動(dòng)物科學(xué)外文翻譯---爭鬧雞群的沙浴對四種不同底物的偏好的比較

1、<p>　　Dustbathing by broiler chickens: a comparison</p><p>　　of preference for four different substrates</p><p>　　Sara J. Shields, Joseph P. Garner, Joy A. Mench?</p><p>　　Depa

2、rtment of Animal Science, University of California at Davis, one Shields Avenue, Davis, CA 95616, USA</p><p>　　Received 28 February 2003; received in revised form 28 August 2003; accepted 21 January 2004<

3、/p><p><b>　　Abstract</b></p><p>　　Leg abnormalities leading to lameness in broiler chickens are a serious welfare problem. Previous work in our laboratory demonstrated that providing br

4、oiler chickens with the opportunity to exercise by performing more natural behaviors (such as perching, walking up and down inclines and dustbathing) can improve their ability to walk normally [J.A. Mench, J.P. Garner, C

5、. Falcone, Behavioral activity and its effects on leg problems in broiler chickens, in: H. Oester, C. Wyss (Eds.), Proceedings of</p><p>　　Switzerland, 2001, pp. 152–156]. With the long-term goal of stimulat

6、ing dustbathing to improve leg condition, the aim of this study was to determine the dustbathing substrate preferred by broiler chickens.We conducted a dustbathing choice test experiment using four different bedding type

7、s (pine wood shavings, rice hulls, construction grade sand, and a recycled paper animal bedding product) .Four different broiler chickens were tested each week for 6 weeks starting when the chicks were 1 week old</p&g

8、t;<p>　　consecutive days per week. During an observation, each corner of the test pen was filled with a different bedding type, and the behavior of the focal chick recorded. Vertical wing shakes (VWS) were used as

9、 the primary measure of dustbathing activity. Broilers performed significantly moreVWS per hour in sand (F3,36 = 13.52,P < 0.0005) and spent a greater proportion of their total time in sand (F5,60 = 5.15, P = 0.001) t

10、han in the rice hulls, paper, or wood shavings. They also visited the sand sig</p><p>　　dustbathing. Further work is needed to determine if stimulating broiler chickens to dustbathe by</p><p>　　

11、providing sand can improve their leg condition, and thus their welfare.</p><p>　　© 2004 Elsevier B.V. All rights reserved. 1. Introduction</p><p>　　Exercise is essential for the health and

12、well-being of animals. For broiler chickens even</p><p>　　walking may be difficult as the birds age due to rapid growth rate and the increasing incidence</p><p>　　of leg disorders (Weeks et al.,

13、 2000; Kestin et al., 1992; Mench, 2004). Previous work in our laboratory (Mench et al., 2001) and other work (Thorp and Duff, 1988) suggest that exercise is important for reducing the incidence and severity of leg probl

14、ems. For broiler chickens,one form of exercise is dustbathing behavior. Because dustbathing involves rotational and pushing motions of the legs, it could be a form of exercise that improves leg condition. Laying hens hav

15、e been found to have clear pr</p><p>　　A dustbathing bout is composed of a sequence of behavioral components (Kruijt, 1964).</p><p>　　Pecking and scratching at a potential dustbathing site usual

16、ly precede a dustbathing bout.</p><p>　　The sequence of dustbathing behavioral components usually begins with “bill-raking”,</p><p>　　where the bird, in a sitting position, pulls loose substrate

17、 closer to its body, constructing a</p><p>　　small ridge of loose substrate. Then, while still in a sitting position, the bird performs vertical wing shakes (VWS) during which small particles are tossed upwa

18、rd into the feathers. Once dirt particles have been collected in the feathers, the bird lies down on its side and performs ‘side-rubs’ or ‘head-rubs’. Side-rubs involve motion of the legs as the bird pushes its body whil

19、e in a lying position. When the dustbathing bird is finished with its bath, it stands and concludes the bout with a ‘r</p><p>　　Like laying hens, broiler chickens probably also have preferences for particula

20、r substrates</p><p>　　in which to dustbathe. If the bedding provided is not of a preferred type, it may further deter them from dustbathing. Young and adult laying strain chickens prefer peat to sand, and sa

21、nd towood-shavings and straw, for dustbathing (Petherick and Duncan, 1989; Sanotra et al., 1995; van Liere, 1991;Vestergaard and Baranyiova, 1996). However, dustbathing preferences of broiler chickens have been examined

22、in only one study. Vestergaard and Sanotra (1999) provided broiler chicks with either sand or s</p><p>　　that will elicit the most dustbathing behavior from a broiler chicken need to be determined.The presen

23、t experiment was performed in order to determine which of four bedding types,wood shavings, rice hulls, masonry grade sand, and a recycled paper-bedding product,would elicit the most dustbathing behavior in commercial st

24、rain broiler chickens. These substrates were chosen either because they are already in widespread use in the US, are available on a commercial scale, or are being considered as a</p><p>　　substrate, and the

25、amount of pre-dustbathing appetitive pecking behavior performed in each substrate.</p><p>　　2. Methods</p><p>　　2.1. Subjects and housing</p><p>　　This study, which was part of a la

26、rger study of the effects of strain differences on gait,</p><p>　　was approved by the University of California, Davis Animal Use and Care Administrative</p><p>　　Advisory Committee. Cobb (N = 52

27、) and Ross (N = 52) day-old male broiler chicks</p><p>　　were obtained from a commercial hatchery. The birds were marked with colored, numbered identification tags. Half of the birds of each strain were plac

28、ed in one floor pen (measuring 3.05m square), and the other half of the birds were placed in an identical adjacent floor pen. Each pen contained wood shavings for bedding and an overhead brooder for heat. There were wind

29、ows along the length of the building that allowed daylight to enter the pens. Overhead fluorescent lights were on continuously for</p><p>　　2.2. Substrate preference tests</p><p>　　Each week, be

30、ginning when the chicks were one wk old and ending when they were 7</p><p>　　weeks old, eight Ross chicks (four focal birds and four pair-mates) were removed from</p><p>　　the two home pens and

31、taken to a different room in the same building to test substrate</p><p>　　preference. No chick was ever used twice. The chicks were placed in pairs into one of four different 1.52m × 1.52m experimental

32、pens (Fig. 1), constructed of wood and chicken wire, for dustbathing substrate choice tests. Chicks remained in these pens for 4 days. The experimental pens had a raised floor so that the corners of the pen floor could b

33、e removed to access square (0.61m×0.61 m) 10 cm deep boxes sunken into the corners. The boxes were each filled to the top with a different substrate, su</p><p>　　the corners containing the different dus

34、tbathing substrates were closed with a wooden lid</p><p>　　and the entire pen floor was covered with lab bench paper. This material kept the chicks</p><p>　　clean and dry while still allowing us

35、 to deprive them of loose bedding material until the</p><p>　　beginning of each test session. Two heat lamps were hung above the center of each pen;</p><p>　　these were raised as the chicks grew

36、 so that the pen was kept at a temperature appropriate</p><p>　　for their age (FASS, 1999). The light cycle in the testing room was the same as that in the</p><p>　　home pen area, but the testin

37、g room did not have windows.</p><p>　　One chick in each pen was designated as the focal chick and marked on the back with a</p><p>　　non-toxic marker. Chicks were tested in pairs to reduce fearf

38、ulness, but data were collected only on the focal bird. The chicks were given approximately 24 h to habituate to the testing environment without access to loose bedding before observations began. Before each test,the fou

39、r different substrates (rice hulls, construction sand, wood shavings, and a recycled paper waste product) were randomly allocated to each corner of the testing pen, but these substrates remained covered until the observ&

40、lt;/p><p>　　then followed by the next three observations for that day so that each pen was observed</p><p>　　as close to peak dustbathing hours (Vestergaard et al., 1990; Hogan and Van Boxel, 1993;

41、</p><p>　　Statkiewicz and Schein, 1980) as possible.We continuously recorded behavioral data from the focal chick using a laptop computer with a custom-designed Microsoft Access program. We divided the pen i

42、nto six different areas to record the location of the focal chick: the pen center, the walkways, and the four different dustbathing areas. The latency to enter and the amount of time spent in each area of the pen were re

43、corded. The number of pecks, scratches, vertical wing shakes (VWS), head rubs, side</p><p>　　the same dustbathing bout.</p><p>　　2.3. Statistical analysis</p><p>　　All analyses were

44、 performed using GLM (Minitab 12 for Windows; SAS v8 for Windows).</p><p>　　The number of VWS per hour in each substrate type, the percent of the total observation</p><p>　　time each focal bird

45、spent in each area (empty, center, or substrate), and the percent</p><p>　　of total visits a bird made to each area were analyzed using repeated measures GLM, with</p><p>　　repeated measures mad

46、e on bird nested within home pen and age at testing. Substrate and</p><p>　　age at testing were the variables of interest in all the analyses except one (latency to enter</p><p>　　each substrate

47、). VWS per hour data were square-root transformed, and the proportion of</p><p>　　the total observation time and proportion of the total visits were angular transformed, to</p><p>　　meet the ass

48、umptions of GLM; the success of the transformations was confirmed post hoc. Significant effects were investigated post-hoc using Tukey-corrected pairwise comparisons.</p><p>　　The family error rate for these

49、 comparisons was set at 0.05.</p><p>　　We also examined several measures of preference using data collected on bout length and</p><p>　　various latencies. These included latency to the first ver

50、tical wing shake a bird performed,</p><p>　　latency to enter the first substrate in the session, latency to enter each different substrate</p><p>　　within the session, and the latency to enter t

51、he first substrate in which a dustbath occurred.</p><p>　　Analyses of the latency data, and data comparing bout lengths in each of the four substrates,were complicated by the fact that not every bird entered

52、 or dustbathed in every substrate, and sometimes birds entered and dustbathed in substrates during more than one testing session.To avoid pseudoreplication, only one dustbath was used for each bird in any one analysis. D

53、ustbaths were selected in a pseudo-random manner, so that the number of dustbaths for each substrate was maximized. This created a </p><p>　　A larger data set was available for the latency to enter each subs

54、trate measure because</p><p>　　most birds entered most of the substrates over the course of their three testing sessions. In</p><p>　　order to achieve a balanced data set, we randomly chose one

55、bird from each home pen at</p><p>　　each age (i.e. 12 birds in total). Because each bird was only tested at one age, the term home pen×age uniquely identified each bird.We therefore performed a repeated

56、 measures GLM by treating the term pen×age as a random factor in a mixed model. The substrate term was then the only factor of interest.For the latency to enter the first substrate in a session, we were unable to cr

57、eate a data set</p><p>　　that was balanced by age at testing by discarding data as in the analysis of latency to enter</p><p>　　each substrate. One substrate was randomly chosen for each bird so

58、 that each substrate was represented by six data points (i.e. six birds), thus creating a data set that was balanced by the substrate term but not by age at testing term. The age at testing term was log transformed to im

59、prove the linearity and error structure of the data, and was then treated as a covariate. In order to determine whether birds were choosing the first substrate entered in order to dustbathe, we assessed whether the</p

60、><p>　　to dustbathe in that substrate. For each substrate we counted the number of occasions on</p><p>　　which a bird entered that substrate first in the session and stayed to dustbathe versus the&

61、lt;/p><p>　　number of occasions on which a bird entered that substrate first in the session and then</p><p>　　moved on to first dustbathe in a different substrate. These data were analyzed using a

62、4×2</p><p>　　chi-square.</p><p>　　The final analysis was performed on ground pecking, and the potential difference in the</p><p>　　performance of this behavior while birds were

63、 in each of the different substrates. The mean</p><p>　　rate of ground pecking during the observation period (i.e. pecks per hour) was calculated.</p><p>　　The proportion of time during the obse

64、rvation period spent pecking was also calculated.</p><p>　　These were analyzed using repeated measures GLM, with bird nested within home pen and</p><p>　　age at testing.</p><p>　　3.

65、 Results</p><p>　　We observed a total of 27 dustbathing bouts. Of these, 20 were performed in sand, 6</p><p>　　in paper, and 1 in wood shavings. No focal bird ever dustbathed in the rice hulls.

66、After</p><p>　　averaging the data for birds that dustbathed in the same substrate for two or three sessions,</p><p>　　there were 21 dustbaths. The mean number of VWS per dustbath was 21.06 ±

67、; 2.44. We</p><p>　　also observed the performance of a single VWS on three separate occasions, once in the</p><p>　　sand, once in the wood shavings, and once in the rice hulls.</p><p&

68、gt;　　The rate of VWS per hour was significantly affected by the substrate in which a bird</p><p>　　dustbathed (repeated measures GLM: F3,36 = 13.52, P < 0005; Fig. 2). Post hoc tests</p><p>　

69、　revealed that the rate of VWS per hour was higher in sand than in any other substrate. There</p><p>　　were no differences in VWS per hour among the remaining three substrates. There was also</p><

70、p>　　a significant difference in the proportion of the total visits made to the different locations</p><p>　　in the pen (repeated measures GLM: F5,60 = 96.47, P < 0.0005; Fig. 3A). Post hoc tests</p&

71、gt;<p>　　showed that the proportion of visits was highest for the empty areas of the pen that birds hadto cross in order to enter another substrate. The center of the pen where the food was located</p><

72、p>　　was visited significantly less than the empty areas of the pen, but significantly more than</p><p>　　any of the dustbathing substrates. The sand was visited significantly more often than the</p>

73、<p>　　paper or the wood shavings. There was also a significant difference in the proportion of the</p><p>　　total time spent in different resources (repeated measures GLM: F5,60 = 5.15, P = 0.001;<

74、/p><p>　　Fig. 3B). Post hoc tests revealed that the birds spent more time in the sand than in the rice</p><p>　　hulls, paper, or wood shavings.</p><p>　　Average latencies to enter the

75、first substrate, perform the first vertical wing shake, and</p><p>　　enter the first substrate in which a full dustbath occurred during a session, were 3.32±1.29,</p><p>　　18 ± 2.62, 1

76、5.22 ± 2.72 min, respectively. There were no significant substrate differences</p><p>　　for these measures. There was, however, a significant difference between the latencies to</p><p>　　en

77、ter each of the four substrates in a testing session (repeated measures GLM: F3,15 = 5.24,</p><p>　　P = 0.0113; Fig. 4). Tukey pairwise comparisons revealed that the latency to enter the sand</p><

78、p>　　was significantly less than the latencies to enter the rice hulls, paper, or wood shavings.</p><p>　　There were no differences in dustbathing bout lengths in the different substrates (GLM:</p>

79、<p>　　F2,15 = 2.37, P = 0.164). The average dustbathing bout length was 14.78 ± 1.9 min.</p><p>　　Chi-square revealed that birds were disproportionately more likely to enter the sand first</p>

80、;<p>　　and stay to dustbathe than they were to enter another substrate first and stay to dustbathe</p><p>　　(chi-square = 16.62, d.f. = 3, P = 0.0017). In 14 out of 27 sessions in which we observed<

81、;/p><p>　　VWS, the first VWS observed occurred in the resource the bird first entered. In 11 out of</p><p>　　14 of these cases the bird first entered and dustbathed in the sand. Thus, the birds sta

82、yed to</p><p>　　dustbathe in 11/12 cases where the sand was first entered; 2/7 cases where the paper was</p><p>　　first entered; 0/7 cases where the rice hulls were first entered; and 1/2 cases

83、where the wood</p><p>　　shavings were first entered.</p><p>　　For rate of pecking, there was a significant difference between the number of pecks</p><p>　　per hour in each substrate

84、 (repeated measures GLM: F3,51 = 24.49, P < 0.0001). TheLSM ± S.E.M. for pecks per hour in sand was 534 ± 2.6. For paper, rice hulls and wood</p><p>　　shavings the rates were 46 ± 2.6, 54 &

85、#177; 2.6, and 76 ± 2.6, respectively. There was also a</p><p>　　significant difference in the proportion of the total observation time spent pecking (repeated</p><p>　　measures GLM: F3,51

86、= 15.28,P < 0.0001; Fig. 5). Tukey pairwise comparisons showed</p><p>　　that there were significantly more pecks in sand than in any of the other substrates and that</p><p>　　therewas signifi

87、cantly more time spent pecking in the sand than in any of the other substrates. There were no general age-related trends in preference or amount of dustbathing for: rate</p><p>　　ofVWS(repeated measures GLM:

88、 F5,12 = 0.78, P = 0.0.585); time spent in each substrate</p><p>　　(repeated measures GLM: F5,12 = 0.74, P = 0.607); proportion of total visits (repeated</p><p>　　measures GLM: F5,12 = 0.75, P =

89、 0.602); latency to dustbathe (GLM: F5,15 = 0.19,</p><p>　　P = 0.958); or bout length (GLM: F5,15 = 3.59, P = 0.063). There were also no changes</p><p>　　in pecking preference with age (F15,51 =

90、 0.72, P = 0.7537), or in pecking in general with</p><p>　　age (F3,51 = 0.91, P = 0.4816). 4. Discussion</p><p>　　Sand was preferred for dustbathing over the other three bedding types tested. Br

91、oiler</p><p>　　chickens performed significantly more VWS per hour in sand, and spent significantly more</p><p>　　time in sand than in the rice hulls, paper, or wood shavings. They entered the sa

92、nd in</p><p>　　significantly less time than the other three substrates and visited the sand significantly more</p><p>　　often than the paper or the wood shavings. Pre-dustbathing behavior (pecki

93、ng) was also</p><p>　　significantly higher in the sand than in the other three substrates.</p><p>　　Although the latency to enter the sand was significantly lower than the latency to enter</p

94、><p>　　any of the other three substrates, there was no difference in the latency to dustbathe once</p><p>　　in a substrate. Further, there was no difference in the latency to enter the first substr

95、ate</p><p>　　in which a dustbath occurred. This suggests that although the sand was more attractive</p><p>　　overall, the broilers did not initially enter it in order to dustbathe. The sand appe

96、ars to have</p><p>　　been initially more interesting for exploring or foraging rather than for dustbathing, and in</p><p>　　fact the chickens seemed to be attracted to the sand because they want

97、ed to ingest it. In</p><p>　　some observations, pecking at the sand lasted for as long as 20 min, and it appeared that</p><p>　　the chickens swallowed many of the particles. Both the rate of pec

98、king and the proportion</p><p>　　of the total time during test periods spent pecking were significantly greater in the sand</p><p>　　than in any of the other substrates. This behavior suggests t

99、hat the motivation to find and</p><p>　　ingest small pebbles such as those found in sand to aid in digestion may still be present</p><p>　　even though broilers do not need grit in order to diges

100、t commercially prepared rations. High</p><p>　　motivation to ingest grit would have important welfare implications, and this topic should</p><p>　　be examined in future studies.</p><p

101、>　　Although it has been proposed that early pecking experience in a substrate might influence</p><p>　　later dustbathing activity in that same substrate, a clear predictive relationship has not been</p

102、><p>　　shown (Vestergaard and Baranyiova, 1996; Nicol et al., 2001). Vestergaard and Baranyiova</p><p>　　(1996) found that chicks pecked significantly more in the substrate they preferred for dustb