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Plumage Condition and Health of Aviary-Kept Hens Fed Mash or Crumbled Pellets
Plumage Condition and Health of Aviary-Kept Hens Fed Mash or Crumbled Pellets A. Wahlstro¨m, R. Tauson,1 and K. Elwinger Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Funbo-Lo¨vsta Research Centre, S-755 97 Uppsala, Sweden
(Key words: heat treatment, mash, crumbled pellets, diets, layer, aviary) 2001 Poultry Science 80:266–271
In birds, fear is thought to be positively correlated with feather pecking, implying that fearful groups of birds show more feather damage (Hughes and Duncan, 1972; Ouart and Adams, 1982; Vestergaard et al., 1993). Fear is also regarded as an important component of stress (Beuving et al., 1989), which may affect both the welfare and performance of poultry (Jones, 1997). The degree of fear may be estimated by the duration time of tonic immobility (TI), longer pecking times mean that birds are more fearful (Jones, 1986; Campo and Redondo, 1996; Jones et al., 1996), and also by the number of inductions needed to cause TI, with few inductions meaning more fearful birds (Campo and Redondo, 1996). Genetic differences in duration of TI have been reported in numerous studies comparing lines of laying hens (Craig et al., 1983, 1984; Campo and Redondo, 1996). Health traits, such as bumble foot syndrome, keel bone deformation, and hyperkeratosis in layers are influenced by genotype and housing system (Abrahamsson and Tauson, 1995). Feed structure seems to have no or limited effect on mortality, as shown in earlier studies (Black et al., 1958; Morgan and Heywang, 1941; Hamilton and Proudfoot, 1995). Several of the reports concerning effects of feed structure on laying hens refer to experiments carried out when factors such as genotype and housing system differed
INTRODUCTION Feather pecking is a major problem in intensively housed poultry. By keeping hens in large groups, problems with feather pecking and cannibalism may arise and spread in a flock (Hughes, 1982; Nørgaard-Nielsen et al., 1993; Abrahamsson and Tauson, 1995). Feather pecking and cannibalistic behavior may also appear differently depending on the genotype of the birds (Hughes and Duncan, 1972; Cuthbertson, 1980; Abrahamsson and Tauson, 1995; Wahlstro¨m et al., 1998). In older studies, feather pecking has been shown to be more common when White Leghorn pullets were fed pelleted compared with mash diets (Bearse et al., 1949). Laying hens (Savory and Hetherington, 1997) and chicks (Jensen et al., 1962; Savory, 1974) fed mash diets spent more time eating than birds given pelleted diets, thereby fulfilling more of their foraging behavior, which may lead to a decrease in feather pecking (Blokhuis and Arkes; 1984). Some researchers explain feather pecking as a redirected foraging behavior (e.g., Blokhuis and Arkes, 1984), whereas others claim that the birds use feathers as a dustbathing substrate (Vestergaard, 1994). In ostriches, Paxton et al. (1997) observed that nonfood pecking was generally associated with a decreased number of food pecks.
Received for publication February 16, 2000. Accepted for publication September 26, 2000. 1 To whom correspondence should be addressed: Ragnar.Tauson@ huv.slu.se.
Abbrevation Key: LSL = Lohmann Selected Leghorn; TI = tonic immobility.
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ment (diet × hybrid). Diet generally had little effect on plumage condition, health, and tonic immobility. However, birds fed the crumbled diet had significantly fewer problems with bumble foot than those fed the mash diet. Hybrids reacted differently in most traits studied; SLU1329 had better health scores but more problems with cannibalism and salpingitis than Lohmann Selected Leghorns, whereas the reverse was found in the proportion of cases with coccidiosis. The hybrid differences found underline the importance of genotype.
ABSTRACT In the present experiment, we evaluated the effects on plumage condition and health of feeding a mash or a crumbled diet to two hybrids of laying hens in an aviary system. The two diets had the same composition and calculated nutrient content. A total of 3,204 birds was studied from 20 to 80 wk of age. Two hybrids, Lohmann Selected Leghorn and SLU-1329 (two line crosses of Leghorn and Rhode Island Red), were housed in six pens each of an aviary system with groups of 269 and 265 birds, respectively. There were three replicates per treat-
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from those currently in use. The object of this investigation was to study effects of feeding a mash diet compared with a crumbled diet on plumage condition and health. Crumbles were included because that is the feed structure most commonly used in commercial egg production in Europe. The investigation also used two genotypes that have been reported to behave differently, depending on diet, when kept in a modern multitiered aviary system (Wahlstro¨ m et al., 1998).
MATERIALS AND METHODS Housing and Birds
Feeding The pullets were fed a commercial grower diet in crumbles without coccidiostats until 17 wk. From 17 to 18 wk the hens were phased in with one of two experimental diets with identical composition (based on 37% barley, 25% wheat, and 10% oats) but fed as mash or as crumbled pellets. The mash diet was not heat treated. Prior to entering the die, the crumbled diet was exposed to approximately 80 C in a steam conditioner for 20 to 30 s. The outlet temperature from the pelleter die was also approximately 80 C. The pellets were finally crumbled down to 2- to 3-mm pieces. Within 7 to 8 min after pelleting, the crumbled pellets were cooled to approximately 20 C. Nutrient contents of the diets are shown in Table 1. A description of the analyzed dietary composition is given by Wahlstro¨ m et al. (1999).
Experimental diets
Nutrient contents
Mash
Metabolizable energy,1 MJ/kg Ash Dry matter Crude protein Crude fat Starch Cysteine Methionine Lysine Arginine Sodium Calcium Phosphorus
10.41 ± 131 ± 909 ± 157 ± 42 ± 379 ± 3.2 4.1 7.5 8.7 1.5 ± 44.3 ± 6.0 ±
Crumbled pellets 0.19 12 5 4.1 1.5 13
0.2 2.5 0.3
± 0.06 ± 14 ± 8 ± 4.7 ± 3.1 ± 6 2.9 4.0 7.2 8.6 1.2 ± 0.2 41.0 ± 4.6 5.8 ± 0.3
10.36 129 908 156 44 374
1 The ME was calculated according to the EEC model, ME = (0.1551 × crude protein) + (0.3431 × crude fat) + (0.1669 × starch) + 0.1301 × sucrose).
claws (length), and keel bone deformation. A special scoring of wounds on combs and vents was performed on 90 randomly selected birds per treatment (30 per pen) at 26 wk. The scoring system assigned values of 1 to 4 points for each trait, where 4 points was the best condition and 1 was the worst (Tauson et al., 1984). The six parameters for plumage condition were summarized and indicated a total score ranging from 6 to 24 points. Mortality was recorded daily, and necropsies were performed at the National Veterinary Institute, Uppsala, Sweden, from 20 until 80 wk. Bird TI was tested at 20 and 70 wk on 60 randomly selected birds from each treatment (20 per pen) for a total of 240 birds. Testing of the birds was spread over the day from 0800 h until 1600 h. Duration of TI was induced by restraining the birds for 15 s in a wooden V-shaped cradle, covered with a dark towel, with the birds’ head hanging as described by Jones and Faure (1981), and with one hand over the breast and one covering the head (Jones et al., 1996). Time from catching until placement in the cradle was 60 s. The maximum number of inductions (15s periods of restraint) necessary to obtain TI was limited to five. The bird had to remain on its back for a minimum of 10 s to consider TI to have been induced. The duration time of TI, i.e., until the bird righted itself, was recorded for individual hens (Jones and Faure, 1981). Maximum duration time was set to 1,500 s per test, and that was the time recorded if the bird failed to right itself during the test period.
Data Recording The experiment included four treatments, with three replicates per treatment (hybrid × diet). Scoring of exterior conditions was carried out on 90 randomly selected birds from each treatment (30 per pen) at 35 and 55 wk and on 60 birds per treatment (20 per pen) at 70 wk. The traits scored were condition of plumage (neck, breast, back, wings, tail, and vent), wounds on the skin of the comb and around the vent, cleanliness of feet and plumage, foot condition (bumble foot and toe pad hyperkeratosis),
Statistical Analyses Statistical analyses were carried out using GLM, MIXED, and CATMOD procedures of the statistical system SAS (SAS Institute Inc., 1996). G2 was used as a goodness-of-fit test with CATMOD (Freeman, 1987). Partial correlation (MANOVA options) was performed between the traits of plumage condition, comb and rear body wounds, and duration of TI and number of inductions. Before analysis, mortality was subjected to arcsin
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The Marielund aviary system was used with three welded wire tiers and nipple drinkers; the two lower tiers were equipped with feed troughs, and the top resting tier had perches (Abrahamsson and Tauson, 1995). Six pens housed 269 Lohmann Selected Leghorn (LSL) each, and six others contained 265 SLU-1329, a cross-breed of Leghorn × Rhode Island Red-line (Liljedahl and Weyde, 1980), for a total of 3,204 birds. Each pen measured 3.0 × 5.8 m, implying 15.5 and 15.3 hens/m2 floor area for the two genotypes, respectively. All pullets were reared from 1 d old under the same conditions, with feed and water on raised slatted floors with high perches. From 5 wk they also had access to litter between the slatted floor areas. The birds were vaccinated against Marek’s disease, coccidiosis, and avian encephalomyelitis.
TABLE 1. Analyzed nutrient content of diets (mean ± sd; g/kg feed)
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transformation (Snedecor and Cochran, 1968). Three of the most frequently appearing autopsy findings (cannibalism, salpingitis, and coccidiosis) in the experiment were statistically analyzed. Results are generally presented as least squares means. However, values that had been arcsin transformed are shown as means values. The following model was used for scoring exterior conditions. Interactions with age were excluded from the model if not found significant (P > 0.05). Yijkl = µ + αi + βj + γk + (αβ)ij + (αγ)ik + (βγ)jk + dijk + eijkl.
Yijm = µ + αi + βj + (αβ)ij + eijm. In these models Yijkl, Yijm = response variable, µ = overall mean, αi = fixed effect of hybrid (i = 1,2), βj = fixed effect of diet (j = 1,2), γk = effects of age (l = 1,2,3), (αβ)ij, (αγ)ik and (βγ)jk = effects of interactions, dijk = random effect of group, and eijkl, eijm = random variation.
RESULTS The first scores for frequency of comb wounds at 26 wk (not in tables) were not affected by diet (P < 0.6). However, wounds were more common for LSL birds than for SLU-1329 birds (P < 0.001). No rear body wounds were registered at this age. Scores for exterior condition at 35, 55, and 70 wk are shown in Table 2. Diets had no significant effect on score
TABLE 2. Scores1 for plumage condition and other health characteristics as affected by diet, genotype, and age Experimental diets Mash
Crumbled pellet
Characteristic
LSL
SLU-1329
LSL
SLU-1329
Diet (D)
Hybrid (H)
D×H
Age (A)
Interaction2
Plumage condition Comb wounds Rear body wounds Cleanliness of plumage Cleanliness of feet Bumble foot
20.3 3.99 4.00
21.7 3.97 4.00
20.5 3.98 4.00
21.2 3.93 4.00
0.52 0.22 —
0.001 0.10 —
0.08 0.35 —
0.001 0.01 —
— — —
3.47 3.72 3.34
3.57 3.68 3.54
3.43 3.76 3.31
3.70 3.67 3.44
0.38 0.86 0.05
0.01 0.20 0.001
0.1 0.60 0.24
0.001 0.06 0.01
0.89
0.001
0.51
0.001
4.00
—
—
—
—
— — D×A 0.001 H×A 0.02 —
Claw condition
3.52
3.85
3.54
3.81
Toe hyperkeratosis Keel bone deformation
4.00
4.00
4.00
3.74
3.59
3.61
3.55
0.06
0.02
0.25
0.001
—
(P)
1
Except for plumage condition for which the range was 24 to 6 points, the scores ranged from 4 points to 1. Higher numbers (score) indicated better conditions. 2 D × A, H × A, and D × H × A were tested, but, if not found significant (P > 0.05), these effects were excluded from the model.
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For mortality, TI, and autopsy findings, the following model was used. For autopsy findings, interactions were not found significant (P > 0.05) and, therefore, were excluded from the model.
for body parts except for bumble foot (P < 0.05). Birds fed the mash diet had a lower frequency of bumble foot than birds fed the crumbled diet. There was also a tendency (P < 0.06) for the latter treatment groups to show more keel bone deformation. SLU-1329 had significantly better plumage conditions, less bumble foot, and better claw conditions (P < 0.001), and cleaner plumage (P < 0.01) but more keel bone deformation (P < 0.05) than LSL. Age significantly affected all parameters except for rear body wounds, toe hyperkeratosis (no defects registered for these two parameters), and cleanliness of feet. Thus, increased age (35 vs. 55 and 70 wk) implied inferior plumage condition scores (P < 0.001; 22.9, 20.6, and 19.3 points, respectively), more bumble foot (P < 0.01; 3.44, 3.43, and 3.34 points, respectively), longer claws (P < 0.001; 3.89, 3.60, and 3.55 points, respectively), and more keel bone deformation (P < 0.001; 3.87, 3.63, and 3.37 points, respectively). However, age increased the cleanliness of plumage (P < 0.001, 3.32, 3.57, and 3.74 points, respectively) and slightly decreased the incidence of comb wounds (P < 0.01, 3.94, 3.98, and 3.98 points, respectively). There was a tendency (P < 0.06) for cleaner feet at higher age (3.64, 3.74, and 3.74 points, respectively). Interactions between diet and age were found in the incidence of bumble foot (P < 0.001; 3.48, 3.54, 3.28 points, respectively, for the mash diet at 35, 55, and 70 wk and 3.41, 3.31, 3.39 points, respectively for the crumbled diet). Also, hybrid ( age interactions were found in claw condition (P < 0.05; 3.82, 3.42, and 3.36 points, respectively, for LSL at 35, 55, and 70 wk and 3.96, 3.78, and 3.75 points, respectively for SLU-1329). Results of the TI recordings are presented in Table 3. Diet had no significant effect on the induction of TI duration. However, at 20 wk there was a tendency for longer duration of TI for birds fed the mash diet (P < 0.07). At 20 wk there was no difference between hybrids in dura-
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DIETARY EFFECTS ON LAYER HEALTH TABLE 3. Mortality and autopsy findings (mean values) and tonic immobility (least squares means values) as affected by diet and genotype Experimental diets Mash LSL
SLU-1329
Crumbled pellet LSL
SLU-1329
CV %
Diets (D)
Hybrids (H)
D×H
(P) Mortality, % of hh1 Cannibalism, % of hh Salpingitis, % of hh Coccidiosis, % of hh 20 wk of age Tonic immobility, s Number of inductions3 70 wk of age Tonic immobility, s Number of inductions3
4.2 0.1 1.6 1.6
4.0 0.1 3.5 0.0
4.3 0.0 1.6 1.4
4.0 0.9 3.1 0.3
22 3/12 0.1/12 3/12
0.92
0.79
0.93
0.12 0.74 1.0
0.05 0.01 0.001
— — —
301 1.1
251 1.5
199 1.2
253 1.3
83 56
0.07 0.64
0.94 0.01
0.05 0.12
255 1.3
343 1.4
265 1.2
350 1.2
94 43
0.82 0.11
0.02 0.81
0.96 0.31
2
tion of TI, but at 70 wk SLU-1329 showed longer duration than LSL birds (P < 0.05). More inductions were needed for SLU-1329 to obtain TI duration than for LSL at 20 wk (P < 0.01), although this difference was not found at 70 wk. There was also, at 20 wk, an interaction between diet and hybrid, showing longer duration of TI for LSL birds fed the mash diet compared with the crumbled diet, whereas SLU-1329 birds were unaffected (P < 0.05). No partial correlations of interest were found except for a negative correlation between the number of inductions at 20 wk and the scoring points for comb wounds at 26 wk (−0.78; P < 0.01), 35 wk (−0.69; P < 0.05), and 55 wk (−0.64; P < 0.07). No significant relation was found between number of inductions at 20 wk and scores for comb wounds at 70 wk (−0.46; P < 0.21). Mortality was not affected by diet or hybrid (Table 3), but autopsy recordings showed that SLU-1329 more often than LSL exhibited cannibalistic wounds and salpingitis (P < 0.05 and 0.01, respectively). However, LSL were more frequently affected by coccidiosis than SLU-1329 were (P < 0.001).
DISCUSSION Generally, feed structure had limited effects in this experiment, whereas bird genotype had a large impact on the results. Also, birds had very good plumage condition as well as low incidence of cannibalism throughout the production period. Despite a superior plumage condition for SLU-1329 birds, this hybrid exhibited a higher frequency of cannibalism, which indicates that these traits can appear with different behavioral origins, in agreement with, e.g., Allen and Perry (1975). Diet had little influence on plumage condition, but there was an interaction with hybrid in accordance with Wahlstro¨ m et al. (1998), involving the same hybrids. However, in that experiment, the LSL birds were more affected by diet,
whereas SLU-1329 showed no dietary response of plumage condition. The duration of TI and the number of inductions do not indicate the same fear levels. Probably more emphasis should be put on the duration of TI, because it is more widely used than the number of inductions. Differences between hybrids found in duration of TI at 70 wk are in accordance with several other reports using strains of White Leghorns (Craig et al., 1983, 1984) and brown egg Spanish breeds (Campo and Redondo, 1996). Because this difference was not observed at 20 wk, different social development within hybrids or pens might have occurred. Hence, at 70 wk the results may reflect the real effects of the experiment more than at 20 wk. At 20 wk, LSL hens appeared to be sensitive to the dietary treatment, showing more fearfulness (longer duration of TI) when fed the mash compared with the crumbled diet, whereas SLU-1329 hens were unaffected. The duration of TI generally increased with age except for one treatment (LSL fed the mash diet) in accordance with Hansen et al. (1993), inducing TI in White Leghorn hens at 30 and 70 wk, and Newberry and Blair (1993) inducing TI on chicks at 3 and 6 wk. Better plumage conditions were found on SLU-1329 birds, as also shown by Wahlstro¨ m et al. (1998), but they had more incidences of cannibalism and longer durations of TI (at 70 wk) than LSL birds. This finding is in contrast to several reports showing that fearful groups of birds have more problems with feather damage (Hughes and Duncan, 1972; Ouart and Adams, 1982; Vestergaard et al., 1993). However, this result might indicate that the limited feather pecking observed did not affect the fear response enough. The correlations observed on a group basis between the number of inductions (at 20 wk) and comb wounds indicated that groups of birds with low fear level had a higher frequency of aggressive pecks. The latter is indicated by numerous pecks on the comb
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hh = Hen housed. Indicates the degree of explanation in the model used (Freeman, 1987). Described in the table as G2/df (G2 was used as goodness-of-fit test). 3 Indicates number of 15-s periods of restraint needed to induce tonic immobility. 1
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ACKNOWLEDGMENTS The National Board of Agriculture and the Swedish Farmers’ Foundation for Agricultural Research are thanked for financial support. The authors are also grateful to Sigvard Thomke, Swedish University of Agricultural Sciences, Uppsala, Sweden for valuable comments on the manuscript.
REFERENCES Abrahamsson, P., and R. Tauson, 1995. Aviary systems and conventional cages for laying hens. Effects on production, egg quality, health and birds location in three hybrids. Acta Agric. Scand. Sect. A, Anim. Sci. 45:191–203. Abrahamsson, P., R. Tauson, and K. Elwinger, 1996. Effects on production, health and egg quality of varying proportions of wheat and barley in diets for two hybrids of laying hens kept in different housing systems. Acta Agric. Scand. Sect. A, Anim. Sci. 46:173–182. Allen, J., and G. C. Perry, 1975. Feather pecking and cannibalism in caged layer flocks. Br. Poult. Sci. 16:441–451. Bearse, G. E., L. R. Berg, C. F. McClary, and V. L. Miller, 1949. The effect of pelleting chicken rations on the incidence of cannibalism. Poultry Sci. 28:756. Beuving, G., R. B. Jones, and H. J. Blokhuis, 1989. Adrenocortical and heterophil/lymphocyte responses to challenge in hens showing short or long tonic immobility reactions. Br. Poult. Sci. 30:175–184. Black, D. J. G., R. C. Jennings, and T. R. Morris, 1958. The relative merits of pellets and mash for laying stock. Poultry Sci. 37:707–722. Blokhuis, H. J., and J. G. Arkes, 1984. The development and causation of feather pecking in the domestic fowl. Appl. Anim. Behav. Sci. 12:145–157. Campo, J. L., and A. Redondo, 1996. Tonic immobility reaction and heterophil to lymphocyte ratio in hens from three Spanish breeds laying pink eggshells. Poultry Sci. 75:155–159. Craig, J. V., T. P. Craig, and T. P. Dayton, 1983. Fearful behavior by cages hens of two genetic stocks. Appl. Anim. Ethol. 10:263–273. Craig, J. V., S. K. Kujiyat, and A. D. Dayton, 1984. Tonic immobility responses of white leghorn hens affected by induction techniques and genetic stock differences. Poultry Sci. 63:1–10. Cuthbertson, G. J., 1980. Genetic variation in feather-pecking behavior. Br. Poult. Sci. 21:447–450. Freeman, D. H. Jr., 1987. Pages 11–54, 109–177 in: Applied Categorical Data Analysis. Marcel Dekker, Inc., New York, NY. Hamilton, R.M.G., and F. G. Proudfoot, 1995. Effects of ingredient particle size and feed form on the performance of Leghorn hens. Can. J. Anim. Sci. 75:109–144. Hansen, I., B. O. Braastad, J. Storbra˚ ten, and M. Tofastrud, M. 1993. Differences in fearfulness indicated by Tonic immobility between laying hens in aviaries and in cages. Anim. Welfare 2:105–112. Hughes, B. O., 1982. The social behaviour of the fowl. Appl. Anim. Ethol. 9:84–85. Hughes, B. O., and I.J.H. Duncan, 1972. The influence of strain and environmental factors upon feather pecking and cannibalism in fowls. Br. Poult. Sci. 13:525–547. Jensen, L. S., L. H. Merrill, C. V. Reddy, and J. McGinnis, 1962. Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poultry Sci. 41:1414–1419. Jones, R. B., 1986. The tonic immobility reaction of the domestic fowl: a review. World’s Poult. Sci. J. 42:82–96. Jones, R. B., 1997. Vitamin C can reduce fear in poultry. World Poult. 7:25–26.
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(Keeling, 1995). The lack of a significant correlation at higher age was probably due to low incidences of comb wounds as a result of the establishment of a stable social hierarchy. The incidence of bumble foot increased with age and was also affected by an interaction between diet and age. Birds fed the mash diet had, at 55 wk, the highest score, whereas birds given the crumbled diet had increased problems at that age. These results do not agree with other reports showing that bumble foot usually is partly healed with increased age (e.g., Abrahamsson and Tauson, 1995; Abrahamsson et al., 1996). Our results, however, reveal that bumble foot is not only affected by housing system, genotype, and age but also by diet. This finding may be related to differences, not significant, in excreta dry matter contents, which indicate that birds fed the mash diet had drier excreta compared with those fed crumbled pellets (Wahlstro¨ m et al., 1999). Plumage and claw condition were generally inferior with higher age, in accordance with numerous reports (e.g., Abrahamsson et al., 1996; Wahlstro¨ m et al., 1998), although claw condition was less affected by age in SLU-1329 than in LSL hens. More keel bone deformation was found at increased age, in accordance with earlier studies (e.g., Abrahamsson et al., 1996; Wahlstro¨ m et al., 1998). Less keel bone deformations were found in LSL birds, which is in agreement with Wahlstro¨ m et al. (1998), who also used SLU-1329 and LSL housed in the same system. Because keel bone deformation is regarded as a result of long-term pressure to the sternum, mainly from perches, it is logical that the heavier bird (SLU-1329) suffers more from this than the lighter one (LSL). Mortality was not affected by feeding crumbles, in accordance with other studies (Morgan and Heywang, 1941; Hamilton and Proudfoot, 1995). Neither did genotype affect mortality, as earlier shown by Wahlstro¨ m et al. (1998) using LSL and SLU-1329. The major cause of death was salpingitis, which was more often displayed in SLU1329 than in LSL (3.3 vs. 1.6% of hens housed), probably because SLU-1329 birds crowded on the tiers, resulting in impaired hygiene due to body contact with the wire tiers. They also had a higher proportion of misplaced eggs (shown by Wahlstro¨ m et al., 1999), mainly laid on the wire tier floor. Mortality due to coccidiosis (although vaccinated birds were used) occurred most frequently among LSL hens, indicating a hereditary factor in susceptibility to Eimeria infections, in accordance with Long (1968), but in disagreement with Wahlstro¨ m et al. (1998), who were unable to observe any difference using LSL and SLU-1329. Possibly, the incidence of coccidiosis was too low in that experiment to enable any conclusions to be drawn concerning hereditary, behavioral, or dietary factors. In conclusion, feeding crumbled compared with mash diets generally had limited effects on birds’ plumage conditions and health. However, hybrid differences were found for most traits measured, underlining the importance of genotype.
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(Key words: heat treatment, mash, crumbled pellets, diets, layer, aviary) 2001 Poultry Science 80:266–271
In birds, fear is thought to be positively correlated with feather pecking, implying that fearful groups of birds show more feather damage (Hughes and Duncan, 1972; Ouart and Adams, 1982; Vestergaard et al., 1993). Fear is also regarded as an important component of stress (Beuving et al., 1989), which may affect both the welfare and performance of poultry (Jones, 1997). The degree of fear may be estimated by the duration time of tonic immobility (TI), longer pecking times mean that birds are more fearful (Jones, 1986; Campo and Redondo, 1996; Jones et al., 1996), and also by the number of inductions needed to cause TI, with few inductions meaning more fearful birds (Campo and Redondo, 1996). Genetic differences in duration of TI have been reported in numerous studies comparing lines of laying hens (Craig et al., 1983, 1984; Campo and Redondo, 1996). Health traits, such as bumble foot syndrome, keel bone deformation, and hyperkeratosis in layers are influenced by genotype and housing system (Abrahamsson and Tauson, 1995). Feed structure seems to have no or limited effect on mortality, as shown in earlier studies (Black et al., 1958; Morgan and Heywang, 1941; Hamilton and Proudfoot, 1995). Several of the reports concerning effects of feed structure on laying hens refer to experiments carried out when factors such as genotype and housing system differed
INTRODUCTION Feather pecking is a major problem in intensively housed poultry. By keeping hens in large groups, problems with feather pecking and cannibalism may arise and spread in a flock (Hughes, 1982; Nørgaard-Nielsen et al., 1993; Abrahamsson and Tauson, 1995). Feather pecking and cannibalistic behavior may also appear differently depending on the genotype of the birds (Hughes and Duncan, 1972; Cuthbertson, 1980; Abrahamsson and Tauson, 1995; Wahlstro¨m et al., 1998). In older studies, feather pecking has been shown to be more common when White Leghorn pullets were fed pelleted compared with mash diets (Bearse et al., 1949). Laying hens (Savory and Hetherington, 1997) and chicks (Jensen et al., 1962; Savory, 1974) fed mash diets spent more time eating than birds given pelleted diets, thereby fulfilling more of their foraging behavior, which may lead to a decrease in feather pecking (Blokhuis and Arkes; 1984). Some researchers explain feather pecking as a redirected foraging behavior (e.g., Blokhuis and Arkes, 1984), whereas others claim that the birds use feathers as a dustbathing substrate (Vestergaard, 1994). In ostriches, Paxton et al. (1997) observed that nonfood pecking was generally associated with a decreased number of food pecks.
Received for publication February 16, 2000. Accepted for publication September 26, 2000. 1 To whom correspondence should be addressed: Ragnar.Tauson@ huv.slu.se.
Abbrevation Key: LSL = Lohmann Selected Leghorn; TI = tonic immobility.
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ment (diet × hybrid). Diet generally had little effect on plumage condition, health, and tonic immobility. However, birds fed the crumbled diet had significantly fewer problems with bumble foot than those fed the mash diet. Hybrids reacted differently in most traits studied; SLU1329 had better health scores but more problems with cannibalism and salpingitis than Lohmann Selected Leghorns, whereas the reverse was found in the proportion of cases with coccidiosis. The hybrid differences found underline the importance of genotype.
ABSTRACT In the present experiment, we evaluated the effects on plumage condition and health of feeding a mash or a crumbled diet to two hybrids of laying hens in an aviary system. The two diets had the same composition and calculated nutrient content. A total of 3,204 birds was studied from 20 to 80 wk of age. Two hybrids, Lohmann Selected Leghorn and SLU-1329 (two line crosses of Leghorn and Rhode Island Red), were housed in six pens each of an aviary system with groups of 269 and 265 birds, respectively. There were three replicates per treat-
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from those currently in use. The object of this investigation was to study effects of feeding a mash diet compared with a crumbled diet on plumage condition and health. Crumbles were included because that is the feed structure most commonly used in commercial egg production in Europe. The investigation also used two genotypes that have been reported to behave differently, depending on diet, when kept in a modern multitiered aviary system (Wahlstro¨ m et al., 1998).
MATERIALS AND METHODS Housing and Birds
Feeding The pullets were fed a commercial grower diet in crumbles without coccidiostats until 17 wk. From 17 to 18 wk the hens were phased in with one of two experimental diets with identical composition (based on 37% barley, 25% wheat, and 10% oats) but fed as mash or as crumbled pellets. The mash diet was not heat treated. Prior to entering the die, the crumbled diet was exposed to approximately 80 C in a steam conditioner for 20 to 30 s. The outlet temperature from the pelleter die was also approximately 80 C. The pellets were finally crumbled down to 2- to 3-mm pieces. Within 7 to 8 min after pelleting, the crumbled pellets were cooled to approximately 20 C. Nutrient contents of the diets are shown in Table 1. A description of the analyzed dietary composition is given by Wahlstro¨ m et al. (1999).
Experimental diets
Nutrient contents
Mash
Metabolizable energy,1 MJ/kg Ash Dry matter Crude protein Crude fat Starch Cysteine Methionine Lysine Arginine Sodium Calcium Phosphorus
10.41 ± 131 ± 909 ± 157 ± 42 ± 379 ± 3.2 4.1 7.5 8.7 1.5 ± 44.3 ± 6.0 ±
Crumbled pellets 0.19 12 5 4.1 1.5 13
0.2 2.5 0.3
± 0.06 ± 14 ± 8 ± 4.7 ± 3.1 ± 6 2.9 4.0 7.2 8.6 1.2 ± 0.2 41.0 ± 4.6 5.8 ± 0.3
10.36 129 908 156 44 374
1 The ME was calculated according to the EEC model, ME = (0.1551 × crude protein) + (0.3431 × crude fat) + (0.1669 × starch) + 0.1301 × sucrose).
claws (length), and keel bone deformation. A special scoring of wounds on combs and vents was performed on 90 randomly selected birds per treatment (30 per pen) at 26 wk. The scoring system assigned values of 1 to 4 points for each trait, where 4 points was the best condition and 1 was the worst (Tauson et al., 1984). The six parameters for plumage condition were summarized and indicated a total score ranging from 6 to 24 points. Mortality was recorded daily, and necropsies were performed at the National Veterinary Institute, Uppsala, Sweden, from 20 until 80 wk. Bird TI was tested at 20 and 70 wk on 60 randomly selected birds from each treatment (20 per pen) for a total of 240 birds. Testing of the birds was spread over the day from 0800 h until 1600 h. Duration of TI was induced by restraining the birds for 15 s in a wooden V-shaped cradle, covered with a dark towel, with the birds’ head hanging as described by Jones and Faure (1981), and with one hand over the breast and one covering the head (Jones et al., 1996). Time from catching until placement in the cradle was 60 s. The maximum number of inductions (15s periods of restraint) necessary to obtain TI was limited to five. The bird had to remain on its back for a minimum of 10 s to consider TI to have been induced. The duration time of TI, i.e., until the bird righted itself, was recorded for individual hens (Jones and Faure, 1981). Maximum duration time was set to 1,500 s per test, and that was the time recorded if the bird failed to right itself during the test period.
Data Recording The experiment included four treatments, with three replicates per treatment (hybrid × diet). Scoring of exterior conditions was carried out on 90 randomly selected birds from each treatment (30 per pen) at 35 and 55 wk and on 60 birds per treatment (20 per pen) at 70 wk. The traits scored were condition of plumage (neck, breast, back, wings, tail, and vent), wounds on the skin of the comb and around the vent, cleanliness of feet and plumage, foot condition (bumble foot and toe pad hyperkeratosis),
Statistical Analyses Statistical analyses were carried out using GLM, MIXED, and CATMOD procedures of the statistical system SAS (SAS Institute Inc., 1996). G2 was used as a goodness-of-fit test with CATMOD (Freeman, 1987). Partial correlation (MANOVA options) was performed between the traits of plumage condition, comb and rear body wounds, and duration of TI and number of inductions. Before analysis, mortality was subjected to arcsin
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The Marielund aviary system was used with three welded wire tiers and nipple drinkers; the two lower tiers were equipped with feed troughs, and the top resting tier had perches (Abrahamsson and Tauson, 1995). Six pens housed 269 Lohmann Selected Leghorn (LSL) each, and six others contained 265 SLU-1329, a cross-breed of Leghorn × Rhode Island Red-line (Liljedahl and Weyde, 1980), for a total of 3,204 birds. Each pen measured 3.0 × 5.8 m, implying 15.5 and 15.3 hens/m2 floor area for the two genotypes, respectively. All pullets were reared from 1 d old under the same conditions, with feed and water on raised slatted floors with high perches. From 5 wk they also had access to litter between the slatted floor areas. The birds were vaccinated against Marek’s disease, coccidiosis, and avian encephalomyelitis.
TABLE 1. Analyzed nutrient content of diets (mean ± sd; g/kg feed)
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transformation (Snedecor and Cochran, 1968). Three of the most frequently appearing autopsy findings (cannibalism, salpingitis, and coccidiosis) in the experiment were statistically analyzed. Results are generally presented as least squares means. However, values that had been arcsin transformed are shown as means values. The following model was used for scoring exterior conditions. Interactions with age were excluded from the model if not found significant (P > 0.05). Yijkl = µ + αi + βj + γk + (αβ)ij + (αγ)ik + (βγ)jk + dijk + eijkl.
Yijm = µ + αi + βj + (αβ)ij + eijm. In these models Yijkl, Yijm = response variable, µ = overall mean, αi = fixed effect of hybrid (i = 1,2), βj = fixed effect of diet (j = 1,2), γk = effects of age (l = 1,2,3), (αβ)ij, (αγ)ik and (βγ)jk = effects of interactions, dijk = random effect of group, and eijkl, eijm = random variation.
RESULTS The first scores for frequency of comb wounds at 26 wk (not in tables) were not affected by diet (P < 0.6). However, wounds were more common for LSL birds than for SLU-1329 birds (P < 0.001). No rear body wounds were registered at this age. Scores for exterior condition at 35, 55, and 70 wk are shown in Table 2. Diets had no significant effect on score
TABLE 2. Scores1 for plumage condition and other health characteristics as affected by diet, genotype, and age Experimental diets Mash
Crumbled pellet
Characteristic
LSL
SLU-1329
LSL
SLU-1329
Diet (D)
Hybrid (H)
D×H
Age (A)
Interaction2
Plumage condition Comb wounds Rear body wounds Cleanliness of plumage Cleanliness of feet Bumble foot
20.3 3.99 4.00
21.7 3.97 4.00
20.5 3.98 4.00
21.2 3.93 4.00
0.52 0.22 —
0.001 0.10 —
0.08 0.35 —
0.001 0.01 —
— — —
3.47 3.72 3.34
3.57 3.68 3.54
3.43 3.76 3.31
3.70 3.67 3.44
0.38 0.86 0.05
0.01 0.20 0.001
0.1 0.60 0.24
0.001 0.06 0.01
0.89
0.001
0.51
0.001
4.00
—
—
—
—
— — D×A 0.001 H×A 0.02 —
Claw condition
3.52
3.85
3.54
3.81
Toe hyperkeratosis Keel bone deformation
4.00
4.00
4.00
3.74
3.59
3.61
3.55
0.06
0.02
0.25
0.001
—
(P)
1
Except for plumage condition for which the range was 24 to 6 points, the scores ranged from 4 points to 1. Higher numbers (score) indicated better conditions. 2 D × A, H × A, and D × H × A were tested, but, if not found significant (P > 0.05), these effects were excluded from the model.
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For mortality, TI, and autopsy findings, the following model was used. For autopsy findings, interactions were not found significant (P > 0.05) and, therefore, were excluded from the model.
for body parts except for bumble foot (P < 0.05). Birds fed the mash diet had a lower frequency of bumble foot than birds fed the crumbled diet. There was also a tendency (P < 0.06) for the latter treatment groups to show more keel bone deformation. SLU-1329 had significantly better plumage conditions, less bumble foot, and better claw conditions (P < 0.001), and cleaner plumage (P < 0.01) but more keel bone deformation (P < 0.05) than LSL. Age significantly affected all parameters except for rear body wounds, toe hyperkeratosis (no defects registered for these two parameters), and cleanliness of feet. Thus, increased age (35 vs. 55 and 70 wk) implied inferior plumage condition scores (P < 0.001; 22.9, 20.6, and 19.3 points, respectively), more bumble foot (P < 0.01; 3.44, 3.43, and 3.34 points, respectively), longer claws (P < 0.001; 3.89, 3.60, and 3.55 points, respectively), and more keel bone deformation (P < 0.001; 3.87, 3.63, and 3.37 points, respectively). However, age increased the cleanliness of plumage (P < 0.001, 3.32, 3.57, and 3.74 points, respectively) and slightly decreased the incidence of comb wounds (P < 0.01, 3.94, 3.98, and 3.98 points, respectively). There was a tendency (P < 0.06) for cleaner feet at higher age (3.64, 3.74, and 3.74 points, respectively). Interactions between diet and age were found in the incidence of bumble foot (P < 0.001; 3.48, 3.54, 3.28 points, respectively, for the mash diet at 35, 55, and 70 wk and 3.41, 3.31, 3.39 points, respectively for the crumbled diet). Also, hybrid ( age interactions were found in claw condition (P < 0.05; 3.82, 3.42, and 3.36 points, respectively, for LSL at 35, 55, and 70 wk and 3.96, 3.78, and 3.75 points, respectively for SLU-1329). Results of the TI recordings are presented in Table 3. Diet had no significant effect on the induction of TI duration. However, at 20 wk there was a tendency for longer duration of TI for birds fed the mash diet (P < 0.07). At 20 wk there was no difference between hybrids in dura-
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DIETARY EFFECTS ON LAYER HEALTH TABLE 3. Mortality and autopsy findings (mean values) and tonic immobility (least squares means values) as affected by diet and genotype Experimental diets Mash LSL
SLU-1329
Crumbled pellet LSL
SLU-1329
CV %
Diets (D)
Hybrids (H)
D×H
(P) Mortality, % of hh1 Cannibalism, % of hh Salpingitis, % of hh Coccidiosis, % of hh 20 wk of age Tonic immobility, s Number of inductions3 70 wk of age Tonic immobility, s Number of inductions3
4.2 0.1 1.6 1.6
4.0 0.1 3.5 0.0
4.3 0.0 1.6 1.4
4.0 0.9 3.1 0.3
22 3/12 0.1/12 3/12
0.92
0.79
0.93
0.12 0.74 1.0
0.05 0.01 0.001
— — —
301 1.1
251 1.5
199 1.2
253 1.3
83 56
0.07 0.64
0.94 0.01
0.05 0.12
255 1.3
343 1.4
265 1.2
350 1.2
94 43
0.82 0.11
0.02 0.81
0.96 0.31
2
tion of TI, but at 70 wk SLU-1329 showed longer duration than LSL birds (P < 0.05). More inductions were needed for SLU-1329 to obtain TI duration than for LSL at 20 wk (P < 0.01), although this difference was not found at 70 wk. There was also, at 20 wk, an interaction between diet and hybrid, showing longer duration of TI for LSL birds fed the mash diet compared with the crumbled diet, whereas SLU-1329 birds were unaffected (P < 0.05). No partial correlations of interest were found except for a negative correlation between the number of inductions at 20 wk and the scoring points for comb wounds at 26 wk (−0.78; P < 0.01), 35 wk (−0.69; P < 0.05), and 55 wk (−0.64; P < 0.07). No significant relation was found between number of inductions at 20 wk and scores for comb wounds at 70 wk (−0.46; P < 0.21). Mortality was not affected by diet or hybrid (Table 3), but autopsy recordings showed that SLU-1329 more often than LSL exhibited cannibalistic wounds and salpingitis (P < 0.05 and 0.01, respectively). However, LSL were more frequently affected by coccidiosis than SLU-1329 were (P < 0.001).
DISCUSSION Generally, feed structure had limited effects in this experiment, whereas bird genotype had a large impact on the results. Also, birds had very good plumage condition as well as low incidence of cannibalism throughout the production period. Despite a superior plumage condition for SLU-1329 birds, this hybrid exhibited a higher frequency of cannibalism, which indicates that these traits can appear with different behavioral origins, in agreement with, e.g., Allen and Perry (1975). Diet had little influence on plumage condition, but there was an interaction with hybrid in accordance with Wahlstro¨ m et al. (1998), involving the same hybrids. However, in that experiment, the LSL birds were more affected by diet,
whereas SLU-1329 showed no dietary response of plumage condition. The duration of TI and the number of inductions do not indicate the same fear levels. Probably more emphasis should be put on the duration of TI, because it is more widely used than the number of inductions. Differences between hybrids found in duration of TI at 70 wk are in accordance with several other reports using strains of White Leghorns (Craig et al., 1983, 1984) and brown egg Spanish breeds (Campo and Redondo, 1996). Because this difference was not observed at 20 wk, different social development within hybrids or pens might have occurred. Hence, at 70 wk the results may reflect the real effects of the experiment more than at 20 wk. At 20 wk, LSL hens appeared to be sensitive to the dietary treatment, showing more fearfulness (longer duration of TI) when fed the mash compared with the crumbled diet, whereas SLU-1329 hens were unaffected. The duration of TI generally increased with age except for one treatment (LSL fed the mash diet) in accordance with Hansen et al. (1993), inducing TI in White Leghorn hens at 30 and 70 wk, and Newberry and Blair (1993) inducing TI on chicks at 3 and 6 wk. Better plumage conditions were found on SLU-1329 birds, as also shown by Wahlstro¨ m et al. (1998), but they had more incidences of cannibalism and longer durations of TI (at 70 wk) than LSL birds. This finding is in contrast to several reports showing that fearful groups of birds have more problems with feather damage (Hughes and Duncan, 1972; Ouart and Adams, 1982; Vestergaard et al., 1993). However, this result might indicate that the limited feather pecking observed did not affect the fear response enough. The correlations observed on a group basis between the number of inductions (at 20 wk) and comb wounds indicated that groups of birds with low fear level had a higher frequency of aggressive pecks. The latter is indicated by numerous pecks on the comb
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hh = Hen housed. Indicates the degree of explanation in the model used (Freeman, 1987). Described in the table as G2/df (G2 was used as goodness-of-fit test). 3 Indicates number of 15-s periods of restraint needed to induce tonic immobility. 1
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ACKNOWLEDGMENTS The National Board of Agriculture and the Swedish Farmers’ Foundation for Agricultural Research are thanked for financial support. The authors are also grateful to Sigvard Thomke, Swedish University of Agricultural Sciences, Uppsala, Sweden for valuable comments on the manuscript.
REFERENCES Abrahamsson, P., and R. Tauson, 1995. Aviary systems and conventional cages for laying hens. Effects on production, egg quality, health and birds location in three hybrids. Acta Agric. Scand. Sect. A, Anim. Sci. 45:191–203. Abrahamsson, P., R. Tauson, and K. Elwinger, 1996. Effects on production, health and egg quality of varying proportions of wheat and barley in diets for two hybrids of laying hens kept in different housing systems. Acta Agric. Scand. Sect. A, Anim. Sci. 46:173–182. Allen, J., and G. C. Perry, 1975. Feather pecking and cannibalism in caged layer flocks. Br. Poult. Sci. 16:441–451. Bearse, G. E., L. R. Berg, C. F. McClary, and V. L. Miller, 1949. The effect of pelleting chicken rations on the incidence of cannibalism. Poultry Sci. 28:756. Beuving, G., R. B. Jones, and H. J. Blokhuis, 1989. Adrenocortical and heterophil/lymphocyte responses to challenge in hens showing short or long tonic immobility reactions. Br. Poult. Sci. 30:175–184. Black, D. J. G., R. C. Jennings, and T. R. Morris, 1958. The relative merits of pellets and mash for laying stock. Poultry Sci. 37:707–722. Blokhuis, H. J., and J. G. Arkes, 1984. The development and causation of feather pecking in the domestic fowl. Appl. Anim. Behav. Sci. 12:145–157. Campo, J. L., and A. Redondo, 1996. Tonic immobility reaction and heterophil to lymphocyte ratio in hens from three Spanish breeds laying pink eggshells. Poultry Sci. 75:155–159. Craig, J. V., T. P. Craig, and T. P. Dayton, 1983. Fearful behavior by cages hens of two genetic stocks. Appl. Anim. Ethol. 10:263–273. Craig, J. V., S. K. Kujiyat, and A. D. Dayton, 1984. Tonic immobility responses of white leghorn hens affected by induction techniques and genetic stock differences. Poultry Sci. 63:1–10. Cuthbertson, G. J., 1980. Genetic variation in feather-pecking behavior. Br. Poult. Sci. 21:447–450. Freeman, D. H. Jr., 1987. Pages 11–54, 109–177 in: Applied Categorical Data Analysis. Marcel Dekker, Inc., New York, NY. Hamilton, R.M.G., and F. G. Proudfoot, 1995. Effects of ingredient particle size and feed form on the performance of Leghorn hens. Can. J. Anim. Sci. 75:109–144. Hansen, I., B. O. Braastad, J. Storbra˚ ten, and M. Tofastrud, M. 1993. Differences in fearfulness indicated by Tonic immobility between laying hens in aviaries and in cages. Anim. Welfare 2:105–112. Hughes, B. O., 1982. The social behaviour of the fowl. Appl. Anim. Ethol. 9:84–85. Hughes, B. O., and I.J.H. Duncan, 1972. The influence of strain and environmental factors upon feather pecking and cannibalism in fowls. Br. Poult. Sci. 13:525–547. Jensen, L. S., L. H. Merrill, C. V. Reddy, and J. McGinnis, 1962. Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poultry Sci. 41:1414–1419. Jones, R. B., 1986. The tonic immobility reaction of the domestic fowl: a review. World’s Poult. Sci. J. 42:82–96. Jones, R. B., 1997. Vitamin C can reduce fear in poultry. World Poult. 7:25–26.
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(Keeling, 1995). The lack of a significant correlation at higher age was probably due to low incidences of comb wounds as a result of the establishment of a stable social hierarchy. The incidence of bumble foot increased with age and was also affected by an interaction between diet and age. Birds fed the mash diet had, at 55 wk, the highest score, whereas birds given the crumbled diet had increased problems at that age. These results do not agree with other reports showing that bumble foot usually is partly healed with increased age (e.g., Abrahamsson and Tauson, 1995; Abrahamsson et al., 1996). Our results, however, reveal that bumble foot is not only affected by housing system, genotype, and age but also by diet. This finding may be related to differences, not significant, in excreta dry matter contents, which indicate that birds fed the mash diet had drier excreta compared with those fed crumbled pellets (Wahlstro¨ m et al., 1999). Plumage and claw condition were generally inferior with higher age, in accordance with numerous reports (e.g., Abrahamsson et al., 1996; Wahlstro¨ m et al., 1998), although claw condition was less affected by age in SLU-1329 than in LSL hens. More keel bone deformation was found at increased age, in accordance with earlier studies (e.g., Abrahamsson et al., 1996; Wahlstro¨ m et al., 1998). Less keel bone deformations were found in LSL birds, which is in agreement with Wahlstro¨ m et al. (1998), who also used SLU-1329 and LSL housed in the same system. Because keel bone deformation is regarded as a result of long-term pressure to the sternum, mainly from perches, it is logical that the heavier bird (SLU-1329) suffers more from this than the lighter one (LSL). Mortality was not affected by feeding crumbles, in accordance with other studies (Morgan and Heywang, 1941; Hamilton and Proudfoot, 1995). Neither did genotype affect mortality, as earlier shown by Wahlstro¨ m et al. (1998) using LSL and SLU-1329. The major cause of death was salpingitis, which was more often displayed in SLU1329 than in LSL (3.3 vs. 1.6% of hens housed), probably because SLU-1329 birds crowded on the tiers, resulting in impaired hygiene due to body contact with the wire tiers. They also had a higher proportion of misplaced eggs (shown by Wahlstro¨ m et al., 1999), mainly laid on the wire tier floor. Mortality due to coccidiosis (although vaccinated birds were used) occurred most frequently among LSL hens, indicating a hereditary factor in susceptibility to Eimeria infections, in accordance with Long (1968), but in disagreement with Wahlstro¨ m et al. (1998), who were unable to observe any difference using LSL and SLU-1329. Possibly, the incidence of coccidiosis was too low in that experiment to enable any conclusions to be drawn concerning hereditary, behavioral, or dietary factors. In conclusion, feeding crumbled compared with mash diets generally had limited effects on birds’ plumage conditions and health. However, hybrid differences were found for most traits measured, underlining the importance of genotype.
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