Astroturf as a dustbathing substrate for laying hens

Astroturf as a dustbathing substrate for laying hens

Applied Animal Behaviour Science 146 (2013) 88–95 Contents lists available at SciVerse ScienceDirect Applied Animal Behaviour Science journal homepa...

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Applied Animal Behaviour Science 146 (2013) 88–95

Contents lists available at SciVerse ScienceDirect

Applied Animal Behaviour Science journal homepage: www.elsevier.com/locate/applanim

Astroturf as a dustbathing substrate for laying hens Gina M. Alvino, Cassandra B. Tucker, Gregory S. Archer 1 , Joy A. Mench ∗ Department of Animal Science & Center for Animal Welfare, University of California, Davis, One Shields Avenue, Davis, CA 95616-8521, USA

a r t i c l e

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Article history: Accepted 21 March 2013 Available online 23 April 2013 Keywords: Hen Dustbathe Furnished cage Astroturf sand Welfare

a b s t r a c t Furnished cages for laying hens often contain an Astroturf (AT) pad which may be sprinkled with feed to promote foraging and dustbathing. We evaluated AT and AT plus feed (ATF) to determine if hens use these substrates for dustbathing. Hens (N = 30) without prior exposure to substrate were housed singly in cages at 34 weeks of age. Using a 3 × 3 Latin square design, groups of 10 hens were provided with a dustbox containing either sand (control), an AT pad, or an AT pad with 200 g of feed (ATF) delivered daily, with three 20-day treatment Periods. The treatment order was: sand–ATF–AT (1); ATF–AT–sand (2); AT–sand–ATF (3). Behavior was recorded for 8 or 9 days each Period, from 11:00 to 22:00 h. Three measures of dustbathing were evaluated: bout number per day, bout length, and total time spent dustbathing per day. Data were collected and processed to evaluate dustbathing activity in the substrate, on the wire floor and in both locations combined (overall). Data were analyzed using the GLM or Kruskal–Wallis and Dwass-Steel-Critchlow-Fligner tests. Although there were some differences in statistical significance between Periods, in general hens provided with sand exhibited fewer bouts both overall and on wire, and longer bouts both overall and one wire, than AT or ATF hens, and longer bouts both overall and in substrate than AT. Hens with sand also spent significantly (all P ≤ 0.04) more time dustbathing on substrate (median min = 18.71 ± 5.16) and less time on wire (0.59 ± 1.56) than AT (0.33 ± 2.62 and 13.39 ± 7.15, respectively) and ATF (2.05 ± 4.43 and 11.26 ± 4.37, respectively) treatments during Period 1, and also more time dustbathing on substrate (7.66 ± 8.13) than hens in the AT treatment (0.00 ± 2.52) during Period 2. Exposure to AT and ATF during the first two treatment periods reduced hens’ use of sand during the third treatment period, with only 11% of bouts occurring in sand during Period 3 as compared to 64% and 41% during Periods 1 and 2, respectively. These findings demonstrated that AT did not provide an adequate dustbathing substrate, even with the addition of feed, as hens were less likely to dustbathe on both AT and ATF than sand, and were also less likely to dustbathe on sand if they were initially exposed to AT and ATF as dustbathing substrates. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Dustbathing is an intricate comfort behavior performed by many species of birds that is distinctive in appearance (Olsson and Keeling, 2005). Studies suggest that laying

∗ Corresponding author at: Tel.: +1 530 752 7125; fax: +1 530 752 0175. E-mail address: [email protected] (J.A. Mench). 1 Current address: Texas A&M University, Department of Poultry Science, 101 Kleberg Center, 2472 TAMU, College Station, TX 77843-2472, USA. 0168-1591/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.applanim.2013.03.006

hens are highly motivated to dustbathe and that failing to provide an adequate dustbathing substrate in a commercial setting, i.e. in conventional cages, may compromise welfare (reviewed in Appleby et al., 2004; Olsson and Keeling, 2005). In recent years there has been increasing adoption commercially of furnished (enriched) colony cages. These cages incorporate a nest, perches and a polyethylene Astroturf® (AT) pad secured to the floor of the cage for scratching, foraging and dustbathing. However, relatively little is known about hens’ dustbathing behavior in these types of cages.

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The configuration of furnished colony cages with regard to the AT pad differs from some earlier models of the furnished cage, in which the dustbath was placed above the nest and filled with sand (Appleby and Hughes, 1995; Appleby et al., 2002). Although sand has been shown to be a highly preferred dustbathing substrate (Sanotra et al., 1995; Shields et al., 2004; van Liere et al., 1990), it can damage the machinery of cage systems. In addition, loose material in furnished cages must be replenished frequently, which makes it difficult to use in the commercial setting (Appleby et al., 2002; Lindberg and Nicol, 1997). Thus, AT is provided in place of loose material. To encourage the performance of pecking, scratching and dustbathing on the AT, feed is dispensed from an overhead auger, diverted from the main feed line, onto the surface of the pad. There are few published studies evaluating the use of AT as a dustbathing substrate. In an experiment evaluating the preferences for AT over wire as a nesting site, Hughes (1993) reported that the majority of the hens dustbathed on the AT rather than the wire cage floor. In a study investigating floor type preferences of hens in furnished cages, Merrill et al. (2006) found that the majority of the birds showed a clear preference for dustbathing on perforated AT over the wire floor. The hens in that study were raised on litter, which may have affected the results due to the influence of previous substrate experience (see Olsson et al., 2002; Vestergaard et al., 1990; Wichman and Keeling, 2008). In a more recent study evaluating hens’ dustbathing substrate preferences, Scholz et al. (2010) found that time spent dustbathing on AT was less than that on lignocellulose and there were fewer dustbathing bouts on AT than on both wood shavings and lignocellulose, suggesting that the hens may have perceived AT to be unsuitable for dustbathing. Unlike Merrill et al. (2006), the hens in Scholz et al. (2010) study were raised on wire and were therefore naïve to substrates at the outset of the experiment. These few published findings provide mixed results about the suitability of AT as a dustbathing substrate and highlight the potential challenge of interpreting results of studies in which the subject birds have varying levels of substrate experience. The aim of our experiment was to use paired comparisons to evaluate the effects of AT – both on its own and with the addition of laying hen feed – on dustbathing behavior as compared to sand, a positive control. The hens we utilized had been reared in wire cages without access to litter. We chose these hens in order to mimic the common industry practice of raising layer pullets that will ultimately be housed in furnished cages on wire, and to control for previous experience. We hypothesized that the provision of friable substrates, either on their own (sand) or coupled with a non-friable surface (ATF), would promote dustbathing. We therefore predicted that hens would exhibit more dustbathing in sand and ATF than AT. Further, we predicted that the bouts in sand and ATF would be more complete than those on AT, as evidenced by fewer bouts of a longer duration in/on the substrate. We also predicted that ATF would be a moderately preferred substrate while the non-friable AT would be the least preferred.

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2. Materials and methods 2.1. Animals and Husbandry Hyline CV-22 laying hens (N = 30) from UC Davis’s Hopkins Avian Research Facility were used in the experiment. The hens were 32 weeks old and had been reared in wire cages, without any exposure to litter. Each hen was randomly assigned to a single-hen cage measuring 91.4 cm (length) × 45.7 cm (depth) × 53.3 cm (height) in the experimental room. There were four two-tier cage racks each containing eight cages. Thus, each hen had neighboring hens in the cages behind and adjacent to her. Each cage had a feed trough (40.6 cm in length) at the front; the linear automatic water trough ran down the middle of each tier of the cage block. Purina Layena® feed (Purina Mills® , St. Louis, MO, USA) was fed ad libitum and replenished daily. The hens were housed and managed according to the Guide for the Care and Use of Agricultural Animals in Agricultural Research and Teaching (FASS, 2010). The photoperiod was 16L:8D (photophase from 06:00 to 22:00 h) and the ambient temperature was maintained at approximately 21.5 ◦ C. A wooden-framed dustbox measuring 39.4 cm × 40.6 cm was secured to the floor in the back corner near the outer side of each cage. This box contained either: (a) children’s play sand (3 cm deep); (b) a dark green Astroturf® (Grassworx, LLC, St. Louis, MO, USA) pad (AT) measuring 35.8 cm × 34.3 cm with a pile height of approximately 1.5 cm; or (c) an AT pad of identical color and size with 200 g of Layena® feed evenly distributed on to its surface (ATF). The amount of feed added to the pad was determined by conducting a pilot study where the pads were covered with either 50, 200 or 400 g of feed. The 200 g amount was chosen for use because it adequately covered approximately 75% of the pad’s surface without sparse areas or small piles of feed that created wastage. At approximately 09:00 h each morning all AT pads were cleaned and the friable substrates (i.e. feed and sand) were fully replaced. Although there were ample amounts of friable substrate available to the birds at the end of each 24-h period, the cleaning and replacing process was necessary to reduce the accumulation of excreta. Assignment of substrate treatments to cages was balanced to control for potential location effects such that neighboring hens did not receive the same substrate treatment. Additionally, each cage was configured such that the dustboxes in adjacent cages were placed on opposite sides, i.e. the dustbox in the left cage was placed in the back corner on the left side whereas the dustbox in the adjacent cage was placed in the back corner on the right side. Dark green polyethylene tarpaulins (25.4 cm tall) were secured to the interior of the two cage sides that formed the corner where the dustbox was placed so that the substrates would remain inside the cage during dustbathing bouts. 2.2. Data collection and processing The experiment was designed as a 3 × 3 Latin Square with groups of 10 hens receiving the treatments in the following order: Sand–ATF–AT; ATF–AT–Sand; and

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AT–Sand–ATF. Each treatment period lasted for 20 days. We attached a miniature board-lens video camera (Sony Products, New York, New York, USA) to a camera stand which was placed approximately 0.3 m in front of each cage. Realtime video recordings of the hens’ behavior began on the third day of each treatment period following a 2-day period of acclimatization to the substrate. Behavior was recorded continuously during the 16-h photophase every other day for a total of 9 days. During the first and third treatment periods a technical issue prevented the collection of 1 day’s worth of video data for all hens. Also, two hens were permanently removed from the study during the first and second treatment periods for health reasons. Since it was observed from the video recordings that the majority of the hens exhibited dustbathing activity mainly after 11:00 h, only dustbathing behavior occurring between 11:00 and 22:00 h was coded. This 11-h period is henceforth referred to as “day”. The beginning of a dustbathing bout was identified by the appearance of the first vertical wing shake; the bout was considered to be complete when the hen walked away from the dustbathing site or engaged in a different behavior, such as feeding or drinking. Body shaking and/or grooming that occurred near the end of a dustbathing bout were considered to be part of that bout. For each treatment period dustbathing bout location (i.e. dustbox or wire floor), number, and length, as well as total time spent dustbathing per day, were recorded using the EthoLog program (Ottoni, 2000). For each treatment period we also determined: (1) the number of hens from each treatment that dustbathed either exclusively in/on the substrate, on the wire floor (“wire”) or in both locations; (2) the proportion of dustbaths performed in either location for each treatment group across all three periods; and (3) the mean bout length for dustbathing bouts that took place on the substrate or wire floor for the three treatments combined. 2.3. Statistical analyses To determine the effect of treatment on the number of bouts per day, time spent dustbathing per day and bout length we utilized a general linear model (GLM), with treatment as a fixed variable for each treatment period. Within each model statement the dependent variables were substrate, wire and overall (i.e., substrate and wire combined), providing measures of the total number of bouts, mean total bout length, and total time spent dustbathing regardless of substrate. An unpaired two-sample t-test was also used to investigate differences in bout lengths taking place on substrate versus the wire floor for all treatments combined. For this analysis location (i.e. substrate or wire floor) was the fixed variable. To evaluate potential differences across the three treatment periods, we carried out separate GLMs for each of the three substrate treatments for bout number and total time, with period as the fixed variable. When a test yielded a P-value of ≤ 0.10 (indicative of a significant difference for P ≤ 0.05 or trend toward significance if P > 0.05–0.10), an LSD post hoc test was employed to identify differences among treatments. Data were tested

to ensure that they met the assumptions of the GLM and t-test using the Shapiro–Wilk test for normality and the Levene’s test for equal variances. Portions of the dataset were non-normal due to floor effects. Because these data could not be successfully transformed, we analyzed them using either a nonparametric Kruskal–Wallis (KW) test followed by the Dwass Steele Critchlow-Flinger post hoc test or a non-parametric Mann–Whitney U test. We also used the Mann–Whitney U test for analysis of the bout length measure when comparing bouts lengths on wire versus substrate for all treatments combined. All statistical analyses were carried out using the Statistical Analysis Software (SAS® ) 9.3 for Windows (SAS Institute Inc, 2010) or Minitab® Release 14 (Minitab Inc., 2004). 3. Results 3.1. Treatment Period 1 Data for Period 1 are shown in Table 1. During Period 1 there was a treatment effect on bout number in substrate, wire floor, and overall. The post hoc analysis revealed that hens provided with sand tended to perform more bouts in substrate than those provided with ATF and AT and conversely performed significantly fewer bouts on wire than both ATF and AT. Hens given sand exhibited fewer bouts overall than hens provided with AT. There was also a treatment effect on bout length overall, whereby hens with sand exhibited longer bouts overall than those with AT. Although there was an overall pattern for bout length, there were no treatment effects on bout length in substrate or on wire. However, for all three treatments combined bouts on substrate were longer than those on wire (medians with 95% CI: substrate = 7.90 min ± 2.83 and wire = 1.89 min ± 0.62; U = 713.0; P = < 0.0001). Finally, there was a treatment effect for total time spent dustbathing per day in substrate as well as on the wire floor. Hens given sand spent more time dustbathing in substrate than those with both ATF and AT and less time dustbathing on the wire floor than both ATF and AT. There were no treatment effects on total time spent dustbathing per day overall. 3.2. Treatment Period 2 Data for Period 2 are shown in Table 2. Although there were no differences in the number of bouts performed on wire or overall, there was a treatment effect for substrate, whereby hens with sand performed more bouts in substrate than those with AT and longer bouts overall than those given ATF. There were no treatment differences on bout length on wire or in substrate. For all three treatments combined bouts on substrate were longer than those on wire (medians with 95% CI: substrate = 4.08 min ± 2.36; wire = 1.68 min ± 0.52; U = 643.0; P = 0.0001). Similar to bout number, there were no differences in total time spent dustbathing on wire or overall, but there was a treatment effect associated with substrate bouts, whereby hens with sand spent more time dustbathing per day in substrate than those with AT.

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Table 1 Dustbathing behavior on substrate, wire, and overall for hens given Sand, Astroturf (AT), or Astroturf plus feed (ATF) during Treatment Period 1. Measure

Location

Medians ± 95% CI

Test statistic and P-value

Post hoc

Bout number per day

Substrate

Sand: 1.83 ± 0.77 ATF: 0.22 ± 0.84 AT: 0.12 ± 0.87 Sand: 0.56 ± 1.20 ATF: 3.38 ± 1.59 AT: 5.99 ± 2.67 Sand: 2.65 ± 0.94 ATF: 4.78 ± 1.31 AT: 6.38 ± 2.64

H2 = 7.14 P = 0.03

Sand > ATF and AT P = 0.06, 0.07

H2 = 11.06 P = 0.004

Sand < ATF and AT P = 0.04, 0.007

H2 = 6.98 P = 0.03

Sand < AT P = 0.05

Sand: 11.10 ± 3.69 ATF: 9.24 ± 4.46 AT: 3.93 ± 6.63 Sand: 1.23 ± 0.60 ATF: 2.35 ± 1.55 AT: 1.73 ± 0.73 Sand: 13.84 ± 4.11 ATF: 4.92 ± 5.97 AT: 4.20 ± 5.52

NS

H2 : 7.13 P = 0.03

Sand > AT P = 0.03

Sand: 18.71 ± 5.16 ATF: 2.05 ± 4.43 AT: 0.33 ± 2.62 Sand: 0.59 ± 1.56 ATF: 11.26 ± 4.37 AT: 13.39 ± 7.15 Sand: 19.07 ± 4.51 ATF: 15.54 ± 4.00 AT: 17.86 ± 6.21

H2 : 14.16 P = 0.0008

Sand > ATF and AT P = 0.007, 0.003

H2 : 12.48 P = 0.002

Sand < ATF and AT P = 0.009, 0.007

Wire

Overall

Bout length (min)

Substrate

Wire

Overall

Total time per day (min)

Substrate

Wire

Overall

NS

NS

Table 2 Dustbathing behavior on substrate, wire, and overall for hens given Sand, Astroturf (AT), or Astroturf plus feed (ATF) during Treatment Period 2. Measure

Location

Medians ± 95% CI (unless indicated as Means ± S.E.M.)

Test statistic and P-value

Post hoc

Bout number per day

Substrate

Sand: 0.89 ± 1.24 ATF: 0.44 ± 0.48 AT: 0.00 ± 0.40 Means ± S.E.M.: Sand: 3.91 ± 1.47 ATF: 5.43 ± 1.23 AT: 6.75 ± 1.06 Means ± S.E.M.: Sand: 5.28 ± 1.27 ATF: 6.18 ± 1.23 AT: 7.06 ± 1.14

H2 = 6.47 P = 0.04

Sand > AT P = 0.04

Sand: 13.05 ± 3.76 ATF: 3.98 ± 4.12 AT: 3.17 ± 5.96 Means ± S.E.M.: Sand: 2.29 ± 0.35 ATF: 1.90 ± 0.49 AT: 2.34 ± 0.49 Sand: 15.09 ± 3.82 ATF: 4.93 ± 3.07 AT: 2.68 ± 2.41

NS

H2 = 9.76 P = 0.008

Sand > AT P = 0.02

Sand: 7.66 ± 8.13 ATF: 1.30 ± 4.84 AT: 0.00 ± 2.52 Sand: 2.67 ± 6.86 ATF: 9.55 ± 5.88 AT: 12.38 ± 4.23 Sand: 21.40 ± 5.84 ATF: 18.98 ± 4.15 AT: 12.38 ± 5.08

H2 = 7.87 P = 0.02

Sand > AT P = 0.02

Wire

Overall

Bout length (min)

Substrate

Wire

Overall

Total time per day (min)

Substrate

Wire

Overall

NS

NS

NS

NS

NS

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3.3. Treatment Period 3

The only difference between treatment periods was for the sand treatment (Fig. 1). Hens with sand during Period 1 performed more dustbaths per day in the substrate than those with sand during Period 3 (H2 : 7.35, P = 0.03) and performed fewer dustbaths on wire than hens with sand during Periods 2 and 3 (H2 : 4.81, P = 0.09). Hens with sand during Period 1 also spent more time dustbathing per day in the substrate than those with sand in Period 3 (H2 : 7.13, P = 0.02). For descriptive purposes, Table 4 and Fig. 2 show the percentages of hens dustbathing either exclusively in substrate, on wire or in both locations across the treatment periods, and the proportions of bouts that took place on substrate and wire, respectively. The percentage of hens dustbathing in sand and the proportion of dustbaths in sand declined over the three treatment periods. No hens given ATF or AT dustbathed exclusively on those surfaces, although between 1/5 and 2/3 of these hens dustbathed exclusively on wire during the different periods. 4. Discussion The results of our study suggest that AT, either on its own or with the addition of feed, may be an unsuitable dustbathing substrate for laying hens given their minimal usage of the pads as compared to the sand control. In general, hens provided with sand exhibited fewer bouts both overall and on wire, and longer bouts both overall and in sand, as compared to the two AT treatments. Hens with sand also spent more time dustbathing on substrate and less time on wire than both AT treatments. Exposure to AT and ATF during the first two treatment periods reduced hens’ use of sand during the third treatment period as compared to the hens who received sand initially, suggesting that exposure to AT could have created an aversion to dustbathing in the box – even when it was filled with a highly preferred substrate such as sand. There are a relatively small number of published studies of dustbathing in furnished cage systems. In one of the first studies assessing the use of resources in furnished

Median bout number per day +/- 95% CI

A a, b

2 1.5 1

b

0.5 0

-0.5

Period 1

Period 2

Period 3

Bouts in substrate 6 Median bout number per day +/- 95% CI

3.4. Treatment period comparisons

a

2.5

b

b

5

B

4 3 2

a

1 0 -1

Period 1

Period 2

-2

Period 3

Bouts on wire

C

30 25 Median min per day +/- 95% CI

Data for Period 3 are shown in Table 3. During Period 3 there was a treatment effect on the number of dustbathing bouts occurring on wire and overall. Hens with sand performed fewer dustbaths on wire and overall relative to ATF. There was no treatment difference in the number of substrate bouts, but there was a treatment effect on bout length for bouts on substrate and wire separately as well as overall. Hens with sand had longer bouts in substrate than those with AT and hens provided with ATF exhibited shorter bouts on wire than those with AT. Hens with ATF performed shorter bouts overall than AT. For all three treatments combined, bout lengths on substrate were longer than those on wire (medians with 95% CI: substrate = 3.53 min ± 2.40; wire = 1.77 min ± 0.55 = 530.0; P < 0.0001). There were no treatment differences in total time spent dustbathing per day.

3

a

20

a, b

15

b

10 5 0 -5

Period 1

Period 2

Period 3

Total me dustbathing in substrate Fig. 1. Period comparison analyses for the sand treatment (treatment medians ± 95% CI), showing (A) Bout number per day in substrate (post hoc: P = 0.03); (B) Bout number per day on wire (post hoc: P = 0.06); and (C) Total time per day dustbathing in substrate (post hoc: P = 0.02). Different superscripts show significant differences between the treatment periods.

cages, Appleby and Hughes (1995) found that hens performed 100% of their dustbaths in the sand-filled dustbath. However, other studies (reviewed in Hoerning, 2005) generally show that the dustbaths in furnished cages are under-utilized, although the range of utilization reported is variable. For example, Lindberg and Nicol (1997) found that about 27% of the dustbaths on a commercial farm with furnished cages occurred in the sand dustbathing area, while most of the rest took place on the wire floor beneath the feed trough. In another study conducted on commercial farms with different models of furnished cages, de Jong et al. (LayWel Deliverable 4.5, 2007) found that fewer than 6% of hens dustbathed in the wood-shavings substrate area provided. It thus appears that the dustbathing area in commercial furnished cages is under-utilized even when desirable dustbathing substrates are provided. Our results with respect to the minimal/infrequent use of AT and

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Table 3 Dustbathing behavior on substrate, wire, and overall for hens given Sand, Astroturf (AT), or Astroturf plus feed (ATF) during Treatment Period 3. Measure

Location

Medians ± 95% CI (unless indicated as Means ± S.E.M.)

Test statistic and P-value

Bout number per day

Substrate

Sand: 0.25 ± 0.35 ATF: 0.00 ± 0.53 AT: 0.13 ± 0.25 Means ± S.E.M.: Sand: 3.75 ± 0.85 ATF: 6.72 ± 0.63; AT: 4.86 ± 1.03 Means ± S.E.M.: Sand: 4.24 ± 0.78 ATF: 7.15 ± 0.51 AT: 5.19 ± 0.99

NS

Wire

Overall

Bout length (min)

Substrate

Wire

Overall

Total time per day (min)

Substrate

Wire

Overall

Post hoc

F2 ,25 = 2.88 P = 0.08

Sand < ATF P = 0.03

F2 ,25 = 3.30 P = 0.05

Sand < ATF P = 0.02

Sand: 10.48 ± 12.91 ATF: 3.69 ± 4.70 AT: 4.53 ± 3.80 Sand: 1.22 ± 2.37 ATF: 1.58 ± 0.97 AT: 2.82 ± 3.98 Sand: 9.76 ± 15.22 ATF: 1.95 ± 3.40 AT: 4.49 ± 5.50

H2 = 9.15 P = 0.01

Sand > AT P = 0.03

H2 = 5.78 P = 0.06

ATF < AT P = 0.04

H2 = 6.13 P = 0.04

ATF < AT P = 0.05

Sand: 3.27 ± 7.35 ATF: 0.00 ± 2.33 AT: 0.00 ± 1.18 Sand: 10.25 ± 5.36 ATF: 11.58 ± 3.03 AT: 13.07 ± 6.03 Sand: 19.48 ± 5.61 ATF: 12.13 ± 2.20 AT: 18.32 ± 5.58

NS

NS

NS

Table 4 The percentage of hens that dustbathed in either the substrate exclusively, on the wire floor exclusively or on both across the three treatment periods. Treatment Period Treatment Period 1 Sand (n = 10) ATF (n = 9) AT (n = 10) Treatment Period 2 Sand (n = 9) ATF (n = 10) AT (n = 9) Treatment Period 3 Sand (n = 10) ATF (n = 9) AT (n = 10)

Fig. 2. The proportion of dustbathing bouts that took place on: (A) substrate or (B) wire for all substrate treatments and all three treatment periods.

Substrate

Wire floor

Both

40 0 0

0 33 40

60 67 60

22 0 0

0 20 67

78 80 33

0 0 0

33 50 40

67 50 60

ATF for dustbathing and prevalence of sham dustbathing are consistent with these previous findings, but are most comparable to de Jong et al. (2007) result, as some of the hens in their study were provided with matting onto which wood-shavings were dispensed. However, our finding that hens provided with sand during treatment Period 1 used it for the majority of their dustbaths is not consistent with the findings of Lindberg and Nicol (1997) and Abrahamsson and Tauson (1997), who reported low usage of sand dustbaths by wire-reared hens. Instead, our results confirmed previous findings with regard to hens’ preference for dustbathing in friable substrates such as sand, particularly for birds in Period 1

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whose only previous experience was with wire. That the substrate-naïve hens used in this study recognized and utilized sand supports earlier hypotheses that chickens have an innate predisposition for dustbathing in friable substrates (see: Petherick et al., 1995; Vestergaard and Hogan, 1992; Wichman and Keeling, 2008, 2009). 4.1. Treatment effects Bouts performed by birds provided with either AT or ATF were shorter both overall and on the substrate than bouts by hens with sand. Scholz et al. (2010) similarly found that hens prefer friable to non-friable substrates for dustbathing. They provided hens with AT, lignocellulose, feed or wood shavings in a simultaneous choice test and found that hens given AT exhibited fewer bouts and spent less time dustbathing than those given wood shavings or lignocellulose. However, because the five different substrates used in their study were presented simultaneously, hens’ preference for AT could have been underestimated. In our study we used pair-wise comparisons to decrease the possibility of underestimation of substrate preference, but nevertheless found that hens provided with AT or ATF performed the majority of their bouts on wire rather than on the AT. Another conclusion of Scholz et al. (2010) was that feed is not a suitable dustbathing substrate, possibly because the fat content makes it less effective than other substrates like sand at reducing feather lipids. Similarly, our results showed that the addition of feed onto the AT pad did not stimulate dustbathing. The crude fat content of the feed we used was 2.5%, which is lower than the 4.2% used by Scholz et al. (2010), although not as low as the 0.82% fat feed found by Scholz et al. (2011) in a subsequent study to be preferred for dustbathing in comparison to higher-fat feeds. Even though we did not analyze the individual components of the bouts in the present study, our results showing that hens provided with sand performed fewer bouts of longer lengths (both overall and on substrate) and spent more time dustbathing on substrate suggest that these bouts may have been more complete than those on either the AT or wire. Merrill and Nicol (2005) also reported a similar result for birds dustbathing in wood shavings relative to wire, string or rubber. In his review, van Rooijen (2005) suggested that bouts that are less than 5 min long end prior to the consummatory phase. The majority of bout lengths on AT and ATF in our study were less than 5 min long, as were all bout lengths on wire for all treatments. It has been suggested that such short bouts may be associated with frustration (Merrill and Nicol, 2005; van Rooijen, 2005). Wichman and Keeling (2009) found that birds who did not have access to peat exhibited dustbaths that were either much shorter or much longer than those of birds with access to peat. They attributed these effects to a lack of feedback (van Liere, 1992), which resulted in an interruption of a bout (i.e. short) or a continual restarting of the bout (i.e. long). An additional consideration pertaining to hens’ use of AT (with or without feed) is that Astroturf® pads can become dirty due to the accumulation of waste (Hoerning, 2005), which could deter birds from performing dustbaths. Also, the majority of sham dustbaths take place close to the

feed trough (Hoerning, 2005; Lindberg and Nicol, 1997; Olsson and Keeling, 2002), and Lindberg and Nicol (1997) surmised that the more frequent replenishment of feed in the troughs relative to the replenishment of the dustbath may explain the greater interest in the feed trough as a dustbathing site. However, in our study all pads were cleaned and friable substrates (feed and sand) were replenished daily–typically during the same window of time as feed replenishment in the troughs. Social competition has also been identified as a possible reason for suboptimal use of the dustbathing area in furnished cages (Shimmura et al., 2007, 2008). However, in our study there was only one hen per cage. Thus, our study demonstrates that neither pad cleanliness/replenishment nor social competition is responsible for underutilization of the Astroturf dustbathing substrate and the prevalence of sham dustbathing. 4.2. Order effects and substrate experience Sand use was less for hens that had been provided with AT during the first two treatment periods than for hens given sand during the first treatment period. In consequence, the proportion of bouts that took place in sand decreased from 64% to 41% to 11% over the course of the three treatment periods. This suggests that hens may have developed an aversion to the AT/ATF, thus potentially discouraging their use of sand when it was subsequently offered to them in the dustbox. The hens we used were 32 weeks of age at the beginning of the experiment and had never had exposure to substrate, which could have influenced their dustbathing behavior and substrate utilization. Olsson and Keeling (2002) found that the amount of sham dustbathing did not differ between their conventional and furnished cage treatments, and suggested that the hens’ rearing environment may have been important. Sham dustbathing is already established by 16 weeks (Vestergaard et al., 1990), the time that pullets – many of whom are wire-reared – are transferred to laying cages. Previous research has also shown that birds reared without litter may continue to exhibit sham dustbathing once they are provided with a friable substrate (Olsson et al., 2002; van Liere and Siard, 1991; Vestergaard and Baranyiova, 1996). An effect of habit (Olsson et al., 2002; Olsson and Keeling, 2002) cannot completely explain the widespread performance of sham dustbathing in our study, however, since the wire-reared hens provided with sand during the first treatment period performed more than half (59%) of their dustbathing bouts in the substrate rather than on wire. 5. Conclusion Wire-reared hens provided with Astroturf® , either with or without feed dispensed on the surface, showed less dustbathing activity on those substrates than on sand, a well-established positive control. Our findings suggest that the Astroturf area in furnished colony systems is not optimal for dustbathing. Further, our results regarding the prevalence of sham dustbathing by the wirereared birds given AT and ATF raise questions about early

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substrate experience. A potential future direction is to investigate how AT provision during rearing affects adult dustbathing behavior and substrate utilization. Though the link between early experience and hen dustbathing behavior is not entirely clear, the generation of such empirical evidence could be critical for the configuration of pullet-rearing cages, as well as the continuing refinement of furnished cage systems. Acknowledgements We thank Grassworx, LLC for their generous donation of the AT pads, and Cargill Kitchen Solutions and the W.K. Kellogg Endowment for their financial support of our laying hen welfare and husbandry research. We gratefully acknowledge the infrastructure support of the Department of Animal Science, the College of Agricultural and Environmental Sciences, and the California Agricultural Experiment Station of the University of California-Davis. We also thank the staff of the Department of Animal Science Hopkins Avian Research Facility for providing and caring for the hens, and the graduate students of the Mench and Tucker labs for their assistance, especially Richard Blatchford. Lastly, we acknowledge the undergraduate interns who helped with bird care and data collection. References Abrahamsson, P., Tauson, R., 1997. Effects of group size on performance, health and birds’ use of facilities in furnished cages for laying hens. Acta Agric. Scand. A: Anim. Sci. 47, 254–260. Appleby, M.C., Hughes, B.O., 1995. The Edinburgh modified cage for laying hens. Br. Poult. Sci. 36, 707–718. Appleby, M.C., Walker, A.W., Nicol, C.J., Lindberg, A.C., Freire, R., Hughes, B.O., Elson, H.A., 2002. Development of furnished cages for laying hens. Br. Poult. Sci. 43, 489–500. Appleby, C.M., Mench, J.A., Hughes, B.O., 2004. Poultry Behaviour and Welfare. CABI, Oxfordshire, UK. de Jong, I.C., Fillerup, M., Reuvekamp, B., Fiks, T., 2007. Evaluation of substrate quality in two different housing systems (barn systems and furnished cages) for laying hens with respect to dustbathing and foraging behavior. LayWel Report: Deliverable 4.5: Evaluation of litter quality in various housing systems. http://www.laywel.eu/ Federation of Animal Science Societies (FASS), 2010. Guide for the Care and Use of Agricultural Animals in Research and Teaching. Federation of Animal Science Societies, Savoy, IL, USA. Hoerning, B., 2005. Welfare of laying hens in furnished cages. In: Martin, G., Sambraus, H., Steiger, A. (Eds.), Welfare of Laying Hens in Europe. University of Kassel, Germany, pp. 198–246. Hughes, B.O., 1993. Choice between artificial turf and wire floor as nest sites in individually caged laying hens. Appl. Anim. Behav. Sci. 36, 327–335. Lindberg, A.C., Nicol, C.J., 1997. Dustbathing in modified battery cages: is sham dustbathing an adequate substitute? Appl. Anim. Behav. Sci. 55, 113–128. Merrill, R.J.N., Nicol, C.J., 2005. The effects of novel floorings on dustbathing, pecking and scratching behaviour of caged hens. Anim. Welf. 14, 179–186.

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Merrill, R.J.N., Cooper, J.J., Albentosa, M.J., Nicol, C.J., 2006. The preferences of laying hens for perforated Astroturf over conventional wire as a dustbathing substrate in furnished cages. Anim. Welf. 15, 173–178. Minitab® 14. 2004. Version 14.1. State College, PA, USA. Olsson, I.A.S., Keeling, L.J., 2002. No effect of social competition on sham dustbathing in furnished cages for laying hens. Acta Agric. Scand. A: Anim Sci. 52, 253–256. Olsson, I.A.S., Keeling, L.J., 2005. Why in earth? Dustbathing behaviour in jungle and domestic fowl reviewed from a Tinbergian and animal welfare perspective. Appl. Anim. Behav. Sci. 92, 259–282. Olsson, I.A.S., Keeling, L.J., Duncan, I.J.H., 2002. Why do hens sham dustbathe when they have litter? Appl. Anim. Behav. Sci. 76, 53–64. Ottoni, E.B., 2000. EthoLog 2.2—a tool for the transcription and timing of behavior observation sessions. Behav. Res. Methods Insrum. Comput. 32, 446–449. Petherick, J.C., Seawright, E., Waddington, D., Duncan, I.J.H., Murphy, L.B., 1995. The role of perception in the causation of dustbathing behaviour in domestic fowl. Anim. Behav. 49, 1521–1530. Sanotra, G.S., Vestergaard, K.S., Agger, J.F., Lawson, L.G., 1995. The relative preferences for feathers, straw, wood-shavings and sand for dustbathing, pecking and scratching in domestic chicks. Appl. Anim. Behav. Sci. 43, 263–277. Scholz, B., Urselmans, S., Kjaer, J.B., Schrader, L., 2010. Food, wood, or plastic as substrates for dustbathing and foraging in laying hens: a preference test. Poult. Sci. 89, 1584–1589. Scholz, B., Kjaer, J.B., Urselmans, S., Schrader, L., 2011. Litter lipid content affects dustbathing behavior in laying hens. Poult. Sci. 90, 2433–2439. Shields, S., Garner, J.P., Mench, J.A., 2004. Dustbathing by broiler chickens: a comparison of preference for four different substrates. Appl. Anim. Behav. Sci. 86, 291–298. Shimmura, T., Eguchi, Y., Uetaki, K., Tanaka, T., 2007. Differences of behavior, use of resources and physical conditions between dominant and subordinate hens in furnished cages. Anim. Sci. J. 78, 307–313. Shimmura, T., Eguchi, Y., Uetake, K., Tanaka, T., 2008. Effects of separation of resources on behaviour of high-, medium- and low-ranked hens in furnished cages. Appl. Anim. Behav. Sci. 113, 74–86. Statistical Analysis Software® (SAS) Institute, 2010. Guide for Personal Computers, Version 9.3. SAS Institute, Cary, NC, USA. van Liere, D.W., 1992. The significance of fowls’ bathing in dust. Anim. Welf. 1, 187–202. van Liere, D.W., Siard, N., 1991. Towards an understanding of litter bathing quality in hens. 24th International Congress of the ISAE, Edinburgh, Scotland, UFAW, p. 132. van Liere, D.W., Kooijman, J., Wiepkema, P.R., 1990. Dustbathing behaviour of laying hens as related to quality of dustbathing material. Appl. Anim. Behav. Sci. 26, 127–141. van Rooijen, J., 2005. Dust-bathing and other comfort behaviours of dometic hens. In: Martin, Sambraus, Steiger (Eds.), Welfare of the Laying Hens in Europe- Reports, Analyses and Conclusions. Saeriswil, Switzerland, pp. 110–123. Vestergaard, K.S., Hogan, J.A., Kruijt, J.P., 1990. The development of a behavior system: dustbathing in the Burmese red junglefowl. 1. The influence of rearing environment on the organization of dustbathing. Behaviour 112, 35–42. Vestergaard, K.S., Hogan, J.A., 1992. The development of a behavior system—dustbathing in the Burmese red junglefowl. 3. Effects of experience on stimulus preference. Behaviour 121, 215–230. Vestergaard, K.S., Baranyiova, E., 1996. Pecking and scratching in the development of dust perception in young chicks. Acta Vet. Brno 65, 133–142. Wichman, A., Keeling, L.J., 2008. Hens are motivated to dustbathe in peat irrespective of being reared with or without a suitable dustbathing substrate. Anim. Behav. 75, 1525–1533. Wichman, A., Keeling, L.J., 2009. The influence of losing or gaining access to peat on the dustbathing behaviour of laying hens. Anim. Welf. 18, 149–157.