Impact of Different Monochromatic LED Light Colours and Bird Age on the Behavioural Output and Fear Response in Ducks

Italian Journal of Animal Science ISSN: (Print) 1828-051X (Online) Journal homepage: https://www.tandfonline.com/loi/tjas20 Impact of Different Monochromatic LED Colours and Bird Age on the Behavioural Output and Fear Response in Ducks Shabiha Sultana, Md. Rakibul Hassan, Ho Sung Choe & Kyeong Seon Ryu To cite this article: Shabiha Sultana, Md. Rakibul Hassan, Ho Sung Choe & Kyeong Seon Ryu (2013) Impact of Different Monochromatic LED Colours and Bird Age on the Behavioural Output and Fear Response in Ducks, Italian Journal of Animal Science, 12:4, e94 To link to this article: https://doi.org/10.4081/ijas.2013.e94 Copyright S. Sultana et al. Published online: 18 Feb 2016. Submit your article to this journal Article views: 399 Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=tjas20

Italian Journal of Animal Science 2013; volume 12:e94 PAPER Impact of different monochromatic LED light colours and bird age on the behavioural output and fear response in ducks Shabiha Sultana, 1 Md. Rakibul Hassan, 1 Ho Sung Choe, 2 Kyeong Seon Ryu 1 1 Department of Animal Science, Chonbuk National University, Jeonju, Korea 2 Department of Animal Biotechnology, Chonbuk National University, Jeonju, Korea Abstract This study was performed to observe the effect of monochromatic light emitting diode (LED) light colour and bird age on the behaviour and fear response of ducks. A total of 200 1-day-old ducklings were used in the experiment (two replications, 25 ducklings/pen), and lighting was set up as follows: white (W, control, 400-770 nm), yellow (Y, 600 nm), green (G, 520 nm) and blue (B, 460 nm) LED lights. Ducks were subjected to 23L: 1D h lighting with 0.1 Watt/m 2 light intensity. Video was recorded twice per day (2 h in the morning and 2 h in the afternoon) and observed five consecutive days per week. Duration of feeding, drinking, sitting, walking, standing, preening, wing flapping, wing stretching, tail wagging, head shaking, body shaking, ground pecking, peck object, and social interaction behaviour were recorded. At 3 and 6 weeks of age, 10 birds per treatment were subjected to the tonic immobility (TI) test (three times/duck). Ducks reared in Y and W light were more active, as expressed by more walking, ground pecking, drinking and social interaction activities than those of ducks under the B light treatment (P<0.05). Ducks showed more time sitting, standing, and preening under B light (P<0.05). Feeding, sitting, standing and drinking behaviours increased, and walking and social interaction behaviours decreased with age of the ducks (P<0.05). Differences in behaviours among different light colours were observed. In addition, the TI test results indicated that B and G light reduced the fear response of the ducks. Introduction According to FAO statistics, the world s duck meat production has increased to 762 million processed birds in the last 10 years (FAOSTATS, 2012; last data updated in 2010). Asia is the leading production region, and this is where the industry is expanding most rapidly. Therefore, duck farming in Korea has increased greatly in size due to increased internal demand, improvements in technology, and higher production performance. Although ducks are waterfowl, they have been reared under indoor housing systems in recent years. Indoor houses are usually lit with a conventional lighting system. Therefore, substantial effort needs to be expended to identify which light colour(s) minimize normal duck behaviours. Most researchers have focused on laying hens (Huber-Eicher et al., 2013; Mohammad et al., 2010) and broilers (Sultana et al., 2013; Prayitno et al., 1997), whereas little is known about duck behaviour. Our previous study suggested that blue (B) light decreases movement and increases inactive behaviour in broiler chicks (Sultana et al., 2013). Most researchers assess water resources (O Driscoll et al., 2012; Waitt et al., 2009), the environment (Jones and Dawkins, 2010), and/or stress conditions (Arnaud et al., 2010) in duck behavioural observation trials. But, the behaviour of ducks is different from that of chickens because ducks are less aggressive and engage in more social contact, and these social elements contribute to synchronized feed intake and increase comforting behaviours, and activity and resting phases among flock mates. In contrast, duck vision is based on lenticular (lens) mechanisms (Martin, 1993). However, ducks do perform complex behavioural sequences of feeding followed by bathing, preening, and sleeping (Reiter et al., 1997). stimulation can also affect a duck s ability to cope with stressors (Campo et al., 2007) and has effects on brain organization that influences behavioural responses including fearfulness (Dharmaretnam and Rogers, 2005). Moreover, published information on the effect of monochromatic light on behaviour and fear response of ducks is very limited. Therefore, the present experiment was undertaken to identify the behaviour of ducks of different ages reared under four different monochromatic light colours to assess their behaviour and fear responses. Corresponding author: Prof. Kyeong Seon Ryu, Department of Animal Science, College of Agriculture and Life Science, Chonbuk National University, Jeonju 561-756, Korea. Tel. +82.63.2702638 - Fax: +82.63.2712612. E-mail: seon@jbnu.ac.kr Key words: LED light colour, Behaviour, Tonic immobility, Ducks. Received for publication: 9 July 2013. Last revision received: 2 October 2013. Accepted for publication: 12 October 2013. This work is licensed under a Creative Commons Attribution NonCommercial 3.0 License (CC BY- NC 3.0). Copyright S. Sultana et al., 2013 Licensee PAGEPress, Italy Italian Journal of Animal Science 2013; 12:e94 doi:10.4081/ijas.2013.e94 Materials and methods Birds and management A total of 200 1-day-old mixed sex cherry valley strains of ducklings were placed into eight lightproof rooms (two replicate rooms were used for each lighting treatment) and each room contained 25 birds. The light treatments were: i) control (W; fluorescent white lamps, 400-770 nm); ii) green (G, 560 nm); iii) blue (B, 460nm); and iv) yellow (Y, 600 nm). Six different age groups were considered in which LED light was provided for 23 h under 0.1 Watt/m 2 light intensity. All identical lightproof pens were bedded with rice husk. The ducks had free access to feed (a starter pellet with 220 g CP and 12.56 MJ/kg from 1 to 21 days of age, followed by a grower (22-42 days) ration with 180 g CP and 12.77 MJ/kg to the end of the experiment) and water at all times. At 7-daysof-age, ducklings were individually observed and abnormal ducks (abnormal weight or leg deformities) were culled from the pen. To prevent any preferences to familiar odours interfering with the light treatments, each pen was cleaned daily, and fresh water, feed, and rice husks were provided. A ventilation fan in the roof of the central arena in each pen extracted the polluted air and circulated fresh air inside the pen. Air temperature and humidity were measured at bird height inside each pen to ensure that any differences in the pens occurred due to the light environment and not temperature or humidity. [Ital J Anim Sci vol.12:e94, 2013] [page 573]

Sultana et al. Behavioural observations Video cameras were set so that a full view of the pen and the central arena of each pen were visible. Behaviours were recorded for the following activities: consummatory behaviour (eating and drinking), comfort behaviour (body-shaking, wing-flapping, tail-wagging and social behaviour), maintenance behaviour (preening), inactive behaviour (standing and sitting), stereotypical behaviours (object pecking and head shaking), exploring (litter scratching and litter pecking), locomotory behaviour (walking), and others. A duck was considered to be walking only when the duck was locomoting and not engaged in any other activity; short periods of immobility were recorded as standing or standing not engaged in any other activity. Eating and drinking were considered to have stopped as soon as the bird stood inactive, even if it was in front of a feeder or a drinker. Bird was considered to be drinking when they stood in front of the drinker with a raised head and the beak was touching the drinker nipple. The observer noted feeding when a duck ate feed from the feeder. It is very difficult to distinguish among sitting, lying, resting, and sleeping behaviours; thus, these behaviours were jointly categorized as sitting. Ducks pecking at any object other than a feeder or drinker were considered to be pecking an object. Preening was considered when plumage was manipulated with the beak. Ground pecking was observed when a duck pecked the ground but not in or around a feeder. Extending both wings out from the body simultaneously and flapping were considered wing flapping behaviour. Stretching behaviour included head stretching, wing stretching, and leg, wing, and leg stretching. Tail wagging was characterized when the tail moved rapidly from side to side. These behaviours were recorded on video twice (morning and afternoon) for 5 days/week. During the 42-day video observations (both morning and afternoon), feeding, drinking, sitting, walking, standing, preening, wing flapping, wing stretching, tail wagging, head shaking, body shaking, ground pecking, peck object, and social interacting behaviour were recorded as time counts and were expressed as counts per hour. The recorded video was analyzed at 5 min intervals (Prayitno et al., 1997) and the durations of these behaviours were recorded. Tonic immobility measurements At weeks 3 and 6 of the experiment, 10 ducks per treatment were used three times each for tonic immobility (TI) measurements. Each duck was manually restrained for 15 s in an independent testing room and then the temporal duration of immobility was measured in seconds as described by Sonatra et al., 2002. To avoid eye contact, the observer stood 1.5-2.0 m away from the birds, and the duration of immobility was measured. The TI duration was considered between 10 and 600 s. If the duck terminated in <10 s, it was captured, and the trial was repeated. Statistical analysis Data from 10 ducks/pen were averaged; therefore, each pen produced one data point for each behaviour both in the morning and afternoon. Since the data of each observation in a pen were linked, 10 birds per lighting pen, 5 days/week for 6 weeks with two replicate pens were used to measure each variable. During the observation time of the day, 100 data units (10 ducks per pen five observation days in a week two replicate pens) were considered for each behaviour. Therefore, we utilized the non parametric two-way analysis of variance (light colour bird age) procedure in SAS 9.1. (SAS, 2005). Duncan s new multiplerange test were performed when significant differences were found (Steel and Torrie, 1980). A P<0.05 was considered significant. Results Behavioural observations The ducks spent the majority of their time sitting, drinking, and feeding, whereas tail wagging, stretching, and shaking behaviours were less frequent. Age also influenced behaviour, as feeding, drinking, walking, preening, and social interacting behaviours were performed in an age-dependent manner. Feeding (morning F 3,36=6.23, P=0.0657 and afternoon F 3,36=26.98, P=0.0160) and drinking (morning F 3,36=1.57, P<0.0001 and afternoon F 3,36=3.98, P=0.0196) behaviours increased remarkably under Y light in the morning and afternoon. These behaviours also increased with duck age. During the grower period (4-6 weeks) ducks spent significantly more time drinking (morning, F 5,54=4.22, P=0.0068 and afternoon F 5,54=11.81, P<0.0001) than that during the starter period and more feeding (morning, F 5,54=34.40, P<0.0001 and afternoon F 5,54=38.57, P<0.0001) in the last few weeks of the experiment. Therefore, consummatory behaviours were influenced significantly (P<0.05) by different LED light colours and age both in the morning and afternoon. Sitting (morning, F 3,36=17.10, P<0.0001 and afternoon F 3,36=10.64, P<0.0001) and standing (morning, F 3,36=7.12, P=0.0014 and afternoon F 3,36=44.79, P<0.0001) behaviours were also influenced by light colour and age. Inactive behaviours were wavelength and age dependent in which short wavelength (B)-exposed ducks spent most of their time sitting. In contrast, age also significantly increased sitting (morning F 5,54=2.31, P=0.0356 and afternoon F 5,54=4.76, P=0.0037) and standing (morning F 5,54=1.65, P=0.0454 and afternoon F 5,54= 2.67, P=0.0469) behaviours in which heavier ducks (4-6 weeks of age) spent the majority of their time compared to that of younger birds (1-3 weeks of age). The interaction between light colour and age also influenced sitting (morning F 15,135=2.69, P=0.0150, and afternoon F 15,135=1.34, P=0.2554) behaviour. Walking behaviour was also controlled significantly by either light colour (morning F 3,36=5.68, P=0.004, and afternoon F 3,36=12.49, P<0.0001) or age (morning F 5,54=3.76, P=0.0118 and afternoon F 5,54=22.45, P<0.0001) of the duck. B light significantly decreased walking activity. In contrast, young ducks (1 3 weeks-of-age) walked more than that of older ducks (4-5 weeks of age). Thus, the interaction between age and light colour was significant (morning, F 15,135=0.83, P=0.5595 and afternoon F 15,135=0.92, P=0.558) and controlled locomotory behaviour. Preening behaviour was affected by light colour during the 1-6 week video observations in the morning (Table 1) and afternoon (Table 2). B light colour influenced duck preening behaviour in the morning (F 3,36=6.77, P=0.0018) and afternoon (F 3,36=11.08, P<0.0001). Age significantly decreased preening (morning F 5,54=1.54, P=0.004 and afternoon F 5,54=13.75, P<0.0001) behaviour in which older ducks (4-6 weeks of age) reduced their preening time compared to that of younger birds (1-3 weeks of age). Ground pecking behaviour (morning F 3,36=22.31, P<0.0001 and afternoon F 3,36=5.99, P=0.0034) increased significantly (P<0.05) in Y and G exposed ducks but decreased remarkably under B light. Stretching behaviour remained unchanged. Age of the ducks also influenced ground pecking behaviour (morning F 5,54=1.53, P=0.2183 and afternoon F 5,54=4.28, P=0.0063) in the afternoon. The interaction between light colour and age also influenced ground pecking behaviour in the afternoon (F 15,135=2.41, P=0.0264) compared to that in the morning (F 15,135=1.12, P=0.3888). Body shaking, wing flapping, and tail wagging behaviours were not altered by light colour (Tables 3 and 4) but social interacting behaviours were significantly influenced by light colour in the morning [page 574] [Ital J Anim Sci vol.12:e94, 2013]

LED light colours and ducks behaviour Table 1. Effect of light emitting diode light colour and age on morning duck behaviour. Behaviour Feeding, Drinking, Sitting, Walking, Standing, Preening, Wing flapping, Stretching, min/h min/h min/h min/h min/h min/h min/h min/h G 7.14 10.23 12.78 a 3.42 b 5.61 ab 7.33 b 0.81 1.55 B 5.90 10.13 13.29 a 3.15 b 6.80 a 10.11 a 0.88 1.75 W 6.21 11.17 11.49 a 3.87 b 4.34 bc 8.01 b 0.91 1.05 Y 7.35 11.59 9.52 b 5.05 a 4.14 c 4.26 c 0.94 0.85 Age, weeks 1 4.72 c 8.79 b 9.82 b 4.49 ab 4.16 b 8.56 ab 0.92 1.64 2 4.56 c 9.79 b 12.46 ab 4.30 ab 4.61 b 9.78 a 1.10 1.83 3 5.84 bc 10.07 ab 10.94 b 4.98 a 5.58 ab 7.71 b 0.93 1.65 4 7.13 ab 11.76 a 12.36 ab 3.31 bc 5.36 ab 5.75 c 0.71 1.0 5 6.38 b 11.70 a 12.73 a 3.28 bc 5.40 ab 8.32 ab 0.88 1.14 6 7.97 a 10.40 ab 13.31 a 2.86 c 6.21 a 7.44 bc 0.77 1.13 SEM 0.31 0.37 0.38 0.22 0.30 0.52 0.05 0.11 Test statistics F 3,36 6.23 1.57 17.10 5.68 7.12 6.77 0.24 1.97 Age F 5,54 34.40 4.22 2.31 3.76 1.65 1.54 0.97 1.23 age F 15,135 1.73 1.14 2.69 0.83 1.78 0.54 0.72 0.60 Treatment interaction effect (P>F) 0.0657 0.1726 <0.0001 0.004 0.0014 0.0018 0.8703 0.1473 Age <0.0001 0.0068 0.0356 0.0118 0.0454 0.004 0.4539 0.3301 age 0.1120 0.3728 0.0150 0.5595 0.1002 0.12 0.7418 0.8463 G, green; B, blue; W, white; Y, yellow. Two pens of 10 ducks for each mean. The statistical comparisons are related to the effects of light colour (G vs B vs W vs Y), bird age (1 vs 2 vs 3 vs 4 vs 5 vs 6 weeks), and the interaction between colour and bird age. a,b,c Mean values within a column followed by the same letter are not significantly different (P>0.05). Table 2. Effect of light emitting diode light colour and age on afternoon behaviour of ducks. Behaviour Feeding, Drinking, Sitting, Walking, Standing, Preening, Wing flapping, Stretching, min/h min/h min/h min/h min/h min/h min/h min/h G 7.73 a 13.07 a 13.75 b 3.24 c 6.25 a 5.97 b 0.66 0.80 b B 6.12 b 11.89 b 15.11 a 2.87 c 6.74 a 7.83 a 0.53 1.17 a W 6.67 ab 13.09 a 12.68 c 3.76 b 4.87 b 4.86 b 0.81 0.82 b Y 6.80 ab 13.22 a 12.61 c 4.56 a 3.09 c 4.81 b 0.80 0.83 b Age, weeks 1 4.85 c 10.92 c 12.85 c 4.96 a 4.28 b 6.45 b 0.59 1.10 2 5.81 c 11.75 bc 12.34 c 4.70 a 5.48 a 9.05 a 0.69 0.98 3 6.71 b 12.73 b 13.18 bc 3.74 b 5.38 a 6.22 b 0.75 0.95 4 7.56 b 13.28 ab 13.64 abc 3.02 c 5.31 a 5.38 bc 0.66 1.29 5 8.04 b 14.13 a 14.30 ab 2.71 c 5.35 a 4.32 c 0.65 0.78 6 9.53 a 14. 50 a 14.94 a 2.26 c 5.65 a 3.60 c 0.83 0.85 SEM 0.29 0.31 0.26 0.20 0.25 0.43 0.04 0.11 Test statistics F 3,36 26.98 3.98 10.64 12.49 44.79 11.08 2.14 8.29 Age F 5,54 38.57 11.81 4.76 22.45 2.67 13.75 0.58 1.57 age F 15, 135 1.42 1.70 1.34 0.92 1.67 1.51 0.81 2.42 Treatment interaction effect (P>F) 0.0160 0.0196 <.0001 <.0001 <.0001 <.0001 0.1222 0.0006 Age <.0001 <.0001 0.0037 <.0001 0.0469 <.0001 0.7177 0.2092 age 0.9625 0.1193 0.2554 0.5581 0.1266 0.1794 0.6526 0.0241 G, green; B, blue; W, white; Y, yellow. Two pens of 10 ducks for each mean. The statistical comparisons are related to the effects of light colour (G vs B vs W vs Y), bird age (1 vs 2 vs 3 vs 4 vs 5 vs 6 weeks), and the interaction between colour and bird age. a,b,c Mean values within a column followed by the same letter are not significantly different (P>0.05). [Ital J Anim Sci vol.12:e94, 2013] [page 575]

Sultana et al. Table 3. Effect of light emitting diode light colour and age on morning behaviour in ducks. Behaviour Tail wagging, Head shaking, Body shaking, Ground pecking, Peck object, Social interaction, min/h min/h min/h min/h min/h min/h G 0.86 0.79 0.93 5.15 a 2.91 a 1.01 b B 0.93 0.68 0.83 2.27 c 1.44 c 0.78 c W 0.95 0.96 1.03 3.78 b 1.80 c 1.11 b Y 0.99 1.06 1.42 4.72 a 2.27 b 1.38 a Age, weeks 1 1.07 1.0 1.21 4.29 2.56 a 1.20 a 2 0.89 0.90 1.19 4.42 2.39 a 1.28 a 3 0.99 0.89 0.99 3.88 2.24 a 1.07 ab 4 0.96 0.96 0.94 4.19 2.25 a 1.09 ab 5 0.73 0.80 0.92 3.29 1.52 b 0.89 b 6 0.94 0.69 1.04 3.85 1.66 b 0.87 b SEM 0.06 0.03 0.05 0.21 0.12 0.05 Test statistics F 3,36 0.22 2.76 2.47 22.31 22.25 11.86 Age F 5,54 0.68 0.80 0.67 1.53 6.34 3.57 age F 15, 135 2.40 0.69 0.69 1.12 1.84 1.36 Treatment interaction effect (P>F) 0.8793 0.0643 0.0865 <0.0001 <0.0001 <0.0001 Age 0.6399 0.5584 0.6496 0.2183 0.0007 0.0148 age 0.0270 0.7713 0.7700 0.3888 0.0885 0.2431 G, green; B, blue; W, white; Y, yellow. Two pens of 10 ducks for each mean. The statistical comparisons are related to the effects of light colour (G vs B vs W vs Y), bird age (1 vs 2 vs 3 vs 4 vs 5 vs 6 weeks), and the interaction between colour and bird age. a,b,c Mean values within a column followed by the same letter are not significantly different (P>0.05). Table 4. Effect of light emitting diode light colour and age on afternoon behaviour of ducks. Behaviour Tail wagging, Head shaking, Body shaking, Ground pecking, Peck object, Social interaction, min/h min/h min/h min/h min/h min/h G 0.85 0.78 0.83 3.01 b 1.66 0.82 B 0.73 0.63 0.97 2.55 b 1.25 0.80 W 0.89 0.95 1.04 2.56 b 1.84 0.87 Y 0.80 0.77 1.13 4.73 a 1.72 0.97 Age, weeks 1 1.05 0.84 1.03 4.67 a 1.60 0.71 2 0.67 0.58 0.55 1.52 c 1.33 0.99 3 0.48 0.55 0.63 2.70 bc 1.58 0.81 4 1.16 0.78 0.95 3.75 ab 1.59 0.81 5 0.70 0.79 0.95 3.00 bc 1.39 0.83 6 0.84 1.16 1.82 3.63 ab 2.23 1.03 SEM 0.09 0.08 0.13 0.31 0.14 0.06 Test statistics F 3,36 0.15 1.02 0.24 5.99 1.61 1.40 Age F 5,54 1.36 1.96 2.12 4.28 1.67 2.21 age F 15, 135 1.25 1.98 1.29 2.41 3.67 3.07 Treatment interaction effect (P>F) 0.9264 0.4032 0.8675 0.0034 0.2143 0.2672 Age 0.2731 0.1209 0.0991 0.0063 0.1813 0.0877 age 0.3068 0.0655 0.2853 0.0264 0.0823 0.0021 G, green; B, blue; W, white; Y, yellow. Two pens of 10 ducks for each mean. The statistical comparisons are related to the effects of light colour (G vs B vs W vs Y), bird age (1 vs 2 vs 3 vs 4 vs 5 vs 6 weeks), and the interaction between colour and bird age. a,b,c Mean values within a column followed by the same letter are not significantly different (P>0.05). [page 576] [Ital J Anim Sci vol.12:e94, 2013]

LED light colours and ducks behaviour (F 3,36=11.86, P<0.0001) and age (morning F 5,54=3.57, P=0.0148, afternoon F 5,54=2.21, P=0.0877) of the duck. The interaction between light colour and age also influenced the social interacting behaviour of ducks in the afternoon (F 15,135=2.42, P=0.0241) compared to that in the morning (F 15,135=0.60, P=0.8463). Pecking objects increased under G light in the morning (F 3,36=22.25, P<0.0001) but was inconsistent in the afternoon (F 3,36=1.61, P<0.0001). This behaviour was influenced by age of the ducks (morning F 5,54=6.34, P=0.00007). In contrast, head-shaking behaviour was not altered either by light colour or by age. Fear response At 3 weeks, ducks reared under the W light treatment showed significantly (P<0.05) longer TI (F 3,36=2.36, P=0.034) duration than that at other times (Figure 1). Consequently, at 6 weeks, duck under the Y light showed a significantly longer and B light showed a significantly shorter TI (F 3,36=2.41, P=0.031) duration. Therefore, G and B light reduced the fear response of the ducks. TI duration also increased with bird age in a dependent manner. Therefore, older ducks were more fearful than that of younger ducks. Discussion This study compared different LED light colours and age on behaviour and fear response in ducks. Consummatory behaviour occurred more often under the Y and G light treatments in the morning and in the afternoon. This may have been due to G light-stimulated feed intake, which was in agreement with a result obtained with broiler chicks (Prayitno et al., 1997; Rozenboim et al., 2004). Age also influenced feeding behaviour, as the duration of feeding was longer during the grower period than that during the starter period, which may have been due to accelerated growth rate with duck age. In addition, higher body weight requires higher nutrient intake, which increases feeding motivation. Water was supplied by a nipple drinker, which provides only a few drops of water when the beak touches the nipple. Therefore, ducks tended to spend a long time drinking and trying to bathe. The ducks showed more drinking behaviour under Y light, which may have been related to more feeding behaviour. In contrast, older birds spent more time drinking due to the increased bathing tendency with age in ducks. Inactive behaviours (sitting and standing duration) increased in B light-treated birds based on the assumption that light has an effect on the pineal gland. The B light seemed to calm the birds. This result was supported by Prayitno et al. (1997), who also reported that B and G light increases gut content, which reduces rate of food passage and, therefore, reduces bird movement. Walking behaviour was recorded when the ducks were moving inside the room. Though the ducks walked infrequently, the Y light-treated ducks walked more frequently than that of ducks under the other light treatments. Ducks are more active under longer wavelength light, which may be due to longer wavelength passing through the retina, skull, and skin more efficiently than that of short wavelength (Hartwig and Veen, 1979). Ducks spent the least amount of time shaking, wing flapping, tail wagging, and performing social behaviours. Nevertheless, stretching behaviour was performed significantly (P<0.05) more often under the Y light treatment. In the indoor floor rearing system, there is no work on light colour in ducks, which complicates a direct comparison of duck behaviour. Therefore, we speculated better visual sensitivity of ducks under Y light compared with that under B light. Wing flapping, tail wagging and stretching behaviours are influenced by stocking density (Nicol, 1987). Therefore, we predicted that wing flapping, tail wagging, and wing stretching behaviours were also influenced by the nearest neighbour s activity. Fraser and Broom (1990) suggested that wing stretching is an important behaviour that helps to maintain functionality of joints and muscles. Ground pecking and pecking objects increased significantly under Y and G lights and decreased under B light, indicating that ducks preferred to peck the ground under the Y and G light rather than under B light. These results correspond with findings of laying hens (Huber-Eicher et al., 2013) and broiler chicks (Maddocks et al., 2001). Those studies indicated that short wavelength lighting conditions tend to result in less pecking than that of longer wavelengths. Aerni et al. (2000) and Green et al. (2000) recommended that ground pecking is a key behaviour that helps minimize feather pecking and cannibalism. Ducks under B light tended to spend a longer time preening than birds exposed to other lighting, which may have been due to the calming effect of the B light. Appleby et al. (2004) reported that preening is a comfort behaviour that helps oil the feathers with lipids or wax from the uropygial gland. We excluded preening as comfort behaviour, as this behaviour is important for maintaining body condition and evaluating the bird s welfare status. Age affected most behavioural patterns in our study, which may have been due to a change in motivation for different behaviours coupled with increased experience with the predictable lighting regime with age. Thus, feeding behaviour at 6 weeks of age increased significantly, whereas fed less at 1 weeks of age the birds, which may have been due to Figure 1. Effect of light emitting diode light colour on tonic immobility (TI) (fear response) of ducks. [Ital J Anim Sci vol.12:e94, 2013] [page 577]

Sultana et al. increasing body size with age. Overall, standing and walking behaviour decreased significantly (P<0.05) and sitting behaviour increased with age of the ducks, as younger birds were generally more active. The reason for these behaviours increasing in relative frequency may be a result of decreasing frequencies of active behaviours. An increase in the duration of a single behaviour will necessitate the decrease in another within the time budget. Feeding, sitting, standing, and walking behaviours were significantly influenced by light colour and age of the ducks. The TI test is widely used to study the fear response in birds (Jones and Mills, 1983; Mills and Faure, 1986). Consequently, Campo and Carnicer (1994) justified TI by associating high levels of corticosteroid production with an increase in TI time. At 3 and 6 weeks of age, TI duration increased (P<0.05) under Y and W light and decreased under B and G light. Due to the lack of previous studies regarding the effect of light colour on fear response in ducks, a direct comparison was not possible. However, we speculate that ducks spent more active time under longer wavelength compared with the time spent under shorter wavelength; and that this may have influenced the TI duration. In a previous experiment, Xie et al. (2008) found that broiler spleen weight increases significantly under B light treatment, because the weights of the secondary lymphoid organs decrease during the stress response (Donker and Beuving, 1989). Xie et al. (2008) also reported that B light might play a role alleviating stress in broilers, which could reduce their fear responses. Therefore, this result corresponds with the present duck results. Gallup (1977) reported that the higher the number of attempts and the longer the TI duration the stronger the fear. Therefore, older birds showed increased duration of the fear response, which corresponded with the findings of Zulfiki et al. (2009). Conclusions In conclusion, differences in duck behaviour were observed under different light colour exposures. W and Y light activated movement, and B and G decreased movement, as ducks spent more time sitting and standing and these motivation might be reflected on the performance, blood properties an bone health of ducks. Age also had an effect on behaviour in which standing and walking behaviours decreased significantly and sitting behaviour increased with age. In consequence, the TI test indicated that B and G light reduced the duck fear response. Meanwhile, further studies are required to clarify whether and how light colour influence performance, blood and bone properties of meat type ducks. References Aerni, V., El-Lethey, H., Wechsler, B., 2000. Effect of foraging material and food form on feather pecking in laying hens. Brit. 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