The effects of lighting conditions on the behaviour of laying hens

Arch.Geflügelk., 74 (3). S. 197–202, 2010, ISSN 0003-9098. © Verlag Eugen Ulmer, Stuttgart

The effects of lighting conditions on the behaviour of laying hens Einfluss der Beleuchtungsbedingungen auf das Verhalten von Legehennen H.H. Mohammed, M.A. Grashorn and W. Bessei Manuskript eingegangen am 18. Mai 2009, angenommen am 30. Juli 2009

Introduction Many production facets influence performance and welfare of animals. The most important ones are environmental temperature and lighting conditions. Lighting is defined by source, intensity, wavelength spectrum and duration of photoperiod (MANSER, 1996). The knowledge on effects of duration of lighting and light intensity on bird’s performance and behaviour are well documented for laying hens (KUHLES and PETERSEN, 2005; ER et al., 2007), whereas, influences of light source and wavelength spectrum are rarely investigated. Lighting requirements of birds have to be considered for choosing the optimal light source. Here it has to be taken into account that birds cover a broader wave length spectrum than mammalians and that the resolution frequency of pictures is higher (up to 150 images/sec). Especially, birds are capable to see under ultraviolet lighting conditions and light intensity is felt differently by birds due to their different sensitivity to wave length. This was already considered by NUBOER (1993) and PRESCOTT and WATHES (1999) indicating that common light sources adapted to the way of human seeing may not cover requirements of birds adequately. For a long time, incandescent bulbs were used in commercial poultry housing due to their low investment costs. However, there has been a trend towards the use of fluorescent tubes, day light or high pressure sodium discharge lights due to their longer livability and lower operating costs. Recently, developments in light emitting diodes (LED) raised this light source to an interesting future alternative. Available light sources partly do not fulfil the requirements of birds for lighting. Incandescent light covers only a wave length spectrum between 600 and 700 nm and works at 50 Hz current. Fluorescent tubes and energy saving tubes have a broader wave length spectrum (400– 700 nm), but work also at 50 Hz and do not emit ultraviolet light. A current frequency of 50 Hz may be perceived as flickering by birds. LEDs (light emitting diodes) emit nearly monochromatic light with a restricted wave length spectrum (500–600 nm, depending on colour). Meanwhile high frequency (> 2000 Hz) daylight fluorescent tubes (350–700 nm) exist which overcome these restrictions. The knowledge on possible negative effects of restricted wave lengths emission and low frequency current on birds

Dept. of Poultry Science (470 c), University Hohenheim, Stuttgart, Germany

Arch.Geflügelk. 3/2010

is still limited. In general, it is expected that wave length and frequency of light sources mainly influence behaviour rather than performance; e.g., PYRZAK and SIOPES (1986) observed no differences in reproductive performance of hens exposed to incandescent (IL) and blue light when lighting intensity remained constant. SIOPES (1984) compared fluorescent with incandescent light and found that hens stimulated by fluorescent light showed a similar reproductive performance to that of hens kept under incandescent light. More effects of light sources are described for abnormal behaviour. Feather pecking is considered as one of the most serious problems in laying hens. Although, the reasons for feather pecking are still not clear, it is well known that feather pecking results in a damaged plumage leading to increased food consumption. Furthermore, feather pecking may lead to injuries of the skin and consequently to cannibalism resulting in increased mortality and higher economic loss (BLUKHUIS and VAN DER HAAR, 1992). Feather pecking is an animal welfare concern (VESTERGAARD, 1994) and thus has to be prevented. Excessive light has been identified as one factor initiating and/or favouring this abnormal behaviour (KJAER and VESTERGAARD, 1999). However, KJAER and SØRENSEN (2002) found that light intensity had no effect on the rate of feather pecking in any of the tested genotypes, although about twice as much feather pecking was observed at 10 lux compared to 3 lux in ISA breed. HUGHES and BLACK (1974) and BRAASTAAD (1986) showed that light intensity strongly influences the incidence and severity of feather pecking in laying hens with higher light intensity leading to more damage, whilst BOSHOUWERS and NICAISE (1993) reported that fluorescent light resulted in the same positive correlation between light intensity and physical activity at all activity levels, as it was found previously for incandescent light. Physical activity under fluorescent light was higher than under incandescent light at light intensities of 5 lux and above, indicating the fowl’s ability to perceive qualitative light differences. Light intensity perceived by the birds is rather difficult to measure. In practice, light intensity in poultry houses is measured with lux-meters adapted to the human way of seeing. These measuring tools do not consider the different perception of light intensity of birds at distinct wave lengths. Therefore, PRESCOTT and WATHES (1999) developed a method to calculate chicken specific light intensity values on the basis of lux values which they named ‘Gallilux’. The current frequency of light sources may also enhance the incidence of feather pecking as the ‘flickering’ effect is supposed to be a stressor to birds (DENBOW et al., 1990). In their experiment DENBOW et al. (1990) found that pecking and pulling of feathers was not affected by light sources,

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Mohammed et al.: Lighting conditions and behaviour of laying hens

and that agonistic behaviour was rare. But, information on this aspect is rare in literature. Therefore, two experiments were carried out to study the effects of different light sources and light intensities on normal and abnormal behaviour in laying hens.

Materials and methods All experiments were conducted at the Research Farm ‘Unterer Lindenhof’, Hohenheim University, in special windowless rooms equipped with pens with opaque walls under consideration of the German welfare law.

Experiment 1 A total of 80 laying hens (Lohmann Brown Classic), 35 weeks of age, were divided into four groups of 20 birds each. Each group was reared in deep litter pens with a floor area of 2.54 m length × 2.27 m width, providing each bird with 2,280 cm2 of floor space. Height of the pens was about 3 m and pens were separated by opaque walls. Pens were ventilated in a way that daily temperature was maintained between 21°C and 23°C. Each pen was equipped with feeder, drinker, nest box (68 cm length × 31 cm width × 76 cm height) and elevated perches (70 cm height). Feed and water were provided ad libitum. A standard layer diet was fed as given in Table 1, containing (g/kg; calculated) 178 CP, 4.2 Met, 8.5 Lys, 38.2 Ca, 6.5 Pt and 11.4 MJ ME/kg (WPSA, 1984). During the experimental period, a 14-hour lighting schedule was applied (from 3:00 am to 5:00 pm). Pens were equipped with different light sources which were fitted to the roof of the room in a way that light sources could be changed and adjusted in height to providing a defined light intensity, easily. In the first experiment four light sources (incandescent light – IL, fluorescent light – FL, day light – DL, blue light – BL) were tested with the same light intensity (25 lux). IL was fitted in standard sockets without glass covering (50 Hz, 600–700 nm), FL was equipped with warm tone fluorescent tubes (50 Hz, 570–700 nm; Osram, Germany), DL was equipped with day light fluorescent tubes (2000 Hz, 400–750 nm) without coverings (Warnking, Germany), BL was equipped with two blue fluorescent tubes (50 Hz; nm) with plastic covering (Schuch, Germany). During the experiment light

sources were exchanged weekly between pens as described in Table 2. By this, pen effects should be eliminated. For a more practical approach light intensity was measured with Luxmeter Voltcraft MS-1300 (Conrad, Hirschau, Germany) about 0.3 m above the floor in the centre of the pen with the sensor pointing towards the ceiling ignoring the actually perceived light intensity by birds due to different wave lengths range of tested light sources. The following behavioural patterns were recorded: • Standing: hens standing without activity • Sitting • Walking: either walking or running • Feeding • Resting: sitting to remain dormant with the neck withdrawn, the head motionless, no dust bathing or preening movements (according to RUTH et al., 2006). • Feather pecking: only pecks to feathered parts of the body were classified as feather pecking. Repeated pecks to the same individual were judged as one interaction or a bout (ANJA et al., 2006; KJAER and SØRENSEN, 2002). • Aggression: aggressive behaviour towards other birds. The behavioural patterns were recorded through scan sampling method by the same person. The observer stood directly in front of the pen and waited ten minutes before recording to avoid any disturbance in the behaviours. All pens were observed directly for 2 × 10 minutes in the morning (10:00 am till 12:00 am) and for 2 × 10 minutes in the afternoon (2:00 pm till 4:00 pm) on two days every week according to EL-LETHEY et al. (2001) and KJAER and SØRENSEN, 2002). After scanning, the numbers of birds were counted in the observed pens. These numbers were used to calculate the frequencies of activities. Special emphasis was put on feather pecking interactions and aggression. Data were analyzed as repeated measurements by JMP program, Version 2005 (SALL et al., 2005). One-factorial analysis of variance (ANOVA) was performed. Differences between means were tested by Student’s t-test.

Experiment 2 A total of 256 Lohmann Brown Classic hens, 40 weeks of age, were kept in newly constructed floor pens (2.65 m length × 2.58 m width) and were randomly allocated to

Table 1. Composition of the experimental diet (g/kg) Zusammensetzung der Versuchsration (g/kg) Ingredient

g/kg

Ingredient

Soya bean meal (extracted) Ground wheat Ground maize Ground oats Maize gluten meal Soya bean oil Ground lime stone Granular lime stone 120 Monocalcium phosphate Sodium bicarbonate

232 390 80 100 40 40 40 50 12 2.5

Sodium chloride Trace- mineral premix Vitamin premix Choline chloride Methionine Luprosil Avizant1 Y 20S Avizant1 Y 5S Antioxidant Roxazyme G2 Sum

g/kg 2.5 0.8 2 1 1.8 4 0.6 1.6 0.15 0.15 1001.1

1 LAH, Cuxhaven, Germany 2 DSM Nutritional Products, Basel, Switzerland


Mohammed et al.: Lighting conditions and behaviour of laying hens Table 2. Layout of experiment 1 Aufbau von Versuch 1

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Results Experiment 1

Weeks of Experiment 1st 2nd 3rd 4th 5th 6th 7th 8th

1

Pen number 2 3

4

Direct observation

IL IL BL BL FL FL DL DL

BL BL FL FL DL DL IL IL

DL DL IL IL BL BL FL FL

– X – X – X – X

FL FL DL DL IL IL BL BL

Means (± SD) of walking, standing, sitting, resting, feeding, feather pecking (Fp) and aggressive behaviour are listed in Table 4. In general, hens under different light sources with the same light intensity (25 lux) showed no significant differences in all behaviours. Physical activity of hens was higher for fluorescent light and blue light than for other light sources. Sitting and resting was lowest for incandescent light. Minor differences have been observed for feeding. Birds under BL showed the highest level of feather pecking and aggressive behaviour (65.7 and 46.1, respectively). In contrast, birds under fluorescent light tended to show the lowest level of feather pecking and aggressive behaviour.

IL: incandescent light; BL: blue light; FL: fluorescent light; DL: day light

Experiment 2

eight experimental groups of 32 hens each. Husbandry condition, management and light sources were according to experiment 1. The floor space available to each hen was 2,136 cm2. In contrast to experiment 1, two light intensities were applied – 5 and 50 lux. The same behavioural patterns were recorded as in experiment 1. Ten scans were recorded in the morning and ten scans in the afternoon for each pen at two days within the week. Light sources were exchanged between pens as described in Table 3. The experimental data were analyzed as repeated measurements by JMP program. A two-factorial analysis of variance was performed and differences between means were assessed by Student’s t-test.

The second experiment (Table 5) revealed significant effects of light sources and light intensities on feather pecking and aggression, whereas, the other behaviours were not significantly affected. Interaction between light source and light intensity was not significant for any behaviour. Table 6 presents means (± SD) for normal behaviours in regard to light sources and light intensities. Walking activity was higher and standing activity was lower under high light intensity than under low intensity. Only minor differences were observed for sitting and resting. For IL and FL feeding activity was distinctly higher under high light intensity, whereas, for DL and BL no differences were visible.

Table 3. Layout of experiment 2 Aufbau von Versuch 2 Weeks

Pen number 1

1st 2nd 3rd 4th 5th 6th 7th 8th

2

3

4

DO 5

6

7

8

S

Lux

S

Lux

S

Lux

S

Lux

S

Lux

S

Lux

S

Lux

S

Lux

IL IL BL BL FL FL DL DL

5 50 5 50 5 50 5 50

DL IL IL BL BL FL FL DL

50 5 50 5 50 5 50 5

DL DL IL IL BL BL FL FL

5 50 5 50 5 50 5 50

FL DL DL IL IL BL BL FL

50 5 50 5 50 5 50 5

FL FL DL DL IL IL BL BL

5 50 5 50 5 50 5 50

BL FL FL DL DL IL IL BL

50 5 50 5 50 5 50 5

BL BL FL FL DL DL IL IL

5 50 5 50 5 50 5 50

IL BL BL FL FL DL DL IL

50 5 50 5 50 5 50 5

X X X X X X X X

S: light source; IL: incandescent light; BL: blue light; FL: fluorescent light; DL: day light ; DO: direct observation

Table 4. Means (± SD) of behavioural traits of hens in response to light sources (% of hens in observation period) in experiment 1 Mittelwerte (± SD) der Verhaltensweisen der Hennen in Abhängigkeit von der Lichtquelle (% der Hennen im Beobachtungszeitraum; Versuch 1) Light source IL FL DL BL P-Value


Walking

Standing

Sitting

Feeding

Resting

FP

Aggression

77.0 ± 28.9 82.6 ± 36.7 73.2 ± 30.5 84.0 ± 31.5 0.899

94.1 ± 37.5 93.4 ± 34.6 99.2 ± 30.2 97.0 ± 30.0 0.983

5.1 ± 4.9 14.5 ± 15.4 7.4 ± 11.4 15.9 ± 6.3 0.127

63.4 ± 13.0 56.5 ± 10.1 61.4 ± 8.1 66.1 ± 19.7 0.543

0.5 ± 0.9 3.6 ± 2.0 2.2 ± 1.7 3.4 ± 2.3 0.578

52.9 ± 19.2 45.2 ± 19.8 53.7 ± 22.0 65.7 ± 18.2 0.247

32.1 ± 16.6 30.0 ± 16.9 31.7 ± 8.0 46.1 ± 17.5 0.148

200


Table 5. Significance levels (P-values) of main factors and their interaction for different behaviours in laying hens in experiment 2 Irrtumswahrscheinlichkeiten für die Hauptfaktoren und deren Interaktion auf verschiedene Verhaltensweisen der Legehennen (Versuch 2) Source of variance

LS. LI. LS*LI

D.F.

Walking

Standing

Sitting

Resting

Feeding

Feather pecking

Aggression

3 1 3

0.880 0.165 0.442

0.889 0.105 0.947

0.297 0.862 0.972

0.515 0.910 0.749

0.775 0.257 0.534

0.008 0.003 0.122

0.069 0.007 0.751

Table 6. Means (± SD) for normal behaviours of hens in response to light sources and light intensities in experiment 2 (% of hens in observation period) Mittelwerte der Verhaltensweisen der Legehennen in Abhängigkeit von den Lichtquellen und der Beleuchtungsintensität (% der Hennen im Beobachtungszeitraum; Versuch 2) IL Behaviour Walking Standing Sitting Resting Feeding

Low 79.6 73.0 7.2 1.1 51.8

± ± ± ± ±

FL High

14.1 78.2 ± 20.9 25.7 66.8 ± 24.8 8.1 8.1 ± 10.7 2.3 1.4 ± 2.9 26.7 57.9 ± 26.8

Low 77.6 70.9 6.8 1.5 46.0

± ± ± ± ±

DL High

Low

9.5 81.4 ± 10.9 24.6 65.1 ± 17.4 8.3 7.2 ± 7.6 2.5 1.1 ± 2.2 19.2 56.6 ± 21.9

80.4 72.4 5.3 0.7 52.1

± ± ± ± ±

BL High

Low

11.5 81.2 ± 13.1 25.7 66.9 ± 22.4 6.6 5.3 ± 6.4 1.8 1.0 ± 2.6 20.3 50.3 ± 24.4

76.8 68.0 5.4 0.8 52.8

± ± ± ± ±

High

10.7 82.3 ± 13.3 21.4 66.2 ± 15.2 7.4 5.7 ± 7.0 1.6 0.8 ± 1.8 29.8 52.8 ± 22.1

Table 7. Means (± SD) of abnormal behaviour of hens in response to light sources and light intensities in experiment 2 (% of hens in observation period) Mittelwerte (± SD) für Federpicken und aggressives Verhalten der Hennen in Abhängigkeit von den Lichtquellen und der Beleuchtungsintensität (% der Hennen im Beobachtungszeitraum; Versuch 2) Abnormal behaviours

Light intensitis

IL

FL

DL

BL

Means

Feather pecking

5 Lux 50 Lux Means

10.0 ± 9.1 9.0 ± 7.1 9.5 ± 8.1b

8.8 ± 8.7 14.8 ± 10.9 11.8 ± 10.3b

8.6 ± 7.0 12.2 ± 11.7 10.4 ± 9.7b

11.7 ± 8.3 18.7 ± 15.2 15.2 ± 12.6a

9.8 ± 8.3b 13.7 ± 12.0a

Aggression

5 Lux 50 Lux Means

8.9 ± 7.6 11.9 ± 6.6 10.4 ± 7.2

7.4 ± 3.6 10.5 ± 6.3 9.0 ± 5.3

8.8 ± 5.0 9.7 ± 7.6 9.2 ± 6.4

10.9 ± 7.1 12.9 ± 9.2 11.9 ± 8.2

9.0 ± 6.1b 11.3 ± 7.5a

* Means for the same parameter within same column with different letters are significantly different (P < 0.05).

Table 7 presents means (± SD) for abnormal behaviours of hens in regard to light sources and their intensities. In general, feather pecking activity was significantly higher for BL and no differences were observed for the other light sources. In the same way, feather pecking activity was significantly higher under high light intensity than under low. This relation was also obvious for FL, DL and BL, whereas, feather pecking activity was similar for high and low light intensity for the incandescent light. For all light sources a higher aggression level was noticed for high light intensity. In tendency, aggressive behaviour occurred more often under blue light than under the other light sources.

Discussion Behaviour is a good indicator for the assessment of the well-being of laying hens. In experiment 1 light source did not really affect walking, standing and feeding activities of

hens. However, WIDOWSKI et al. (1992) showed that birds observed walking tended to be more evenly distributed between two light sources than the approximately 30% incandescent to 70% fluorescent distribution that was expected. In the present experiment, sitting and resting activities were much higher under fluorescent (FL) and under blue light (BL). The same observation for blue light was described by PRAYITNO et al. (1997) whilst KRISTENSEN et al. (2007) stated that sitting behaviour was not influenced by light sources. According to HUGHES (1982) abnormal behaviour in laying hens, as feather pecking and cannibalism may be favoured by lighting conditions in the house. For fluorescent light a lower sitting and resting activity has been expected due to the assumption that flickering of the light may make birds nervous. Obviously, this was not the case in the present experiment as indicated by the lower levels of feather pecking and aggressive behaviour. Feather pecking and aggressive behaviours were higher under blue light, Arch.Geflügelk. 3/2010

Mohammed et al.: Lighting conditions and behaviour of laying hens but the observed differences did not reach significance. The results on feather pecking and aggressive behaviour were in disagreement with observations of LEIGHTON et al. (1989) that light sources do not affect these behaviours. Probably, results of the present experiment were caused by the reduction in the wavelength distribution of blue light (< 500 nm). Light with a longer wavelength (red to infrared) is needed for a normal function of hypothalamus and pituitary gland. Insufficient emission of light with long wavelengths obviously increased activities of hens. Under blue light activities of walking, feather pecking and aggression were higher. SAVORY and MANN (1999) noted that pecking and cannibalism may be more likely in groups where activity levels are high. Maybe, hens searched for a way to compensate this deficit. BOSHOUWERS and NICAISE (1993) reported that physical activities under fluorescent light are higher than under incandescent light. In the present experiments, higher activity of hens was observed under fluorescent than incandescent light, but abnormal behaviours (feather pecking and aggressive behaviours) have been less frequent under fluorescent than incandescent light. This was also reported by MOINARD et al. (2001), who found that in comparison to incandescent light fluorescent light significantly reduced the incidence of tail injuries and tended to reduce the incidence of wing injuries caused by feather pecking. The observed higher activities of hens under blue light were paralleled by more time for feeding (66.1%) probably reflecting higher energy requirement for activity. Thus, light sources affected feeding behaviour, but the observed difference did not reach significance, as reported by VANDENBERG and WIDOWSKI (2000), who found that feeding occurred more often than expected for incandescent light than for high-pressure sodium light (HPS). In the second experiment similar results to the first experiment were observed. Again, walking and feather pecking activity as well as aggressive behaviour were higher under the blue light, especially, for high light intensity. NEWBERRY et al. (1988) found higher walking and total activity under high light intensity (180 lux) than under low light intensity (6 lux), whereas, feeding and drinking activity was not significantly affected. A significant negative effect of the combination blue light and high light intensity on feather pecking was also described by HUGHES and DUNCAN (1972), HUGHES and BLACK (1974) and APPLEBY et al. (1992). Hence, light sources have effects on plumage condition of hens through the effects on feather pecking, as described by VAN EMOUS et al. (2003), who showed that different light sources might affect plumage condition as judged by the incidence of feather pecking. But, this result is not in agreement with XIE et al. (2008), who reported that blue light may play a role in alleviating the stress response in broilers due to reduction in the level of serum interleukin-1ß. In general, for all tested light sources lower feather pecking activity and incidence of aggressive behaviours was recorded for low light intensity, in accordance with HESTER et al. (1987), CLASSEN et al. (1994), NIXEY (1994), MANSER (1996), SHERWIN (1998) and TAUSON (2005). SHINMURA et al. (2006) could not observe a significant difference in aggression between before and after decreasing light intensity in any housing system. From our results, we can recommend to use low light intensity for controlling abnormal behaviours in laying hens as suggested by HUGHES (1982) for all light sources. In conclusion, this study showed that light sources with low wave lengths spectrum may impair the behaviour of laying hens and, thus, should not be used as a sole light source in layer houses. Furthermore, irrespective of light source high light intensity (50 Lux) may enhance pecking activity and aggressive behaviour in laying hens. Arch.Geflügelk. 3/2010

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Acknowledgements Authors want to thank the Regional Council Tübingen of the State Baden-Württemberg (Germany) for financial support.

Summary Behaviour of laying hens is affected by lighting conditions in the house. Effects of lighting intensity and photoperiod are well described, whereas, knowledge on the effects of light sources (wave length spectrum, frequency of current) is still limited. Therefore, two experiments were carried out to study the effects of different light sources (incandescent bulbs, fluorescent tubes, high frequency daylight tubes, blue fluorescent tubes) and light intensities (low intensity = 5 lux, high intensity = 50 lux) on normal (activity, resting, feeding) and abnormal behaviour (feather pecking, aggressive behaviour) in laying hens. Hens were kept in pens with opaque walls and were observed directly for different behaviours several times per week. It was found that pecking activity and aggressive behaviour were significantly higher in birds under high light intensity. In the same way, blue light resulted in higher activity of hens and higher frequency of feather pecking and aggressive behaviour. Birds tended to rest more under fluorescent light. It was concluded that light sources with low wave lengths spectrum should not be used as a sole light source and that high light intensities should be avoided in layer houses.

Key words Laying hens, light sources, light intensity, behaviour, feather pecking, aggression

Zusammenfassung Einfluss der Beleuchtungsbedingungen auf das Verhalten von Legehennen Das Verhalten von Legehennen wird durch die Beleuchtungsbedingungen im Stall beeinflusst. Während zur Bedeutung der Lichtintensität und der Beleuchtungsdauer viele Informationen vorliegen, ist der Kenntnisstand zur Bedeutung der Lichtquellen (Wellenlängenspektrum, Stromfrequenz) noch begrenzt. In zwei Versuchen sollte daher untersucht werden, inwieweit sich verschiedene Lichtquellen (Glühbirne, Leuchtstoffröhre, Hochfrequenz-Tageslichtleuchte, Blaue Leuchtstoffröhre) und Lichtintensitäten (niedrig = 5 Lux, hoch = 50 Lux) auf normales (Aktivität, Ruhen, Fressen) und abnormales (Federpicken, Aggression) Verhalten von Legehennen auswirken. Hierzu wurden die Hennen in Lichtdichten Abteilen gehalten und die Verhaltensweisen mehrmals wöchentlich erfasst. Bei hoher Beleuchtungsintensität wurden signifikant häufiger Federpicken und aggressives Verhalten beobachtet. In ähnlicher Weise lag bei dem blauen Licht eine höhere Aktivität der Hennen vor und es trat häufiger Federpicken auf. Dagegen wurde bei den Leuchtstoffröhren vermehrt Ruhen der Hennen beobachtet. Es wurde der Schluss gezogen, dass Lichtquellen mit überwiegend kurzwelligem Lichtspektrum nicht als alleinige Lichtquelle im Stall verwendet und dass hohe Beleuchtungsintensitäten in Legehennenställen vermieden werden sollten.

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Stichworte Legehenne, Lichtquelle, Lichtintensität, Verhalten, Federpicken, Aggression

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