Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-28T02:07:14.292Z Has data issue: false hasContentIssue false
  • English
  • Français

Impact of feeding management on feather pecking in laying hens

Published online by Cambridge University Press:  18 September 2007

M.M. Van Krimpen ,
R.P. Kwakkel ,
B.F.J. Reuvekamp ,
C.M.C. Van Der Peet-Schwering ,
L.A. Den Hartog  and
M.W.A. Verstegen
M.M. Van Krimpen*
Affiliation:
Applied Research, Animal Sciences Group, Wageningen UR, PO Box 65, NL-8200 AB Lelystad, The, Netherlands
R.P. Kwakkel
Affiliation:
Animal Nutrition Group
B.F.J. Reuvekamp
Affiliation:
Applied Research, Animal Sciences Group, Wageningen UR, PO Box 65, NL-8200 AB Lelystad, The, Netherlands
C.M.C. Van Der Peet-Schwering
Affiliation:
Applied Research, Animal Sciences Group, Wageningen UR, PO Box 65, NL-8200 AB Lelystad, The, Netherlands
L.A. Den Hartog
Affiliation:
Animal Production Systems Group, Department of Animal Sciences, Wageningen University, PO Box 338, NL-6700 AH Wageningen, The, Netherlands Nutreco R&D, PO Box 220, NL-5830 AE Boxmeer, The, Netherlands
M.W.A. Verstegen
Affiliation:
Animal Nutrition Group
*
*Corresponding author: marinus.vankrimpen@wur.nl
Get access

Abstract

In the near future EU-legislation will ban the use of conventional battery cages, while national legislation in some countries in Western Europe will ban beak trimming as well. The ban on battery cages and beak trimming causes an increased risk of feather pecking and cannibalism in laying hens. Many factors influence feather pecking behaviour, but this paper focuses on nutritional factors. Nutritional factors can have positive and negative effects on feather pecking behaviour in laying hens. Severe feather pecking has been demonstrated in birds that were fed a too low mineral level in the diet, a too low protein level or a too low amino acid level (methionine, arginine). Sometimes somewhat more feather pecking was found when layers were fed diets with mainly vegetable protein sources as compared with diets with protein from animal origin. Also more feather pecking may occur when the diets were fed restrictedly, fed coarsely ground, or fed as pellets. Feeding high-fibre diets, low energy diets, or roughages reduced feather pecking. Providing additional grain or straw in the litter during rearing could result in lower levels of feather pecking behaviour in adult stages. Some of these positive effects on feather pecking seem to be related to the time birds spend on feed intake and foraging. This paper gives an overview of the relationships between the occurrence of feather pecking behaviour and nutritional factors, such as diet composition and feeding strategies in laying hens.

Keywords

nutritionfeather peckingpulletslaying hensdiet compositionfeeding management
Type
Reviews
Information
World's Poultry Science Journal , Volume 61 , Issue 4 , December 2005 , pp. 663 - 686
Copyright
Copyright © Cambridge University Press 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abrahamsson, P., Tauson, R. and Elwinger, K. (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 Agriculturae Scandinavica. Section A, Animal Science 46 (3): 173–182.Google Scholar
Aerni, V., El Lethey, H. and Wechsler, B. (2000) Effect of foraging material and food form on feather pecking in laying hens. British Poultry Science 41 (1): 16–21.CrossRefGoogle ScholarPubMed
Al Bustany, Z. and Elwinger, K. (1987a) Comparison between barley/fish meal- and maize/soybean meal-based diets with various lysine and protein levels fed to different strains of laying hens. Acta Agriculturae Scandinavica 37 (1): 41–49.Google Scholar
Al Bustany, Z. and Elwinger, K. (1987b) Response of laying hens to different dietary lysine intakes. A comparison of some commercial hybrids with strains selected on a low protein diet. Acta Agriculturae Scandinavica 37 (1): 27–40.CrossRefGoogle Scholar
Al Bustany, Z. and Elwinger, K. (1988) Whole grains, unprocessed rapeseed and beta-glucanase in diets for laying hens. Swedish Journal of Agricultural Research 18: 31–40.Google Scholar
Allen, J. and Perry, G.C. (1975) Feather pecking and cannibalism in a caged layer flock. British Poultry Science 16 (5): 441–451.CrossRefGoogle Scholar
Ambrosen, T. and Petersen, V.E. (1997) The influence of protein level in the diet on cannibalism and quality of plumage of layers. Poultry Science 76 (4): 559–563.Google Scholar
Appleby, M.C., Hogarth, G.S., Anderson, J.A., Hughes, B.O. and Whittemore, C.T. (1988) Performance of a deep litter system for egg production. British Poultry Science 29 (4): 735–751.CrossRefGoogle Scholar
Bearse, G.E., Berg, L.R., McClary, C.F. and Miller, V.L. (1949) The effect of pelleting chicken rations on the incidence of cannibalism. Poultry Science 28: 756.Google Scholar
Bearse, G.E., Miller, V.L. and McClary, C.F. (1940) The cannibalism preventing properties of fibre fraction of oat hulls. Poultry Science 19: 210–215.Google Scholar
Bessei, W. (1983) Zum Problem des Federpickens und Kannibalismus. DGS Magazin 24: 656–665.Google Scholar
Bessei, W. (1984) On the heritability of feather pecking in pullets. 1st report. Archiv fur Geflügelkunde 48 (6): 224–231.Google Scholar
Bessei, W., Reiter, K., Bley, T. and Zeep, F. (1999) Measuring pecking of a bunch of feathers in individually housed hens: first results of genetic studies and feeding related reactions. Lohmann Information(22): 27–31.Google Scholar
Bilcik, B. and Keeling, L.J. (1999) Changes in feather condition in relation to feather pecking and aggressive behaviour in laying hens. British Poultry Science 40 (4): 444–451.CrossRefGoogle ScholarPubMed
Blokhuis, H.J. (1986) Feather-pecking in poultry: its relation with ground-pecking. Applied Animal Behaviour Science 16 (1): 63–67.CrossRefGoogle Scholar
Blokhuis, H.J. (1989) The development and causation of feather pecking in the domestic fowl. Landbouw Universiteit Wageningen Wageningen.Google Scholar
Blokhuis, H.J. and Arkes, J.G. (1984) Some observations on the development of feather-pecking in poultry. Applied Animal Behaviour Science 12 (1–2): 145–157.Google Scholar
Blokhuis, H.J. and Van Der Haar, J.W. (1989) Effects of floor type during rearing and of beak trimming on ground pecking and feather pecking in laying hens. Applied Animal Behaviour Science 22 (3–4): 359–369.Google Scholar
Blokhuis, H.J. and Van Der Haar, J.W. (1992) Effects of pecking incentives during rearing on feather pecking of laying hens. British Poultry Science 33 (1): 17–24.Google Scholar
Blokhuis, H.J. and Wiepkema, P.R. (1998) Studies of feather pecking in poultry. Veterinary Quarterly 20 (1): 6–9.Google Scholar
Buitenhuis, A.J., Rodenburg, T.B., Hierden, Y.M.Van, Siwek, M., Cornelissen, S.J.B., Nieuwland, M.G.B., Crooijmans, R., Groenen, M.A.M., Koene, P., Korte, S.M., Bovenhuis, H. and Poel, J.J.v.d. (2003) Mapping quantitative trait loci affecting feather pecking behavior and stress response in laying hens. Poultry Science 82 (8): 1215–1222.Google Scholar
Buitenhuis, A.J., Rodenburg, T.B., Siwek, M., Cornelissen, S.J.B., Nieuwland, M.G.B., Crooijmans, R., Groenen, M.A.M., Koene, P., Bovenhuis, H., Hierden, Y.M.Van, Korte, S.M. and Poel, J.J.v.d. (2004) Identification of QTLs involved in open-field behavior in young and adult laying hens. Poultry Science 82 (8): 1215–1222.CrossRefGoogle Scholar
Cloutier, S., Newberry, R.C., Forster, C.T. and Girsberger, K.M. (2000) Does pecking at inanimate stimuli predict cannibalistic behaviour in domestic fowl? Applied Animal Behaviour Science 66 (1–2): 119–133.CrossRefGoogle Scholar
Curtis, P.E. and Marsh, N.W.A. (1992) Cannibalism in laying hens. Veterinary Record 131 (18): 424.Google Scholar
CVB (2003) Veevoedertabel 2003, Centraal Veevoederbureau, Lelystad, The Netherlands.Google Scholar
D'Eath, R. and Stone, R.J. (1999) Chickens use visual cues in social discrimination: an experiment with coloured lighting. Applied Animal Behaviour Science 62 (2–3): 233–242.Google Scholar
Deschutter, A. and Leeson, S. (1986) Feather growth and development. World's Poultry Science Journal 42 (3): 259–267.CrossRefGoogle Scholar
EC_1139/98 (1988) Council Regulation (EC) No 1139/98, amended by Commission Regulation (EC) No 49/2000 and Commission Regulation (EC) No 50/2000.Google Scholar
El Lethey, H., Aerni, V., Jungi, T.W. and Wechsler, B. (2000) Stress and feather pecking in laying hens in relation to housing conditions. British Poultry Science 41 (1): 22–28.Google Scholar
Elwinger, K. (1981) Different energy levels and restricted feeding to three strains of SCWL hybrids. 1. Effects on egg production. Swedish Journal of Agricultural Research 11 (4): 149–157.Google Scholar
Elwinger, K. and Andersson, K. (1978) Restricted feeding and different protein levels to two strains of SCWL hybrids. 1. Effects on egg production. Swedish Journal of Agricultural Research 8 (4): 231–240.Google Scholar
Elwinger, K., Tauson, R., Tufvesson, M. and Hartmann, C. (2002) Feeding of layers kept in an organic feed environment. In 11th. European Poultry ConferenceBremen.Google Scholar
Esmail, S.H.M. (1997) Fibre Nutrition. Poultry International 36 (7): 31–34.Google Scholar
Gentle, M.J. and Hunter, L.N. (1990) Physiological and behavioural responses associated with feather removal in Gallus gallus var domesticus. Research in Veterinary Science 50: 95–101.CrossRefGoogle Scholar
Hadorn, R., Gloor, A. and Wiedmer, H. (1999) Exclusion of animal protein from layer diets. In 12th European Symposium of Poultry Nutrition: pp. 349–351, Veldhoven (NL).Google Scholar
Hadorn, R., Gloor, A. and Wiedmer, H. (2001) Effect of dietary magnesium and crude fibre content on performance, mortality rate and plumage condition of brown laying hens. In Proceedings of the 6th European symposium on poultry welfare. (ed. Wyss, H. O. a. C.).Google Scholar
Hadorn, R. and Wiedmer, H. (2001) Effect of whole wheat feeding and different aviary systems on the development of white and brown growing pullets. In Proceedings of the 6th European symposium on poultry welfare. (eds. Oester, H. and Wyss, C.).Google Scholar
Hadorn, R., Wiedmer, H. and Gloor, A. (1998) Effect of the exclusion of animal proteins from layer diets. Agrarforschung 5 (9): 409–412.Google Scholar
Hansen, I. and Braastad, B.O. (1994) Effect of rearing density on pecking behaviour and plumage condition of laying hens in two types of aviary. Applied Animal Behaviour Science 40 (3–4): 263–272.Google Scholar
Hartini, S., Choct, M., Hinch, G., Kocher, A. and Nolan, J.V. (2002) Effects of light intensity during rearing and beak trimming and dietary fiber sources on mortality, egg production, and performance of ISA brown laying hens. The Journal of Applied Poultry Research 11: 104–110.CrossRefGoogle Scholar
Herremans, M., Decuypere, E. and Siau, O. (1989) Effects of feather wear and temperature on prediction of food intake and residual food consumption. British Poultry Science 30 (1): 15–22.Google Scholar
Hetland, H. and Choct, M. (2003a) Accumulation of fibre structures in the gizzard may decrease feather pecking among layers. British Poultry Science: Submitted.Google Scholar
Hetland, H. and Choct, M. (2003b) Role of insoluble non-starch polysaccharides in poultry nutrition. In Proceedings of the 14 th European Symposium of Poultry Nutrition: pp. 64–69, Lillehammer Norway.Google Scholar
Hetland, H. and Svihus, B. (2001) Effect of oat hulls on performance, gut capacity and feed passage time in broiler chickens. British Poultry Science 42 (3): 354–361.Google Scholar
Hetland, H. and Svihus, B. (2003) Insoluble fibre structures are major gizzard stimulators in layers. British Poultry Science: Submitted for publication.Google Scholar
Hetland, H., Svihus, B., Lervik, S. and Moe, R. (2003) Effect of feed structure on performance and welfare of laying hens housed in conventional and furnished cages. Acta Agriculturae Scandinavica. Section A, Animal Science 53 (2): 92–100.Google Scholar
Hetland, H., Svihus, B. and Olaisen, V. (2002) Effect of feeding whole cereals on performance, starch digestibility and duodenal particle size distribution in broiler chickens. British Poultry Science 43 (3): 416–423.Google Scholar
Heywang, B.W. and Morgan, R.B. (1944) A comparison of a pelleted and unpelleted all-mash diet for growing chickens. Poultry Science 23: 16–20.Google Scholar
Hierden, Y.M.Van, Boer, S.F.D., Korte, S.M. and Koolhaas, J.M. (2004) The control of feather pecking by serotonin. Behavioural Neuroscience 118 (3): 575–583.Google Scholar
Hierden, Y.M.Van, Korte, S.M. and Koolhaas, J.M. (2004) Chronic increase of dietary L-Tryptophan decreases gentle feather pecking behaviour. Applied Animal Behaviour Science: 89 (1/2): 71–84.Google Scholar
Hierden, Y.M.Van, Korte, S.M., Ruesink, E.W., Reenen, C.G.V., Engel, B., Korte Bouws, G.A.H., Koolhaas, J.M. and Blokhuis, H.J. (2002) Adrenocortical reactivity and central serotonin and dopamine turnover in young chicks from a high and low feather-pecking line of laying hens. Physiology and Behavior 75 (5): 653–659.CrossRefGoogle ScholarPubMed
Hoffmeyer, I. (1969) Feather pecking in pheasants - an ethological approach to the problem. Danish review of game biology 6 (1): 1–36.Google Scholar
Huber Eicher, B. and Sebo, F. (2001) The prevalence of feather pecking and development in commercial flocks of laying hens. Applied Animal Behaviour Science 74 (3): 223–231.CrossRefGoogle Scholar
Huber Eicher, B. and Wechsler, B. (1998) The effect of quality and availability of foraging materials on feather pecking in laying hen chicks. Animal Behaviour 55 (4): 861–873.CrossRefGoogle ScholarPubMed
Hughes, B.O. (1973) The effect of implanted gonadal hormones in feather pecking and cannibalism in pullets. British Poultry Science 14 (No.4): 341–348.CrossRefGoogle ScholarPubMed
Hughes, B.O. and Whitehead, C.C. (1974) Sodium deprivation, feather pecking and activity in laying hens. British Poultry Science 15 (5): 435–439.CrossRefGoogle ScholarPubMed
Hughes, B.O. and Whitehead, C.C. (1979) Behavioural changes associated with the feeding of lowsodium diets to laying hens. Applied Animal Ethology 5 (3): 255–266.Google Scholar
Jensen, L.S., Merill, L.H., Reddy, C.V. and McGinnis, J. (1962) Observations on eating patterns and rate of food passage of birds fed pelleted and unpelleted diets. Poultry Science 41: 1414–1419.Google Scholar
Johnsen, P.F., Vestergaard, K.S. and Norgaard Nielsen, G. (1998) Influence of early rearing conditions on the development of feather pecking and cannibalism in domestic fowl. Applied Animal Behaviour Science 60 (1): 25–41.CrossRefGoogle Scholar
Jones, R.B. and Hocking, P.M. (1999) Genetic selection for poultry behaviour: big bad wolf or friend in need? Animal Welfare 8 (4): 343–359.Google Scholar
Keeling, L.J. (1994) Feather pecking - who in the group does it, how often and under what circumstances? In Proceedings of the 9th European Poultry Conference: pp. 288–289, Glasgow, United Kingdom.Google Scholar
Kjaer, J.B. and Sørensen, P. (1997) Feather pecking behaviour in White Leghorns, a genetic study. British Poultry Science 38 (4): 333–341.CrossRefGoogle ScholarPubMed
Kjaer, J.B. and Sørensen, P. (2002) Feather pecking and cannibalism in free-range laying hens as affected by genotype, dietary level of methionine+cystine, light intensity during rearing and age at first access to the range area. Applied Animal Behaviour Science 76 (1): 21–39.Google Scholar
Kjaer, J.B. and Vestergaard, K.S. (1999) Development of feather pecking in relation to light intensity. Applied Animal Behaviour Science 62 (2–3): 243–254.CrossRefGoogle Scholar
Köhler, B., Föhlsch, J., Strube, J. and Lange, K. (2001) Influences of green forage and lighting conditions on egg quality and hen welfare. In Proceedings of the 6th European symposium on poultry welfare. (eds. Oester, H. and Wyss, C.).Google Scholar
Lee, A.G.v.d., Hemke, G. and Kwakkel, R.P. (2001) Low density diets improve plumage condition in non-debeaked layers. In 13th European Symposium on poultry nutrition: pp. 244–245, Blankenbergen.Google Scholar
Lee, H.Y. and Craig, J.V. (1991) Beak trimming effects on behavior patterns, fearfulness, feathering, and mortality among three stocks of White Leghorn pullets in cages or floor pens. Poultry Science 70 (2): 211–221.Google Scholar
Lindberg, A.C. and Nicol, C.J. (1994) An evaluation of the effect of operant feeders on welfare of hens maintained on litter. Applied Animal Behaviour Science 41 (3–4): 211–227.Google Scholar
McAdie, T.M. and Keeling, L.J. (2000) Effect of manipulating feathers of laying hens on the incidence of feather pecking and cannibalism. Applied Animal Behaviour Science 68 (3): 215–229.Google Scholar
McAdie, T.M. and Keeling, L.J. (2002) The social transmission of feather pecking in laying hens: effects of environment and age. Applied Animal Behaviour Science 75 (2): 147–159.CrossRefGoogle Scholar
McKeegan, D.E.F. and Savory, C.J. (1999) Feather eating in layer pullets and its possible role in the aetiology of feather pecking damage. Applied Animal Behaviour Science 65 (1): 73–85.Google Scholar
McKeegan, D.E.F. and Savory, C.J. (2001) Feather eating in individually caged hens which differ in their propensity to feather peck. Applied Animal Behaviour Science 73 (2): 131–140.CrossRefGoogle ScholarPubMed
McKeegan, D.E.F., Savory, C.J., Macleod, M.G. and Mitchell, M.A. (2001) Development of pecking damage in layer pullets in relation to dietary protein source. British Poultry Science 42 (1): 33–42.Google Scholar
Miller, M.W. and Bearse, G.E. (1937) The cannibalism preventing properties of oats. Poultry Science 16 (5): 314–321.Google Scholar
Morgenstern, R. (1995) Alternative Haltung in der Schweiz: Woran erkranken die Legehennen? DGS Magazin 4–2–1995: 11–14.Google Scholar
Nicol, C.J., Gregory, N.G., Knowles, T.G., Parkman, I.D. and Wilkins, L.J. (1999) Differential effects of increased stocking density, mediated by increased flock size, on feather pecking and aggression in laying hens. Applied Animal Behaviour Science 65 (2): 137–152.CrossRefGoogle Scholar
Nrc, N.R.C. (1994) Nutrient requirements of poultry, Washington DC.Google Scholar
Peguri, A. and Coon, C. (1993) Effect of feather coverage and temperature on layer performance. Poultry Science 72 (7): 1318–1329.Google Scholar
Pfirter, H.P. and Walser, P. (1998) Wieviel und welches protein? UFA-Reveu 11: 26–28.Google Scholar
Piliang, W.G., Bird, H.R., Sunde, M.L. and Pringle, D.J. (1984) Rice bran as the major energy source of laying hens. Poultry Adviser 17 (6): 21–31.Google Scholar
Preston, A.P. (1987) Restricted feeding time and the behaviour of caged laying hens. British Poultry Science 28 (3): 387–396.Google Scholar
Richter, G. and Hartung, H. (2003) Pflanzliche Rationen im Vergleich. DGS Magazin 1: 20–24.Google Scholar
Riedstra, B. and Groothuis, T.G.G. (2002) Early feather pecking as a form of social exploration: the effect of group stability on feather pecking and tonic immobility in domestic chicks. Applied Animal Behaviour Science 77 (2): 127–138.Google Scholar
Robel, E.J. (1977) A feather abnormality in chicks fed diets deficient in certain amino acids. Poultry Science 56: 1968–1971.Google Scholar
Rodenburg, T.B., Buitenhuis, A.J., Ask, B., Uitdehaag, K.A., Koene, P., Poel, J.J.v.d., Van, A.J.A.M. and Bovenhuis, H. (2004) Genetic and phenotypic correlations between feather pecking and open-field response in laying hens at two different ages. Behavior Genetics 34 (4): 407–415.CrossRefGoogle ScholarPubMed
Rodenburg, T.B., Buitenhuis, A.J., Ask, B., Uitdehaag, K.A., Koene, P., Van Der Poel, J.J. and Bovenhuis, H. (2003) Heritability of feather pecking and open-field response in laying hens at two different ages. Poultry Science 82: 861–867.Google Scholar
Rodenburg, T.B. and Koene, P. (2003) Comparison of individual and social feather pecking tests in two lines of laying hens at ten different ages. Applied Animal Behaviour Science 81 (2): 133–148.CrossRefGoogle Scholar
Savory, C.J. (1974) Growth and behaviour of chicks fed on pellets or mash. British Poultry Science 15 (3): 281–286.Google Scholar
Savory, C.J. (1980) Meal occurrence in Japanese quail in relation to particle size and nutrient density. Animal Behaviour 28 (1): 160–171.Google Scholar
Savory, C.J. (1995) Feather pecking and cannibalism. World's Poultry Science Journal 51 (2): 215–219.Google Scholar
Savory, C.J. (1998) Feather pecking damage in growing bantams is influenced by dietary tryptofphan concentration but not dietary protein source. Supplement British Poultry Science 39: S17–S18.Google Scholar
Savory, C.J. and Fisher, R.D.A. (1992) Influence of a period of [freeze-feeding] on behaviour of growing layers pullets. Applied Animal Behaviour Science 35 (1): 55–66.Google Scholar
Savory, C.J. and Mann, J.S. (1997) Behavioural development in groups of pen-housed pullets in relation genetic strain, age and food form. British Poultry Science 38 (1): 38–47.CrossRefGoogle ScholarPubMed
Savory, C.J. and Mann, J.S. (1999) Feather pecking in groups of growing bantams in relation to floor litter substrate and plumage colour. British Poultry Science 40 (5): 565–572.Google Scholar
Savory, C.J., Mann, J.S. and Macleod, M.G. (1999) Incidence of pecking damage in growing bantams in relation to food form, group size, stocking density, dietary tryptophan concentration and dietary protein source. British Poultry Science 40 (5): 579–584.CrossRefGoogle ScholarPubMed
Schaible, P.J., Davidson, J.A. and Bandemer, S.L. (1947) Cannibalism and feather pecking in chicks as influenced by certain changes in a specific ration. Poultry Science 26: 651–656.Google Scholar
Sirén, M.J. (1963) Cannibalism in cockerels and pheasants. Acta Veterinaria Scandinavica 4 (Supplementum 1): 1–47.Google Scholar
Steenfeldt, S., Engberg, R.M. and Kjaer, J.B. (2001) Feeding roughage to laying hens affects egg production, gastro-intestinal parameters and mortality. In Proceedings of the 13th European symposium on poultry nutrition.Blankenbergen.Google Scholar
Sunde, M.L. (1972) Zinc requirement for normal feathering of commercial Leghorn-type pullets. Poultry Science 51 (4): 1316–1322.Google Scholar
Supplee, W.C., Combs, G.F. and Blamberg, D.L. (1958) Zinc and potassium effects on bone formation, feathering and growth of poults. Poultry Science: 63–67.CrossRefGoogle Scholar
Svihus, B., Hetland, H., Choct, M. and Sundby, F. (2002) Passage rate through the anterior digestive tract of broiler chickens fed on diets with ground and whole wheat. British Poultry Science 43 (5 & Supplement): 662–668.Google Scholar
Tanaka, T., Yoshimoto, T. and Mimura, K. (1983) Feeding behaviour of laying hens fed pellets, crumbles or mash feed. Japanese Journal of Zootechnical Science 54 (7): 433–438.Google Scholar
Tauson, R. and Svensson, S.A. (1980) Influence of plumage conditions on the hen's feed requirement. Swedish Journal of Agricultural Research 10 (1): 35–39.Google Scholar
Vestergaard, K.S., Kruijt, J.P. and Hogan, J.A. (1993) Feather pecking and chronic fear in groups of red junglefowl: their relations to dustbathing, rearing environment and social status. Animal Behaviour 45: 1127–1140.CrossRefGoogle Scholar
Wahlstrom, A., Tauson, R. and Elwinger, K. (1998) Effects on plumage condition, health and mortality of dietary oats/wheat ratios to three hybrids of laying hens in different housing systems. Acta Agriculturae Scandinavica. Section A, Animal Science 48 (4): 250–259.Google Scholar
Wahlstrom, A., Tauson, R. and Elwinger, K. (2001) Plumage condition and health of aviary-kept hens fed mash or crumbled pellets. Poultry Science 80 (3): 266–271.Google Scholar
Walser, P. and Pfirter, H.P. (2001) Feed structure influences behaviour of laying hens. In Proceedings of the 6th European symposium on poultry welfare. (eds. Oester, H. and Wyss, C.).Google Scholar
Wechsler, B., Huber Eicher, B. and Nash, D.R. (1998) Feather pecking in growers: a study with individually marked birds. British Poultry Science 39 (2): 178–185.Google Scholar
Willimon, C.P. and Morgan, C.L. (1953) The effect of minor nutrient mineral elements in the diet of chickens on feather pulling and cannibalism. Poultry Science 32: 309–313.Google Scholar
Wouw, S.v.d (1995) Kannibalisme bij biologische legkippen. Landbouw Universiteit Wageningen Wageningen.Google Scholar
Zeltner, E., Klein, T. and Huber Eicher, B. (2000) Is there social transmission of feather pecking in groups of laying hen chicks? Animal Behaviour 60 (2): 211–216.Google Scholar