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Research Reports |
Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, S-753 23 Uppsala, Sweden
Correspondence: 1 Corresponding author: Helena.Wall{at}huv.slu.se
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SUMMARY |
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 TOP SUMMARY DESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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Key Words: furnished cage • conventional cage • egg quality and production • perch • hygiene • nest • genotype
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DESCRIPTION OF PROBLEM |
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TOPSUMMARYDESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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When new perch arrangements are introduced, it is of great importance that cage hygiene is not impaired. It is important that birds can move over all areas in the cage to efficiently trample manure down through the cage floor [6]. Otherwise, not only bird hygiene but most likely also hygiene of eggs will be impaired. Furthermore, it is essential that perches are perceived attractive to the hens and enable a simultaneous use at night. A high use of perches at night reduces the risk of hens spending the night inside nests, causing poor nest hygiene. With the exception of Sweden, washing of table eggs is not allowed in the European Union [7]. Therefore, producing clean eggs is very important to get as high an economic yield as possible.
The objective of this study was to compare 3 arrangements of perches in furnished cages identical in all other respects. The study, comprising 2 trials on entire production cycles, focused on production, egg quality, hygiene, and use of perches by hens at night. Genotype differences were also considered. Furthermore, a conventional 4-hen cage was included as comparison.
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MATERIALS AND METHODS |
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TOPSUMMARYDESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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). The cage, nest and litter box excluded, measured 96 x 50 cm (width x depth) and was 45 cm high at the rear. A nest box, 27-cm high in the front, 24-cm wide and 50-cm deep, was positioned at one end of the cage. On top of the nest was a litter box. A time-controlled closing mechanism enabled birds to visit the litter box only in the period from 8 h after lights on until 30 min before dark. All cages fulfilled the Swedish Animal Welfare Directives of a minimum of a 600-cm2 cage floor area per hen, with areas of nest and litter box excluded [4].
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In the furnished cages, perches were arranged in 3 ways (Figure 2). One-third of the cages had a perch parallel to the feed trough, providing 12 cm of perch per hen (A). In the second perch arrangement, a transverse perch was added to the perch parallel to the feed trough (B). In the third perch arrangement, the perch parallel to the feed trough was shortened by 10 cm and the transverse perch lengthened correspondingly (C). The perch arrangements with a transverse perch added (cage models B and C) provided 15 cm of perch per hen.
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Trial 2 included 1,160 hens—580 Hy-Line White birds and 580 Hy-Line Brown (HYB) [11] birds. These hens were 17 wk old when transferred to the experimental building. Light was then on for 12 h per day and was successively increased to 16 h at 25 wk of age.
In both trials, light was increased for 6 min at lights-on in the morning to imitate dawn and dimmed for 6 min in the evening—dusk. Manure was removed twice a week with belts, and litter boxes in the furnished cages were filled by hand with sawdust. During rearing, the pullets were fed a conventional grower crumbled diet. At arrival to the experimental building and continuing until slaughter, the birds received a normal layer crumbled diet. In trial 1, the diet had a calculated content of 16.0% CP, 2,700 kcal/kg of ME, 3.6% Ca, and 0.6% P. In trial 2, the calculated content of the diet was 16.1% CP, 2,680 kcal/kg of ME, 3.8% Ca, and 0.6% P. The feed was distributed by automatic chain feeders 4 times a day.
Recording and Statistical Analysis of Data
In trial 1, there were 18 replicates of conventional cages in total, each replicate comprising 9 cages (i.e., 36 birds). In trial 2, the total number of replicates of conventional cages was 10, each replicate comprising 5 cages (i.e., 20 birds). In both trials, the total number of replicates of furnished cages was 24 (i.e., 4 replicates for each combination of furnished cage design and hybrid). Each replicate in the furnished cages consisted of 5 cages (i.e., 40 birds).
Production and mortality were recorded daily per replicate from 20 to 80 wk of age in trial 1 and from 20 to 78 wk of age in trial 2. Hens that died during the study were subjected to autopsy and were not replaced. There were no egg collection belts in the egg cradles, and eggs were collected manually. Egg weight was recorded weekly. A small version of a commercial egg-candling machine was used to detect cracked and dirty eggs. All eggs collected during 5 consecutive days were candled on 5 occasions in trial 1 (at 22, 32, 45, 57, and 77 wk of age) and on 6 occasions in trial 2 (at 24, 35, 51, 56, 64, and 73 wk of age).
Scoring of hygiene of plumage and foot was carried out at 55 wk of age in trial 1 and at 39 wk of age in trial 2. The scoring system assigned 1 to 4 points for each character, in which a higher score indicated a better condition [12]. Scoring was performed on all birds in 2 furnished cages per replicate (trial 1 and trial 2) and in all birds in 3 (trial 1) or 2 (trial 2) conventional cages per replicate.
At the end of trial 1, when birds had been removed from the cages, scoring of hygiene of nests and cage floors was conducted in all cages. The scoring comprised 1 to 4 points, in which a higher score indicated a cleaner condition.
The location of all birds in the furnished cages was recorded 1 h after lights-out on 3 occasions (at 21, 41, and 76 wk of age) in trial 1 and once (at 75 wk of age) in trial 2. The position of all eggs in the furnished cages before egg collection was recorded on 4 occasions in trial 1 (at 21, 33, 46, and 56 wk of age) and on 6 occasions in trial 2 (at 23, 35, 51, 56, 65, and 74 wk of age).
Before statistical analysis, traits given in proportions (mortality, cracked eggs, dirty eggs, egg position, and bird location) were subjected to arcsine transformation [13]. Statistical analyses were performed using the GLM procedure of SAS software [14]. To analyze individual differences among treatments, Fisher’s protected least-significant difference test was used. In the statistical models hybrid, cage design and battery tier were considered fixed. Two-way interactions between fixed effects were included in all analyses.
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RESULTS AND DISCUSSION |
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TOPSUMMARYDESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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), whereas in trial 2, there was a tendency (P 
0.09) of mortality being higher in the conventional cage model as compared with the furnished models (Table 2). This fairly high mortality in the conventional cages was mainly due to problems with cannibalism in a limited number of cages. In the present study, the group size can be considered as small in the furnished cages. If furnished cages for larger groups of hens had been used, it is possible that the mortality rate would have been different [15]. In trial 2, there was an interaction between battery tier and hybrid (not in table). The interaction occurred because the mortality of HYB hens was higher in the top battery tier than in the other tiers.
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0.07) of egg weight being higher in the conventional cages than in the furnished cages (Table 2
). However, cage model did not affect laying percentage or egg mass produced per hen housed, either in trial 1 or in trial 2, which agrees with earlier studies on furnished cages very similar to the ones presently used [16]. Although not significantly different in trial 2, egg production per hen housed was variable among treatments, perhaps due to the rather high mortality in some of the conventional cages.
In trial 1 (Table 1), there were differences in production between the hybrids LSL and LB. Compared with LSL, LB hens had a lower laying percentage but higher egg weight and higher egg mass production per hen housed. A higher weight of eggs from LB hens compared with LSL has been found in several other studies [17, 18]. Genotype differences in production capacity are a common finding and not surprising [19, 20]. In trial 1, an interaction between hybrid and battery tier was found (not in table). This interaction occurred because the weight of eggs from LB hens was lower in the top battery tier compared with the other tiers, whereas battery tier did not affect the weight of eggs from LSL. In trial 2, there were no differences in production between the genotypes Hy-Line White and Hy-Line Brown.
Laying percentage was higher in the top battery tier than in the middle in trial 1, and in trial 2, there was a tendency of lower laying percentages in the bottom tier. These differences are difficult to explain but may have been caused by differences in lighting in the battery tiers. However, no effect of tier was found for the other production traits.
Exterior Egg Quality and Hygiene
Perch arrangement in the furnished cages had no effect on proportions of cracked eggs. In trial 1 (Table 1), the proportion of cracked eggs was lower in the conventional cage than in the furnished cage models, whereas there was no difference in trial 2 (Table 2). Higher proportions of cracked eggs in furnished cages compared with conventional cages have been reported in several earlier studies [16, 21, 22]. However, the furnished cages used in the present trials have developed in this respect, showing that it is possible to achieve similar results in furnished and conventional cages. In conventional cages, eggs rolling out from the cage are spread over the whole cage width, whereas in furnished cages, there is an accumulation of eggs in the cradle in front of the nest, especially when the nest is narrow and most eggs are laid in there. Furthermore, when the nest is deep, an egg laid in the rear of the nest accelerates on its way out of the nest and rolls with a rather high speed into the egg cradle. If it rolls into other eggs already positioned in the cradle, there is a considerable risk that the shells of some eggs will crack. Devices stopping eggs or reducing the speed of them on their way out of the nest have proven to be very efficient in reducing the proportion of cracked eggs in this concept of furnished cages [16]. The nest curtain hanging in the front of nests in the furnished cages used in the present trials is an example of an efficient egg-saving device [16].
The difference regarding cracked eggs found between the furnished and conventional cages in trial 1 and between genotypes in both trials may be related to the behavior of the genotypes. For example, a hen preferring to stay close to the egg cradle or in the rear of the nest when laying its egg may have affected incidence of cracked eggs. Possible genotype differences (e.g., in egg weight, egg shape index, or in other eggshell characteristics) may also affect proportions of cracked eggs [22].
In general, hygiene of the feet and plumage of birds was inferior in the furnished cages as compared with the conventional cage, which agrees with an earlier study [21]. Interactions between hybrid and cage model in plumage hygiene were found in both trials. These occurred because differences in plumage hygiene between the cage models (conventional vs. furnished cages) were larger in the white genotypes than in the brown. However, most likely these interactions as well as the superior hygiene of the plumage of brown birds, found in both trials, occurred because dirt is easier to detect on white feathers than on brown.
Cage floor hygiene (measured only in trial 1) was better in the conventional cages than in the furnished, but no difference in dirty eggs was found between the cage models. In both trials, the brown hybrids had lower percentages of dirty eggs than the white ones, which is a common finding [16]. The grading of cage hygiene in trial 1 showed that LSL hens had dirtier nest linings and a tendency to have dirtier cage floors than LB hens. The inferior nest hygiene may have contributed to the higher levels of dirty eggs produced by LSL, but likely, eggshell color influenced the result, because dirty spots are easier to detect on white egg shells than on brown.
Hygiene of nests and cage floors was better in the top tiers than in the middle and bottom tiers (trial 1; Table 1). It is possible that birds in the top tiers were more active, because they received more light than birds in cages below and kept the cage floor clean by increased movement. The superior hygiene of nests in top tiers is surprising, because those nests were occupied by hens resting in them at night to the same extent as nests in the other tiers. However, no effect of tier was found in proportions of dirty eggs.
Use of Facilities
There was a significant effect of perch arrangement on the use of perches by birds in trial 2 (Table 2) and a tendency (P 0.07) of effect in trial 1 (Table 1). Interestingly, in both trials, simultaneous use at night was lower with perch C than with the other 2 arrangements. Thus, although perch A provided only 12 cm of perch per hen, which means 3 cm less space per hen than with perch B or C, use was as high as with perch B and higher than with perch C. In the present trials, both perch arrangements providing 15 cm per hen were constructed by 2 perches forming a cross. Only 1 hen could sit where the perches crossed each other, and this hen then occupied a considerable perch length. This may explain why perch use was not higher in the 15-cm perch arrangements than with the perch providing only 12 cm per hen. Hence, the way perches are arranged in the cage may be as important as perch length itself to achieve a high use of perches at night.
Several studies have shown that hens are motivated to rest on perches at night [23, 24], and in housing conditions in which perching is not possible, hens may experience reduced welfare [23]. In the present study, we do not know the reason why some hens did not rest on the perches at night, and, in fact, it is possible that they preferred to spend the night on the cage floor or in the nest. However, if all hens in a cage are motivated to rest on perches at night, it is important from a bird welfare point of view that there is enough room to allow simultaneous use.
The risk of hens defecating in the nests due to spending the night in there may be lower with a high use of perches. In the present trials, averages of 83.5 and 85.7% of the birds rested on the perches at night, which agrees well with earlier experiences in research [16, 22] and in practice [25]. Although perches were used to a fairly high extent after dark, it is possible that an even higher use can be achieved with alternative perch arrangements if the cross formation can be avoided. However, in the present concept of a furnished cage with the litter box located on top of the nest, it is important that the perch is not located too far away from the litter box, because birds make use of the perch when entering the litter box. If the litter box is perceived as difficult to enter, hens may not use it [26].
Genotype differences in the use of perches after dark were found in both trials. In trial 1, use was higher for LSL compared with LB, and in trial 2, HYB hens tended to use perches to a higher extent than Hy-Line White hens. Hens not resting on perches spent the night either on the cage floor or in the nest. Interestingly, in both trials, the proportions of hens spending the night in nest were higher for the white genotype than for the brown. Likely, the unintended use of nests at night caused the inferior hygiene of nest linings in cages with LSL hens (measured only in trial 1). In the present trials, the proportions of hens spending the night in nests were high, especially in the white genotypes. In other studies, conducted in similar cages with either a higher [21] or a lower [16] use of perches than in the present trials, proportions of hens staying in nests overight were lower.
On average, 95.5 and 96.0% of all eggs were laid in nests in trial 1 and 2, respectively. This indicates a high acceptance of nests, which agrees with other studies on furnished cages with well-designed nests [27, 28]. Due to the time-controlled closing of the litter boxes, no eggs were laid in the litter boxes.
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CONCLUSIONS AND APPLICATIONS |
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TOPSUMMARYDESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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ACKNOWLEDGMENTS |
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REFERENCES AND NOTES |
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TOPSUMMARYDESCRIPTION OF PROBLEMMATERIALS AND METHODSRESULTS AND DISCUSSIONCONCLUSIONS AND APPLICATIONSREFERENCES AND NOTES |
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of the Swedish Animal Welfare Ordinance and according to the New-Technique Evaluation Program at the Swedish Board of Agriculture (English tables, figures and summary). Report 251. Swedish Univ. Agric. Sci., Dept. Anim. Nutr. Manage. Uppsala, Sweden.This article has been cited by other articles:
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  H. Wall, R. Tauson, and S. Sorgjerd Bacterial Contamination of Eggshells in Furnished and Conventional Cages J. Appl. Poult. Res., January 1, 2008; 17(1): 11 - 16. [Abstract] [Full Text] [PDF]
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