season a balanced concentrated diet provided
by a commercial feed mill specializing in ostrich feed. The levels of protein in this feed was 16%, and
2750 kcal of energy with the addition of a balanced premix formulated for breeding ostriches
containing balanced levels of macro and microelements as well as recommended levels of vitamins.
Materials and Methods
Commercial ostrich farming has been carried out in Israel for almost 20 years. During this period,
management procedures, nutrition, incubation and hatching conditions have reached very good levels
and today Israel is considered the second largest producer of ostriches in the world after South Africa.
The economic situation of the ostrich industry in 1998, forced some of the farms to try and cut costs
of production to a minimum. Reduction in the cost of production included in some cases reduction in
the quality of the feed provided, such as the use of maintenance feeds during the breeding season or
withdrawal of premixes containing vitamins and microelements.
During the breeding season of 1998, a significant reduction of hatchability was reported by a regional
ostrich hatchery in the Negev area in Israel. Analysis of the data accumulated in the hatchery showed
that most of the reduction observed was related to a significantly lower hatchability in the eggs
originating from one of the ostrich farms incubating eggs at the same time in this hatchery.
Examination of the eggs and piping embryos revealed that many of the dead in shell chicks suffered
from leg deformations and severe micrognathia.
Analysis of the feed provided to the breeding flock as well as determination of the levels of macroand microelements in the yolk and liver of affected embryos were performed in order to try to
determine the possible cause of this unusual and interesting case.
To our best knowledge, this is the first report of nutritional related micrognathia in ostrich chicks
caused by an apparent deficiency in the feed of the parent flock.
Description of the clinical case:
A significantly lower hatchability rate was first observed in a commercial hatchery for ostriches
located in the Southern part of Israel. The commercial hatchery incubates and hatches ostrich eggs
from different ostrich farms and is equipped with modern Pro-Hatch setters and hatchers with accurate
environmental electronic control during the incubation and hatch periods. The incubation lasts 42 days
in temperature of 360C and relative humidity of 30%. The hatchery carries out routine candling and
examination of eggs, and keeps an accurate computerized data follow up and records.
During the breeding season of 1998, eggs originating from one of the ostrich farms (Farm A)
suffered from a significantly lower hatchability rate when compared to ostrich eggs originating from
other ostrich farms (B and C) and incubated in the same setters and hatchers under the same incubation
and hatching conditions.
Examination of piping non-hatched fertile eggs revealed that most of the dead in shell ostrich
embryos originating from Farm A were well developed but more than 30% of the embryos examined
showed bent tarsal bones and severe micrognathia.
All the farms supplying eggs to this commercial hatchery have the same genetic source.
The affected ostrich breeding flock is located in the northern part of the Negev and has a
population of breeding ostriches of about 900 birds in their second year of production. About
50% of the breeding birds are kept as trios in closed pens of 50X50 meters. Water is provided
ad lib. and the farmer provides all their feed on a daily basis. The rest of the breeding flock is
located in two large pens called the "Safari" (about 250 birds each) and kept as a large mixed
flock with males and females under semi-extensive management conditions.
The feed provided to the ostriches in this farm was a mixture of hay, silage and grains
without any vitamin or minerals additions. This mix was calculated to provide a minimum of
16% protein and about 2750 Kcal energy per kg feed.
All the birds in the trio pens received this diet as the only feed, while the birds at the large
enclosure pens received the same feed prepared by the farm but had the chance to eat the
natural vegetation that grew inside the large pen during the first months of the breeding
season (between January and September).
All the other farms in the area received during the same season a balanced concentrated diet provided
by a commercial feed mill specializing in ostrich feed. The levels of protein in this feed was 16%, and
2750 kcal of energy with the addition of a balanced premix formulated for breeding ostriches
containing balanced levels of macro and microelements as well as recommended levels of vitamins.
Results
Incubation and hatching parameters:
Fertility rates from the beginning of the breeding season ranged from 55% in farm B to 60% in farm
A and reached 68% in eggs from farm C (table 1). These fertility rates are within acceptable limits for
ostrich farms and the differences observed among the different farms will be further discussed.
Early mortality levels as determined by examination of eggs at 14 days of incubation showed that
early embryo mortality was 6% in farm A, and 4% in farms B and C (table 1).
Egg contamination was observed in 2% of the eggs from farms A and B but not in eggs from farm C
(table 1). Embryo contamination was related in most of the cases to early mortality of the embryos and
in a much less extent to late mortality.
The most outstanding finding was the great difference in the late embryo mortality observed among
the three different farms. As summarized in table 1, late mortality ranged from 12% and 16% in farms
C and B respectively to 26% in farm A.
According to the summarized data, the hatchability rates observed ranged from 66% for farm A to
78% for farm B and 84% for farm C (table 1), and correlated with the levels of the late embryo
mortality observed for each one of the ostrich farms.
Comparison of incubation and hatching parameters of eggs and embryos
from three different ostrich farms incubated and hatched at the same hatchery under
the same conditions.
Table.1.:
Farm
No.
of
eggs
Fertility
(%)
Early
mortality
(%)
Contaminated
(%)
Late
Mortality
(%)
hatchability
from fertile
(%)
Micrognathia
in embryos
A
3506
60
6
2
26
66
Yes
B
2256
55
4
2
16
78
No
C
415
68
4
0
12
84
No
Examination and analysis of the data accumulated at the hatchery during the breeding season,
revealed great differences in the levels of fertility and hatchability between the breeding systems used
in the affected farm A as summarized in table 2.
Fertility was almost ten percent higher (65%) in the safari system compared to the trio pens (56%).
But the difference in the hatchability rates reached 20% with 58% hatchability observed in the trio pens
compared with 78% in the safari system (table 2).
Pathological examination of dead in shell and piping embryos.
The pathological examination of eggs and piping embryos from the different farms revealed that
early mortality in all the farms was within normal limits and ranged from 4% in farms B and C to 6 %
in farm A (table.1). No specific pathological changes were observed in the small embryos examined
from any one of the farms.
Examination of (late) dead in shell and piping embryos revealed great differences in the percentage
of late mortality between the farms (table 1). The most outstanding finding was that 15 out of 40
(37.5%) of the dead in shell and piping embryos from farm A, suffered from severe micrognathia of the
lower jaw (fig.1) and short bent tarsal bones (fig.2). These findings were not observed in any of the
examined embryos originating from farms B and C.
Fig.1: Typical and severe micrognatia in a dead in
shell ostrich chick. Some of the affected chicks
hatched and suvived but most of them had to be
culled later because of retarded growth and
development of leg deformities.
Fig. 2. Short
and bent tarsal - metatarsal
bones as observed in all affected ostrich
chicks. It seems that the leg deformities
were the main cause of death in shell of
full developed chicks.
More accurate examination of the origin of the dead in shell and piping embryos from farm A
revealed the fact that micrognathia and bent legs were observed only in eggs originating from
the trio pens but not in eggs originating from the "safari" camps, thus explaining the big
difference in the hatchability rate observed between camps in farm A (table 2).
Comparison of incubation parameters of eggs and embryos from trio pens
and safari system in farm A.
Table. 2.:
Farm A
Total
eggs
Total
fertile
%
Fertile
Total
hatched
Hatched from
fertile %
Micrognathia
in embryos
Trio
pens
1879
1045
56
612
58
Yes
Safari
1627
1055
65
820
78
No
Table 3 summarizes the levels of macro- and microelements found in the self-made feed at farm A
and the commercial feed provided to the ostriches in the other farms. According to the data
summarized in table 3, major differences were found in the levels of some of the macro- and
microelements that can be related to the development of the skeletal system such as Ca, Cr, Cu, Mg,
Mn, Zn and Si.
According to data summarized in table 3 the levels of Ca were 3900 mg/Kg in feed from farm A,
compared to 31400mg/Kg found in the commercial feed. The level of Cr found in the feed from farm A
was 0.87mg/Kg as compared with 5.07 mg/Kg in the commercial feed. The level of Cu in feed from
farm A was 12.4 mg/Kg compared to 27.8 mg/Kg in the commercial feed. The level of Mg in the feed
from farm A was much higher than that found in the commercial feed reaching 4400mg/Kg compared
to 1780 mg/Kg in the commercial feed. The level of Mn in the feed at farm A was 110mg/Kg
compared to 200mg/Kg in the commercial feed. The level of Zn in feed from farm A was 55mg/Kg
compared to 158 mg/Kg in the commercial feed. The level of Si was much higher in the feed from farm
A, 436 mg/Kg, compared with 66 mg/Kg in the commercial feed.
Comparison of macro- and microelements in the self-made feed and the
commercial concentrate.
Table. 3.
Self-made feed - Farm A
Average
Std. Div.
mg/Kg
Commercial Concentrate for Ostriches
Average
Std. Div
mg/Kg
Al
216
9
92
14
B
4.2
0.9
11.3
2.0
Ba
21.4
0.9
7.91
0.6
Ca
3900
1200
31400
1000
Cd
0.15
0.03
0.62
0.05
Cr
0.86
0.0
5.07
0.56
Cu
12.4
0.2
27.8
9.4
Fe
316
2
150
15
K
16300
1800
8600
740
Mg
4400
170
1780
220
Mn
110
7
200
21
Mo
0.8
0.1
2.7
0.1
Na
2000
480
2030
604
Ni
2.8
0.3
6.9
1.2
Sn
2.0
0.5
2.6
0.4
Sr
12.6
0.7
9.3
0.7
Ti
4.3
0.3
2.0
0.3
V
0.8
0.0
6.6
0.7
Zn
55
1
158
34
S
2260
160
2310
293
Si
436
45
66
8
P
9400
240
11200
1040
Element
Table 4 summarizes the levels of macro- and microelements found in the liver of normal and affected
embryos showing micrognathia and leg deformations.
According to the data summarized in table 4, the only constant finding was a much lower level of Ca
in the liver of affected embryos (61-62 mg/Kg) as compared to the levels observed in the liver of
apparently normal embryos (80 - 86 mg/Kg).
Table. 4: Mineral
Ca
Mg
Sn
Zn
content (mg/Kg)* of the liver of normal and affected embryos.
Normal
pool 1
Normal
pool 2
Normal
pool 3
Short beak
pool 1
Short beak
pool 2
80
79
0.75
6.4
86
52
0.48
3.7
83
90
1.26
4.5
61
65
0.67
4.3
62
119
0.77
4.0
S
Si
P
1400
4.2
1030
864
2.0
409
1190
1.7
1950
1270
1.7
1050
2055
1.6
590
*Pool of 2 embryo livers per sample
Table 5 summarizes the results obtained from the determination of the macro- and microelements in
the yolk of eggs obtained from farms A and B.
Levels of microelements in the yolk of ostrich eggs obtained from affected pens at farm A were quite
similar to the values obtained in the yolk of ostrich eggs without any apparent problem originating
from not affected farms.
There are two samples from farm A that show very low levels of most of the microelements.
Comparison of mineral content (mg/Kg) in the yolk of 11 ostrich eggs from
the affected farm (A) and a non-affected farm (B).
Table.5:
Farm A
EGG
Ca
Cd
Co
Cr
Cu
Fe
Hg
Farm B
1
2
3
4
471*
406*
2100 1950
>0.02
>0.02
0.04* 0.04* 0.2
0.21
0.99
1.18
1.13 1.03
16.5
10.8* 106
73
Less than 0.02 in all samples
5
6
1
1900 1720 1690
0.04
>0.02
0.2
0.2
0.17
1.04 1.14 1.13
100
78
85
2
3
4
5
1800 1930 1420 1700
0.05 0.03 0.03 0.03
0.2
1.2
83
0.22
1.15
88
0.13
1.07
52
0.15
1.1
68
K
Li
Mg
Mn
1170 985
1760 1500 1650 1510 1550 1467 1777 1240 1410
Less than 0.02 in all samples
169
146
163
159
134
146
141
156
157
164
166
0.15* 0.06* 0.87 0.3
0.8
0.53 0.55 0.67 0.67 0.32 0.34
Mo
Na
0.10* 0.10* 0.28
1950* 2190* 455
Ni
Se
Sn
Pb
S
Si
Less than 0.05 in all samples
0.2*
0.2*
0.5
0.54
0.9*
1.0*
2.4
2.64
Less than 0.1 in all samples
1500* 1400* 1800 1800
2.6
3.3
5.4
2.5
P
1200* 1090* 6000 5900 5800 5600 5300 5540 6400 4310 4900
0.16
520
0.47
375
0.39
500
0.18
690
0.16
530
0.23
530
0.20 0.14
1140 790
0.53
2.43
0.62
2.47
0.75
1.9
0.93
2.2
0.76
2.1
0.45
1.9
0.55
2.1
1720 1680 1800 1820 1980 1680 1800
4.3
5.8
2.6
3.3
2.6
3.2
3.7
* Significant p< 0.005
Discussion
Micrognathia in birds and poultry is a very seldom reported disorder that may have a hereditary,
vitamin deficiencies or incubation conditions background (1).
The fact that the same ostriches produced completely normal chicks in the previous breeding season
greatly reduces the possibility of a genetic or hereditary disorder.
A hereditary or congenital disorder related to inbreeding or other reason would be a seldom observed
finding and would not appear in such a big scale.
The incubation and hatching conditions in the hatchery were the same for all eggs incubated during
the same season. The fact that the disorder was observed only in eggs from the trio pens but not in any
of the eggs incubated at the same time in the same setters and hatchers greatly reduces the possibility of
an incubation related problem.
There is no doubt that the low hatchability was directly related to the high rate of late mortality.
Ostrich chicks hatch from the eggs with the help of the toes and legs. Malpositions and deformed bones
and legs would lead to large numbers of chicks unable to hatch properly as happened in this case.
In this report the reduced hatchability due to high embryo mortality at the end of the incubation
process as well as the micrognathia and the short and bent tarsus, seem to be directly related to some
nutritional deficiencies or imbalance in the feed provided to the breeding birds.
Despite the fact that the self prepared feed contained different grains and a normal amount of protein
and energy, the lack of a balanced premix containing the right amounts of vitamins and/or
microelements in the diet seems to be directly related to the embryo mortality as well as the
malformations observed in the ostrich chicks (1).
An outstanding finding is the fact that the low hatchability and the malformations of the beak and the
legs were observed only in eggs and ostrich chicks from ostriches kept in trio pens, where all the diet
consumed by the ostriches was the self made feed without any options of consumption of a more varied
diet, as was the case with ostriches in the safari system that received the same diet but were able to
include in their diets other components such as insects or plants growing in the pens.
The analysis of the feed in the affected ostrich farm revealed many significant differences between
the self-made feed and the balanced concentrate. According to the data obtained in the analysis of the
feed as that showed in Table 3, it is not possible to pinpoint a specific element as the most probable
cause of the findings and disorders reported.
It is most probable that not only the absolute level of a single element was the main cause of the
micrognathia and the leg deformation, but an imbalance of the major minerals in the feed thus causing
a further imbalance in the egg content and the shell (2,3).
Determination and comparison of the levels of macro- and microelements in the yolk and liver of
affected chicks were supposed to provide some indication about a probable specific imbalance or
deficiency, but the low number of samples does not enable to obtain any conclusion.
The significant lower levels of minerals (Ca, P, Mg, Fe) as well as the high levels of sodium (Na)
found in two of the egg yolk samples, strongly suggest dilution of the yolk with the albumen (4),
probably related to a technical mistake. The levels of macro- and microelements found in the yolk of
the ostrich eggs are quite similar to those reported in chicken eggs (4).
This seems to be the first report of micrognathia and leg deformations in ostrich embryos directly
related to a multimineral or even vitamin deficiency or misbalance in the diet of the parent flock.
References
1. Deeming, D. C.: Ratite egg incubation a practical guide. Ratite Conference, c/o 2 Milldun
Way, High Wycombe, Buckinghamshire, HP12 3JA, UK. 1997.
2. Austic, R. E. and Scott, M. L.: Nutritional Diseases. In: Calnek, B. W., Barnes, H.J., Beard, C.
W., McDougal, L. M. and Saif, M. Y. (Eds.): Diseases of Poultry. 10th Ed. Iowa State
University Press, Ames, Iowa, USA. pp. 47-73, 1997.
3. Toone, C. K.: Causes of Embryonic malformations and mortality. Proceedings of the
American Association of Zoo Veterinarians. Tampa, Fl. 1983.
4. Romanoff, A. L. and Romanoff, A. J.: The Avian Egg. John Wiley & Sons, Inc., New York,
1949.