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901
INTRODUCTION
Angel wing (AW) occurs on either or both wings of
birds and affects the carpometacarpus or the joint between
the third and fourth metacarpals that twists outward away
from body mostly during growth, resulting in wings
resembling those of an angel (Grow, 1972; Mildred and
Holderread, 1981). AW occurs in various species, including
swan goose, giant Canada goose, Hawaiian goose, Andean
goose, Magellan goose, blue-winged goose, Egyptian goose,
Indian spotbill, Puna teal, New Zealand gray duck, African
yellow-billed duck, chestnut-breasted teal, crested duck,
red-crested pochard, rosybill, mountain duck, and wild-type
Muscovy (Kear, 1973). Moreover, the inability of wild
waterfowls to fly substantially posed threat to their lives
and conservation. Domestic geese can also be affected by
AW (Francis et al., 1967); nevertheless, their production
efficiency is unaffected.
Few studies have reported the incidence of AW (IAW).
Francis et al. (1967) indicated that AW in White Chinese
geese was mainly due to hereditary factors; however, most
studies on wild waterfowl have revealed that environmental
factors are more crucial. Kear (1973) reported that
inappropriate nutrition, high-protein diet, and lack of
exercise were the main causes of AW in wild waterfowl.
Kreeger and Walser (1984) hypothesized that AW in giant
Canada geese occurs because of their rapidly growing flight
feathers, with the consequent weight gain exceeding the
muscular stabilization of the carpal joints; eventually,
gravity pulls the wing tip outward. AW also occurs in
rapidly growing birds, such as domestic and wild waterfowl
fed by humans. IAW is associated with overfeeding; an
unbalanced diet, including excessive protein intake; and
calcium, manganese, and vitamin D deficiency (Kuiken et
al., 1999). However, these results were based only on the
observation of wild birds. Thus far, no rigorous experiments
Open Access
Asian Australas. J. Anim. Sci.
Vol. 29, No. 6 : 901-907 June 2016
http://dx.doi.org/10.5713/ajas.15.0456
www.ajas.info
pISSN 1011-2367 eISSN 1976-5517
Factors Affecting the Incidence of Angel Wing in White Roman Geese:
Stocking Density and Genetic Selection
M. J. Lin1,2, S. C. Chang1,2, T. Y. Lin2, Y. S. Cheng3, Y. P. Lee1, and Y. K. Fan1,*
1 Department of Animal Science, National Chung Hsing University, Taichung 40227, Taiwan
ABSTRACT: The present study investigated stocking density and genetic lines, factors that may alter the severity and incidence of
angel wing (AW), in White Roman geese. Geese (n = 384) from two genetically selected lines (normal- winged line, NL, and angel-
winged line, AL, respectively) and one commercial line (CL) were raised in four pens. Following common commercial practice, low-
stocking-density (LD), medium-stocking-density, and high-stocking-density treatments were respectively administered to 24, 32, and 40
geese per pen at 0 to 3 weeks (1.92 m2/pen) and 4 to 6 weeks (13.2 m2/pen) of age and to 24, 30, and 36 geese at 7 to 14 weeks (20.0
m2/pen) of age. The results revealed that stocking density mainly affected body weight gain in geese younger than 4 weeks, and that
geese subjected to LD had a high body weight at 2 weeks of age. However, the effect of stocking density on the severity score of AW
(SSAW) and incidence of AW (IAW) did not differ significantly among the treatments. Differences were observed among the genetic
stocks; that is, SSAW and IAW were significantly higher in AL than in NL and CL. Genetic selection generally aggravates AW,
complicating its elimination. To effectively reduce IAW, stocking density, a suspected causal factor, should be lower than that presently
applied commercially. (Key Words: Angel Wing, Stocking Density, Genetics, White Roman Geese)
Copyright © 2016
by Asian-
A
ustralasian Journal of Animal Sciences
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/),
which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
* Corresponding Author: Y. K. Fan. Tel: +886-4-22853748,
Fax: +886-4-22860265, E-mail: ykfan@dragon.nchu.edu.tw
2 Changhua Animal Propagation Station, Livestock Research
Institute, Council of Agriculture, Executive Yuan, Changhua
52149, Taiwan.
3 Livestock Research Institute, Council of Agriculture, Executive
Yuan, Tainan 71246, Taiwan.
Submitted May 24, 2015; Revised Jul. 6, 2015; Accepted Aug. 2, 2015
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
902
have been conducted for elucidating the mechanism of AW.
Geese rearing is a vital farming activity in Taiwan, and
White Roman geese account for approximately 97.6% of
the market share (Wang et al., 1996). An on-farm
investigation revealed a 5% to 50% IAW in a flock (Lee,
2004). If AW is observed in >30% of the birds in a flock,
the entire flock is commercially rejected in Taiwan.
Considering the aforementioned factors, we performed a
series of experiments investigating factors such as etiology,
stocking density, dietary mycotoxin effects, dietary nutrition
concentration, and heredity, which may be associated with
IAW in White Roman geese. In this study, we examined the
effect of stocking density, which possibly causes, triggers,
or prevents IAW, in three genetic lines of White Roman
geese.
MATERIALS AND METHODS
Birds and management
All geese were reared and maintained according to the
Regulations of Laboratory Animals, Changhua Animal
Propagation Station, Livestock Research Institute (CAPS-
LRI, 23°51ʹN and 120°33ʹE), Council of Agriculture,
Taiwan. Normal lines and AW lines (hereafter, NL and AL,
respectively) originating from the same lineage of high-
body-weight geese (Lin et al., 2010) were established at
CAPS-LRI in 2008 by divergent selection for normal wings
(NWs) and AWs, judged by the appearance at 14 weeks of
age. Geese obtained from a commercial farm comprised the
commercial line (CL).
Day-old goslings were placed in the primary house with
a cemented floor after vent sexing and foot band aging. The
goslings were moved to the growing house at 3 weeks of
age and relocated at 6 weeks to another growing house with
a pool.
The geese were fed commercial rations containing 20%
crude protein (CP) in addition to 2,900 kcal/kg
metabolizable energy (ME) and 15% CP in addition to
2,800 kcal/kg ME (Table 1) during 0 to 4 (brooding stage)
and 5 to 14 weeks (growing stage) of age, respectively. At 0
to 14 weeks of age, the geese were fed dietary CP according
to the concentration recommended by the National
Research Council (NRC, 1994). The dietary ME content fed
to the geese in the brooding stage was also in conformance
with NRC recommendations (1994). However, the dietary
ME content fed to the geese in the growing stage was lower
than that recommended (3,000 kcal/kg) by the NRC,
following the commendations of studies pertaining to and
conducted under the high ambient temperature and
humidity in Taiwan.
The goose house was cleaned two times weekly.
Mashed diets and drinking water were provided ad libitum.
Table 1. Components and compositions of the experimental diets
Item Experimental diet
Starter (0 to 4 week) Grower (5 to 14 week)
Ingredients (g/kg)
Yellow corn 614 642.5
Soybean meal, 44% 260 215
Wheat bran 20 50
Fish meal, 65% crude protein 50
Molasses 30 30
Salt 3 3
Dicalcium phosphate, 22% phosphorous 10 16
Limestone, pulverized 7 8
Choline chloride, 50% 1 1
DL-methionine 2.5 2
Rice bran - 30
Vitamin premix1 1 1
Mineral premix2 1.5 1.5
Calculated values
Crude protein (%) 20 15
Metabolizable energy (kcal/kg) 2,900 2,800
Analyzed values
Crude protein (%) 19.8±0.11 (N = 3) 14.8±0.13 (N = 3)
Gross energy (kcal/kg) 3,880±74.7 (N = 3) 3,621±22.8 (N = 3)
1 Vitamin premix: Each kilogram contained 3 g retinol, l0.05 g cholecalcifero, 18.2 g D-a-tocopherol, 1 g thiamin, 4.8 g riboflavin, 3 g pyridoxine, 0.01 g
cobalamin, 0.2 g biotin, 1.5 g menadione, 10 g D-calcium pantothenate, 0.5 g folic acid, and 25 g nicotinic acid.
2 Mineral premix: Each kilogram contained 15.0 g copper, 80 g ferrum, 50 g zinc, 80 g manganese, 0.25 g cobalt, and 0.85 g iodine.
Mean±standard deviation.
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
903
During 0 to 3 weeks of age, light and heat were supplied all
day by using a 60-W incandescent bulb, and the highest and
lowest ambient temperatures of the nursery house were
31.2°C±1.62°C and 27.2°C±1.03°C, respectively.
Subsequently, the birds were exposed to natural light, and
the average ambient temperature was 26.4°C±4.05°C.
Experimental design
Twelve pens were randomly assigned to low, medium,
and high stocking density (hereafter, LD, MD, and HD,
respectively), and each pen included the genetic lines NL,
AL, and CL.
LD, MD, and HD treatments were administered to 24,
32, and 40 geese in a wire-floor pen of area 1.92 m2 (12.5,
16.7, and 20.8 kg body weight/m2) from hatching to 3
weeks of age, in a cemented floor pen of area 13.2 m2 (4.64,
6.18, and 7.73 kg body weight/m2) from 4 to 6 weeks of age,
and in a cemented floor pen of area 20.0 m2 (5.75, 7.18, and
8.62 kg body weight/m2) from 7 to 14 weeks of age. In total,
384 geese (90, 69, and 225 AL, NL, and CL geese,
respectively) were included. Each pen comprised 7 to 8
geese with NWs and 6 to 7 geese with AWs; the rest were
CL geese included to balance the number of males and
females.
Growth performance
The body weight and weight gain of the geese were
measured biweekly and individually. Feed consumption was
recorded on a pen basis up to 14 weeks of age, and feed
conversion ratios were accordingly calculated.
Severity score and incidence of angel wing
Field observations in Taiwan show that goslings
generally start molting feathers at 2 weeks of age, and their
primary feathers completely grow by 5 to 6 weeks of age.
Furthermore, AW in geese occurs at 6 weeks of age; no AW
occurs after 13 to 14 weeks of age.
Therefore, the severity score of AW (SSAW) and IAW
of geese were recorded biweekly and individually at 6 to 14
weeks of age. A wing was judged to be AW if the end of the
primary feather did not closely and smoothly fit into its
body. AWs were visually categorized as slight, medium, and
severe according to the degree of projection of the primary
feathers away from the body ([<30°, 30° to 60°, and >60°
and Figures 1b to 1d], respectively). The slight, medium,
and severe AWs were scored 1, 2, and 3, respectively, and
the sum score of a pair of wings, ranging from 0 to 6, was
defined as the SSAW of a goose. A score of 0 indicated NW
(Figure 1a) and 6 indicated severe AW in both wings
(Figure 1d). The IAW of a flock was defined as the
proportion of geese with AW.
Statistical analyses
Growth performance and SSAW were statistically
(a) Normal wing (b) Slight angel wing
(c) Medium angel wing (d) Severe angel wing
Figure 1. Appearances of a normal wing and the severity of angel wing in White Roman goose. (a) A normal bird wing is covered with
smooth, neat, and clean feathers that fit neatly along its body. Angel wings with the primary feathers projecting away from the body at an
angle of <30°, 30° to 60°, and >60° were categorized as (b) slight, (c) medium, and (d) severe, and scored 1, 2, and 3, respectively. The
severity score of a pair of angel wings ranged from 0 (normal wings [a]) to 6 (two severe angel wings [d]). These definitions are from Lin
et al. (2012).
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
904
analyzed using the general linear model procedure of SAS
(2004), and the mean AW and NW of geese were compared
by using the LSMEANS statement. The significances of
IAW among the three stocking densities and genetic lines
were tested using the chi-square test and the frequency
procedure of SAS.
RESULTS
Growth performance
The effects of stocking density and genetic lines on
body weight and weight gain are shown in Table 2. The
body weight of geese subjected to LD was higher because
of the weight gain at 4 weeks of age. By contrast, body
weight gain was higher for AL and NL geese at 6 weeks of
age, resulting in higher body weights than that of CL geese
at ≥8 weeks of age. No significant interaction effects of
stocking densities with genetic lines were observed on body
weight gain.
The average feed consumption for the three stocking
densities are detailed in Table 3. Geese subjected to HD had
less feed consumption at ≤8 weeks of age. However, no
significant differences were observed in the feed conversion
ratio among the three stocking densities during the growth
stage.
Severity score of angel wing and incidence of angel wing
The effects of stocking density and genetic line on
SSAW and IAW in White Roman geese during 6 to 14
weeks of age are shown in Table 4. Geese subjected to LD
reported a lower IAW at 6 weeks of age; however, no
significant differences were observed in SSAW and IAW
among the three stocking densities from 8 to 14 weeks of
age. Compared with CL and NL, AL, a line genetically
selected for a high IAW, had a higher SSAW and IAW at ≥8
weeks of age (p<0.001). In AL, NL, and CL, IAW, and
SSAW, measured at 14 weeks of age when AWs were
morphologically visible, were 69.5%, 32.5%, and 32.6%
and 2.54, 0.98, and 0.90, respectively. The stocking density
and genetic lines revealed no significant interaction effects
on SSAW and IAW.
Tabl e 2. Effects of stocking density and genetic lineage on body weight and weight gain in 0 to 14-week-old White Roman geese
Age Stocking density SEM1 Line SEM2 Significance3
LD MD HD AL NL CL D L D×L
Body weight (kg/bird)
0 wk 0.105 0.102 0.103 0.001 0.107 0.104 0.099 0.001 NS NS NS
2 wk 0.689a 0.611
b
0.558
b
0.02 0.599 0.584 0.642 0.01 ** NS NS
4 wk 1.55a 1.31
b
1.15c 0.04 1.36 1.33 1.34 0.03 ** NS NS
6 wk 2.87a 2.51
b
2.38c 0.03 2.59 2.64 2.55 0.03 *** NS *
8 wk 3.97a 3.62
b
3.41c 0.03 3.75a 3.78a 3.57
b
0.04 *** ** NS
10 wk 4.66a 4.42
b
4.17c 0.04 4.52a 4.59a 4.29
b
0.04 *** *** †
12 wk 4.96a 4.72
b
4.38c 0.07 4.79a 4.90a 4.56
b
0.06 ** ** NS
14 wk 5.09a 4.84
b
4.56c 0.05 4.93
b
5.13a 4.67c 0.05 *** *** NS
Body weight gain (kg/bird)
0 to 4 wk 1.44a 1.21
b
1.05c 0.04 1.25 1.22 1.24 0.03 ** NS NS
5 to 8 wk 2.42 2.30 2.24 0.06 2.37 2.42 2.23 0.05 NS NS NS
9 to 14 wk 1.12 1.22 1.14 0.04 1.19
b
1.33a 1.10
b
0.03 NS *** NS
0 to 14 wk 4.98a 4.74
b
4.45c 0.04 4.82a 4.99a 4.57
b
0.06 *** *** NS
LD, low stocking density; MD, medium stocking density; HD, high stocking density; AL, angel wing line; NL, normal wing line; CL, commercial line; L,
genetic line; D, stocking density; L×D, the interaction of stocking density with genetic line.
1 SEM, standard error of the mean of stocking densities. 2 Standard error of the mean of genetic lines.
3 NS, nonsignificantly different or p>0.1. † p<0.1; * p<0.05; ** p<0.01; *** p<0.001.
a,b,c Stocking densities and genetic lines with different superscripts differ significantly (p<0.05).
Tabl e 3 . Effect of stocking density on feed consumption and the
conversion ratio in 0 to 14-week-old White Roman geese
Age Stocking density SEM Significance1
LD MD HD
Feed consumption (kg/bird)
0 to 4 wk 2.93a2.47
b
2.05c 0.06 ***
5 to 8 wk 9.59a8.68
b
8.15
b
0.17 **
9 to 14 wk 11.3 11.1 10.5 0.15 NS
0 to 14 wk 23.8a22.2
b
20.7c 0.14 ***
Feed conversion ratio
(kg feed/kg body weight gain)
0 to 4 wk 2.03 2.04 1.95 0.02 †
5 to 8 wk 3.97 3.77 3.66 0.13 NS
9 to 14 wk 10.0 9.09 9.17 0.27 NS
0 to 14 wk 4.77 4.70 4.65 0.06 NS
LD, low stocking density; MD, medium stocking density; HD, high
stocking density; SEM, standard error of means.
NS, nonsignificantly different or p>0.1; † p<0.1. ** p<0.01; *** p< 0.001.
a,b,c Entries in the same row with different superscripts differ significantly
(p<0.05).
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
905
DISCUSSION
Kear (1973) reported that IAW in wild geese is affected
by several factors, including; lack of exercise, large flock
size, improper feeding, rearing under heat stress because of
high ambient temperatures, feeling frightened frequently,
and improper management.
Among all unfavorable factors, HD is observed most
frequently. Commercial farms usually rear as many birds as
possible in as little space as possible to reduce the fixed
production cost. The amount of space that sustains
favorable productivity is not necessarily sufficient for the
exercise necessary for a normally developing wing and
muscle strengthening. Stocking density may cause stressful
social and physical environments, subsequently triggering
IAW in geese and other birds. In Taiwan, a common
practice is to rear 500 goslings in a 36 m2 pen during the
brooding stage (13.9 birds/m2), gradually increasing the
space to 1.2–1.5 birds/m2 as the geese grow. The stocking
density in this experiment was 12.5 to 20.8, 1.8 to 3.0, and
1.2 to 1.8 birds/m2 for 0 to 3, 4 to 6, and 7 to 14-week-old
birds, respectively.
The stocking density implemented in this study for
geese from hatching to 3 weeks of age appeared to be
ineffective, and the outcomes deteriorated with increasing
stocking density. Furthermore, the body weight gain by 4
weeks of age (Table 2) was mostly attributable to the
restriction of feed consumption by HD (Table 3). The effect
of stocking density on IAW was not as clear as it was on
body weight gain; however, LD significantly reduced IAW
(Table 4). The effect of LD and that of the average of MD
and HD on IAW at 6 weeks of age was non-significant
(15.4% vs 25.3%; x2 = 3.53, df = 2, p>0.10). By contrast,
compared with the average of MD and HD, LD
significantly influenced NL (4.17% vs 25.8%, x2 = 5.57, df
= 2, p<0.10). In this study, NL more sensitively responded
to the stocking density than did AL, which probably
required more space for avoiding AW. These results suggest
that the stocking density required for triggering IAW varies
among genetic lines. Additional related studies are required
for elucidating the cause–effect of AW and stocking density.
No significant difference was observed in SSAW and
IAW among the three stocking densities at 6 weeks of age
(Table 4), suggesting that the HD applied in this study
presented a satisfactory growth performance but not
sufficient space for avoiding IAW. In rapidly growing
poultry, bone development and maturity cannot keep pace
with the overall growth, generating excess physical load
and predisposing bones to deformity and fragility (Rath et
al., 2000). Furthermore, the extremely high IAW observed
in the LD group after 8 weeks of age suggests that geese
require more space than was provided for exercising and
stretching wings for normal growth and healthy wings.
According to our review of relevant literature, the
genetics of AW in geese was first reported by Francis et al.
(1967). They observed AW in 53% of White Chinese
goslings with AW parents, thus indicating that IAW in geese
is attributable to polygenic determinism. Moreover, Lin et
al. (2012) reported that the SSAW and IAW of White
Roman goslings with AW at 8 weeks of age were 1.45%
and 48.6%, respectively, whereas those of commercial
White Roman goslings at the same age were 0.40% and
Tabl e 4 . Effect of stocking density and genetic lineage on the severity score and incidence of angel wing in 6 to 14-week-old White
Roman geese
Age Stocking density SEM1 Line SEM2 Significance3
LD MD HD AL NL CL D L D×L
Severity score of angel wing
6 wk 0.34 0.63 0.50 0.14 1.07 0.44 0.28 0.16 NS NS NS
8 wk 0.93 1.12 1.09 0.12 2.09a 0.69
b
0.72
b
0.17 NS *** NS
10 wk 0.92 1.23 0.98 0.14 2.16a 0.84
b
0.62
b
0.19 NS *** NS
12 wk 0.99 1.48 1.21 0.15 2.46a 0.91
b
0.79
b
0.22 NS *** NS
14 wk 1.16 1.49 1.28 0.22 2.54a 0.98
b
0.90
b
0.25 NS *** NS
Incidence of angel wing (%)
6 wk 15.5 30.1 21.3 5.66 46.2 18.4 15.2 5.96 NS NS NS
8 wk 37.5 45.8 42.1 3.58 69.8a 29.8
b
32.7
b
4.28 NS *** †
10 wk 34.4 47.5 36.5 6.64 69.5a 31.0
b
27.7
b
5.38 NS *** NS
12 wk 39.9 47.5 41.9 7.25 71.0a 33.1
b
33.1
b
6.30 NS *** NS
14 wk 39.9 46.7 39.4 5.91 69.5a 32.5
b
32.6
b
5.87 NS *** NS
LD, low stocking density; MD, middle stocking density; HD, high stocking density; AL, angel wing line; NL, normal wing line; CL, commercial line; L,
genetic line; D, stocking density; L×D, the interaction of stocking density with genetic line.
1 SEM, standard error of means of stocking densities. 2 Standard error of means of genetic lines.
3 NS, non significantly different or p>0.1; † p<0.1;*** p<0.001.
a,b Stocking densities and genetic lines with different superscripts differ significantly (p<0.05).
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
906
14.8%, respectively. These results revealed that parental and
genetic factors play a substantial role in IAW and SSAW.
Therefore, we conducted a divergent genetic selection for A
Lin White Roman geese in Taiwan; the results will be
published separately.
In this study, the SSAW and IAW results revealed that
AW was more severe in AL than in NL. However, the IAW
was higher in NL than in CL, implying that genetic
selection effectively increases IAW and improves the
production efficiency of domestic geese. The results also
imply that natural selection is crucial in decreasing IAW.
The findings of IAW in White Roman geese revealed
that only a few geese with slight AW of one wing or both
wings during 6 to 12 weeks of age returned to NW during
10 to 14 weeks of age (data not shown), possibly because
the primary wings grow completely during 6 to 12 weeks of
age, whereas the secondary wings grow incompletely at the
same time. Therefore, wings with a slight appearance of
AW are misjudged as temporarily unfolded wings, leading
to an error in observation. Moreover, Pitman et al. (2012)
reported that the AW of masked boobies returned to NW at
the fledging age. In this study, a few geese were observed
with slight AW at 8 weeks of age, which resumed to NW at
10 weeks of age. Therefore, AW was more frequently
observed in geese at 8 weeks than at 10 weeks of age,
suggesting that the IAW and SSAW of a flock vary at
different ages.
An optimal stocking density positively promotes animal
health and performance. The effects of stocking density on
feed consumption, feed conversion ratio, and carcass
characteristics have been comprehensively investigated in
various poultry species (Cain et al., 1984; Shanawany, 1988;
Şengület al., 2000; Chang et al., 2010). Moreover, White
Italian geese under HD exhibited a lower growth
performance than did those under LD (4 geese/m2 vs 2 to 3
geese/m2; Kaszynsko et al., 1986).
Chang et al. (2010) revealed that the body weight under
LD (0.8 geese/m2) was higher than that under HD (1.6
geese/m2) during winter; a similar association between body
weight and three stocking densities was observed in the
present study.
Growth performance in terms of feed intake, body
weight gain, and body weight uniformity reduces when
geese are subjected to HD or crowded conditions. Therefore,
after examining only the body weight, feed consumption,
and feed conversion rate under high and low temperatures,
Chang et al. (2010) suggested that geese be housed and
reared under a stocking density of 1.2 geese/m2 on a slat
floor. To avoid IAW and for the welfare of geese, a stocking
density of <1.2 geese/m2 is recommended, although the
exact optimal space for rearing a goose has not been
determined yet, thus necessitating future studies.
CONCLUSION
To improve production efficiency and reduce production
cost, geese with a high body weight and a fast growth rate
have been selected and subjected to limited space or a
crowded environment. These factors may increase the risk
of AW. This study showed that the stocking density applied
in commercial goose farming and in our experiments did
not completely avoid IAW, although a satisfactory growth
performance was observed. Additional studies are required
to elucidate the optimal stocking density for reducing IAW
to an acceptable level in commercial goose farming.
CONFLICT OF INTEREST
We certify that there is no conflict of interest with any
financial organization regarding the material discussed in
the manuscript.
ACKNOWLEDGMENTS
We thank our colleagues at Changhua Animal
Propagation Station, Livestock Research Institute of
Council of Agriculture, Taiwan for feeding and managing
the geese.
REFERENCES
Cain, J. R., J. M. Weber, T. A. Lockamy, and C. R. Crager. 1984.
Grower diets and bird density effects on growth and
cannibalism in ring necked pheasants. Poult. Sci. 63:450-457.
Chang, Y. C., C. M. Wang, P. C. Nien, C. L. Hu, and Y. S. Jea.
2010. The effects of stocking density on the growth
performance of growing geese raised in a slat floor house. J.
Taiwan Livest. Res. 43:51-58.
Francis, D. W., R. H. Roberson, and L. A. Holland. 1967.
Observations on “Angel wing” in White Chinese geese. Poult.
Sci. 46:768-769.
Grow, O. 1972. Slipped or twisted wing, in: modern waterfowl
management and breeding guide. American Bantam
Association, Three Rivers, MI, USA. pp. 171.
Kaszynsko, J., K. Bielinska, and K. Bielinski. 1986. Effect of
stocking rate on geese rearing and fattening results. Rocz.
Nauk. Zoot. 13:273-281.
Kear J. 1973. Notes on the nutrition of young waterfowl, with
special reference to slipped-wing. Int. Zoo Yearb. 13:97-100.
Kreeger, T. J. and M. M. Walser. 1984. Carpometacarpal deformity
in giant Canada geese (Branta canadensis maxima delacour). J.
Wild. Dis. 20:245-248.
Kuiken, T., F. A. Leighton, G. Wobeser, and B. Wagner. 1999.
Causes of morbidity and mortality and their effect on
reproductive success in double-crested cormorants from
Saskatchewan. J. Wild. Dis. 35:331-346.
Lee, C. H. 2004. Investigating the Causes Affecting the Incidence
of Angel Wings in Geese. Master thesis, University of Chung
Lin et al. (2016) Asian Australas. J. Anim. Sci. 29:901-907
907
Hsing, Taichung, Taiwan. pp. 6-8.
Lin, M. J., S. C. Chang, S. R. Lee, Y. S. Jea, C. F. Chen, Y. K. Fan,
and Y. S. Cheng. 2010. Selection for heavy White Roman
goose line. J. Chin. Soc. Anim. Sci. 39:253-260.
Lin, M. J., S. C. Chang, Y. S. Jea, Y. S. Cheng, and Y. K. Fan. 2012.
Effects of line and nutrition concentration of diet on
occurrence of angel wing in White Roman geese. J. Chin. Soc.
Anim. Sci. 41:187-196.
Mildred, M. and W. D. Holderread. 1981. Slipped wing. In: The
Book of Geese - A Complete Guide to Raising the Home Flock,
pp. 140 Oregon, Hew House Publications, Corvallis, OR,
USA.
NRC (National Research Council). 1994. Nutrient Requirements
of Poultry. 9th rev. edn, National Academy Press, Washington,
DC, USA.
Pitman, R. L., T. B. Lisa, and A. B. Charles. 2012. Incidence of
wing deformities (‘Angel Wing’) among Masked Boobies at
Clipperton Island: life history consequences and insight into
etiology. Wilson J. Ornithol. 124:597-602.
Rath, N. C., G. R. Huff, W. E. Huff, and J. M. Balog. 2000.
Factors regulating bone maturity and strength in poultry. Poult.
Sci. 79:1024-1032.
SAS Institute. 2004. SAS/STAT Guide for Personal Computers.
Version 9.0.1. SAS Inst. Inc., Cary, NC, USA.
Şengül, T., A. Yildiz, and Y. Konca. 2000. Effect of stocking
density on the growth performance and carcass characteristics
in bronze Turkey. J. Poult. Res. 2:33-39.
Shanawany, M. M. 1988. Broiler performance under high stocking
densities. Br. Poult. Sci. 29:43-52.
Wang, S. D., K. C. Wu, T. S. Chiou, Z. T. Chen, and L. T. Yeh.
1996. The investigation of breeder geese's information in 1995.
Taiwan Agric. 32:82-88.