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Factors Affecting the Incidence of Angel Wing in White Roman Geese: Stocking Density and Genetic Selection

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The present study investigated stocking density and genetic lines, factors that may alter the severity and incidence of angel wing (IAW), in White Roman geese. Geese (n = 384) from two genetically selected lines (normal and AW wing, hereafter, NL and AL, respectively) and one commercial line (CL) were raised in four pens. Following common commercial practice, low- (LD), medium-, and high-stocking-density treatments were respectively administered to 24, 32, and 40 geese per pen at 0-3 weeks (1.92 m2/pen) and 4-6 weeks (13.2 m2/pen) of age and to 24, 30, and 36 geese at 7-14 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 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.
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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.
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... Another problem associated with metabolic disorders is the angel wing syndrome, a deformity that causes an outwards of one or both wings, affecting the carpometacarpus or the joint between the third and fourth metacarpals (Lin et al. 2016). This disease mainly affects waterfowl and is attributed to accelerated growth due to overfeeding in organized farming conditions (Olsen 1994). ...
... This disease mainly affects waterfowl and is attributed to accelerated growth due to overfeeding in organized farming conditions (Olsen 1994). However, scientific studies or reports of the syndrome are very limited and mainly focus on geese (Lin et al. 2016). Therefore, there is a lack of information on incidence rates, the role of management conditions, etiology, and the effect on productivity in ducks. ...
... The incidence of angel wing syndrome was 10.6%, much lower than the 39% reported in a white Roman geese farm (Lin et al. 2016). A diet that promotes faster growth has been suggested to be the main cause of angel wing development (Olsen 1994;Lin et al. 2016), and this is consistent with the development of this syndrome only in the organized group with probiotics supplementation, although in our study, only males developed this syndrome. ...
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Proper health management is essential for productivity in duck farming. However, there is limited information on the effect of management conditions on rates of metabolic problems and parasitic infections in anatids. We evaluated the rates of metabolic syndromes and gastrointestinal parasite involvement in Muscovy ducks up to 12 weeks of age, under 3 management conditions: backyard, organized, and organized with probiotics. Individuals under organized management developed 2 metabolic problems: ascites, which was rare (3.5%), fatal, and affected both males and females, and angel wing syndrome, which was more frequent (10.6%), has low impact on general health, and only affected males. The treatments do not have a significant effect on the development of ascites, but only individuals in controlled conditions presented this syndrome, and due to its low prevalence, further studies with a larger sample size are required. The risk of angel wing syndrome increased significantly with probiotic supplementation. Regarding to parasitic infection, the improvement of sanitary management and the use of probiotics supplementation reduced the occurrence of coccidiosis. Similarly organized management with probiotic supplementation showed a protective effect on helminthiasis by reducing the frequency of Heterakis gallinarum and greatly reducing the helminth egg load. Coccidiosis and helminthiasis infections were not significantly correlated with the final weight of the ducks. Therefore, organized management and the use of probiotics seems to reduce the impact of parasitic infection, although it increases the risk of developing metabolic syndrome.
... Angel wing (AW) is characterized by outward twisting along the wrist joint on the unilateral or bilateral wing in birds, which is universal occurring in waterfowl including geese (Francis et al., 1967;Kreeger and Walser, 1984;Lin et al., 2016;Lin et al., 2017), swans (Mustafa et al., 2019), ducks (Shaw et al., 2012;Jeong et al., 2019), pelicans (Drew and Kreeger, 1986), and cormorants (Kuiken et al., 1999), even in other birds such as commercial chickens (Riddell, 1983), masked boobies (Pitman et al., 2012), Accipiter gentilis (Zsivanovits et al., 2006), and Grus americana (Vasseur et al., 2019). In addition to inferior appearance, AW also results in flight lessness in birds (Pitman et al., 2012;Vasseur et al., 2019) and compromises the birds' welfare (Rodenburg et al., 2005). ...
... Francis et al. (1967) concluded that if inheritance involved in AW, the characteristic must be affected by more than one pair of genes. Lin et al. (2016) found that genetic selection of the AW phenotype aggravated the occurrence of AW in a study aimed to evaluate the effects of stocking density and genetic selection on the incidence of AW. ...
... NW, normal wings form normal wing geese; AW, angel wings from bilateral angel wing geese; wings were from the right-side wing of HW goose. n = 4 2008; Vasseur et al., 2019), even it might reach 71% in AW offspring (Lin et al., 2016). Various studies have reported figures for the prevalence of AW in offspring of goose. ...
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The first purpose of this study was to reveal the distribution of the angel wing (AW) of geese. Our data showed that the total incidence of AW was 6.67% in 150-d-old White Zhedong (ZD) geese, the occurrence of AW in left wing is higher than that in right wing and bilateral wing than unilateral wing (both P < 0.01). In 70-d-old Hybrid-Wanxi (HW) geese, the total incidence of AW was 8.86%, with similar incidence rate between unilateral and bilateral. The sex has not apparently affected the incidence of AW in both ZD and HW geese. To explore the potential relationship between wing type with body weight, organ index, bone characteristic, or blood biochemical parameters in 70-d-old HW geese. We found that the body weight and organ index were similar between normal wing (NW) and AW geese. The length for the humerus, metacarpal and phalanx, and the phalanx weights, as well as the angle between the humerus and the radial ulna (HRU) in NW geese were pronounced greater than that in AW geese (P < 0.05). Furthermore, the angel wing was strongly associated with lower platelet size indicators. Collectively, AW affected the wing bone length, phalanx weight, and HRU, and the occurrence of AW may be related with dysfunctional platelet activation in geese.
... Twisted wing is a musculoskeletal disorder in which the flight feathers of one or both wings of a bird twist away from the body, mainly during growth [17,18]. As reported in [19], welfare problems such as a high stocking density, a fast growth rate, and genetic selection are the main factors contributing to the twisted wing in white geese. Visually examining the wing posture can provide a feasible assessment measure of the presence of wing deformities in commercially reared geese [19]. ...
... As reported in [19], welfare problems such as a high stocking density, a fast growth rate, and genetic selection are the main factors contributing to the twisted wing in white geese. Visually examining the wing posture can provide a feasible assessment measure of the presence of wing deformities in commercially reared geese [19]. ...
... Few studies have reported the prevalence of twisted wings in commercially raised geese [19]. According to our study, a small number of geese showed wing deformity. ...
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Currently, no specific animal-based measures (ABMs) protocols are available for geese in commercial meat production systems. Following a critical review of the literature and consultation of experts, seven ABMs, potentially valid and feasible for the on-farm welfare assessment of geese, were identified and then tested in 12 farms in Poland to assess their inter-observer reliability. Two observers conducted the assessment, which was divided into two phases. First, a handling test assessed the human–animal relationship (HAR), and a 100% inter-observer reliability was achieved by the observers when evaluating the attitudes of stockpeople and the reactions of geese to humans. Next, an animal inspection was conducted, and the observers simultaneously and independently visually evaluated 100 randomly selected geese per farm and assessed whether the selected ABMs could be identified. In terms of inter-observer reliability, high correlation coefficients were found for plumage dirtiness (ρ = 0.745; p < 0.01), twisted wings (ρ = 0.890; p < 0.001), and broken/twisted wings (ρ = 0.858; p < 0.001). The results showed that plumage dirtiness, twisted wings, and broken/twisted wings are valid and reliable measures. Further research should address the reliability of ABMs of geese in other types of production systems.
... Recently, Lin et al. (2016) indicated that stocking density and genetic selection were 2 factors affecting the incidence of angel wing in White Roman geese, which were reared in a house with a cement floor. In their study, the body weight gain of geese were affected by stocking density only at 0 to 4 wk of age, but the body weights of geese at 2, 4, 6, 8, 10, 12, and 14 wk of age were all affected by stocking density, and as stocking density increased, the body weights of White Roman geese at 2, 4, 6, 8, 10, 12, and 14 wk of age were reduced by 19.01%, 25.81%, 17.07%, 14.11%, 10.52%, 11.69%, and 10.41%, respectively. ...
... In the present study, an increased stocking density resulted in the reduction of BW at 42 d and 70 d of age, and the reduction of metatarsal bone circumference, but resulted in the increase of F/G for 28-to 42-d period and 28-to 70-d period. Our results agreed with Lin et al. (2016), who observed that the stocking density affected the body weight of White Roman geese. In their study, differences in body weight gain were observed only at 0 to 4 wk of age, but the BW of geese at 2, 4, 6, 8, 10, 12 and 14 week of age were all affected by stocking density, and as stocking density increased, the body weights of White Roman geese at 2, 4, 6, 8, 10, 12 and 14 week of age were reduced by 19.01%, 25.81%, 17.07%, 14.11%, 10.52%, 11.69%, and 10.41%, respectively. ...
... Previous research explored the effects of stocking density on the incidences of angel wing (Lin et al., 2016) and feather pecking (Lindberg and Nicol, 1996;Wagenaar, 2003, 2006;Albentosa and Cooper, 2004). In the present study, when the stocking density was increased to 5 birds/m 2 , the PFL of geese at 42 d of age was significantly reduced, and when the stocking density was increased to 6 birds/m 2 , the PFL of geese at 70 d of age was negatively influenced. ...
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This experiment was conducted to evaluate the effects of stocking density on the growth performance, feather growth, intestinal development, and serum parameters of geese. In total, 336 healthy, 28-day-old, male Yangzhou goslings were randomly allotted to 30 plastic wire-floor pens according to 5 stocking densities (2, 3, 4, 5 and 6 birds/m²). The results showed that with the stocking density increased from 2 birds/m² to 6 birds/m², the body weights of geese at 42 d (P < 0.001) and 70 d (P < 0.001) were reduced by 10.53% and 10.43% respectively, the primary feather lengths of geese at 42 d (P < 0.001) and 70 d (P = 0.021) were reduced by 20.38% and 6.62% respectively, whereas the feed/gain ratios for 28- to 42-d period and 28- to 70-d period increased from 2.50 to 2.90 (P = 0.001), and 3.80 to 4.24 (P < 0.001), respectively. The relative weights of the jejunum, ileum, and small intestine and the lengths of the jejunum, ileum, and small intestine were all adversely affected (P < 0.05) when stocking density was increased to 6 birds/m². Serum concentrations of alkaline phosphatase (P = 0.013) and triiodothyronine (P < 0.001) decreased as the stocking density increased. The serum thyroxine concentration of geese from the 6 birds/m² group was lower than that of geese from the other groups (P < 0.05). The reduction in thyroid hormone concentrations was similar to what was observed in growth rate. All the results suggested that high stocking density will adversely influence thyroid function and the developments of the body weight, body size, feathers, and small intestine. Under our experimental conditions, we recommend that the stocking density of geese should be kept to 5 or fewer birds/m² to avoid the negative effects of high stocking density on geese.
... The estimated pooled LHIAW was 0.31 (Lin et al. 2008). Lin et al. (2016) further indicated that differences were observed among the genetic stock; that is, SSAW and IAW are significantly higher in the AW line than in the normal or commercial lines. ...
... 2.6. Severity, severity scores, and IAW Lin et al. (2016) defined severity, severity score, and IAW. A bird's normal wing (NW) was defined as being covered with smooth, neat, and clean feathers along its body. ...
... The IAW was expressed as a percentage and calculated as the number of birds with AW (SSAW = 1-6) divided by the number of birds in the pen multiplied by 100. Alternatively, it was obtained by deducting the percentage of NW from 100; the former value was calculated as the number of birds with NW (SSAW = 0) divided by the number of birds in the pen multiplied by 100 (Lin et al. 2016). ...
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This study investigates the effects of T-2 toxin and antioxidants on the incidence and severity of angel wing in White Roman geese. Twelve pens were used in this study, and half of them received dietary supplementation of T-2 toxin (10 ppm) and antioxidants (vitamin C 1000 ppm plus Se 0.3 ppm). Each pen contained birds from the normal wing line (NL), the selected angel wing line (AL), and a controlled commercial line (CL). The results showed that there was no significant difference in the body weight, body weight gain, and feed intake of goslings that were supplemented from birth to 6 weeks of age with T-2 toxin and antioxidants. The alkaline phosphatase level in the T-2 toxin group was lower than that in the control group at 4 and 6 weeks. The haemoglobin level in the T-2 toxin group was lower than that in the control group at 6 weeks. There was a significant interaction between T-2 toxin and antioxidants in the severity score of angel wing (SSAW) and incidence of angel wing (IAW) at 6 weeks. In conclusion, the results suggest that a diet supplemented with T-2 toxin does reduce alkaline phosphatase levels. When the diet contained T-2 toxin and antioxidants, the SSAW and IAW increased.
... However, there is very little applied research on how to manage stocking density such that optimum welfare and production efficiency are achieved. Studies suggested that high stocking density diversely influenced thyroid function and growth performance of geese (Lin et al., 2016;Yin et al., 2017a) and the stocking density should be kept to 5 or fewer birds/m 2 for Yangzhou geese from 28 to 70 d of age (Yin et al., 2017a). In geese production, multiple-phase feeding strategy is generally adopted when considering the long raise period for geese. ...
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This study was conducted to investigate the effect of stocking density on growth performance, feather quality, serum hormone, and intestinal development of geese from 1 to 14 d of age. A total of 450 1-d-old geese were randomly allotted to 45 battery cage (0.65 m × 0.62 m) pens according to 5 stocking densities (15, 20, 25, 30 and 35 birds/m²). The results showed that ADG and ADFI were reduced (P<0.05) as stocking density increased from 15 to 35 birds/m², but increasing stocking density did not influence (P>0.05) feed conversion ratio (FCR) and body measurement traits. High stocking density significantly decreased (P<0.05) the feather quality of back, thoracic and abdominal, wing, and tail. No significant difference (P>0.05) was found in serum concentration of adrenocorticotrophic hormone, cortisol, corticosterone, triiodothyronine, and thyroxine. The weight of cecum and intestine decreased (P<0.05) as the stocking density increased. Increasing stocking density decreased (P<0.05) jejunal villus height and villus height-to-crypt depth ratio, and increased (P<0.05) jejunal crypt depth and ileal crypt depth in geese. Consequently, the high stocking density could depress the growth and impaired feather quality and intestinal development of geese. Under our experimental conditions, we recommend that the stocking density of geese from 1 to 14 d of age should not more than 20 birds/m².
... As the stocking density exceeded 2.5 and 3.5 birds/m 2 , ADG throughout the experimental period significantly decreased (P < 0.05), while the F/G from 49 to 70 d of age significantly increased (P < 0.05). The results were similar to those in chickens [19,20,21,22], ducks [5,6,23] and geese [10,24]. In present experiment, the ADFI tended to linearly decrease with increase of stocking density (Table 3), which may partly explain the reason for low grow rate in the high density treatment. ...
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An excessively high-stocking density can adversely influence performance, health, and welfare of geese. The optimum-stocking density also should be changed with the increase of age and weight in geese. However, the corresponding density parameter is lacking in different feeding phase. The experiment was conducted to investigate the effect of stocking density on geese from 49 to 70 d of age. Three hundred and sixty 49-d-old female Sichuan white geese were randomly allotted to 6 stocking treatments with 6 replicate pens, stocking densities in each group were 2.5, 3.5, 4.5, 5.5, 6.5, and 7.5 birds/m2. Average daily gain (ADG) was reduced as stocking density increased (P < 0.05), and feed gain ratio (F/G) increased as stocking density increased (P < 0.05). High-stocking density significantly decreased feather cleanliness of geese (P < 0.05). Stocking density did not influence slaughter yield, breast meat, leg meat, subcutaneous fat and skin, and abdominal fat yields at 70 d (P > 0.05). High-stocking density tended to linearly decrease intramuscular fat content of breast meat (P < 0.05), while stocking density did not influence the content of crude protein and amino acids in breast meat (P > 0.05). Based on broken-line linear regression analysis, the stocking density of female Sichuan white geese from 49 to 70 d of age was 3.5 and 3.6 birds/m2 for ADG and F/G, respectively.
... If diet is the primary issue, reducing the protein by adding wheat to the birds› feed may be recommended. A diet that provides sufficient amounts of vitamin D (the «sunshine» vitamin), vitamin E and manganese may also be indicated [6,14] . ...
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In the present study 6 male swans two black (Cygnus atratus) and four white (Cygnus cygnus), weighing about 5.5-7.5 kg, with bilateral wing sagging and turning out of the wing tips belonging to Parks and Gardens Directorate of Metropolitan Municipality were used as materials. The swans were being fed on daily ration (pellet feed) as well as food residues such as bread, bagels, chips, etc. thrown by visitors. The clinical examination revealed that developing feathers and the tips of the wings of swans were stuck up from its normal position. The wings of the swans were bandaged adjacent to their bodies for one week and their rations were arranged. Angel wings have a high chance of being treated if the problem is diagnosed early
Article
A high stocking density can have a negatively effect on growth performance, walking ability and antioxidant capacity of poultry. In geese production, multiple-phase feeding strategy is generally adopted when considering the long raise period for geese. However, the corresponding density parameters are lacking in different growth stages. The aim of this study was to estimate the optimum stocking density of geese from 14 to 28 d of age and 28 to 49 d of age and investigate the effects of stocking density on antioxidant capacity of geese from 28 to 49 d of age. Two trials were used in this study. In experiment 1, a total of 432, 14 d of age female White Sichuan geese were allocated randomly to 6 treatments with 6 replicate pens per treatment according to the stocking densities of 4.67, 6.00, 7.33, 8.67, 10.00 and 11.33 birds/m², respectively. In experiment 2, a total of 324, 28 d of age female White Sichuan geese were allocated randomly to 6 treatments with 6 replicate pens per treatment according to the stocking densities of 2.50, 3.75, 5.00, 6.25, 7.50 and 8.75 birds/m², respectively. With the stocking density increasing, body weight and weight gain decreased linearly or quadratically in experiment 1 (P < 0.05), feed intake decreased quadratically (P < 0.05), and feed/gain ratio (F/G) increased (P < 0.05). In experiment 2, as the stocking density increased, the body weight and weight gain decreased linearly (P < 0.05), while F/G increased linearly (P < 0.05). In addition, the increasing stocking density resulted in that the serum total antioxidant capacity (T-AOC) level and activity of superoxide dismutase (SOD) both decreased linearly (P < 0.05). According to linear broken-line regression, the upper critical stocking density of geese from 14 to 28 d of age for weight gain was 6.15 birds/m² (or 8.34 kg of actually achieved BW/m²) and it was 4.83 birds/m² (or 11.4 kg of actually achieved BW/m²) for F/G of geese from 28 to 49 d of age.
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1. Stocking density is an issue for poultry production. High stocking density can impact biochemical parameters, production, and reproductive performance; however, information regarding the effects of stocking density on serum metabolites in geese is limited. 2. Twenty-day-old, Sanhua male geese (n=240) were allocated to one of two experimental groups for 50 days. One group was housed under a low stocking density (LSD; two birds per m²) and one under a high stocking density (HSD; five birds per m²). Body weight and feed intake were recorded every 10 d. Eight serum samples per group were used for metabonomic analysis by liquid chromatography-mass spectrometry. 3. Stocking density did not affect the spleen, liver, thymus, or bursa of Fabricius weights after 50 d. Feed intake and body weight was significantly lower in geese from the HSD group versus the LSD group (P<0.05). Thirty-six differential serum metabolites were identified (P<0.05), indicating altered amino acid, carbohydrate, lipid and vitamin cofactor metabolism. 4. The results demonstrated that high-density stocking impacts geese, and provides insights into the mechanisms underlying the adverse health effects associated with HSD.
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This wing deformity in waterfowl has been known for many years (Peters, 1933; and Luhmann, 1936). Domestic ducks, geese, swans, and numerous other waterfowl kept in zoos or parks exhibit the character (Peters, 1933; Luhmann, 1936; and Groves, 1960). Angel wing is normal in the Sebastopol goose, but it is a defect causing disqualification in other breeds. According to Peters (1933), the deformity is seen only in birds bred by man. Peyton and Peyton (1961) stated that the turned-up wing tip is the most common deformity of incubator-hatched geese. The abnormality may be observed as a unilateral or bilateral twisting of the wing feathers (Figures 1 and 2). The wings will not lie in the normal position along the body due to a malformation of the skeleton (Peters, 1933). The ligaments, especially on the lateral side of the carpel joint, are loose so that the joint shakes when the bird . . .
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'Angel wing' is a developmental wing deformity among birds that can cause flightlessness; it is mostly known from domestic birds, especially waterfowl, and has only rarely been reported among wild bird populations. We estimated that 508 (4.9%) Masked Booby (Sula dactylatra) chicks on Clipperton Island (10° 18′ N, 109° 13′ W) in the eastern tropical Pacific Ocean exhibited angel wing during March 2005. Both hatching-year birds and after-hatching-year birds exhibited the condition; the latter included seven flightless birds in adult plumage (i.e., minimum 2 yrs of age) which were still being fed by their presumed parents. The angel wing outbreak coincided in time with high nestling mortality, apparently related to food shortage, and we speculate on causal linkages.
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The effects of bird density and dietary protein and energy level on growth rate and feather pecking in Ring-Necked pheasants were investigated in two experiments. After brooding, pheasants in Experiment 1 were housed at densities of .19, .38, or .74 m2/bird and fed grower diets containing 16, 19, or 22% protein. Experiment 2 pheasants were housed at .4 m2/bird and fed diets containing 16 or 22% protein with energy levels of 2530, 2750, 2970 or 3190 kcal/kg. Body weight was not affected by bird density differences, but feather pecking was significantly reduced by increasing floor space per bird. Body weight, cannibalism, and feed conversion were poorer in groups fed the 16% protein diet than those fed the 19 or 22% protein diets. Body weight gains, feed efficiency, and feather pecking scores improved as the energy content of grower diets increased. Significant interactions existed between dietary protein and bird density and between dietary protein and energy for feather picking in pheasants. Total performance was best for groups fed a grower diet of 22% protein and 2970 kcal/kg metabolizable energy level with a floor space of .38 m2 or greater per bird.
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The objectives of this study were to describe causes of morbidity and mortality in a breeding colony of double-crested cormorants (Phalacrocorax auritus) on Doré Lake (Saskatchewan, Canada), and to determine cause-specific mortality rates of juvenile birds. Morbidity and mortality were monitored every third day during the breeding season from 1994 to 1996 from inside a tunnel-and-blind system. Affected eggs and birds were collected for examination and diagnosis. The cause of mortality was determined for 105 eggs, 178 nestlings (< or = 4-wk-old), 1393 post-nestling chicks (> 4-wk-old), and 10 adults. The main causes of mortality were infertility or embryonal death, avian predation, displacement of eggs and chicks from the nest, starvation from sibling competition, Newcastle disease, coyote predation, human-induced suffocation, and entrapment. In 49% of the cases, avian predation and displacement from the nest of eggs or nestlings was associated with human disturbance. Thirty-six nestlings, 40 post-nestling chicks, and three adults were examined for the presence of parasites. Contracaecum spiculigerum was found in the proventriculus; Amphimerus elongatus in the liver. Piagetiella incomposita in the gular pouch; Eidmanniella pellucida, Pectinopygus farallonii, and Ceratophyllus lari in the plumage; and Theromyzon sp. in the nasal and oral cavity. Contracaecum spiculigerum was associated with ulcerative gastritis, A. elongatus with multifocal hepatitis and bile duct hyperplasia, and P. incomposita with ulcerative stomatitis, but these lesions were not considered fatal. Other diseases included beak deformity, abnormal rotation of the carpal joint, hypopigmentation, and eye loss. Overall mortality of cormorant chicks between hatching and the end of the breeding season varied from 25 to 48%. The most important causes of mortality were Newcastle disease, which killed 21% of hatched chicks in 1995, sibling competition (maximum 12% in 1994), and coyote predation (2% in 1994).
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Adolescent meat-type poultry and cage layers exhibit a high incidence of bone problems that include bone weakness, deformity, breakage, and infection and osteoporosis-related mortalities. These problems include economic and welfare issues. To improve bone quality in poultry, it is essential to understand the physiological basis of bone maturity and strength in poultry. A complex array of factors that include structural, architectural, compositional, physiological, and nutritional factors interactively determine bone quality and strength. Bone is approximately 70% mineral, 20% organic, and 10% water. Collagen is the major organic matrix that confers tensile strength to the bone, whereas hydroxyapatite provides compressional strength. In recent years, the roles of different collagen crosslinks have been shown to be important in the increase of bone mechanical strength. Similarly, age-related glyco-oxidative modifications of collagen have been shown to increase the stiffness of collagen. These posttranslational modifications of matrix can affect bone quality as it would be affected by the changes in the mineralization process. Our studies show that the growth in the tibia continued until 25 wk of age, which correlated with the increase in the content of hydroxylysylpridinoline (HP) and lysylpyridinoline (LP), the collagen crosslinks. The tibia from 5-wk-old chicks were strong but brittle because of low collagen crosslinks and high mineral content. Bone maturity may relate to its crosslink content. Compared to crosslink content, bone density and ash content showed moderate increases during growth. The bones from younger turkeys were more susceptible to corticosteroid-induced stunting of growth, which also resulted in decreased bone strength. This review discusses how different factors can compromise bone strength by reducing growth, altering shape, affecting mineralization, and affecting collagen crosslinking.
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1. In two consecutive experiments a total of 4,780 broilers were reared at high stocking densities. 2. In experiment 1, the birds were housed at 10, 20, 30, 40 or 50/m2 till 6 weeks. In experiment 2 densities of 20, 40 and 50/m2 were compared; the two higher densities were reduced to 30/m2 at either 3 or 5 weeks of age. 3. In the first experiment 6-week body weight was a curvilinear function of stocking density. Average food intake over the whole experimental period declined linearly with densities above 20/m2. 4. A slight but significant improvement in the efficiency of food utilisation was recorded from birds at high densities in the first experiment only. 5. Reducing the stocking density from 40 or 50/m2 to 30/m2 at 3 weeks increased food consumption and body weight gain and led to a recovery in their body weight by 6 weeks. 6. No significant differences were observed in mortality as a result of high stocking densities in either experiment. 7. Profit margin per m2 increased almost linearly in experiment 1, by about 65 p for every bird/m2 increase in stocking density. 8. The implications for poultry welfare are briefly discussed.