Effects of fiber supply in furnished cages on performance, egg quality, and feather cover in 2 egg-laying hybrids 1

2013 Poultry Science Association, Inc. Effects of fiber supply in furnished cages on performance, egg quality, and feather cover in 2 egg-laying hybrids 1 R. Kalmendal, 2 F. Johansson, and H. Wall Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Uppsala, Sweden Primary Audience: Nutritionists, Researchers DESCRIPTION OF PROBLEM SUMMARY Poultry may obtain fiber from the feed or from the ingestion of, e.g., fibrous litter materials. In earlier studies, it was shown that insoluble fiber may stimulate digestion and exert a calming effect on laying hens. Fiber may also influence the metabolism of minerals and fat, which might affect egg quality. In this paper, we describe the effects of 2 means of fiber supply on production performance, feather cover, and egg quality in Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) hens housed in furnished cages between 20 and 60 wk of age. Insoluble fiber was supplied by either including 3% ground straw pellets in the feed or by substituting the saw dust in the litter bath with crumbled straw pellets. Overall, hens were frequently pecking the litter, but litter bath occupation, litter pecking, and litter intake was higher in LB than in LSL. In LB, more crumbled straw pellets were consumed from the litter bath compared with saw dust. Compared with the control, adding straw pellets to the feed reduced egg shell thickness in LB but not in LSL. Otherwise, treatments had no significant effects on production performance, egg quality, or feather cover. Therefore, litter may constitute a significant source of insoluble fiber to laying hens, but notable hybrid differences in the interaction with litter were observed. Key words: layer, insoluble fiber, production performance, egg quality, feather cover 2013 J. Appl. Poult. Res. 22 :109 117 http://dx.doi.org/10.3382/japr.2012-00641 Recently, there has been an increased understanding of the significance of the fiber fraction in poultry feeds. The fraction of insoluble fiber in vegetable materials is particularly abundant in lignified materials, such as hulls and straw. Similarly, insoluble fiber characterizes materials derived from wood processing. In poultry nutrition, the roles of fiber are many and diverse. It was shown that feeds supplemented with ingredients rich in insoluble fiber may improve the performance of broilers and nutrient utilization in layers [1 3], and there are indications that such diets may decrease feather pecking [4] and cannibalism in layers [5]. Further, ingested fiber is also known to influence the metabolism of fat [6] and minerals [7, 8], and this may hypotheti- 1 Preliminary data were partially presented at the 18th European Symposium on Poultry Nutrition, Cesme, Turkey, October 31 to November 4, 2011. 2 Corresponding author: robin.kalmendal@slu.se

110 JAPR: Research Report cally affect both interior and exterior egg quality. Because fibrous fractions are typically low in nutritional value, their inclusion in the diet necessitates an increase of nutrient concentration from other feed ingredients. In other words, the use of fiber-rich ingredients may impose limitations on feed formulators. This raises the question of whether the response to fiber can be generated by fiber intake from sources other than the feed. Layers housed in furnished cages have access to litter baths intended for dust bathing and scratching. Although feed is typically used as litter substrate in many countries, fibrous by-products from the wood industry are often used in Scandinavia. Layers are frequently seen pecking the litter, and it was shown that layers housed in furnished cages voluntarily ingest wood shavings or paper presented as litter [9]. In parallel, layers housed in floor systems are also known to consume litter substrates [10], but the propensity to ingest litter appears to differ between hybrids [11]. Where litter substrates such as saw dust, wood shavings, and straw products are used, the litter may consequently constitute a source of insoluble fiber. However, there is limited information on the quantity consumed by different hybrids, and whether the ingestion of litter from the litter bath in furnished cages may replace a supplementation of insoluble fiber in the diet. This experiment was conducted to study production performance, egg quality, feather cover, and interactions with the litter substrate in 2 non-beak-trimmed layer hybrids given either saw dust or crumbled straw pellets as substrate in the litter bath of furnished cages. A comparison was made with the use of ground straw pellets as a fiber supplementation of the diet. MATERIALS AND METHODS Husbandry Practices The study involved an adaptation phase from 16 to 20 wk of age, followed by an experimental period from 20 to 60 wk of age. A total of 720 Lohmann Selected Leghorn (LSL) and 720 Lohmann Brown (LB), vaccinated against infectious bronchitis, Marek s disease, and avian encephalomyelitis, were purchased from a commercial pullet breeder [12] at 16 wk of age. No beak-trimming was performed. The pullets were allotted to groups of 8 and housed in furnished cages, equipped with a perch, nest, and litter bath [13]. A commercial pre-lay feeding program was used from 16 to 20 wk of age, common to all hens. Feed was provided ad libitum in a trough in front of the cage and feed chains were run thrice daily. Each cage was supplied with water via 2 nipples. Artificial lights were on from 0700 to 1600 h at 16 wk of age, and the hours of light were gradually increased to 0200 to 1600 h at 23 wk of age. Between 16 and 20 wk of age, all litter baths were open daily between 1100 and 1500 h and filled with saw dust. At 20 wk of age, all litter baths were emptied and refilled (300 g) with either of 2 litter substrates, according to the experimental design (see next subsection). From 20 wk of age and onward, the litter baths were opened daily between 1000 and 1500 h and refilled (60 g) thrice weekly. The study was approved by the Swedish Ethical Committee for Scientific Experiments. Experimental Design Between 20 and 60 wk of age, both hybrids were randomly assigned to one of 3 treatments. This implied a total of 6 experimental combinations, and if not stated otherwise, 3 replicates (10 cages with 8 birds in each) per combination. A pelleted and crumbled basal diet was formulated based on wheat and soybean meal, and used in 2 treatments with either saw dust or crumbled straw pellets used as litter substrates. The third treatment represented a dietary supplementation with insoluble fiber, wherein the pelleted straw product was added to the basal diet. Here, saw dust was used as litter substrate. Thus, treatments were 1) basal diet and sawdust in the litter bath (CON), 2) basal diet and crumbled straw pellets in the litter bath (LIT) and 3) basal diet supplemented with 3% ground straw pellets on the expense of wheat, and sawdust in the litter bath (FED). Grinding of the straw product in FED was made to facilitate pelleting of the feed, but apart from the particle size, the straw product used [14] was identical in LIT and FED. Diets were formulated to be iso-energetic and isonitrogenous; therefore, the inclusion of straw

Kalmendal et al.: FIBER SUPPLY IN FURNISHED CAGE 111 pellets at the expense of wheat (FED) necessitated an increase in soybean meal and a mixture of fatty acids. Both diets were formulated with adequate amounts of xylanase, β-glucanase, and phytase, included in the premix. Mean compositions and laboratory analyses of 4 batches of the feeds are given in Table 1. Data Acquisition Table 1. Feed ingredients and nutritional compositions Item CON/LIT 1 FED 1 Ingredient Wheat 68.8 62.4 Soybean meal 16.9 18.5 Fatty acid mixture 2.7 4.6 Straw pellets 2 0.0 3.0 Calcium carbonate 9.9 9.8 Monocalcium phosphate 0.5 0.5 Salt 0.4 0.4 Premix 0.9 0.9 Analyzed nutrient (g/kg) DM 886.0 885.0 Starch 420.0 396.0 CP 181.0 184.0 Ash 131.0 123.0 EE 46.0 60.0 CF 26.0 32.0 Klason lignin 3 0.9 1.4 Insoluble fiber 3 76.5 78.8 Soluble fiber 3 12.3 14.1 Calcium 40.8 37.5 Phosphorus (total) 4.7 4.7 Methionine 4.1 4.0 Cystine 3.6 3.6 Threonine 6.4 6.4 Lysine 8.7 8.6 1 CON = basal diet, sawdust as litter bath substrate; FED = basal diet with 3% straw pellets, sawdust as litter bath substrate; LIT = basal diet, crumbled straw pellets as litter bath substrate. 2 Analyses (g/kg) of straw pellets: 937.5 DM, 7.5 starch, 25.5 CP, 41.3 ash, 11.9 EE, 389.6 CF, 148.4 Klason lignin, 592.4 insoluble fiber, 0.0 soluble fiber, 4.3 calcium, 0.9 phosphorus (total), 0.4 methionine, 0.4 cystine, 1.1 threonine, 1.0 lysine. 3 Measured in single, representative samples of feeds, as described in [15]. Feeds were analyzed for DM, starch, CP, ash, EE, CF, soluble and insoluble fiber (nonstarch polysaccharides), minerals, and the amino acids methionine, cystine, threonine, and lysine [15]. Mortality and rate of lay were registered daily, and egg weight was recorded in all eggs collected during one day each week. Feed intake and FCR were calculated on a 4-wk basis. All production figures were summed over the 40 wk experimental period and are presented as means for the entire period in the results. Fresh feces samples were collected and analyzed for DM at 20, 30, and 50 wk of age. At 20, 30, 40, 50, and 60 wk of age, the numbers of cracked and dirty eggs, i.e., eggs contaminated by feces or blood, were registered both visually in the stable and with aid of an experimental candling machine. In total, between 160 and 240 eggs per replicate were assessed at each occasion, depending on the rate of lay. At 30 and 50 wk of age, 10 eggs per replicate were collected for determination of shell breaking strength using the Canadian Egg Shell Tester [16], shell thickness, and shell weight. Feather cover was recorded at 40 and 60 wk of age using an integument condition scoring protocol in which 6 body parts are scored from 1 (denuded) to 4 (intact plumage) points [17]. The sums of these scores (6 to 24 points) are presented in the results. This protocol also includes BW and a scoring (1 to 4 points) of pecking wounds on the comb and in the vent, plumage cleanliness, foot cleanliness, foot lesions, and bumble foot condition, where 1 is the worst and 4 is the best condition. Bumble foot was defined as a prominent inflammation of the foot pad sole and foot lesions included any physical damage following, e.g., wear or dermatitis. The mean scores of all hens in 2 cages represented the statistical unit and 3 pairs of cages, i.e., replicates, per hybrid and treatment were assessed. The same cages were used at both scoring occasions. Litter bath utilization was studied at 20, 30, 37, and 49 wk of age. Fifteen and forty-five min after the opening of the litter baths, an observer walked slowly along the cage row and registered the number of birds inside the litter bath and the number of birds pecking in the litter from outside the baths, i.e., standing either on the cage floor or on the perch. For the 2 records per observation week, the mean percentage of hens per cage inside the litter bath, or pecking in the litter bath, was calculated. Actual litter intake was recorded during one week (45 wk of age) by disconnecting the opening mechanism of the litter bath in a total of 120 cages. Here, each cage was considered the

112 JAPR: Research Report statistical unit, allowing for 20 replications per hybrid and treatment. The birds could still peck and ingest the litter but not remove it by e.g., dust bathing or scratching. The litter baths were first emptied and renewed (300 g) with either saw dust or straw pellets, according to the experimental design. The litter was refilled (60 g) twice during the week, after which the remainder was weighed and the mean daily litter intake per hen calculated. As supporting evidence that the litter material was consumed during this period, the frequency of all pecks in the litter bath was recorded in the morning (5 min) and in the afternoon (5 min) in one day during the week in which the litter baths were closed. A peck was defined as the placement of any hen s beak into the litter bath and considered terminated when the beak was lifted up from the litter bath again. Pecks were counted per hen, so 2 or 3 hens simultaneously pecking the litter bath could contribute to the pecking frequency independently. The registration was repeated 1 wk following the reopening of the litter baths (46 wk of age), to ensure that the pecking activity was not due to the exclusion from it. In addition, the manure belts were scrutinized to confirm that the litter was not moved out of the litter baths. Statistical Analyses All statistical analyses were performed with SAS 9.3 [18], and the choice of procedure employed depended on the nature of data. Mortality, production performance, and litter intake were analyzed with ANOVA. The frequency of pecks in the closed (45 wk of age) and reopened (46 wk of age) litter bath was analyzed with the GLIMMIX procedure, using a log-link and Poisson distribution. Figures were back-transformed using the ILINK option before presentation. The repeated measurements of fecal DM, egg shell quality, proportion of cracked and dirty eggs, integument condition, and litter bath utilization were analyzed in the MIXED procedure. Figures of mortality, litter bath utilization, and cracked or dirty eggs were arcsin transformed before analysis [19], but when figures are shown, they are untransformed. For spatial reasons, not all interactions are presented in tables. Differences were considered statistically significant at P < 0.05. RESULTS AND DISCUSSION Litter Bath Utilization The number of hens visiting the litter bath increased with age (P < 0.01), and over the entire period, LB were more frequently registered in the litter bath (P < 0.01) than LSL (data not shown). There was a tendentious effect of treatment (P = 0.06), and the proportions of hens registered in the litter bath were in falling order CON > FED > LIT. Thus, crumbled straw pellets (LIT) appeared to be less favored as litter substrate than saw dust (CON, FED). Higher proportions of LB were seen pecking the litter bath compared with LSL (P < 0.01), and the proportion of hens pecking the litter increased with age (P < 0.01), but more so in LB (P < 0.05) than in LSL (data not shown). Litter Intake When measured at 45 wk of age, LB consumed more litter (3.3 g/hen-day) than LSL (1.3 g/hen-day) from the litter bath (P < 0.01), see Table 2. This agrees with the aforementioned observed differences between LB and LSL in litter bath utilization. Earlier estimations of wood shavings consumption from the litter bath in LSL hens range between 4 and 11 g/hen and day [9]. The underlying discrepancy between the latter study and the present may relate to the accessibility of the litter bath. From Table 2, it is evident that the exclusion from the litter bath had a hampering effect on the pecking frequency in the litter. On the other hand, this procedure guaranteed that the litter removed was actually ingested, and not removed by scratching and dust bathing. This was also confirmed by the absence of litter on the manure belts. In the present trial, LB consumed more substrate from litter baths containing crumbled straw pellets (LIT) than saw dust (CON, FED). As seen in Table 2, LSL showed no differences in consumption of the 2 litter materials, but decreased their pecking frequency when crumbled straw pellets were provided. This likely relates to the fact that more litter can be grasped per peck when in the form of crumbled pellets compared with dust. Why LB fed the fiber-enriched diet (FED) pecked more in the litter bath than when fed the control

Kalmendal et al.: FIBER SUPPLY IN FURNISHED CAGE 113 Table 2. Main effects of hybrid and treatment, and their interactions, on litter intake and the total number of pecks in the litter bath per cage during 2 observation sessions at wk 45 (closed litter bath) and 46 wk of age (reopened litter bath) 1 Item 2 Litter intake (g/hen and d) No. pecks per cage, closed litter bath No. pecks per cage, reopened litter bath Hybrid (H) LB 3.3 a 11.6 a 12.8 a LSL 1.3 b 4.5 b 7.0 b Treatment (T) CON 2.1 b 8.1 a 10.2 b FED 2.0 b 8.7 a 12.7 a LIT 2.6 a 5.4 b 6.4 c Interactions (H T) LB CON 2.8 b 8.4 b 9.3 d FED 2.9 b 13.8 a 16.8 a LIT 4.1 a 13.6 a 13.4 b LSL CON 1.4 c 7.8 b 11.3 bc FED 1.2 c 5.5 c 9.7 cd LIT 1.2 c 2.2 d 3.1 e SEM 0.10 0.28 0.31 P-value Hybrid (H) <0.0001 <0.0001 <0.0001 Treatment (T) 0.0207 <0.0001 <0.0001 H T 0.0043 <0.0001 <0.0001 a e In columns, values within the sections hybrid, or treatment, or their interactions not sharing common superscripts are significantly different at P < 0.05. 1 Values are least squares means. 2 CON = basal diet, sawdust as litter bath substrate; FED = basal diet with 3% straw pellets, sawdust as litter bath substrate; LB = Lohmann Brown; LIT = basal diet, crumbled straw pellets as litter bath substrate; LSL = Lohmann Selected Leghorn. diet (CON), whereas the opposite trend was seen in LSL, remains obscure. Production Performance Production performance and mortality figures from 20 to 60 wk of age are presented in Table 3. Similar to a previous study [9], fiber supplementation to the diet had no significant effects on production performance. In the current trial, however, it should be noted that the inclusion of straw pellets in the feed (FED) implied a very modest increase in the amount of insoluble fiber. In fact, calculations of the total daily intake of insoluble fiber from both feed and litter (in our laboratory, saw dust contained an insoluble fiber content of 581 g/kg) showed that the highest insoluble fiber intake was found in LB given straw pellets in the litter bath. In Table 3, it is therefore interesting to note that treatments tended (P = 0.05) to affect egg weight, and that the largest difference (+1 g) was seen in LB assigned to LIT compared with CON. Others have found that consumption of wood shavings improved the digestibility of starch [2] and feed AME [9]. As expected, feed intake, egg weight, and egg mass were higher in LB, and rate of lay was higher in LSL. Such differences between the lines have been reported previously [10, 20, 21]. In the present trial, the FCR was equal in the 2 hybrids, and not affected by treatments. Mortality was on average 2.9%, and not different between hybrids or treatments. Egg Quality Effects of hybrid and treatment, and their interactions, and age on egg quality are presented in Table 4. Shell breaking strength decreased from 30 to 50 wk of age (P < 0.01). The shell breaking strength was higher in LB than in LSL (P < 0.05) and tended to be affected by treatment (P = 0.08). Numbers were in falling order

114 JAPR: Research Report Table 3. Main effects of hybrid and treatment, and their interactions, on production performance (per hen and day) and mortality from 20 to 60 wk of age 1 Item 2 Feed intake (g/d) Lay Egg weight (g) Egg mass (g/d) FCR (g/g) Mortality Hybrid (H) LB 111.5 a 92.8 b 65.0 a 60.4 a 1.85 3.3 LSL 108.9 b 94.2 a 62.3 b 58.7 b 1.85 2.5 Treatment (T) CON 110.3 93.8 63.6 59.7 1.85 3.3 FED 110.4 93.6 63.4 59.4 1.86 2.7 LIT 109.9 93.1 64.0 59.5 1.85 2.7 Interaction (H T) LB CON 112.1 93.2 64.8 60.5 1.85 4.6 FED 110.9 92.7 64.5 59.8 1.85 2.5 LIT 111.5 92.4 65.8 60.8 1.83 2.9 LSL CON 108.5 94.3 62.4 58.9 1.84 2.1 FED 109.8 94.5 62.3 58.9 1.86 2.9 LIT 108.2 93.8 62.1 58.3 1.86 2.5 SEM 0.31 0.25 0.11 0.18 0.01 0.33 P-value Hybrid (H) 0.0012 0.0138 <0.0001 0.0006 0.5281 0.1786 Treatment (T) 0.7717 0.5286 0.1747 0.7813 0.5649 0.7909 H T 0.2798 0.8511 0.0532 0.2760 0.5106 0.2279 a,b In columns, values within the sections hybrid, or treatment, or their interactions not sharing common superscripts are significantly different at P < 0.05. 1 Values are least squares means. 2 CON = basal diet, sawdust as litter bath substrate; FED = basal diet with 3% straw pellets, sawdust as litter bath substrate; LB = Lohmann Brown; LIT = basal diet, crumbled straw pellets as litter bath substrate; LSL = Lohmann Selected Leghorn. CON > LIT > FED. A significant interaction between treatment and age (interactions involving age not shown in Table 4) revealed that hens assigned to LIT laid eggs with the lowest shell breaking strength at 30 wk, but then highest at 50 wk of age. The underlying causes of this finding remain unclear. Further, shell breaking strength was higher in CON than in LIT at 30 wk of age (P < 0.01), and because these hens were fed the same basal diet, the observed difference was related to ingestion of the litter material. Egg shell thickness was higher in LB than in LSL (P < 0.05) and decreased with age (P < 0.01). On average for both hybrids, treatments failed to influence egg shell thickness but in LB it was lower in FED compared with CON and LIT. The proportional weight of egg shells decreased with time (P < 0.01) but was unaffected by hybrid. Treatments tended to affect the proportional weight of egg shells (P = 0.07), and similarly to shell breaking strength, figures were in falling order CON > LIT > FED. It has been shown that certain fractions of fiber exhibit a binding capacity to cations in the intestines, making them inaccessible to the bird [8]. In view of this notion, we suggest that interactions between hybrid, fibrous litter intake, and egg shell quality may warrant further investigations. The proportion of eggs contaminated by feces or blood increased on average with age, but were unaffected by hybrid and treatment. This proportion was higher in LB than in LSL at 20 wk of age (8.2% vs. 3.5%), but then lower in LB than in LSL at 50 wk of age (11.0% vs. 14.0%), data not shown in Table 4. Although these data do not discriminate between eggs contaminated by feces or blood, 2 reasons for these findings can be suggested. First, at 20 wk of age, LB laid significantly heavier eggs (51.5 g) compared with LSL (49.2 g), whereby the risk of small bleedings occurring at egg position would be greater (only data for the whole production period are shown in Table 3). Second, at 50 wk of age, the DM of feces was lower (P < 0.01) in LSL (20.9%) than in LB (23.9%), which might have increased the incidence of fecal contamination of the egg

Kalmendal et al.: FIBER SUPPLY IN FURNISHED CAGE 115 Table 4. Main effects of hybrid and treatment, and their interaction, on breaking strength, thickness, and proportional weight of egg shells at 30 and 50 wk of age, and the summed proportions of dirty and cracked eggs every 10 wk during the whole experimental period 1 Item 2 Shell strength (g) Shell thickness (0.01 mm) Shell weight Dirty eggs Cracked eggs Hybrid (H) LB 4,447 a 33.5 a 9.5 7.7 2.0 LSL 4,287 b 32.8 b 9.4 8.7 1.6 Treatment (T) CON 4,470 33.4 9.5 8.1 1.6 FED 4,293 32.8 9.4 8.1 1.8 LIT 4,338 33.3 9.5 8.3 1.8 Age (A) 20 wk 5.9 de 1.2 c 30 wk 4,737 a 34.3 a 9.8 a 4.6 d 1.2 cd 40 wk 7.7 c 2.0 ab 50 wk 3,997 b 32.0 b 9.1 b 12.5 a 1.8 bd 60 wk 10.2 b 2.6 a Interaction (H T) LB CON 4,619 33.9 ac 9.6 8.0 1.7 FED 4,272 32.6 b 9.3 7.8 2.0 LIT 4,449 34.1 a 9.5 7.2 2.2 LSL CON 4,321 32.9 b 9.4 8.3 1.6 FED 4,315 33.0 bc 9.4 8.4 1.7 LIT 4,226 32.6 b 9.4 9.3 1.4 SEM 1 29.73 0.134 0.028 0.293 0.103 P-values Hybrid (H) 0.0199 0.0221 0.655 0.1053 0.0764 Treatment (T) 0.0769 0.194 0.0678 0.9580 0.7737 Age (A) <0.0001 <0.0001 <0.0001 <0.0001 0.0004 H T 0.0880 0.0279 0.0583 0.4462 0.2707 H A 0.0649 0.629 0.716 <0.0001 0.0718 T A 0.0439 0.244 0.106 0.9140 0.7137 a e In columns, values within the sections hybrid, treatment, or their interactions not sharing common superscripts are significantly different at P < 0.05. 1 Interactions including age are omitted for spatial reasons. Values are least squares means. 2 CON = basal diet, sawdust as litter bath substrate; FED = basal diet with 3% straw pellets, sawdust as litter bath substrate; LB = Lohmann Brown; LIT = basal diet, crumbled straw pellets as litter bath substrate; LSL = Lohmann Selected Leghorn. shells. On average, fecal DM was higher in LB (25.7%) than in LSL (23.4%), but was unaffected by treatment. Further data on fecal DM are not shown. The proportion of cracked eggs increased with time (P < 0.01), but equally so in both hybrids. No main effect of treatments on the proportion of cracked eggs was observed between LB (2.0%) and LSL (1.6%). Wall and Tauson [21] reported differences in eggs laid in or out of the nest, which would increase the risk of shell damage resulting from bird activity in the cage. The egg shell quality measures discussed previously support this hypothesis; eggs from LB had significantly higher shell strength and thickness than eggs from LSL (Table 4). Integument Condition The LB hens were heavier than LSL and both hybrids increased their BW from 40 to 60 wk of age, but the increase was more prominent in LSL (+6.7%) than in LB (+1.6%), as indicated by a significant interaction between hybrid and age (Table 5). Scores of feather cover were equally good in both hybrids and decreased moderately from 40 to 60 wk. Treatments had no effect on BW, feather cover, or other integument scores. A previous study showed no effect of providing wood shavings in the litter bath on feather cover [9]. Others have found that dietary supplementation with insoluble fiber reduced feather pecking

116 JAPR: Research Report Table 5. Main effects of hybrid, treatment, age, and the interaction between hybrid and age on BW and integument scores at 40 and 60 wk of age 1 Item 2 Weight (kg) Feather cover Pecking wounds Comb Vent Plumage cleanliness Foot lesions Bumble foot Foot cleanliness Hybrid LB 2.095 a 19.9 3.8 a 4.0 3.9 a 3.4 4.0 a 3.6 a LSL 1.830 b 20.4 3.5 b 4.0 2.5 b 3.3 3.8 b 3.4 b Treatment CON 1.981 20.3 3.7 4.0 3.3 3.4 3.9 3.5 FED 1.916 20.2 3.6 4.0 3.2 3.3 3.8 3.5 LIT 1.991 20.0 3.7 4.0 3.2 3.4 3.9 3.5 Age 40 wk 1.925 b 22.2 a 3.7 4.0 3.3 a 3.2 b 3.8 b 3.8 a 60 wk 2.000 a 18.1 b 3.6 4.0 3.2 b 3.5 a 3.9 a 3.2 b Interaction (H A) LB 40 wk 2.079 b 22.0 3.8 a 4.0 4.0 3.2 3.9 3.8 a 60 wk 2.112 a 17.9 3.8 ab 4.0 3.9 3.5 4.0 3.4 b LSL 40 wk 1.771 d 22.5 3.6 b 4.0 2.6 3.1 3.7 3.7 a 60 wk 1.889 c 18.4 3.4 c 4.0 2.5 3.6 3.9 3.1 c SEM 1 0.0187 0.15 0.03 0.01 0.05 0.06 0.02 0.03 P-value Hybrid (H) <0.0001 0.1121 <0.0001 0.6385 <0.0001 0.8789 0.0003 0.0014 Treatment (T) 0.2416 0.5681 0.3909 0.6111 0.7456 0.6431 0.3579 0.7260 Age (A) <0.0001 <0.0001 0.1654 0.7801 0.1948 <0.0001 0.0119 <0.0001 H A <0.0001 0.9891 0.0316 0.3158 0.8470 0.0796 0.1025 0.0468 a d In columns, values within the sections hybrid, treatment, or age interactions between hybrid and age, not sharing common superscripts are significantly different at P < 0.05. 1 Interactions between hybrid and treatment, and age and treatment, were not significant (P > 0.05), and consequently not used in the statistical model. All parameters were scored from 1 (worst) to 4 (best) on the same hens on 2 occasions. Feather cover represents the sum of 6 body parts (6 to 24 points). Values are least squares means. 2 CON = basal diet, sawdust as litter bath substrate; FED = basal diet with 3% straw pellets, sawdust as litter bath substrate; LB = Lohmann Brown; LIT = basal diet, crumbled straw pellets as litter bath substrate; LSL = Lohmann Selected Leghorn. [4, 22], but the diets used in those studies were characterized by a larger inclusion of fibrous components than in the present trial. It may well be that the effect of dietary fiber on feather pecking is threshold- or dose-dependent. Wahlström et al. [23] reported a positive linear trend in feather condition when increasing amounts of whole oats were used. Pecking wounds on the comb were more abundant in LSL than in LB, but increased with age only in the former. This finding confirms earlier reports and may be ascribed the fact that the larger comb of LSL likely attracts more pecks [11]. Pecking wounds in the vent were virtually absent in both hybrids at both ages. The plumage of LSL was much dirtier than LB, likely because dirt is more easily detected on a white plumage than a brown. Scores of foot lesions and bumble foot conditions improved from 40 to 60 wk of age. In contrast, foot cleanliness was reduced with age. This reduction was more prominent in LSL (Table 5), and again, this may reflect the lower DM of feces in later stages of lay in LSL. Both bumble foot condition and foot cleanliness were superior in LB compared with LSL. Earlier studies have found that LSL are more likely to develop bumble foot than LB [11, 24]. CONCLUSIONS AND APPLICATIONS 1. Litter may constitute a potential source of fiber to laying hens, but the consumption of litter from the litter bath varies with the hybrid used. 2. The inclusion of 3% crumbled straw pellets in the feed is probably too low to have any effects on performance and feather pecking.

Kalmendal et al.: FIBER SUPPLY IN FURNISHED CAGE 117 3. Interactions between hybrid, fiber intake, and egg shell quality warrant further investigations. REFERENCES AND NOTES 1. González-Alvarado, J. M., E. Jiménez-Moreno, R. Lázaro, and G. G. Mateos. 2007. Effect of type of cereal, heat processing of the cereal, and inclusion of fiber in the diet on productive performance and digestive traits of broilers. Poult. Sci. 86:1705 1715. 2. Hetland, H., B. Svihus, and Å. Krogdahl. 2003. Effects of oat hulls and wood shavings on digestion in broilers and layers fed diets based on whole or ground wheat. Br. Poult. Sci. 44:275 282. 3. Hetland, H., M. Choct, and B. Svihus. 2004. Role of insoluble non-starch polysaccharides in poultry nutrition. World s Poult. Sci. J. 60:415 422. 4. Hartini, S., M. Choct, G. Hinch, A. Kocher, and J. V. Nolan. 2002. 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Foot and skeletal disorders in laying hens Effects of perch design, hybrid, housing system and stocking density. Acta Agric. Scand. A Anim. Sci. 44:110 119. Acknowledgments This study was performed with funds granted by the Swedish Research Council for Environment, Agricultural Sciences, and Spatial Planning. The authors thank Dansk Dyrestimuli A/S (Denmark) for providing the straw products free of charge.