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Feather performance, walking ability, and behavioral changes of geese in response to different stocking densities
Applied Animal Behaviour Science 196 (2017) 108–112
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Feather performance, walking ability, and behavioral changes of geese in response to different stocking densities
MARK
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Luyao Yin, Haiming Yang, Lei Xu, Jun Zhang, Hao Xing, Zhiyue Wang College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu Province 225009, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords: Stocking density (in accompany with group size) Goose Welfare Feather performance Walking ability Behaviour
In recent decades, goose production has become more specialized and widespread, and rearing geese in plastic wire-floor pens is common in China. This type of rearing pattern is more productive than other rearing patterns since it allows for more birds per square meter. However, it brings some problems due to high stocking density such as poor feather performance and walking ability, and some behavioral changes. This experiment was conducted to preliminarily evaluate the effects of different stocking densities on goose welfare in terms of feather performance, walking ability and behavioral changes. A total of 336 healthy, 28-day-old, male Yangzhou goslings were allotted to 30 plastic wire-floor pens according to five stocking densities (2, 3, 4, 5 and 6 birds/ m2), adopting randomised block method. Each treatment was represented by six replicates. Feather performance was assessed by two types of measurements: back-feather damage rate, and feather contamination degree which was carried out by feather scoring. Walking ability was assessed by gait scoring. All birds in each pen were individually scanned for back-feather damage measurement at 42 days of age, and individually scored for gait at 68 and 69 days of age. One bird from each pen was randomly selected for feather scoring at 69 days of age. The higher the feather score and the gait score, the worse the goose welfare. From 60–65 days of age, three geese from each pen were randomly selected and tagged for behavioral observation. Results showed that when stocking density was 4 or more birds/m2, standing on one leg (relaxing) behaviour reduced significantly (P ≤ 0.05); when stocking density was 5 or more birds/m2, feather contamination degree (P ≤ 0.05) and preening behaviour (P ≤ 0.05) both increased significantly; when stocking density was 6 birds/m2, the behaviours of lying and feather pecking, and back-feather damage rate all increased (P ≤ 0.05, for all), whereas walking ability declined, which was reflected by the increased proportion of geese with normal gait (P ≤ 0.05) and the decreased proportion of geese with gait problems (P ≤ 0.05). In conclusion, a high stocking density (5 or more birds/m2) led to an increase in feather pecking and poor performances in feather and walking ability, which were harmful to goose welfare and may decrease the quality of goose products. Therefore, based on our experimental conditions, we recommend that the stocking density of geese should be fewer than 5 birds/m2 to ensure relatively good welfare and avoid negative effects. In addition, in our experiment, different stocking densities were in accompany with different group size, in the future, additional studies will be done to explore how stocking density and group size affect goose welfare.
1. Introduction With the rapid development of the poultry industry, many producers have adopted the highest possible stocking density in production because the economic benefit per square meter is often higher when the birds are stocked more densely. However, an excessively high stocking density can adversely influence the performance, behaviour, and welfare of the birds, a situation that has attracted attention in recent years. Although relevant studies on geese are limited, many researchers on chickens (Dawkins et al., 2004; Estevez, 2007; Lay et al., 2011) and
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ducks (Baéza et al., 2003) have indicated that high stocking density can cause adverse effects such as behavioral changes, poor feather and poor walking ability. Baéza et al. (2003) studied changes in behaviour, welfare, performance, and carcass quality of Muscovy ducks in response to three stocking densities (7, 9, and 11 male ducks/m2) and found that the stocking density of 9 birds/m2 gave the best results for all measurements. Xie et al. (2014) indicated that the body weight and the weight gain of starter and growing ducks were both reduced when stocking density increased, but the carcass, breast meat, leg meat, abdominal fat, and foot pad lesions of ducks were not significantly
Corresponding author at: College of Animal Science and Technology, Yangzhou University, Wenhui East Road 48#, Yangzhou City, Jiangsu Province 225009, PR China. E-mail address: [email protected] (Z. Wang).
http://dx.doi.org/10.1016/j.applanim.2017.06.017 Received 28 January 2017; Received in revised form 14 June 2017; Accepted 18 June 2017 Available online 28 June 2017 0168-1591/ © 2017 Elsevier B.V. All rights reserved.
Applied Animal Behaviour Science 196 (2017) 108–112
L. Yin et al.
influenced by stocking density. In recent decades, goose production has become more specialized and widespread, and rearing geese in wirefloor pens is common in China. This type of rearing pattern is more productive than other rearing patterns since it allows for more birds per square meter. However, it results in more adverse effects on goose health and welfare, which may decrease the quality of goose products. Our previous work suggested that when stocking density was 5 or more birds/m2, the growth of individual birds was diminished (Yin et al., 2017); the current article aims to investigate stocking density effects on goose welfare. Animal welfare requests that animals have hygiene environment, and have enough space and freedom to perform normal behaviours. Feather performance (Onbaşılar and Aksoy, 2005; Steenfeldt and Nielsen, 2015), gait scoring (Dawkins et al., 2004; Makagon et al., 2015), and behavioral observation (Nielsen et al., 2004) have been demonstrated to be effective in evaluating the welfare of chickens and ducks. Thus, in our experiment, the welfare of geese in response to different stocking densities was assessed in terms of feather performance, walking ability, and behavioral changes. In a word, the aim of this study was to investigate the effects of stocking density on goose welfare in terms of feather performance, walking ability, and behavioral changes; and to create a preliminary criterion for goose stocking density. Previous researches controlled stocking density mostly by increasing the number of birds in pens with same size. However, an increase in stocking density is often accompanied by an increase in flock size. Zimmerman et al. (2006) designed an experiment which separated the effects of stocking density and group size by setting two different flock sizes (large and small) in the highest stocking density group. In their study, more aggression, preening and allopreening were recorded in small flocks than in large flocks, suggesting that when investigating stocking density effects, it is necessary to consider the effect of group size. In our study, we aim to preliminarily explore the stocking density effects on geese, thus, we carried out it based on a small-scale experiment. In the future, a large scale experiment which is closer to commercial practice will be done.
Table 1 Description of criteria for goose feather score and gait score1. Score
Feather2
Gait3
0
Completely clean
1
Less than 1/4 of the area is contaminated 1/4–1/3 (contain 1/3) of the area is contaminated 1/3 to 1/2 of the area is contaminated More than 1/2 of the area is contaminated
Goose walks at least ten steps with ease and is well balanced Goose has slight defect in the gait
2 3 4
Goose has obvious defect in the gait – trembling, unsteady Goose only walks with difficulty when it is driven or strongly motivated Goose is unable to walk on its feet
1 The areas that were feather scored included back, wings, and thoracoabdominal area of each randomly selected goose in each pen. Gait scoring was conducted by scanning all geese of each pen. 2 Adapted from Mahmoud et al. (2015). 3 Adapted from Kestin et al. (1992) and Jones et al. (2005).
2.2. Back-feather damage Approximately 10 days after starting our experiment, we noticed that the goose back skin in some treatments was bared, so at 42 days of age, the number of the geese with or without a back feather damage in each pen was recorded, and the back-feather damage rate was calculated as the proportion of geese with back-feather damage in each pen. Data are presented as the back feather damage rate in each pen. 2.3. Feather scoring At 69 days of age, one goose from each pen was randomly selected and feather scored. The scoring was based on the degree of feather surface contamination and was conducted by the same person, who was blind to the treatment. The areas which were scored included the back, wings, and thoracoabdominal area of each selected goose, and a scoring system from 0 (completely clean) to 4 (more than 1/2 of the area was contaminated) was used. The scoring criteria are shown in Table 1 (adapted from Mahmoud et al., 2015).
2. Materials and methods 2.4. Gait scoring All the procedures of our experiments were approved by the animal care and use committee of Yangzhou University (Yangzhou, China).
At 68 and 69 days of age, all birds of each pen were individually scanned for gait score by the same person who was blind to the treatment. A scoring system from 0 (goose can walk normally) to 4 (goose is unable to walk on its feet) was used. The scoring criteria are shown in Table 1 and are based on the modification of the systems of Kestin et al. (1992) and Jones et al. (2005). Data are presented as the proportion of geese with each class of gait score in each pen.
2.1. Animals, experimental design, and management This experiment was carried out at Yangzhou University (Yangzhou, China) from April to June 2016. A total of 336 healthy 28-day-old male Yangzhou goslings from the same hatchery (Gaoyou, Yangzhou, China) were randomly allotted to 30 plastic wire-floor pens according to 5 different stocking densities, adopting randomised block method. All the birds were reared in the same house with the same ventilation and lighting regimen. The pen size was 2.83 m2 (2.28 × 1.24 m), and the stocking densities were 2 birds/m2, 3 birds/m2, 4 birds/m2, 5 birds/m2, and 6 birds/m2 during the period from 28 to 70 days of age. Each treatment was represented by six replicates. All geese were provided with the same diets, which were formulated mainly according to the NRC (1994) and prior research results from our laboratory (Shi et al., 2007; Wang et al., 2010). Birds had ad libitum access to feed and water. Water was provided by the same half-open plastic cylindrical water tank, and pelleted feed was provided in feed troughs on the one side of each pen. Mortality and the body weight of the dead goose were recorded when death occurred, and a cubical space was isolated by a plastic wire net to ensure that the density treatment was not affected.
2.5. Behavioral observations From 60–65 days of age, five battery-operated video cameras were used to record the behaviour of the geese in each pen every day, after which the videos were observed by the same observer. Three days before recording, the geese were observed randomly for 15 min per day to determine the behavioral category and ethogram based on Van Krimpen et al. (2011) and Rodriguez-Aurrekoetxea et al. (2015). Then, three geese were randomly selected from each pen and tagged on the neck with a blue permanent marker for observation. From 60–65 days of age, one replicate of each treatment was recorded every day in the morning (from 9:00 to 10:20 h); to eliminate the artificial interference at the beginning and the end of the recording, the middle 1 h of each video was chosen for data collection. Sampling method used was all occurrences of each Behavioral category (Altmann, 1974). Data are presented as all event frequencies of the three tagged birds from each pen. Behaviour categories and the ethogram are shown in Table 2. 109
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Table 2 Ethogram used during observations1. Behavioral events
Definition
Standing
The bird rights itself from the floor and maintains an upright position on extended legs for at least two seconds. The bird lies down and rests on the floor. The bird places its head inside a feeder and pecks food in trough. A fast and strong pecking directed towards the feathers of another bird. The bird combs its feathers with its beak, lasting for at least five seconds. The bird shakes its wings at least twice. Can move forward or remain stationary. The bird stands on only one leg to relax.
Lying Eating Feather pecking Preening Wing-flapping Standing on one leg
1 Modified from van Van Krimpen et al. (2011) and Rodriguez-Aurrekoetxea et al. (2015).
2.6. Statistical analysis
Fig. 1. The effect of stocking density on the proportion of geese with back-feather damage. Statistical testing was carried out with Kruskal-Wallis test followed by the MannWhitney test. Results are presented as box plots (median, first and third quartiles) (n = 6). Different lowercase letters above the columns indicate statistically significant differences (P ≤ 0.05).
The SPSS statistical software (SPSS, Ver. 17.0 for Windows, 2008) was used for analysis. Data of six pens in each treatment were averaged. For the measurements of back-feather damage and gait, pen was considered as the experiment unit; for the measurements of feather contamination degree and behaviour changes, the randomly selected geese from each pen were considered as the experiment unit, and represented each pen. All data are tested for normal distribution by the K-S (Kolmogorov-Smirnov) test. The data of back-feather damage and gait are not normally distributed, and they were analyzed by the nonparameter Kruskal-Wallis test followed by the Mann-Whitney test. The data of feather contamination degree and behaviour changes are normally distributed, and they are analyzed by the one-way ANOVA procedure followed by Duncan’s multiple-range test. When Kruskal-Wallis tests are used, results are expressed as medians (interquartile range) and presented in figures with box plots (median, first and third quartiles); when one-way ANOVA tests are used, means of each treatment and the SEM among treatments are presented. A level of P ≤ 0.05 was set as the criterion for statistical significance.
Fig. 2. The effect of stocking density on the feather score of geese. The feather scoring was carried on the randomly selected bird from each pen. The scoring areas included the back, wings, and thoracoabdominal area. The higher the score, the severer the feather contamination. Statistical testing was carried out with one-way ANOVA followed by Duncan’s multiple-range test. The means and the standard errors of the means of five groups of 6 birds are shown (n = 6). Different lowercase letters above the columns indicate statistically significant differences (P ≤ 0.05).
3. Results 3.1. Feather performance A Kruskal-Wallis test showed that stocking density had significant effects on back-feather damage rate (χ2 = 18.570, DF = 4, P = 0.001) (Fig. 1). In the highest stocking density (6 birds/m2) group, the backfeather damage rate increased compared with that of other groups. The one-way ANOVA showed that stocking density had significant effects on feather contamination degree (feather score) of back (F4,25 = 5.519, P = 0.003), wing (F4,25 = 21.741, P < 0.001), and thoracoabdominal areas (F4,25 = 30.927, P < 0.001) (Fig. 2). The higher the feather score, the severer the feather contamination. In 2 birds/m2 group, the feather score of back area decreased compared with 4–6 birds/m2 group. In 5 and 6 birds/m2 group, the feather scores of wing and thoracoabdominal areas both increased compared with those of 2–4 birds/m2 group.
proportion of the geese with a gait score of three (Goose only walks with difficulty when it is driven or strongly motivated) increased, compared with 2–4 birds/m2 groups. In 5 birds/m2 and 6 birds/m2 groups, the proportions of the geese with a gait score of two (Goose has obvious defect in the gait – trembling, unsteady) both increased compared with 2 and 3 birds/m2 groups. In addition, the gait score of four (Goose is unable to walk on its feet) occurred only in 6 birds/m2 group. The proportions of the geese with a gait score of one (Goose has slight defect in the gait) and four were both unaffected by stocking density (χ2 = 2.712, DF = 4, P = 0.607 and χ2 = 4.000, DF = 4, P = 0.406, respectively). 3.3. Behavioral changes
3.2. Gait score The one-way ANOVA showed that stocking density had significant effects on behavioral changes of geese (Table 4). Behaviours of lying P = 0.046), feather pecking (F4,25 = 9.107, (F4,25 = 2.824, P < 0.001), preening (F4,25 = 7.778, P < 0.001), and standing on one leg (F4,25 = 3.875, P = 0.014) were significantly affected by stocking density. In 4–6 birds/m2 groups, the frequency of standing on one leg behaviour decreased compared with that of 2 birds/m2 group. In 5 and 6 birds/m2 groups, preening behaviour increased compared
A Kruskal-Wallis test showed that stocking density significantly affected the walking ability (gait score) of goose (Table 3). Results showed that stocking density significantly affected the proportions of geese with gait scores of zero (χ2 = 11.607, DF = 4, P = 0.021), two (χ2 = 10.210, DF = 4, P = 0.037), and three (χ2 = 17.402, DF = 4, P = 0.002). In 6 birds/m2 group, the proportion of geese with a gait score of zero (goose can walk normally) decreased whereas the 110
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Table 3 The effect of stocking density on the proportion of geese with each class of gait score1 (%) . Stocking density (birds/m2) Gait score
2
3
4
5
6
χ2-value
P-value
0 1 2 3 4
100 (95–100)a 0 (0–5) 0 (0–0)b 0 (0–0)b 0 (0–0)
100 (87.5–100)ab 0 (0–12.5) 0 (0–0)b 0 (0–0)b 0 (0–0)
95.45 (90–100)ab 0 (0–2.5) 0 (0–9.3)ab 0 (0–0)b 0 (0–0)
88.3 (84.6–92.4)bc 7.1 (0–7.7) 7.4 (0–8)a 0 (0–1.9)ab 0 (0–0)
84.9 (76.1–89.6)c 3.1 (0–7.6) 5.9 (0–9.1)a 5.9 (4.4–6.3)a 0 (0–1.5)
χ2(4) = 11.607 χ2(4) = 2.712 χ2(4) = 10.210 χ2(4) = 17.402 χ2(4) = 4.000
0.021 0.607 0.037 0.002 0.406
1 Data are analyzed by the non-parameter Kruskal-Wallis test followed by the Mann-Whitney test. Results are expressed as the medians (interquartile range) (n = 6). Different lowercase letters indicate significant differences (P ≤ 0.05) among the treatments for each measure. The criteria of each score class are show in Table 2; the higher the score, the worse the walking ability.
with that of 2–4 birds/m2 groups. In 6 birds/m2 group, lying and feather pecking behaviours both increased compared with that of other groups. The frequencies of standing (F4,25 = 2.012, P = 0.123), eating (F4,25 = 0.443, P = 0.777), and wing-flapping (F4,25 = 1.250, P = 0.316) behaviours were not affected by stocking density.
significantly higher than that of geese in the other groups, suggesting that a high stocking density may cause harm to feather integrity. Birds with feather damage are more susceptible to further feather pecking and injurious pecking (McAdie and Keeling, 2000), which harms the growth and welfare of geese. In addition, in our experiment, the feather contamination degree of all the evaluated areas all increased when the stocking density was 5 or more birds/m2, indicating that the environmental hygiene of the higher-stocking-density groups (5 or more birds/ m2) was worse than that of the other groups. It must be point out that, in our study, different stocking densities were in accompany with different group sizes. Therefore, further research with larger scale should be done to explore how stocking density affects goose welfare. At present, it is concluded that under our experiment condition, the stocking density of geese should be kept to 5 or fewer birds/m2 to ensure good feather performance and good hygiene.
4. Discussion At present, few studies have been made on goose welfare, and our study aimed to preliminarily evaluate the effects of different stocking densities on goose welfare. The results showed that high stocking density adversely influenced goose welfare. It must be point out that in our study, different stocking densities were in accompany with different group sizes. Therefore, it is unclear whether the results are due to stocking density or group size. Further research with larger scale should be done to explore how stocking density affects goose welfare. In addition, although the scorers of feather and gait were blind to the treatment, they cannot score precisely because the method and criteria were not quantifiable. In further studies, some criteria more quantifiable should be made.
4.2. The effect of stocking density on the walking ability of geese In the current study, goose walking ability was damaged when the stocking density was 6 birds/m2. Although relative studies on geese are limited, many previous studies on broilers have shown that stocking density had effects on leg health and walking ability (Kestin et al., 1992; Sanotra et al., 2001; Dozier et al., 2005; Jones et al., 2005). In our study, the walking ability of geese was evaluated by goose gait. The results showed that when the stocking density was 6 birds/m2, the proportion of geese with normal gait decreased, whereas the proportion of geese with gait problems increased. In addition, the geese that were unable to walk on feet only occurred in the highest stocking density (6 birds/m2) group. All the results showed that at the highest stocking density, goose walking ability was damaged. In the present study, each goose from the 2 birds/m2, 3 birds/m2, 4 birds/m2, 5 birds/m2 and 6 birds/m2 groups had an average area of 0.472 m2/bird, 0.354 m2/bird, 0.257 m2/bird, 0.202 m2/bird, and 0.166 m2/bird, respectively; therefore, the activity range of geese at the highest stocking density was limited, and long period of space limitation resulted in poor walking
4.1. The effect of stocking density on the feather performance of geese Feathers are an important economic character of geese (Kozák et al., 2010). Good feather coverage will optimize energy metabolism and feed efficiency (Leeson and Walsh, 2004), and feather performance is related to the sales of geese. At present, studies related to stocking density effect on geese are limited. However, previous studies on broilers and hens have shown that feather performance was poor in high-stocking-density group (Onbaşılar and Aksoy, 2005; Steenfeldt and Nielsen, 2015; Toghyani et al., 2016), and feather condition improved when floor-area allowances increased (Davami et al., 1987). Our study showed that stocking density also affected the feather performance of goose. In the present study, the back-feather damage rate of geese in the highest stocking density group (6 birds/m2) was Table 4 The effect of stocking density on activity frequencies of geese1. Stocking density (birds/m2) Behaviour categories
2
3
4
5
6
SEM
F-value
P-value
Standing Lying Eating Feather pecking Preening Wing-flapping Standing on one leg
15.00 14.00b 14.00 1.50d 12.00b 6.00 7.00a
11.50 12.00b 11.00 7.50cd 7.50b 5.50 4.50ab
14.67 16.50ab 10.50 19.33bc 13.00b 8.50 2.50b
15.50 14.00b 7.00 23.50b 33.00a 6.50 0.50b
18.00 20.50a 13.00 38.00a 27.50a 3.50 0.50b
0.782 0.973 1.745 3.078 2.455 0.733 0.747
F4,25 = 2.012 F4,25 = 2.824 F4,25 = 0.443 F4,25 = 9.107 F4,25 = 7.778 F4,25 = 1.250 F4,25 = 3.875
0.123 0.046 0.777 0.000 0.000 0.316 0.014
1 Data are analyzed by the one-way ANOVA followed by Duncan’s multiple-range test. Results are expressed as the means of the frequencies of each activity for each treatment, SEM among treatments is presented (n = 6). The ethogram used during observations is shown in Table 3. The different lowercase letters indicate significant differences (P ≤ 0.05) among the treatments for each measure.
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References
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4.3. The effect of stocking density on the behavioral changes of geese Geese like hygiene environment and need enough space to perform natural behaviours. Animal behaviour can reflect their living environment and welfare (Fraser, 1989). In the current study, when geese at high stocking density, their relaxing behaviour reduced, whereas abnormal behaviours such as feather pecking occurred more frequently. Feather pecking will cause animal welfare and economic problems as they may lead to feather damage and injuries (Sepeur et al., 2015), therefore, high stocking density will adversely affect goose welfare and market. Some studies have found that lower stocking density during rearing results in less feather pecking (Huber-Eicher and Audigé, 1999), as well as the combination of lower stocking density and smaller group size (Nicol et al., 1999; Savory et al., 1999). In our study, different stocking densities were in accompany with different group sizes. Therefore, further research should be done to explore whether the feather pecking problem are due to stocking density or group size. In the current study, the preening behaviour of 5 and 6 birds/m2 groups increased compared with that of 2–4 birds/m2 groups, the change in preening behaviours was similar to the change in feather contamination degree, suggesting that the dirty environment at highstocking-density groups (5 and 6 birds/m2) may drive the geese to comb their contaminated feathers more frequently. In our study, when the stocking density was 6 birds/m2, the frequency of lying behaviour significantly increased. Because in 6 birds/ m2 group, each goose had an average area of 0.166 m2/bird, the space at the highest stocking density was limited, therefore, the rests of the highest-density birds was often disturbed by their nearby birds, and the birds got up and down more often. In addition, the frequency of standing on one leg (relaxing) behaviour significantly decreased when the stocking density was 4 or more birds/m2. These results suggested that the space limitation in high stocking density groups resulted in the reduction of relaxing behaviour but the increase of disruptions by other birds, which is bad for goose welfare. Therefore, it is necessary to keep an appropriate stocking density in goose production. 5. Conclusions In the present study, high stocking density (5 or more birds/m2) led to poor welfare (including poor feather performance, poor gait and an increase in the frequency of abnormal behaviour), which was harmful to the health and the growth of geese. Therefore, under our experimental conditions, the stocking density of geese should be fewer than 5 birds/m2 to ensure relatively good welfare and avoid the negative effects of high stocking density. In addition, in our experiment, different stocking densities were in accompany with different group size, in the future, additional studies will be done to explore how stocking density and group size affect goose welfare. Conflicts of interest None. Acknowledgements This work was supported by the China Agriculture Research System (CARS-43); and the Prospective Production, Learning and Research Joint Research Project of Jiangsu Province(BY201561-11).
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Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim
Feather performance, walking ability, and behavioral changes of geese in response to different stocking densities
MARK
⁎
Luyao Yin, Haiming Yang, Lei Xu, Jun Zhang, Hao Xing, Zhiyue Wang College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu Province 225009, PR China
A R T I C L E I N F O
A B S T R A C T
Keywords: Stocking density (in accompany with group size) Goose Welfare Feather performance Walking ability Behaviour
In recent decades, goose production has become more specialized and widespread, and rearing geese in plastic wire-floor pens is common in China. This type of rearing pattern is more productive than other rearing patterns since it allows for more birds per square meter. However, it brings some problems due to high stocking density such as poor feather performance and walking ability, and some behavioral changes. This experiment was conducted to preliminarily evaluate the effects of different stocking densities on goose welfare in terms of feather performance, walking ability and behavioral changes. A total of 336 healthy, 28-day-old, male Yangzhou goslings were allotted to 30 plastic wire-floor pens according to five stocking densities (2, 3, 4, 5 and 6 birds/ m2), adopting randomised block method. Each treatment was represented by six replicates. Feather performance was assessed by two types of measurements: back-feather damage rate, and feather contamination degree which was carried out by feather scoring. Walking ability was assessed by gait scoring. All birds in each pen were individually scanned for back-feather damage measurement at 42 days of age, and individually scored for gait at 68 and 69 days of age. One bird from each pen was randomly selected for feather scoring at 69 days of age. The higher the feather score and the gait score, the worse the goose welfare. From 60–65 days of age, three geese from each pen were randomly selected and tagged for behavioral observation. Results showed that when stocking density was 4 or more birds/m2, standing on one leg (relaxing) behaviour reduced significantly (P ≤ 0.05); when stocking density was 5 or more birds/m2, feather contamination degree (P ≤ 0.05) and preening behaviour (P ≤ 0.05) both increased significantly; when stocking density was 6 birds/m2, the behaviours of lying and feather pecking, and back-feather damage rate all increased (P ≤ 0.05, for all), whereas walking ability declined, which was reflected by the increased proportion of geese with normal gait (P ≤ 0.05) and the decreased proportion of geese with gait problems (P ≤ 0.05). In conclusion, a high stocking density (5 or more birds/m2) led to an increase in feather pecking and poor performances in feather and walking ability, which were harmful to goose welfare and may decrease the quality of goose products. Therefore, based on our experimental conditions, we recommend that the stocking density of geese should be fewer than 5 birds/m2 to ensure relatively good welfare and avoid negative effects. In addition, in our experiment, different stocking densities were in accompany with different group size, in the future, additional studies will be done to explore how stocking density and group size affect goose welfare.
1. Introduction With the rapid development of the poultry industry, many producers have adopted the highest possible stocking density in production because the economic benefit per square meter is often higher when the birds are stocked more densely. However, an excessively high stocking density can adversely influence the performance, behaviour, and welfare of the birds, a situation that has attracted attention in recent years. Although relevant studies on geese are limited, many researchers on chickens (Dawkins et al., 2004; Estevez, 2007; Lay et al., 2011) and
⁎
ducks (Baéza et al., 2003) have indicated that high stocking density can cause adverse effects such as behavioral changes, poor feather and poor walking ability. Baéza et al. (2003) studied changes in behaviour, welfare, performance, and carcass quality of Muscovy ducks in response to three stocking densities (7, 9, and 11 male ducks/m2) and found that the stocking density of 9 birds/m2 gave the best results for all measurements. Xie et al. (2014) indicated that the body weight and the weight gain of starter and growing ducks were both reduced when stocking density increased, but the carcass, breast meat, leg meat, abdominal fat, and foot pad lesions of ducks were not significantly
Corresponding author at: College of Animal Science and Technology, Yangzhou University, Wenhui East Road 48#, Yangzhou City, Jiangsu Province 225009, PR China. E-mail address: [email protected] (Z. Wang).
http://dx.doi.org/10.1016/j.applanim.2017.06.017 Received 28 January 2017; Received in revised form 14 June 2017; Accepted 18 June 2017 Available online 28 June 2017 0168-1591/ © 2017 Elsevier B.V. All rights reserved.
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influenced by stocking density. In recent decades, goose production has become more specialized and widespread, and rearing geese in wirefloor pens is common in China. This type of rearing pattern is more productive than other rearing patterns since it allows for more birds per square meter. However, it results in more adverse effects on goose health and welfare, which may decrease the quality of goose products. Our previous work suggested that when stocking density was 5 or more birds/m2, the growth of individual birds was diminished (Yin et al., 2017); the current article aims to investigate stocking density effects on goose welfare. Animal welfare requests that animals have hygiene environment, and have enough space and freedom to perform normal behaviours. Feather performance (Onbaşılar and Aksoy, 2005; Steenfeldt and Nielsen, 2015), gait scoring (Dawkins et al., 2004; Makagon et al., 2015), and behavioral observation (Nielsen et al., 2004) have been demonstrated to be effective in evaluating the welfare of chickens and ducks. Thus, in our experiment, the welfare of geese in response to different stocking densities was assessed in terms of feather performance, walking ability, and behavioral changes. In a word, the aim of this study was to investigate the effects of stocking density on goose welfare in terms of feather performance, walking ability, and behavioral changes; and to create a preliminary criterion for goose stocking density. Previous researches controlled stocking density mostly by increasing the number of birds in pens with same size. However, an increase in stocking density is often accompanied by an increase in flock size. Zimmerman et al. (2006) designed an experiment which separated the effects of stocking density and group size by setting two different flock sizes (large and small) in the highest stocking density group. In their study, more aggression, preening and allopreening were recorded in small flocks than in large flocks, suggesting that when investigating stocking density effects, it is necessary to consider the effect of group size. In our study, we aim to preliminarily explore the stocking density effects on geese, thus, we carried out it based on a small-scale experiment. In the future, a large scale experiment which is closer to commercial practice will be done.
Table 1 Description of criteria for goose feather score and gait score1. Score
Feather2
Gait3
0
Completely clean
1
Less than 1/4 of the area is contaminated 1/4–1/3 (contain 1/3) of the area is contaminated 1/3 to 1/2 of the area is contaminated More than 1/2 of the area is contaminated
Goose walks at least ten steps with ease and is well balanced Goose has slight defect in the gait
2 3 4
Goose has obvious defect in the gait – trembling, unsteady Goose only walks with difficulty when it is driven or strongly motivated Goose is unable to walk on its feet
1 The areas that were feather scored included back, wings, and thoracoabdominal area of each randomly selected goose in each pen. Gait scoring was conducted by scanning all geese of each pen. 2 Adapted from Mahmoud et al. (2015). 3 Adapted from Kestin et al. (1992) and Jones et al. (2005).
2.2. Back-feather damage Approximately 10 days after starting our experiment, we noticed that the goose back skin in some treatments was bared, so at 42 days of age, the number of the geese with or without a back feather damage in each pen was recorded, and the back-feather damage rate was calculated as the proportion of geese with back-feather damage in each pen. Data are presented as the back feather damage rate in each pen. 2.3. Feather scoring At 69 days of age, one goose from each pen was randomly selected and feather scored. The scoring was based on the degree of feather surface contamination and was conducted by the same person, who was blind to the treatment. The areas which were scored included the back, wings, and thoracoabdominal area of each selected goose, and a scoring system from 0 (completely clean) to 4 (more than 1/2 of the area was contaminated) was used. The scoring criteria are shown in Table 1 (adapted from Mahmoud et al., 2015).
2. Materials and methods 2.4. Gait scoring All the procedures of our experiments were approved by the animal care and use committee of Yangzhou University (Yangzhou, China).
At 68 and 69 days of age, all birds of each pen were individually scanned for gait score by the same person who was blind to the treatment. A scoring system from 0 (goose can walk normally) to 4 (goose is unable to walk on its feet) was used. The scoring criteria are shown in Table 1 and are based on the modification of the systems of Kestin et al. (1992) and Jones et al. (2005). Data are presented as the proportion of geese with each class of gait score in each pen.
2.1. Animals, experimental design, and management This experiment was carried out at Yangzhou University (Yangzhou, China) from April to June 2016. A total of 336 healthy 28-day-old male Yangzhou goslings from the same hatchery (Gaoyou, Yangzhou, China) were randomly allotted to 30 plastic wire-floor pens according to 5 different stocking densities, adopting randomised block method. All the birds were reared in the same house with the same ventilation and lighting regimen. The pen size was 2.83 m2 (2.28 × 1.24 m), and the stocking densities were 2 birds/m2, 3 birds/m2, 4 birds/m2, 5 birds/m2, and 6 birds/m2 during the period from 28 to 70 days of age. Each treatment was represented by six replicates. All geese were provided with the same diets, which were formulated mainly according to the NRC (1994) and prior research results from our laboratory (Shi et al., 2007; Wang et al., 2010). Birds had ad libitum access to feed and water. Water was provided by the same half-open plastic cylindrical water tank, and pelleted feed was provided in feed troughs on the one side of each pen. Mortality and the body weight of the dead goose were recorded when death occurred, and a cubical space was isolated by a plastic wire net to ensure that the density treatment was not affected.
2.5. Behavioral observations From 60–65 days of age, five battery-operated video cameras were used to record the behaviour of the geese in each pen every day, after which the videos were observed by the same observer. Three days before recording, the geese were observed randomly for 15 min per day to determine the behavioral category and ethogram based on Van Krimpen et al. (2011) and Rodriguez-Aurrekoetxea et al. (2015). Then, three geese were randomly selected from each pen and tagged on the neck with a blue permanent marker for observation. From 60–65 days of age, one replicate of each treatment was recorded every day in the morning (from 9:00 to 10:20 h); to eliminate the artificial interference at the beginning and the end of the recording, the middle 1 h of each video was chosen for data collection. Sampling method used was all occurrences of each Behavioral category (Altmann, 1974). Data are presented as all event frequencies of the three tagged birds from each pen. Behaviour categories and the ethogram are shown in Table 2. 109
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Table 2 Ethogram used during observations1. Behavioral events
Definition
Standing
The bird rights itself from the floor and maintains an upright position on extended legs for at least two seconds. The bird lies down and rests on the floor. The bird places its head inside a feeder and pecks food in trough. A fast and strong pecking directed towards the feathers of another bird. The bird combs its feathers with its beak, lasting for at least five seconds. The bird shakes its wings at least twice. Can move forward or remain stationary. The bird stands on only one leg to relax.
Lying Eating Feather pecking Preening Wing-flapping Standing on one leg
1 Modified from van Van Krimpen et al. (2011) and Rodriguez-Aurrekoetxea et al. (2015).
2.6. Statistical analysis
Fig. 1. The effect of stocking density on the proportion of geese with back-feather damage. Statistical testing was carried out with Kruskal-Wallis test followed by the MannWhitney test. Results are presented as box plots (median, first and third quartiles) (n = 6). Different lowercase letters above the columns indicate statistically significant differences (P ≤ 0.05).
The SPSS statistical software (SPSS, Ver. 17.0 for Windows, 2008) was used for analysis. Data of six pens in each treatment were averaged. For the measurements of back-feather damage and gait, pen was considered as the experiment unit; for the measurements of feather contamination degree and behaviour changes, the randomly selected geese from each pen were considered as the experiment unit, and represented each pen. All data are tested for normal distribution by the K-S (Kolmogorov-Smirnov) test. The data of back-feather damage and gait are not normally distributed, and they were analyzed by the nonparameter Kruskal-Wallis test followed by the Mann-Whitney test. The data of feather contamination degree and behaviour changes are normally distributed, and they are analyzed by the one-way ANOVA procedure followed by Duncan’s multiple-range test. When Kruskal-Wallis tests are used, results are expressed as medians (interquartile range) and presented in figures with box plots (median, first and third quartiles); when one-way ANOVA tests are used, means of each treatment and the SEM among treatments are presented. A level of P ≤ 0.05 was set as the criterion for statistical significance.
Fig. 2. The effect of stocking density on the feather score of geese. The feather scoring was carried on the randomly selected bird from each pen. The scoring areas included the back, wings, and thoracoabdominal area. The higher the score, the severer the feather contamination. Statistical testing was carried out with one-way ANOVA followed by Duncan’s multiple-range test. The means and the standard errors of the means of five groups of 6 birds are shown (n = 6). Different lowercase letters above the columns indicate statistically significant differences (P ≤ 0.05).
3. Results 3.1. Feather performance A Kruskal-Wallis test showed that stocking density had significant effects on back-feather damage rate (χ2 = 18.570, DF = 4, P = 0.001) (Fig. 1). In the highest stocking density (6 birds/m2) group, the backfeather damage rate increased compared with that of other groups. The one-way ANOVA showed that stocking density had significant effects on feather contamination degree (feather score) of back (F4,25 = 5.519, P = 0.003), wing (F4,25 = 21.741, P < 0.001), and thoracoabdominal areas (F4,25 = 30.927, P < 0.001) (Fig. 2). The higher the feather score, the severer the feather contamination. In 2 birds/m2 group, the feather score of back area decreased compared with 4–6 birds/m2 group. In 5 and 6 birds/m2 group, the feather scores of wing and thoracoabdominal areas both increased compared with those of 2–4 birds/m2 group.
proportion of the geese with a gait score of three (Goose only walks with difficulty when it is driven or strongly motivated) increased, compared with 2–4 birds/m2 groups. In 5 birds/m2 and 6 birds/m2 groups, the proportions of the geese with a gait score of two (Goose has obvious defect in the gait – trembling, unsteady) both increased compared with 2 and 3 birds/m2 groups. In addition, the gait score of four (Goose is unable to walk on its feet) occurred only in 6 birds/m2 group. The proportions of the geese with a gait score of one (Goose has slight defect in the gait) and four were both unaffected by stocking density (χ2 = 2.712, DF = 4, P = 0.607 and χ2 = 4.000, DF = 4, P = 0.406, respectively). 3.3. Behavioral changes
3.2. Gait score The one-way ANOVA showed that stocking density had significant effects on behavioral changes of geese (Table 4). Behaviours of lying P = 0.046), feather pecking (F4,25 = 9.107, (F4,25 = 2.824, P < 0.001), preening (F4,25 = 7.778, P < 0.001), and standing on one leg (F4,25 = 3.875, P = 0.014) were significantly affected by stocking density. In 4–6 birds/m2 groups, the frequency of standing on one leg behaviour decreased compared with that of 2 birds/m2 group. In 5 and 6 birds/m2 groups, preening behaviour increased compared
A Kruskal-Wallis test showed that stocking density significantly affected the walking ability (gait score) of goose (Table 3). Results showed that stocking density significantly affected the proportions of geese with gait scores of zero (χ2 = 11.607, DF = 4, P = 0.021), two (χ2 = 10.210, DF = 4, P = 0.037), and three (χ2 = 17.402, DF = 4, P = 0.002). In 6 birds/m2 group, the proportion of geese with a gait score of zero (goose can walk normally) decreased whereas the 110
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Table 3 The effect of stocking density on the proportion of geese with each class of gait score1 (%) . Stocking density (birds/m2) Gait score
2
3
4
5
6
χ2-value
P-value
0 1 2 3 4
100 (95–100)a 0 (0–5) 0 (0–0)b 0 (0–0)b 0 (0–0)
100 (87.5–100)ab 0 (0–12.5) 0 (0–0)b 0 (0–0)b 0 (0–0)
95.45 (90–100)ab 0 (0–2.5) 0 (0–9.3)ab 0 (0–0)b 0 (0–0)
88.3 (84.6–92.4)bc 7.1 (0–7.7) 7.4 (0–8)a 0 (0–1.9)ab 0 (0–0)
84.9 (76.1–89.6)c 3.1 (0–7.6) 5.9 (0–9.1)a 5.9 (4.4–6.3)a 0 (0–1.5)
χ2(4) = 11.607 χ2(4) = 2.712 χ2(4) = 10.210 χ2(4) = 17.402 χ2(4) = 4.000
0.021 0.607 0.037 0.002 0.406
1 Data are analyzed by the non-parameter Kruskal-Wallis test followed by the Mann-Whitney test. Results are expressed as the medians (interquartile range) (n = 6). Different lowercase letters indicate significant differences (P ≤ 0.05) among the treatments for each measure. The criteria of each score class are show in Table 2; the higher the score, the worse the walking ability.
with that of 2–4 birds/m2 groups. In 6 birds/m2 group, lying and feather pecking behaviours both increased compared with that of other groups. The frequencies of standing (F4,25 = 2.012, P = 0.123), eating (F4,25 = 0.443, P = 0.777), and wing-flapping (F4,25 = 1.250, P = 0.316) behaviours were not affected by stocking density.
significantly higher than that of geese in the other groups, suggesting that a high stocking density may cause harm to feather integrity. Birds with feather damage are more susceptible to further feather pecking and injurious pecking (McAdie and Keeling, 2000), which harms the growth and welfare of geese. In addition, in our experiment, the feather contamination degree of all the evaluated areas all increased when the stocking density was 5 or more birds/m2, indicating that the environmental hygiene of the higher-stocking-density groups (5 or more birds/ m2) was worse than that of the other groups. It must be point out that, in our study, different stocking densities were in accompany with different group sizes. Therefore, further research with larger scale should be done to explore how stocking density affects goose welfare. At present, it is concluded that under our experiment condition, the stocking density of geese should be kept to 5 or fewer birds/m2 to ensure good feather performance and good hygiene.
4. Discussion At present, few studies have been made on goose welfare, and our study aimed to preliminarily evaluate the effects of different stocking densities on goose welfare. The results showed that high stocking density adversely influenced goose welfare. It must be point out that in our study, different stocking densities were in accompany with different group sizes. Therefore, it is unclear whether the results are due to stocking density or group size. Further research with larger scale should be done to explore how stocking density affects goose welfare. In addition, although the scorers of feather and gait were blind to the treatment, they cannot score precisely because the method and criteria were not quantifiable. In further studies, some criteria more quantifiable should be made.
4.2. The effect of stocking density on the walking ability of geese In the current study, goose walking ability was damaged when the stocking density was 6 birds/m2. Although relative studies on geese are limited, many previous studies on broilers have shown that stocking density had effects on leg health and walking ability (Kestin et al., 1992; Sanotra et al., 2001; Dozier et al., 2005; Jones et al., 2005). In our study, the walking ability of geese was evaluated by goose gait. The results showed that when the stocking density was 6 birds/m2, the proportion of geese with normal gait decreased, whereas the proportion of geese with gait problems increased. In addition, the geese that were unable to walk on feet only occurred in the highest stocking density (6 birds/m2) group. All the results showed that at the highest stocking density, goose walking ability was damaged. In the present study, each goose from the 2 birds/m2, 3 birds/m2, 4 birds/m2, 5 birds/m2 and 6 birds/m2 groups had an average area of 0.472 m2/bird, 0.354 m2/bird, 0.257 m2/bird, 0.202 m2/bird, and 0.166 m2/bird, respectively; therefore, the activity range of geese at the highest stocking density was limited, and long period of space limitation resulted in poor walking
4.1. The effect of stocking density on the feather performance of geese Feathers are an important economic character of geese (Kozák et al., 2010). Good feather coverage will optimize energy metabolism and feed efficiency (Leeson and Walsh, 2004), and feather performance is related to the sales of geese. At present, studies related to stocking density effect on geese are limited. However, previous studies on broilers and hens have shown that feather performance was poor in high-stocking-density group (Onbaşılar and Aksoy, 2005; Steenfeldt and Nielsen, 2015; Toghyani et al., 2016), and feather condition improved when floor-area allowances increased (Davami et al., 1987). Our study showed that stocking density also affected the feather performance of goose. In the present study, the back-feather damage rate of geese in the highest stocking density group (6 birds/m2) was Table 4 The effect of stocking density on activity frequencies of geese1. Stocking density (birds/m2) Behaviour categories
2
3
4
5
6
SEM
F-value
P-value
Standing Lying Eating Feather pecking Preening Wing-flapping Standing on one leg
15.00 14.00b 14.00 1.50d 12.00b 6.00 7.00a
11.50 12.00b 11.00 7.50cd 7.50b 5.50 4.50ab
14.67 16.50ab 10.50 19.33bc 13.00b 8.50 2.50b
15.50 14.00b 7.00 23.50b 33.00a 6.50 0.50b
18.00 20.50a 13.00 38.00a 27.50a 3.50 0.50b
0.782 0.973 1.745 3.078 2.455 0.733 0.747
F4,25 = 2.012 F4,25 = 2.824 F4,25 = 0.443 F4,25 = 9.107 F4,25 = 7.778 F4,25 = 1.250 F4,25 = 3.875
0.123 0.046 0.777 0.000 0.000 0.316 0.014
1 Data are analyzed by the one-way ANOVA followed by Duncan’s multiple-range test. Results are expressed as the means of the frequencies of each activity for each treatment, SEM among treatments is presented (n = 6). The ethogram used during observations is shown in Table 3. The different lowercase letters indicate significant differences (P ≤ 0.05) among the treatments for each measure.
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4.3. The effect of stocking density on the behavioral changes of geese Geese like hygiene environment and need enough space to perform natural behaviours. Animal behaviour can reflect their living environment and welfare (Fraser, 1989). In the current study, when geese at high stocking density, their relaxing behaviour reduced, whereas abnormal behaviours such as feather pecking occurred more frequently. Feather pecking will cause animal welfare and economic problems as they may lead to feather damage and injuries (Sepeur et al., 2015), therefore, high stocking density will adversely affect goose welfare and market. Some studies have found that lower stocking density during rearing results in less feather pecking (Huber-Eicher and Audigé, 1999), as well as the combination of lower stocking density and smaller group size (Nicol et al., 1999; Savory et al., 1999). In our study, different stocking densities were in accompany with different group sizes. Therefore, further research should be done to explore whether the feather pecking problem are due to stocking density or group size. In the current study, the preening behaviour of 5 and 6 birds/m2 groups increased compared with that of 2–4 birds/m2 groups, the change in preening behaviours was similar to the change in feather contamination degree, suggesting that the dirty environment at highstocking-density groups (5 and 6 birds/m2) may drive the geese to comb their contaminated feathers more frequently. In our study, when the stocking density was 6 birds/m2, the frequency of lying behaviour significantly increased. Because in 6 birds/ m2 group, each goose had an average area of 0.166 m2/bird, the space at the highest stocking density was limited, therefore, the rests of the highest-density birds was often disturbed by their nearby birds, and the birds got up and down more often. In addition, the frequency of standing on one leg (relaxing) behaviour significantly decreased when the stocking density was 4 or more birds/m2. These results suggested that the space limitation in high stocking density groups resulted in the reduction of relaxing behaviour but the increase of disruptions by other birds, which is bad for goose welfare. Therefore, it is necessary to keep an appropriate stocking density in goose production. 5. Conclusions In the present study, high stocking density (5 or more birds/m2) led to poor welfare (including poor feather performance, poor gait and an increase in the frequency of abnormal behaviour), which was harmful to the health and the growth of geese. Therefore, under our experimental conditions, the stocking density of geese should be fewer than 5 birds/m2 to ensure relatively good welfare and avoid the negative effects of high stocking density. In addition, in our experiment, different stocking densities were in accompany with different group size, in the future, additional studies will be done to explore how stocking density and group size affect goose welfare. Conflicts of interest None. Acknowledgements This work was supported by the China Agriculture Research System (CARS-43); and the Prospective Production, Learning and Research Joint Research Project of Jiangsu Province(BY201561-11).
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