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The effects of environmental enrichment devices on feather picking in commercially housed Pekin ducks
ENVIRONMENT, WELL-BEING, AND BEHAVIOR The effects of environmental enrichment devices on feather picking in commercially housed Pekin ducks S. Colton and G. S. Fraley1 Biology Department, Hope College, Holland, MI 49423 EED in one pen per barn, both pens were videotaped for a total of 2 h per day. The physical characteristics of 100 ducks per pen were scored at age 7, 21, 28, and 35. Results showed a decrease (P = 0.034) in both selfpicking and conspecific-pecking in pens with EED compared with pens without EED. Although no differences in body condition scores were observed at 7 d of age, by d 21 ducks with EED showed better (P = 0.021) feather quality and cleanliness scores compared with ducks without EED. In a second experiment, we set out to determine if ducks had a color preference for blue/green, red, or white EED. Again, ducks with EED showed reduced (P = 0.038) feather picking compared with ducks without EED. Ducks interacted considerably more (P = 0.00089) frequently with blue/green EED then either red or white EED. These results suggest that providing environmental enrichment may minimize feather picking and improve feather quality and duck welfare.
Key words: Pekin duck, feather picking, environmental enrichment, feather pecking 2014 Poultry Science 93:2143–2150 http://dx.doi.org/10.3382/ps.2014-03885
INTRODUCTION Feathers provide a large part of the poultry economy in the form of down for pillows, blankets, and clothing. Considerable losses are noted each year due to feather picking and a subsequent reduced health/mortality. Some level of picking is good, however, in the form of preening. Ducks preen their feathers throughout their lives, but increase the level of preening between d 17 to 22 when the feathers change from down to adult plumage. Preening refers to a movement with the bill intended to care for the duck’s plumage aimed toward the breast, shoulders, wings, or back feather (Lersel and Bol, 1958). Injurious feather picking has been described and refers to an auto-mutilation behavior as opposed to feather pecking that occurs between birds, ©2014 Poultry Science Association Inc. Received January 7, 2014. Accepted June 1, 2014. 1 Corresponding author: [email protected]
particularly in galliforms (Madsen, 1966; Grindlinger and Ramsay, 1991; Bordnick et al., 1994; Jenkins, 2001; Seibert et al., 2004). It has been suggested that the incidence of these injurious behaviors may be related to a birds’ ability to forage in their bedding substrate (Rodenburg et al., 2004, 2005). Ducks are very curious creatures and the slightest change in a duck’s appearance, such as blood, can draw the attention of surrounding ducks and lead to pecking. Self-picking and conspecific pecking can cause damage to feathers and skin, and increase the potential for disease in the duck. Thus, picking and pecking in ducks may be different from the feather pecking observed in galliform species. Feather pecking in galliform species refers strictly to conspecifics, pecking at each other, damaging the skin and feathers of conspecifics in the same barn/pen (Keeling et al., 2004; Bright, 2007; Natt et al., 2007). Galliforms do not pick at themselves in the same manner as ducks. Pekin ducks pick mostly at themselves, although occasionally at each other. Both picking and pecking are episodic events in which the cause or stimulus is
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ABSTRACT Like other poultry species, Pekin ducks occasionally show an auto-mutilation behavior referred to as feather picking. Self-picking can lead to further pecking by conspecifics and ultimately to reduced feather quality and poor overall health of the bird. Although the reasons underlying feather picking are not clear, it appears to occur when the ducks are transitioning between downy feathers and adult plumage, between 17 and 22 d of age. We hypothesized that giving Pekin ducks a substitute outlet for this behavior in the form of environmental enrichment devices (EED) would decrease feather picking and improve feather quality and duck health and welfare. The EED were plastic Wifflestyle balls, each threaded with 4 zip-ties. In the first experiment, we set out to determine that placement of EED would not induce fear or harmful behaviors. Five barns were each divided into 2 pens, holding an average combined total of approximately 4,500 ducks with one pen per barn used as control. Upon placement of the
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MATERIALS AND METHODS Birds and Housing The Pekin ducks used in this experiment were raised for production in poultry barns contracted by Maple Leaf Farms Inc. (Leesburg, IN). Male and female ducks (approximately equal ratios) were raised from 1 d of age until approximately 35 d of age in barns with 2 large floor pens (n = 10 barns; thus, 10 pens per treatment) with raised plastic-slatted floors following standard commercial conditions. Briefly, ducks are placed in the pens on the day of hatch where they are restricted to approximately one-third of the pen under brooding conditions [26.5°C, ~0.1 cubic meters/s per duck of ventilation, <60% RH] until d 10 when they are allowed access to the full pen (at d 10: 20°C, 2.8 × 10−5 to 0.003 cubic meters/s per duck of ventilation, <60% humidity). For the remainder of the growout time frame, temperature is maintained at 12.7 to 18.4°C and a RH less than 75%; however, barns are curtain-sided and thus environmental conditions have an impact on internal barn conditions. Ventilation rates are maintained between 8.7 × 10−4 and 0.006 cubic meters/s per duck through d 35. Because there are no external sex differences, we were not able to differentiate between male and female ducks for data analyses for this study. The size of the pens was kept to allow approximately 0.16 m2 per duck with approximately 4,500 to 6,500 ducks per pen. Ducks were raised under industry standards for temperature and light (18L:6D),
and all ducks were allowed ad libitum access to feed and water. The management of the ducks was carried out by growers contracted and regulated by Maple Leaf Farms Inc. To minimize management variability, each barn had EED placed in one pen, and no EED in the opposite pen within the same barn. All procedures used were approved by Hope College Animal Care and Use Committee following Association for Assessment and Accreditation of Laboratory Animal Care guidelines.
Duck Physical Condition Scores The ducks’ physical condition was evaluated at 3 ages: 7 to 8 (7 d), 21 to 24 (21 d), and 30 to 33 (32 d) days posthatch as described previously (Fraley et al., 2013; Karcher et al., 2013). Due to inclement weather and availability of the researcher, travel days had ±1 d; thus, the day represented within the parentheses is the categorical day. One hundred ducks per pen were included in each evaluation; 25 ducks were randomly sampled at each of 4 predetermined pen locations (4 corners of each pen). Groups of ducks (n = 25) were penned at each location through the use of hinged catching frames, and individual ducks within each group were scored by 3 individuals using a previously published scoring rubric (Fraley et al., 2013; Karcher et al., 2013). The individual traits scored were identified on a scale of 0 to 1 (nostril and feather cleanliness) or 0 to 2 (eyes, feather quality, and foot pad quality), where 0 was the best condition or situation and a 1 or 2 indicates a worse condition for that specific quality.
Experiment 1 The purpose of this experiment was to first determine if ducks would interact with EED. Second, we set out to determine if the color of the EED (red vs. white zip ties on red Wiffle-style balls) affects the Pekin ducks’ willingness to interact with them. Third, we set out to determine if the placement of EED would improve feather quality scores, thus indicating a reduction in feather picking. To accomplish these goals, we used a total of 10 barns with raised plastic flooring, and each barn was divided into 2 equal-sized pens. The total number of ducks in each barn ranged from 9,900 to 13,800; one-half the ducks were housed in the treatment pen and the other one-half were housed in the control pen. At 12 d of age (before the age where feather picking is first observed) the EED were placed about 15 m apart in 2 rows down either side of the treatment pen with the red/white EED on one side of the pen and the red/red EED on the other side. The treatment pen in each barn received the EED at a concentration of approximately 120 ducks per EED and the pen within each barn was randomized for position to prevent “end of barn” bias. This layout, along with the control and treatment sides, was alternated between sides and pens across different barns to minimize management differences or pen differences. Each row of EED were placed
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unknown, although one potential stimulus is thought to be due to a lack of environmental enrichment. Previous studies of the effects of environmental enrichment devices (EED) have been done with chickens and turkeys, using objects such as different colored strings, leg bands, or small balls (Gvaryahu et al., 1994; Newberry, 1995; Crowe and Forbes, 1999; Jones et al., 2000; Martrenchar et al., 2001; McAdie et al., 2005). A study on Muscovy ducks demonstrated that outdoor runs and open water sources possibly reduced feather picking; although this study has not been replicated on Pekin ducks (Klemm et al., 1992). However, most these studies were completed on very small numbers of birds and the results may not be translatable to full-size commercial barns. Thus, the effects of EED in chickens and turkeys have only been implemented to a limited extent on a production scale. To date, no EED study has been performed specifically on ducks to determine the effects of environmental enrichment to reduce feather picking. The purpose of our first study was to determine if the placement of EED within commercial barns would cause the ducks distress, as opposed to having beneficial effects. The purpose of our second study was to determine if the body condition scores of the Pekin ducks differ between control and treatment pens and to further determine if EED color affects the amount of interaction the Pekin ducks have with EED.
ENRICHMENT DEVICES REDUCE FEATHER PICKING IN DUCKS
Experiment 2 The purpose of this experiment was to determine if the color of the EED (all red, all white, or blue/green) affects the Pekin ducks’ willingness to interact with them. Red EED had red balls with identically colored red zip-ties. White EED had white balls with identically colored white zip-ties, and blue balls had green zip-ties. The blue/green combination was used because identical shades of blue or green between zip ties and balls could not be obtained. The shades of blue and green were very close together spectrally. The EED were again placed as described for experiment 1 at 12 d of age and remained until the ducks were processed at approximately 35 d of age. Each color of EED was placed in a triad of an approximately 1-m equilateral triangle, and each triad was approximately 5 m apart. Two rows of triads were placed in lines equidistant from each other and food and water sources within the treatment pen. Again, EED were placed such that there were 120 ducks per color of EED. Duck condition scoring occurred on d 14 and again at d 28. To observe duck interactions with EED, we set up a video surveillance system in each barn. A total of 8 (4 per pen) high-definition cameras with fish-eye lenses were arranged so that almost 98% of the floor was observable. The cameras were attached to a 1-TB digital video recorder and ducks were recorded for a 24-h period after placement of EED (d 14–15), and again before processing (d 28–29). The number of ducks that interacted (picking at or investigating) with the different colored EED was analyzed every 30 min across each 24-h period; the number of interactions with each color of EED was totaled over 3 h. It was noted that ducks with the most severe feather damage were typically not caught during the body condition scoring aspect of the experiment. Thus, we developed a total pen
feather picking score of 0 to 4. To determine the score, 2 separate individuals would do a slow walk through both pens and count the total number of birds observed with skin lesions due to feather picking. A 0 score indicated no birds were observed with skin lesions, a score of 4 was given if >40 birds were observed with signs of active picking (thus ~10% of the pen). The total pen score was then averaged between the 2 observers.
Statistical Analyses All data were averaged per pen, and the pen (n = 10/ treatment) was considered an experimental unit. The body condition assessment data were not normally distributed due to the large prevalence of 0 scores; thus, these data in experiments 1 and 2 were analyzed using a chi-squared test. Data are expressed as a percentage of ducks exhibiting a specific score at each age by treatment. A probability value of 0.05 was considered to be significant. For experiment 1, the number of ducks interacting with the EED and the total pen score in experiment 2 were analyzed using a Student’s t-test with a P < 0.05 considered significant. In experiment 2, the color choice was analyzed by repeated measures ANOVA with age as the repeated measure and EED interactions as the dependent variable.
RESULTS Experiment 1 No scientific studies have specifically addressed the behavior of Pekin ducks in a production facility that indicates a stressed flock. However, conversations with numerous growers with decades of experience suggest that stressed flocks show 1) flocking behavior where most ducks in a pen circle the barn, 2) birds tend to evade growers or researchers walking within the barn, 3) feather picking, or 4) a combination of these. The placement of the EED did not initiate any of these behaviors, suggesting that the EED themselves were not doing harm. The body condition scores of the ducks at 7 d of age showed no differences (P = 0.55, n = 10) in any body condition score parameter; however, after placement of EED, the scores at 21 d of age showed decreased (P < 0.021, n = 10) averages (and thus better physical condition) in eyes, feather cleanliness, and feather quality in ducks housed in the treatment pens with the EED compared with the control pens. At age 35, ducks raised in pens with EED showed a trend toward better feather cleanliness and quality scores, though this trend did not achieve significance (P = 0.095, n = 10). Figure 1 summarizes these results. No differences were observed in the number of ducks picking or investigating the all red, or red/white EED (Figure 2). Analyses of video tapes revealed that ducks in pens with EED showed considerably (P = 0.034, n = 10) less self- and conspecific- feather pecking (Figure 3).
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equidistant from feed and water sources. The EED remained in the pens continuously from 14 to 35 d of age. The EED were not anchored down to the floor or reorganized at each visit, allowing the ducks to freely interact with and move the EED throughout the pen. Just before body condition scoring at d 21, an observer slowly walked through the barns, causing minimal disturbance, taking note of the different behaviors displayed by the ducks. In both pens, the observer noted the number of ducks seen self- or conspecificpicking (picking at one’s neighbor) for a 1-h period. In the treatment pen, additional observations were made for the ducks’ reaction to the EED (investigating or picking) while also noting which color (red/white or red/red) the behavior was directed toward. Picking was noted when the duck was actively picking an EED, and investigating was noted when the duck obviously showed interest in the EED but was not actively picking it. A video recording of the ducks’ behavior was also made between 0800 and 1100 h in the absence of human observers and later scored by unbiased individuals.
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Experiment 2
DISCUSSION The purpose of this study was first to determine if EED would themselves elicit stress-related behaviors, if the ducks would interact with the EED, or both. Second, we set out to determine if EED color would affect the Pekin ducks’ willingness to interact with the EED. To accomplish these goals, we placed EED in the barns from 12 d of age continuously until load-out at 35 d of age. We found that ducks interacted enthusiastically with the EED; they prefered blue/green to all other color combinations tested, and the presence of EED reduced picking and may ameliorate feather picking due to environmental stressors. Causative factors that lead to feather picking in ducks are not known; however, there appears to be a seasonal component similar to the occurrence of feather picking in galliforms (Huber-Eicher and Sebö, 2001). During the spring and fall seasons when weather is changing from cold to warm and warm to cold, respectively, ducks have been observed to increase the amount of picking aimed at themselves and others (Huber-Eicher and Sebö, 2001). Hughes and Duncan (1972) observed this behavior in chickens as well and have attributed the causes to factors other than seasonal change including management, overcrowding, overheating, poor ventilation, humidity, lighting, and the presence of injured or sick birds (Schaible et al., 1947). Others (Blokhuis and Wiepkema, 1998) have suggested that conspecific pecking could develop because of “misdirected food pecking” (Blokhuis and van der Haar, 1992). Other groups
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No differences (P = 0.72) were observed in any body condition score at 14 d of age. However, differences were observed at d 28; ducks in pens with EED showed an increased number (P = 0.021, n = 10) of 0 feather quality scores, and fewer (P = 0.032, n = 10) scores of 1 (Figure 4). Analysis of the total pen score further supported the hypothesis that EED would reduce feather picking in Pekin ducks. Ducks in pens with EED showed considerably (P < 0.00076, n = 10) lower total pen scores (number of ducks with obvious skin lesions) then ducks housed without EED (Figure 5). Analyses of the 24-h video recordings at age 14 and 28 supported the physical observations of researchers. Considerably more ducks (P = 0.00089, n = 10) were observed either picking or oriented toward the blue/ green EED compared with the red or white EED. A greater number (P = 0.0079, n = 10) of ducks were observed around the red EED compared with the white EED, though not to the level of the blue EED. Overall, fewer (P = 0.041, n = 10) ducks were observed around all EED at d 28 compared with d 14 (Figure 6). Interestingly, even during the hours of lights out, ducks were observed clustered around EED, particularly the blue/ greens.
have suggested genetic, hormonal, feather conditions, among numerous other factors that may influence feather pecking in chickens and turkeys (Hughes, 1973; Cuthbertson, 1980; Kjaer and Sorensen, 1997; Blokhuis and Wiepkema, 1998; Huber-Eicher and Audige, 1999; Savory and Mann, 1999; Martrenchar et al., 2001; Keeling et al., 2004; Jensen et al., 2005; Bright, 2007; Ramadan and von Borell, 2008). Feather picking in ducks is relatively rare compared with the rate observed in chickens and turkeys but may be due to similar factors. There is an apparent lesser degree of feather picking in European Union systems that use straw as a bedding substrate, yet the claim that feather picking/pecking is not an issue with ducks raised on straw is somewhat confounded by the numerous European Union studies of these behaviors (for review, see Rodenburg et al., 2005). It is possible that the different flooring substrates used in US systems may have an impact on the occurrence of feather picking in ducks; however, recent studies demonstrated no differences in feather picking/ pecking in ducks housed on either pine or raised plastic flooring in US systems (Fraley et al., 2013; Karcher et al., 2013). Thus, more focused research on the actual causes of feather picking and pecking in all poultry species needs to occur. Regardless, in this current study, the worst incidences of feather picking were observed in less than 3% of the population, and as observed in other studies (Fraley et al., 2013; Karcher et al., 2013) the predominant condition score for all ducks was excellent. However, the specific stimuli that induce feather picking in ducks are purely anecdotal and have not been confirmed scientifically. Pekin ducks are related to Mallards, which are considered dabbling ducks as originally defined by Audubon and Peterson. Dabbling was also recently described as when a duck performs rapid nibbling with head moving from side to side (Jones and Dawkins, 2010). Mallards are known to forage/dabble in a variety of substrates, including deep or shallow water, mud, or sand (Guillemain et al., 2000). Some opinions exist that commercial duck barns that use certain flooring types or water systems do not allow ducks’ innate foraging behaviors. Research that compares flooring types or water systems on foraging behaviors in Pekin ducks has not been done in US systems; however, recent studies that compared flooring types in US production barns demonstrated no differences in body condition scores, an indirect measure of duck welfare, based upon flooring systems (Fraley et al., 2013; Karcher et al., 2013). An earlier study suggests that water lines do not provide ducks with environmental enrichment (Jones and Dawkins, 2010); however, that study was in the UK where barn management procedures are very different from US systems. It seems unlikely that the water system plays any role in feather picking in ducks because the water system is in place throughout the ducks’ lives and year round. However, the pathological occurrence of feather picking in ducks only occurs at a specific age of ducks and typi-
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cally only during fall and spring seasons. Regardless, our current findings suggest that the presence of EED may reduce the occurrence of feather picking. In our study, ducks appeared to have a strong preference toward the blue/green EED over other colors. On numerous occasions, ducks were observed on the video surveillance system to walk across the barn and immediately redirect their direction of walking toward a blue/green EED—frequently walking past or over
Figure 1. Body condition score at 3 ages. A) No differences (P = 0.072) were observed in body condition scores at 7 d of age. B) At 21 d of age, ducks housed with environmental enrichment devices (EED) showed better scores for eyes, feather cleanliness, and quality. C) At 35 d of age, ducks housed with EED still showed slightly improved (P = 0.055) feather cleanliness and condition scores. *P < 0.05.
Figure 3. Environmental enrichment devices (EED) associated with reduced feather picking. Observations made at d 21 showed that ducks housed with EED showed fewer incidences of self- and conspecific-feather picking than ducks housed without EED. *P < 0.05.
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Figure 2. All red versus red/white environmental enrichment devices (EED). No differences (P = 0.13) were observed in the number of duck interacting with either the all red or red/white EED.
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a white or red EED—then begin to interact with the blue/green EED. The preference for the blue/green wavelengths may reflect the types of colors the ducks are most capable of visualizing. In a series of studies by the Hart laboratory (Hegmann et al., 1974; Hart et al., 1999; Hart, 2001; Hart and Hunt, 2007; Hart and Vorobyev, 2005; Odeen et al., 2009) the retinas of avians typically have 4 to 5 sets of cones for color visualization
Figure 5. Presence of environmental enrichment devices (EED) reduced feather picking as evidenced by the overall pen score. A reduction in signs of self- and conspecific-feather picking were observed in pens with EED compared with pens without EED. ***P < 0.001.
[UV sensing, short wavelength sensing 1 and 2, medium wavelength sensing, and long wavelength sensing (LWS; Hart and Vorobyev, 2005)]. In these articles, Hart and colleagues demonstrated that many shorebirds, including ducks, have a preponderance of short wavelength sensing (blue-sensitive) cones and relatively few LWS (red-sensitive). Other taxa of birds, such as galliformes and columbiformes, have a much higher percentage of LWS cones—though galliformes and anseriformes have similar types of short wavelength sensing cones (Hart et al., 1999). They further demonstrate that evolutionary selection for color-sensitive vision may reflect behaviors such as diet, behaviors, and environment (e.g., land vs. water dwelling). Thus, it may be that the Pekin duck, due to its Mallard ancestry, may have a preference for blue-colored objects due to the anatomy and physiology of the retina. These observations of retinal physiology make sense in terms of the respective birds’ natural history. Galliformes, such as chickens and turkeys, use red pigmentation of the skin and feathers as a measure of developing social hierarchies and mating, whereas Mallards (anseriformes) do not contain red pigments but rather have blue/green plumage during the reproductive season. Thus, the Pekin ducks’ apparent preference for EED of the blue/green spectra may be related to their Mallard ancestry. After providing Pekin ducks with EED, we found their picking and pecking levels were decreased. Further research on density of EED per barn, and in particu-
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Figure 4. Environmental enrichment devices (EED) improved feather condition scores. A and C) At 14 d of age, no differences were observed in feather quality or cleanliness scores. B and D) Similar to experiment 1 at d 28, the presence of EED led to a larger percentage of ducks with a 0 feather quality score and fewer ducks with a 1 feather quality score compared with ducks housed without EED. *P < 0.05.
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Figure 6. Ducks preferred to interact with blue/green environmental enrichment devices (EED). A) At d 14, more ducks were observed interacting with blue/green EED than any other color. A greater number of ducks were observed interacting with red, then white EED. a = P < 0.001; b = P < 0.05. B) At 28 d of age, fewer (P < 0.05; n = 10) ducks overall were observed interacting with EED compared with d 14. However, a greater number of ducks was observed interacting with blue/green and red EED than with white EED. a = P < 0.01; b = P < 0.05. No time interaction (P = 0.21) across the 24-h observation period was indicated.
lar, on the shape of EED needs to be performed. The shape of EED will be critical to maximize cleaning to prevent spread of pathogens between flocks. Overall, ducks with EED, regardless of color, showed an improved body condition scoring and were observed to
display less feather picking. Given that feather picking can lead to increased sores and open wounds, and ultimately increase mortality, the introduction of EED in duck barns may lead to increased duck welfare and improved economics within the duck industry.
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ACKNOWLEDGMENTS The authors wish to thank Maple Leaf Farms Inc. and the Hope College Biology Department for supporting this research. We further thank Mike Lilburn (The Ohio State University, Wooster) and Susan Fraley (South Crossing Veterinary Center, MI) for their critical comments regarding the experimental design.
REFERENCES
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Blokhuis, H. J., and J. W. van der Haar. 1992. Effects of pecking incentives during rearing on feather pecking of laying hens. Br. Poult. Sci. 33:17–24. Blokhuis, H. J., and P. R. Wiepkema. 1998. Studies of feather pecking in poultry. Vet. Q. 20:6–9. Bordnick, P. S., B. A. Thyer, and B. W. Ritchie. 1994. Feather picking disorder and trichotillomania: An avian model of human psychopathology. J. Behav. Ther. Exp. Psychiatry 25:189–196. Bright, A. 2007. Plumage colour and feather pecking in laying hens, a chicken perspective? Br. Poult. Sci. 48:253–263. Crowe, R., and J. M. Forbes. 1999. Effects of four different environmental enrichment treatments on pecking behaviour in turkeys. Br. Poult. Sci. 40:S11–S12. Cuthbertson, G. J. 1980. Genetic variation in feather-pecking behaviour. Br. Poult. Sci. 21:447–450. Fraley, S. M., G. S. Fraley, D. M. Karcher, M. M. Makagon, and M. S. Lilburn. 2013. Influence of plastic slatted floors compared with pine shaving litter on Pekin Duck condition during the summer months. Poult. Sci. 92:1706–1711. Grindlinger, H. M., and E. Ramsay. 1991. Compulsive feather picking in birds. Arch. Gen. Psychiatry 48:857. Guillemain, M., H. Fritz, and S. Blais. 2000. Foraging methods can affect patch choice: An experimental study in Mallard (Anas platyrhynchos). Behav. Processes 50:123–129. Gvaryahu, G., E. Ararat, E. Asaf, M. Lev, J. I. Weller, B. Robinzon, and N. Snapir. 1994. An enrichment object that reduces aggressiveness and mortality in caged laying hens. Physiol. Behav. 55:313–316. Hart, N. S. 2001. The visual ecology of avian photoreceptors. Prog. Retin. Eye Res. 20:675–703. Hart, N. S., and D. M. Hunt. 2007. Avian visual pigments: Characteristics, spectral tuning, and evolution. Am. Nat. 169(Suppl. 1):S7–S26. Hart, N. S., J. C. Partridge, and I. C. Cuthill. 1999. Visual pigments, cone oil droplets, ocular media and predicted spectral sensitivity in the domestic turkey (Meleagris gallopavo). Vision Res. 39:3321–3328. Hart, N. S., and M. Vorobyev. 2005. Modelling oil droplet absorption spectra and spectral sensitivities of bird cone photoreceptors. J. Comp. Phys. A Neuroethology, Sensory, Neural, and Behavioral Physiology 191:381–392. Hegmann, J. P., R. A. Kieso, and H. B. Hartman. 1974. Gene differences influencing visual system function and behavior. Behav. Genet. 4:165–170. Huber-Eicher, B., and L. Audige. 1999. Analysis of risk factors for the occurrence of feather pecking in laying hen growers. Br. Poult. Sci. 40:599–604. Huber-Eicher, B., and F. Sebö. 2001. The prevalence of feather pecking and development in commercial flocks of laying hens. Appl. Anim. Behav. Sci. 74:223–231. Hughes, B. O. 1973. The effect of implanted gonadal hormones on feather pecking and cannibalism in pullets. Br. Poult. Sci. 14:341–348. Hughes, B. O., and I. J. Duncan. 1972. The influence of strain and environmental factors upon feather pecking and cannibalism in fowls. Br. Poult. Sci. 13:525–547. Jenkins, J. R. 2001. Feather picking and self-mutilation in psittacine birds. The veterinary clinics of North America. Exotic Anim. Practice 4:651–667.
Jensen, P., L. Keeling, K. Schutz, L. Andersson, P. Mormede, H. Brandstrom, B. Forkman, S. Kerje, R. Fredriksson, C. Ohlsson, S. Larsson, H. Mallmin, and A. Kindmark. 2005. Feather pecking in chickens is genetically related to behavioural and developmental traits. Physiol. Behav. 86:52–60. Jones, R. B., N. L. Carmichael, and E. Rayner. 2000. Pecking preferences and pre-dispositions in domestic chicks: Implications for the development of environmental enrichment devices. Appl. Anim. Behav. Sci. 69:291–312. Jones, T. A., and M. S. Dawkins. 2010. Environment and management factors affecting Pekin duck production and welfare on commercial farms in the UK. Br. Poult. Sci. 51:12–21. Karcher, D. M., M. M. Makagon, G. S. Fraley, S. M. Fraley, and M. S. Lilburn. 2013. Influence of raised plastic floors compared with pine shaving litter on environment and Pekin duck condition. Poult. Sci. 92:583–590. Keeling, L., L. Andersson, K. E. Schutz, S. Kerje, R. Fredriksson, O. Carlborg, C. K. Cornwallis, T. Pizzari, and P. Jensen. 2004. Chicken genomics: Feather-pecking and victim pigmentation. Nature 431:645–646. Kjaer, J. B., and P. Sorensen. 1997. Feather pecking behaviour in White Leghorns, a genetic study. Br. Poult. Sci. 38:333–341. Klemm, R., H. Pingel, K. Reiter, F. Bierschenk, and W. Rauch. 1992. Investigations on feather peckin in Muscovy ducks. World’s Poultry Congress 390–393. Lersel, J. J. A. v., and A. C. A. Bol. 1958. Preening of two tern species. A study on displacement activities. Behaviour 13:1–88. Madsen, H. 1966. On feather picking and cannibalism in pheasant and partridge chicks, particularly in relation to the amino acid arginine. Acta Vet. Scand. 7:272–287. Martrenchar, A., D. Huonnic, and J. P. Cotte. 2001. Influence of environmental enrichment on injurious pecking and perching behaviour in young turkeys. Br. Poult. Sci. 42:161–170. McAdie, T. M., L. J. Keeling, H. J. Blokhuis, and R. B. Jones. 2005. Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens. Appl. Anim. Behav. Sci. 93:67–80. Natt, D., S. Kerje, L. Andersson, and P. Jensen. 2007. Plumage color and feather pecking–behavioral differences associated with PMEL17 genotypes in chicken (Gallus gallus). Behav. Genet. 37:399–407. Newberry, R. C. 1995. Environmental enrichment: Increasing the biological relevance of captive environments. Appl. Anim. Behav. Sci. 44:229–243. Odeen, A., N. S. Hart, and O. Hastad. 2009. Assessing the use of genomic DNA as a predictor of the maximum absorbance wavelength of avian SWS1 opsin visual pigments. J. Comp. Phys. A, Neuroethology, Sensory, Neural, and Behavioral Physiology 195:167–173. Ramadan, S. G., and E. von Borell. 2008. Role of loose feathers on the development of feather pecking in laying hens. Br. Poult. Sci. 49:250–256. Rodenburg, T. B., M. B. M. Bracke, J. Berk, J. Cooper, J. M. Faure, D. Guemene, G. Guy, A. Harlander, T. Jones, U. Knierim, K. Kuhnt, H. Pingel, K. Reiter, J. Serviere, and M. A. W. Ruis. 2005. Welfare of ducks in European duck husbandry systems. World’s Poult. Sci. J. 61:633–646. Rodenburg, T. B., P. Koene, and B. M. Spruijt. 2004. Reaction to frustration in high and low feather pecking lines of laying hens from commercial or semi-natural rearing conditions. Behav. Processes 65:179–188. Savory, C. J., and J. S. Mann. 1999. Feather pecking in groups of growing bantams in relation to floor litter substrate and plumage colour. Br. Poult. Sci. 40:565–572. Schaible, P. J., J. A. Davidson, and S. L. Bandemer. 1947. Cannibalism and feather picking in chicks as influenced by certain changes in a specific ration. Poult. Sci. 26:651–656. Seibert, L. M., S. L. Crowell-Davis, G. H. Wilson, and B. W. Ritchie. 2004. Placebo-controlled clomipramine trial for the treatment of feather picking disorder in cockatoos. J. Am. Anim. Hosp. Assoc. 40:261–269.
Key words: Pekin duck, feather picking, environmental enrichment, feather pecking 2014 Poultry Science 93:2143–2150 http://dx.doi.org/10.3382/ps.2014-03885
INTRODUCTION Feathers provide a large part of the poultry economy in the form of down for pillows, blankets, and clothing. Considerable losses are noted each year due to feather picking and a subsequent reduced health/mortality. Some level of picking is good, however, in the form of preening. Ducks preen their feathers throughout their lives, but increase the level of preening between d 17 to 22 when the feathers change from down to adult plumage. Preening refers to a movement with the bill intended to care for the duck’s plumage aimed toward the breast, shoulders, wings, or back feather (Lersel and Bol, 1958). Injurious feather picking has been described and refers to an auto-mutilation behavior as opposed to feather pecking that occurs between birds, ©2014 Poultry Science Association Inc. Received January 7, 2014. Accepted June 1, 2014. 1 Corresponding author: [email protected]
particularly in galliforms (Madsen, 1966; Grindlinger and Ramsay, 1991; Bordnick et al., 1994; Jenkins, 2001; Seibert et al., 2004). It has been suggested that the incidence of these injurious behaviors may be related to a birds’ ability to forage in their bedding substrate (Rodenburg et al., 2004, 2005). Ducks are very curious creatures and the slightest change in a duck’s appearance, such as blood, can draw the attention of surrounding ducks and lead to pecking. Self-picking and conspecific pecking can cause damage to feathers and skin, and increase the potential for disease in the duck. Thus, picking and pecking in ducks may be different from the feather pecking observed in galliform species. Feather pecking in galliform species refers strictly to conspecifics, pecking at each other, damaging the skin and feathers of conspecifics in the same barn/pen (Keeling et al., 2004; Bright, 2007; Natt et al., 2007). Galliforms do not pick at themselves in the same manner as ducks. Pekin ducks pick mostly at themselves, although occasionally at each other. Both picking and pecking are episodic events in which the cause or stimulus is
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ABSTRACT Like other poultry species, Pekin ducks occasionally show an auto-mutilation behavior referred to as feather picking. Self-picking can lead to further pecking by conspecifics and ultimately to reduced feather quality and poor overall health of the bird. Although the reasons underlying feather picking are not clear, it appears to occur when the ducks are transitioning between downy feathers and adult plumage, between 17 and 22 d of age. We hypothesized that giving Pekin ducks a substitute outlet for this behavior in the form of environmental enrichment devices (EED) would decrease feather picking and improve feather quality and duck health and welfare. The EED were plastic Wifflestyle balls, each threaded with 4 zip-ties. In the first experiment, we set out to determine that placement of EED would not induce fear or harmful behaviors. Five barns were each divided into 2 pens, holding an average combined total of approximately 4,500 ducks with one pen per barn used as control. Upon placement of the
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MATERIALS AND METHODS Birds and Housing The Pekin ducks used in this experiment were raised for production in poultry barns contracted by Maple Leaf Farms Inc. (Leesburg, IN). Male and female ducks (approximately equal ratios) were raised from 1 d of age until approximately 35 d of age in barns with 2 large floor pens (n = 10 barns; thus, 10 pens per treatment) with raised plastic-slatted floors following standard commercial conditions. Briefly, ducks are placed in the pens on the day of hatch where they are restricted to approximately one-third of the pen under brooding conditions [26.5°C, ~0.1 cubic meters/s per duck of ventilation, <60% RH] until d 10 when they are allowed access to the full pen (at d 10: 20°C, 2.8 × 10−5 to 0.003 cubic meters/s per duck of ventilation, <60% humidity). For the remainder of the growout time frame, temperature is maintained at 12.7 to 18.4°C and a RH less than 75%; however, barns are curtain-sided and thus environmental conditions have an impact on internal barn conditions. Ventilation rates are maintained between 8.7 × 10−4 and 0.006 cubic meters/s per duck through d 35. Because there are no external sex differences, we were not able to differentiate between male and female ducks for data analyses for this study. The size of the pens was kept to allow approximately 0.16 m2 per duck with approximately 4,500 to 6,500 ducks per pen. Ducks were raised under industry standards for temperature and light (18L:6D),
and all ducks were allowed ad libitum access to feed and water. The management of the ducks was carried out by growers contracted and regulated by Maple Leaf Farms Inc. To minimize management variability, each barn had EED placed in one pen, and no EED in the opposite pen within the same barn. All procedures used were approved by Hope College Animal Care and Use Committee following Association for Assessment and Accreditation of Laboratory Animal Care guidelines.
Duck Physical Condition Scores The ducks’ physical condition was evaluated at 3 ages: 7 to 8 (7 d), 21 to 24 (21 d), and 30 to 33 (32 d) days posthatch as described previously (Fraley et al., 2013; Karcher et al., 2013). Due to inclement weather and availability of the researcher, travel days had ±1 d; thus, the day represented within the parentheses is the categorical day. One hundred ducks per pen were included in each evaluation; 25 ducks were randomly sampled at each of 4 predetermined pen locations (4 corners of each pen). Groups of ducks (n = 25) were penned at each location through the use of hinged catching frames, and individual ducks within each group were scored by 3 individuals using a previously published scoring rubric (Fraley et al., 2013; Karcher et al., 2013). The individual traits scored were identified on a scale of 0 to 1 (nostril and feather cleanliness) or 0 to 2 (eyes, feather quality, and foot pad quality), where 0 was the best condition or situation and a 1 or 2 indicates a worse condition for that specific quality.
Experiment 1 The purpose of this experiment was to first determine if ducks would interact with EED. Second, we set out to determine if the color of the EED (red vs. white zip ties on red Wiffle-style balls) affects the Pekin ducks’ willingness to interact with them. Third, we set out to determine if the placement of EED would improve feather quality scores, thus indicating a reduction in feather picking. To accomplish these goals, we used a total of 10 barns with raised plastic flooring, and each barn was divided into 2 equal-sized pens. The total number of ducks in each barn ranged from 9,900 to 13,800; one-half the ducks were housed in the treatment pen and the other one-half were housed in the control pen. At 12 d of age (before the age where feather picking is first observed) the EED were placed about 15 m apart in 2 rows down either side of the treatment pen with the red/white EED on one side of the pen and the red/red EED on the other side. The treatment pen in each barn received the EED at a concentration of approximately 120 ducks per EED and the pen within each barn was randomized for position to prevent “end of barn” bias. This layout, along with the control and treatment sides, was alternated between sides and pens across different barns to minimize management differences or pen differences. Each row of EED were placed
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unknown, although one potential stimulus is thought to be due to a lack of environmental enrichment. Previous studies of the effects of environmental enrichment devices (EED) have been done with chickens and turkeys, using objects such as different colored strings, leg bands, or small balls (Gvaryahu et al., 1994; Newberry, 1995; Crowe and Forbes, 1999; Jones et al., 2000; Martrenchar et al., 2001; McAdie et al., 2005). A study on Muscovy ducks demonstrated that outdoor runs and open water sources possibly reduced feather picking; although this study has not been replicated on Pekin ducks (Klemm et al., 1992). However, most these studies were completed on very small numbers of birds and the results may not be translatable to full-size commercial barns. Thus, the effects of EED in chickens and turkeys have only been implemented to a limited extent on a production scale. To date, no EED study has been performed specifically on ducks to determine the effects of environmental enrichment to reduce feather picking. The purpose of our first study was to determine if the placement of EED within commercial barns would cause the ducks distress, as opposed to having beneficial effects. The purpose of our second study was to determine if the body condition scores of the Pekin ducks differ between control and treatment pens and to further determine if EED color affects the amount of interaction the Pekin ducks have with EED.
ENRICHMENT DEVICES REDUCE FEATHER PICKING IN DUCKS
Experiment 2 The purpose of this experiment was to determine if the color of the EED (all red, all white, or blue/green) affects the Pekin ducks’ willingness to interact with them. Red EED had red balls with identically colored red zip-ties. White EED had white balls with identically colored white zip-ties, and blue balls had green zip-ties. The blue/green combination was used because identical shades of blue or green between zip ties and balls could not be obtained. The shades of blue and green were very close together spectrally. The EED were again placed as described for experiment 1 at 12 d of age and remained until the ducks were processed at approximately 35 d of age. Each color of EED was placed in a triad of an approximately 1-m equilateral triangle, and each triad was approximately 5 m apart. Two rows of triads were placed in lines equidistant from each other and food and water sources within the treatment pen. Again, EED were placed such that there were 120 ducks per color of EED. Duck condition scoring occurred on d 14 and again at d 28. To observe duck interactions with EED, we set up a video surveillance system in each barn. A total of 8 (4 per pen) high-definition cameras with fish-eye lenses were arranged so that almost 98% of the floor was observable. The cameras were attached to a 1-TB digital video recorder and ducks were recorded for a 24-h period after placement of EED (d 14–15), and again before processing (d 28–29). The number of ducks that interacted (picking at or investigating) with the different colored EED was analyzed every 30 min across each 24-h period; the number of interactions with each color of EED was totaled over 3 h. It was noted that ducks with the most severe feather damage were typically not caught during the body condition scoring aspect of the experiment. Thus, we developed a total pen
feather picking score of 0 to 4. To determine the score, 2 separate individuals would do a slow walk through both pens and count the total number of birds observed with skin lesions due to feather picking. A 0 score indicated no birds were observed with skin lesions, a score of 4 was given if >40 birds were observed with signs of active picking (thus ~10% of the pen). The total pen score was then averaged between the 2 observers.
Statistical Analyses All data were averaged per pen, and the pen (n = 10/ treatment) was considered an experimental unit. The body condition assessment data were not normally distributed due to the large prevalence of 0 scores; thus, these data in experiments 1 and 2 were analyzed using a chi-squared test. Data are expressed as a percentage of ducks exhibiting a specific score at each age by treatment. A probability value of 0.05 was considered to be significant. For experiment 1, the number of ducks interacting with the EED and the total pen score in experiment 2 were analyzed using a Student’s t-test with a P < 0.05 considered significant. In experiment 2, the color choice was analyzed by repeated measures ANOVA with age as the repeated measure and EED interactions as the dependent variable.
RESULTS Experiment 1 No scientific studies have specifically addressed the behavior of Pekin ducks in a production facility that indicates a stressed flock. However, conversations with numerous growers with decades of experience suggest that stressed flocks show 1) flocking behavior where most ducks in a pen circle the barn, 2) birds tend to evade growers or researchers walking within the barn, 3) feather picking, or 4) a combination of these. The placement of the EED did not initiate any of these behaviors, suggesting that the EED themselves were not doing harm. The body condition scores of the ducks at 7 d of age showed no differences (P = 0.55, n = 10) in any body condition score parameter; however, after placement of EED, the scores at 21 d of age showed decreased (P < 0.021, n = 10) averages (and thus better physical condition) in eyes, feather cleanliness, and feather quality in ducks housed in the treatment pens with the EED compared with the control pens. At age 35, ducks raised in pens with EED showed a trend toward better feather cleanliness and quality scores, though this trend did not achieve significance (P = 0.095, n = 10). Figure 1 summarizes these results. No differences were observed in the number of ducks picking or investigating the all red, or red/white EED (Figure 2). Analyses of video tapes revealed that ducks in pens with EED showed considerably (P = 0.034, n = 10) less self- and conspecific- feather pecking (Figure 3).
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equidistant from feed and water sources. The EED remained in the pens continuously from 14 to 35 d of age. The EED were not anchored down to the floor or reorganized at each visit, allowing the ducks to freely interact with and move the EED throughout the pen. Just before body condition scoring at d 21, an observer slowly walked through the barns, causing minimal disturbance, taking note of the different behaviors displayed by the ducks. In both pens, the observer noted the number of ducks seen self- or conspecificpicking (picking at one’s neighbor) for a 1-h period. In the treatment pen, additional observations were made for the ducks’ reaction to the EED (investigating or picking) while also noting which color (red/white or red/red) the behavior was directed toward. Picking was noted when the duck was actively picking an EED, and investigating was noted when the duck obviously showed interest in the EED but was not actively picking it. A video recording of the ducks’ behavior was also made between 0800 and 1100 h in the absence of human observers and later scored by unbiased individuals.
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Experiment 2
DISCUSSION The purpose of this study was first to determine if EED would themselves elicit stress-related behaviors, if the ducks would interact with the EED, or both. Second, we set out to determine if EED color would affect the Pekin ducks’ willingness to interact with the EED. To accomplish these goals, we placed EED in the barns from 12 d of age continuously until load-out at 35 d of age. We found that ducks interacted enthusiastically with the EED; they prefered blue/green to all other color combinations tested, and the presence of EED reduced picking and may ameliorate feather picking due to environmental stressors. Causative factors that lead to feather picking in ducks are not known; however, there appears to be a seasonal component similar to the occurrence of feather picking in galliforms (Huber-Eicher and Sebö, 2001). During the spring and fall seasons when weather is changing from cold to warm and warm to cold, respectively, ducks have been observed to increase the amount of picking aimed at themselves and others (Huber-Eicher and Sebö, 2001). Hughes and Duncan (1972) observed this behavior in chickens as well and have attributed the causes to factors other than seasonal change including management, overcrowding, overheating, poor ventilation, humidity, lighting, and the presence of injured or sick birds (Schaible et al., 1947). Others (Blokhuis and Wiepkema, 1998) have suggested that conspecific pecking could develop because of “misdirected food pecking” (Blokhuis and van der Haar, 1992). Other groups
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No differences (P = 0.72) were observed in any body condition score at 14 d of age. However, differences were observed at d 28; ducks in pens with EED showed an increased number (P = 0.021, n = 10) of 0 feather quality scores, and fewer (P = 0.032, n = 10) scores of 1 (Figure 4). Analysis of the total pen score further supported the hypothesis that EED would reduce feather picking in Pekin ducks. Ducks in pens with EED showed considerably (P < 0.00076, n = 10) lower total pen scores (number of ducks with obvious skin lesions) then ducks housed without EED (Figure 5). Analyses of the 24-h video recordings at age 14 and 28 supported the physical observations of researchers. Considerably more ducks (P = 0.00089, n = 10) were observed either picking or oriented toward the blue/ green EED compared with the red or white EED. A greater number (P = 0.0079, n = 10) of ducks were observed around the red EED compared with the white EED, though not to the level of the blue EED. Overall, fewer (P = 0.041, n = 10) ducks were observed around all EED at d 28 compared with d 14 (Figure 6). Interestingly, even during the hours of lights out, ducks were observed clustered around EED, particularly the blue/ greens.
have suggested genetic, hormonal, feather conditions, among numerous other factors that may influence feather pecking in chickens and turkeys (Hughes, 1973; Cuthbertson, 1980; Kjaer and Sorensen, 1997; Blokhuis and Wiepkema, 1998; Huber-Eicher and Audige, 1999; Savory and Mann, 1999; Martrenchar et al., 2001; Keeling et al., 2004; Jensen et al., 2005; Bright, 2007; Ramadan and von Borell, 2008). Feather picking in ducks is relatively rare compared with the rate observed in chickens and turkeys but may be due to similar factors. There is an apparent lesser degree of feather picking in European Union systems that use straw as a bedding substrate, yet the claim that feather picking/pecking is not an issue with ducks raised on straw is somewhat confounded by the numerous European Union studies of these behaviors (for review, see Rodenburg et al., 2005). It is possible that the different flooring substrates used in US systems may have an impact on the occurrence of feather picking in ducks; however, recent studies demonstrated no differences in feather picking/ pecking in ducks housed on either pine or raised plastic flooring in US systems (Fraley et al., 2013; Karcher et al., 2013). Thus, more focused research on the actual causes of feather picking and pecking in all poultry species needs to occur. Regardless, in this current study, the worst incidences of feather picking were observed in less than 3% of the population, and as observed in other studies (Fraley et al., 2013; Karcher et al., 2013) the predominant condition score for all ducks was excellent. However, the specific stimuli that induce feather picking in ducks are purely anecdotal and have not been confirmed scientifically. Pekin ducks are related to Mallards, which are considered dabbling ducks as originally defined by Audubon and Peterson. Dabbling was also recently described as when a duck performs rapid nibbling with head moving from side to side (Jones and Dawkins, 2010). Mallards are known to forage/dabble in a variety of substrates, including deep or shallow water, mud, or sand (Guillemain et al., 2000). Some opinions exist that commercial duck barns that use certain flooring types or water systems do not allow ducks’ innate foraging behaviors. Research that compares flooring types or water systems on foraging behaviors in Pekin ducks has not been done in US systems; however, recent studies that compared flooring types in US production barns demonstrated no differences in body condition scores, an indirect measure of duck welfare, based upon flooring systems (Fraley et al., 2013; Karcher et al., 2013). An earlier study suggests that water lines do not provide ducks with environmental enrichment (Jones and Dawkins, 2010); however, that study was in the UK where barn management procedures are very different from US systems. It seems unlikely that the water system plays any role in feather picking in ducks because the water system is in place throughout the ducks’ lives and year round. However, the pathological occurrence of feather picking in ducks only occurs at a specific age of ducks and typi-
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cally only during fall and spring seasons. Regardless, our current findings suggest that the presence of EED may reduce the occurrence of feather picking. In our study, ducks appeared to have a strong preference toward the blue/green EED over other colors. On numerous occasions, ducks were observed on the video surveillance system to walk across the barn and immediately redirect their direction of walking toward a blue/green EED—frequently walking past or over
Figure 1. Body condition score at 3 ages. A) No differences (P = 0.072) were observed in body condition scores at 7 d of age. B) At 21 d of age, ducks housed with environmental enrichment devices (EED) showed better scores for eyes, feather cleanliness, and quality. C) At 35 d of age, ducks housed with EED still showed slightly improved (P = 0.055) feather cleanliness and condition scores. *P < 0.05.
Figure 3. Environmental enrichment devices (EED) associated with reduced feather picking. Observations made at d 21 showed that ducks housed with EED showed fewer incidences of self- and conspecific-feather picking than ducks housed without EED. *P < 0.05.
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Figure 2. All red versus red/white environmental enrichment devices (EED). No differences (P = 0.13) were observed in the number of duck interacting with either the all red or red/white EED.
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a white or red EED—then begin to interact with the blue/green EED. The preference for the blue/green wavelengths may reflect the types of colors the ducks are most capable of visualizing. In a series of studies by the Hart laboratory (Hegmann et al., 1974; Hart et al., 1999; Hart, 2001; Hart and Hunt, 2007; Hart and Vorobyev, 2005; Odeen et al., 2009) the retinas of avians typically have 4 to 5 sets of cones for color visualization
Figure 5. Presence of environmental enrichment devices (EED) reduced feather picking as evidenced by the overall pen score. A reduction in signs of self- and conspecific-feather picking were observed in pens with EED compared with pens without EED. ***P < 0.001.
[UV sensing, short wavelength sensing 1 and 2, medium wavelength sensing, and long wavelength sensing (LWS; Hart and Vorobyev, 2005)]. In these articles, Hart and colleagues demonstrated that many shorebirds, including ducks, have a preponderance of short wavelength sensing (blue-sensitive) cones and relatively few LWS (red-sensitive). Other taxa of birds, such as galliformes and columbiformes, have a much higher percentage of LWS cones—though galliformes and anseriformes have similar types of short wavelength sensing cones (Hart et al., 1999). They further demonstrate that evolutionary selection for color-sensitive vision may reflect behaviors such as diet, behaviors, and environment (e.g., land vs. water dwelling). Thus, it may be that the Pekin duck, due to its Mallard ancestry, may have a preference for blue-colored objects due to the anatomy and physiology of the retina. These observations of retinal physiology make sense in terms of the respective birds’ natural history. Galliformes, such as chickens and turkeys, use red pigmentation of the skin and feathers as a measure of developing social hierarchies and mating, whereas Mallards (anseriformes) do not contain red pigments but rather have blue/green plumage during the reproductive season. Thus, the Pekin ducks’ apparent preference for EED of the blue/green spectra may be related to their Mallard ancestry. After providing Pekin ducks with EED, we found their picking and pecking levels were decreased. Further research on density of EED per barn, and in particu-
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Figure 4. Environmental enrichment devices (EED) improved feather condition scores. A and C) At 14 d of age, no differences were observed in feather quality or cleanliness scores. B and D) Similar to experiment 1 at d 28, the presence of EED led to a larger percentage of ducks with a 0 feather quality score and fewer ducks with a 1 feather quality score compared with ducks housed without EED. *P < 0.05.
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Figure 6. Ducks preferred to interact with blue/green environmental enrichment devices (EED). A) At d 14, more ducks were observed interacting with blue/green EED than any other color. A greater number of ducks were observed interacting with red, then white EED. a = P < 0.001; b = P < 0.05. B) At 28 d of age, fewer (P < 0.05; n = 10) ducks overall were observed interacting with EED compared with d 14. However, a greater number of ducks was observed interacting with blue/green and red EED than with white EED. a = P < 0.01; b = P < 0.05. No time interaction (P = 0.21) across the 24-h observation period was indicated.
lar, on the shape of EED needs to be performed. The shape of EED will be critical to maximize cleaning to prevent spread of pathogens between flocks. Overall, ducks with EED, regardless of color, showed an improved body condition scoring and were observed to
display less feather picking. Given that feather picking can lead to increased sores and open wounds, and ultimately increase mortality, the introduction of EED in duck barns may lead to increased duck welfare and improved economics within the duck industry.
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Colton and Fraley
ACKNOWLEDGMENTS The authors wish to thank Maple Leaf Farms Inc. and the Hope College Biology Department for supporting this research. We further thank Mike Lilburn (The Ohio State University, Wooster) and Susan Fraley (South Crossing Veterinary Center, MI) for their critical comments regarding the experimental design.
REFERENCES
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Blokhuis, H. J., and J. W. van der Haar. 1992. Effects of pecking incentives during rearing on feather pecking of laying hens. Br. Poult. Sci. 33:17–24. Blokhuis, H. J., and P. R. Wiepkema. 1998. Studies of feather pecking in poultry. Vet. Q. 20:6–9. Bordnick, P. S., B. A. Thyer, and B. W. Ritchie. 1994. Feather picking disorder and trichotillomania: An avian model of human psychopathology. J. Behav. Ther. Exp. Psychiatry 25:189–196. Bright, A. 2007. Plumage colour and feather pecking in laying hens, a chicken perspective? Br. Poult. Sci. 48:253–263. Crowe, R., and J. M. Forbes. 1999. Effects of four different environmental enrichment treatments on pecking behaviour in turkeys. Br. Poult. Sci. 40:S11–S12. Cuthbertson, G. J. 1980. Genetic variation in feather-pecking behaviour. Br. Poult. Sci. 21:447–450. Fraley, S. M., G. S. Fraley, D. M. Karcher, M. M. Makagon, and M. S. Lilburn. 2013. Influence of plastic slatted floors compared with pine shaving litter on Pekin Duck condition during the summer months. Poult. Sci. 92:1706–1711. Grindlinger, H. M., and E. Ramsay. 1991. Compulsive feather picking in birds. Arch. Gen. Psychiatry 48:857. Guillemain, M., H. Fritz, and S. Blais. 2000. Foraging methods can affect patch choice: An experimental study in Mallard (Anas platyrhynchos). Behav. Processes 50:123–129. Gvaryahu, G., E. Ararat, E. Asaf, M. Lev, J. I. Weller, B. Robinzon, and N. Snapir. 1994. An enrichment object that reduces aggressiveness and mortality in caged laying hens. Physiol. Behav. 55:313–316. Hart, N. S. 2001. The visual ecology of avian photoreceptors. Prog. Retin. Eye Res. 20:675–703. Hart, N. S., and D. M. Hunt. 2007. Avian visual pigments: Characteristics, spectral tuning, and evolution. Am. Nat. 169(Suppl. 1):S7–S26. Hart, N. S., J. C. Partridge, and I. C. Cuthill. 1999. Visual pigments, cone oil droplets, ocular media and predicted spectral sensitivity in the domestic turkey (Meleagris gallopavo). Vision Res. 39:3321–3328. Hart, N. S., and M. Vorobyev. 2005. Modelling oil droplet absorption spectra and spectral sensitivities of bird cone photoreceptors. J. Comp. Phys. A Neuroethology, Sensory, Neural, and Behavioral Physiology 191:381–392. Hegmann, J. P., R. A. Kieso, and H. B. Hartman. 1974. Gene differences influencing visual system function and behavior. Behav. Genet. 4:165–170. Huber-Eicher, B., and L. Audige. 1999. Analysis of risk factors for the occurrence of feather pecking in laying hen growers. Br. Poult. Sci. 40:599–604. Huber-Eicher, B., and F. Sebö. 2001. The prevalence of feather pecking and development in commercial flocks of laying hens. Appl. Anim. Behav. Sci. 74:223–231. Hughes, B. O. 1973. The effect of implanted gonadal hormones on feather pecking and cannibalism in pullets. Br. Poult. Sci. 14:341–348. Hughes, B. O., and I. J. Duncan. 1972. The influence of strain and environmental factors upon feather pecking and cannibalism in fowls. Br. Poult. Sci. 13:525–547. Jenkins, J. R. 2001. Feather picking and self-mutilation in psittacine birds. The veterinary clinics of North America. Exotic Anim. Practice 4:651–667.
Jensen, P., L. Keeling, K. Schutz, L. Andersson, P. Mormede, H. Brandstrom, B. Forkman, S. Kerje, R. Fredriksson, C. Ohlsson, S. Larsson, H. Mallmin, and A. Kindmark. 2005. Feather pecking in chickens is genetically related to behavioural and developmental traits. Physiol. Behav. 86:52–60. Jones, R. B., N. L. Carmichael, and E. Rayner. 2000. Pecking preferences and pre-dispositions in domestic chicks: Implications for the development of environmental enrichment devices. Appl. Anim. Behav. Sci. 69:291–312. Jones, T. A., and M. S. Dawkins. 2010. Environment and management factors affecting Pekin duck production and welfare on commercial farms in the UK. Br. Poult. Sci. 51:12–21. Karcher, D. M., M. M. Makagon, G. S. Fraley, S. M. Fraley, and M. S. Lilburn. 2013. Influence of raised plastic floors compared with pine shaving litter on environment and Pekin duck condition. Poult. Sci. 92:583–590. Keeling, L., L. Andersson, K. E. Schutz, S. Kerje, R. Fredriksson, O. Carlborg, C. K. Cornwallis, T. Pizzari, and P. Jensen. 2004. Chicken genomics: Feather-pecking and victim pigmentation. Nature 431:645–646. Kjaer, J. B., and P. Sorensen. 1997. Feather pecking behaviour in White Leghorns, a genetic study. Br. Poult. Sci. 38:333–341. Klemm, R., H. Pingel, K. Reiter, F. Bierschenk, and W. Rauch. 1992. Investigations on feather peckin in Muscovy ducks. World’s Poultry Congress 390–393. Lersel, J. J. A. v., and A. C. A. Bol. 1958. Preening of two tern species. A study on displacement activities. Behaviour 13:1–88. Madsen, H. 1966. On feather picking and cannibalism in pheasant and partridge chicks, particularly in relation to the amino acid arginine. Acta Vet. Scand. 7:272–287. Martrenchar, A., D. Huonnic, and J. P. Cotte. 2001. Influence of environmental enrichment on injurious pecking and perching behaviour in young turkeys. Br. Poult. Sci. 42:161–170. McAdie, T. M., L. J. Keeling, H. J. Blokhuis, and R. B. Jones. 2005. Reduction in feather pecking and improvement of feather condition with the presentation of a string device to chickens. Appl. Anim. Behav. Sci. 93:67–80. Natt, D., S. Kerje, L. Andersson, and P. Jensen. 2007. Plumage color and feather pecking–behavioral differences associated with PMEL17 genotypes in chicken (Gallus gallus). Behav. Genet. 37:399–407. Newberry, R. C. 1995. Environmental enrichment: Increasing the biological relevance of captive environments. Appl. Anim. Behav. Sci. 44:229–243. Odeen, A., N. S. Hart, and O. Hastad. 2009. Assessing the use of genomic DNA as a predictor of the maximum absorbance wavelength of avian SWS1 opsin visual pigments. J. Comp. Phys. A, Neuroethology, Sensory, Neural, and Behavioral Physiology 195:167–173. Ramadan, S. G., and E. von Borell. 2008. Role of loose feathers on the development of feather pecking in laying hens. Br. Poult. Sci. 49:250–256. Rodenburg, T. B., M. B. M. Bracke, J. Berk, J. Cooper, J. M. Faure, D. Guemene, G. Guy, A. Harlander, T. Jones, U. Knierim, K. Kuhnt, H. Pingel, K. Reiter, J. Serviere, and M. A. W. Ruis. 2005. Welfare of ducks in European duck husbandry systems. World’s Poult. Sci. J. 61:633–646. Rodenburg, T. B., P. Koene, and B. M. Spruijt. 2004. Reaction to frustration in high and low feather pecking lines of laying hens from commercial or semi-natural rearing conditions. Behav. Processes 65:179–188. Savory, C. J., and J. S. Mann. 1999. Feather pecking in groups of growing bantams in relation to floor litter substrate and plumage colour. Br. Poult. Sci. 40:565–572. Schaible, P. J., J. A. Davidson, and S. L. Bandemer. 1947. Cannibalism and feather picking in chicks as influenced by certain changes in a specific ration. Poult. Sci. 26:651–656. Seibert, L. M., S. L. Crowell-Davis, G. H. Wilson, and B. W. Ritchie. 2004. Placebo-controlled clomipramine trial for the treatment of feather picking disorder in cockatoos. J. Am. Anim. Hosp. Assoc. 40:261–269.