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Is there a positive side to stress?*

Published online by Cambridge University Press:  18 September 2007

I. Zulkifli
Affiliation:
Animal Poultry Sciences Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0306, USA
P.B. Siegel
Affiliation:
Animal Poultry Sciences Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061-0306, USA
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Abstract

Although it is generally assumed that stress is detrimental to the well-being of poultry, there are positive aspects which are often overlooked. In the context of evolution, stressors such as infectious agents, climatic extremes, and domestication processes play important roles in inter-population and intra-population genetic variability. Pathological, immunological and behavioural studies in both avian and mammalian species indicate that too much or too little stress is undesirable, and that a certain degree of stress is essential for maintaining normal biological functions. Prior stressful experiences, particularly during the neonatal stage, may have long-term benefits in helping an individual to cope with subsequent stressors. Reliability of stress indicators and their variability at both population and individual levels is a major factor in attempting to quantify ‘optimum stress’.

Type
Research Article
Copyright
Copyright © Cambridge University Press 1995

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References

Adams, A.W. and Craig, J.V. (1985) Effect of crowding and cage shape on productivity and profitability of caged layers: a survey. Poultry Science 64: 238242CrossRefGoogle Scholar
Ahmad, M., Mather, F.B. and Gleaves, E.W. (1974) Effect of environmental temperature and dietary energy on dwarf and normal hens and normal roosters. Poultry Science 53: 927935CrossRefGoogle ScholarPubMed
Allen, W.M., Berrett, S., Harding, J.D.J. and Patterson, D.S.P. (1970) Experimentally induced acute stress syndrome in Pietrain pigs. Veterinary Record 87: 6469CrossRefGoogle ScholarPubMed
Andrews, L.D. and Goodwin, T.L. (1969) The effect of debeaking, floor space and diet energy levels on broiler growth. Poultry Science 48: 191196CrossRefGoogle ScholarPubMed
Archer, J. (1979) Animals under Stress. Edward Arnold, LondonGoogle Scholar
Arjona, A.A., Denbow, D.M. and Weaver, W.D. (1988) Effects of heat stress early in life on mortality of broilers exposed to high environmental temperatures prior to marketing. Poultry Science 67: 226231CrossRefGoogle ScholarPubMed
Bareham, J.R. (1972) Effects of cages and semi-intensive deep-litter pens on the behaviour, adrenal response and production of two strains of laying hens. British Veterinary Journal 128: 153163CrossRefGoogle ScholarPubMed
Beebe, W. (1926) Pheasants: Their Lives and Homes. Vol. 1. Doubleday, Page & Company, Garden City, New YorkGoogle Scholar
Belyaev, D.K. (1979) Destabilizing selection as a factor in domestication. Journal of Heredity 70: 301308CrossRefGoogle ScholarPubMed
Belyaev, D.K. and Borodin, P.M. (1982) The influence of stress on variation and its role in evolution. Biologisches Zentralblatt 100: 705714Google Scholar
Benion, N.L. and Warren, D.C. (1933) Temperature and its effect on egg size in the domestic fowl. Poultry Science 12: 6982CrossRefGoogle Scholar
Besedovsky, H.O., Del Rey, A., Sorkin, E., Da Prada, M. and Keller, H.H. (1979) Immunoregulation mediated by the sympathetic nervous system. Cellular Immunology 48: 346355CrossRefGoogle ScholarPubMed
Bohus, B., Koolhaas, J.M., Nyakas, C., Steffens, A.B., Fokkema, D.S. and Scheurink, A.J.W. (1987) Physiology of stress: a behavioral view. In: Biology of Stress in Farm Animals (Eds Wiepkema, P.R. and van Adrichem, P.W.M.), Martinus Nijhoff, Dordrecht, Netherlands, pp. 5770CrossRefGoogle Scholar
Bolton, W., Dewar, W.A., Jones, R.M. and Thompson, R. (1972) Effect of stocking density on performance of broiler chicks. British Poultry Science 13: 157162CrossRefGoogle Scholar
Bouillon, D.J. and Berdanier, C.D. (1981) Effect of adrenalectomy on the diurnal variation in glycogen metabolism in starved-refed rats. Journal of Nutrition 111: 14721474CrossRefGoogle ScholarPubMed
Bowen, S.J. and Washburn, K.W. (1984) Preconditioning to heat stress by a nontemperature stressor. Poultry Science 63: 917919CrossRefGoogle ScholarPubMed
Brown, C.W., Gross, W.B. and Ehrich, M. (1986) Effect of social stress on the toxicity of malathion in young chickens. Avian Diseases 30: 679682CrossRefGoogle ScholarPubMed
Brown, K.I. and Nestor, K.E. (1973) Some physiological responses of turkeys selected for high and low adrenal response to cold stress. Poultry Science 52: 19481954CrossRefGoogle ScholarPubMed
Brown, K.I. and Nestor, K.E. (1974) Implications of selection for high and low adrenal response to stress. Poultry Science 53: 12971306CrossRefGoogle ScholarPubMed
Cahaner, A. and Leenstra, F. (1992) Effects of high temperature on growth and feed efficiency of male and female broilers from lines selected for high weight gain, favorable feed conversion, and high or low fat content. Poultry Science 71: 12371250CrossRefGoogle ScholarPubMed
Caughley, G., Short, J., Grigg, G.C. and Nix, H. (1987) Kangaroos and climate: an analysis of distribution. Journal of Animal Ecology 56: 751761CrossRefGoogle Scholar
Clark, C.E. and Sarakoon, K. (1967) Influence of ambient temperature on reproductive traits of male and female chickens. Poultry Science 46: 10931098CrossRefGoogle Scholar
Crawford, R.D. (1990) Poultry genetic resources: evolution, diversity, and conservation. In: Poultry Breeding and Genetics (Ed. Crawford, R.D.), Elsevier, Amsterdam, pp. 4360Google Scholar
Dämmrich, K. (1987) Organ changes and damage during stress – morphological diagnosis. In: Biology of Stress in Farm Animals (Eds Wiepkema, P.R. and van Adrichem, P.W.M.), Martinus Nijhoff, Dordrecht, Netherlands, pp. 7181CrossRefGoogle Scholar
Dantzer, R. and Mormede, P. (1985) Stress in domestic animals: a psychoneuroendocrine approach. In: Animal Stress (Ed. Moberg, G.P.) Waverly Press, Baltimore, MD, pp. 8196CrossRefGoogle Scholar
Dawkins, M.S. (1980) Animal Suffering. Chapman and Hall, LondonCrossRefGoogle Scholar
De Andrade, A.N., Rogler, J.C. and Featherston, W.R. (1974) Effect of heat stress and diet in shell quality and performance of laying hens. Poultry Science 53: 19161917Google Scholar
De Andrade, A.N., Rogler, J.C. and Featherston, W.R. (1976) Influence of constant elevated temperature and diet on egg production and shell quality. Poultry Science 55: 685693CrossRefGoogle Scholar
De Andrade, A.N., Rogler, J.C. and Featherston, W.R. (1977) Interrelationships between diet and elevated temperature (cyclic and constant) on egg production and shell quality. Poultry Science 56: 11781188CrossRefGoogle Scholar
Duncan, I.J.H. (1970) Frustration in the fowl. In: Aspects of Poultry Behaviour (Eds Freeman, B.M. and Gordon, R.F.), British Poultry Science, Edinburgh, pp. 1531.Google Scholar
Duncan, I.J.H. and Wood-Gush, D.G.M. (1971) Frustration and aggression in the domestic fowl. Animal Behavior 19: 500504CrossRefGoogle ScholarPubMed
Duncan, I.J.H. and Wood-Gush, D.G.M. (1972) Thwarting of feeding behavior in the domestic fowl. Animal Behavior 20: 444451CrossRefGoogle ScholarPubMed
Dunnington, E.A., Stallard, L.C., Hillel, J. and Siegel, P.B. (1994) Genetic diversity among commercial chicken populations estimated from DNA fingerprints. Poultry Science 73: 12181225CrossRefGoogle ScholarPubMed
Everly, G.S. Jr. and Sobelman, S.A. (1987) Assessment of the Human Stress Response. AMS Press, New YorkGoogle Scholar
Ewbank, R. (1985) Behavioral responses to stress in farm animals. In: Animal Stress (Ed. Moberg, G.P.), Waverly Press, Baltimore, MD, pp. 7180CrossRefGoogle Scholar
Ferguson, W. (1969) The role of social stress in epidemiology. British Veterinary Journal 125: 253254Google Scholar
Freeman, B.M. (1971) Stress and the domestic fowl: a physiological appraisal. World's Poultry Science Journal 27: 263275CrossRefGoogle ScholarPubMed
Freeman, B.M. (1976) Stress and the domestic fowl: a physiological re-appraisal. World's Poultry Science Journal 32: 249256CrossRefGoogle Scholar
Freeman, B.M. (1985) Stress and the domestic fowl: physiological fact or fantasy? World's Poultry Science Journal 41: 4550CrossRefGoogle Scholar
Freeman, B.M., Manning, A.C.C. and Flack, I.H. (1981) The effects of restricted feeding on adrenal cortical activity in the immature domestic fowl. British Poultry Science 22: 295303CrossRefGoogle ScholarPubMed
Garren, H.W. and Shaffner, C.S. (1954) Factors concerned in the response of young New Hampshires to muscular fatigue. Poultry Science 33: 10951104CrossRefGoogle Scholar
Garren, H.W. and Shaffner, C.S. (1956) How the period of exposure to different stress stimuli affects the endocrine and lymphatic gland weight of young chickens. Poultry Science 35: 266272CrossRefGoogle Scholar
Glick, B. (1967) Antibody and gland studies in cortisone and ACTH-injected birds. Journal of Immunology 98: 10761084CrossRefGoogle ScholarPubMed
Gowe, R.S., Johnson, A.S., Crawford, R.D., Downs, J.H., Hill, A.T., Mountain, W.F., Peletier, J.F. and Strain, J.H. (1960) Restricted versus full-feeding during the growing period for egg production stock. British Poultry Science 1: 3756Google Scholar
Gross, W.B. (1962) Blood culture, blood counts, and temperature records in an experimentally produced ‘air sac disease’ and uncomplicated Escherichia coli infection of chickens. Poultry Science 41: 691700CrossRefGoogle Scholar
Gross, W.B. (1972) Effect of social stress on occurrence of Marek's disease. American Journal of Veterinary Research 33: 22752279Google ScholarPubMed
Gross, W.B. (1976) Plasma steroid tendency, social environment and Eimeria necatrix infection. Poultry Science 55: 15081512CrossRefGoogle ScholarPubMed
Gross, W.B. (1983) Chicken-environment interactions. In: Ethics and Animals (Eds Miller, H.B. and Williams, W.H.), Humana Press, Cliffton, NJ, pp. 329337CrossRefGoogle Scholar
Gross, W.B. (1985) Effect of social environment and oocyst dose on resistance and immunity to Eimeria tenella challenge. Avian Diseases 29: 10181028CrossRefGoogle ScholarPubMed
Gross, W.B. (1989) Effect of adrenal blocking chemicals on viral and respiratory infections in chickens. Canadian Journal of Veterinary Research 53: 4851Google ScholarPubMed
Gross, W.B. and Colmano, G. (1969) Effect of social isolation on resistance to some infectious agents. Poultry Science 48: 514520CrossRefGoogle Scholar
Gross, W.B. and Siegel, H.S. (1965) The effect of social stress on resistance to infection with Escherichia coli or Mycoplasma gallisepticum. Poultry Science 44: 9981001CrossRefGoogle Scholar
Gross, W.B. and Siegel, P.B. (1980) Effects of early environmental stresses on chicken body weight, antibody response to RBC antigens, feed efficiency, and response to fasting. Avian Diseases 24: 569579CrossRefGoogle ScholarPubMed
Gross, W.B. and Siegel, P.B. (1981) Long-term exposure of chickens to three levels of social stress. Avian Diseases 25: 312325CrossRefGoogle ScholarPubMed
Gross, W.B. and Siegel, P.B. (1982) Influences of sequences of environmental factors on the response of chicken to fasting and to Staphylococcus aureus infection. American Journal of Veterinary Research 43: 137139Google ScholarPubMed
Gross, W.B. and Siegel, H.S. (1983) Evaluation of heterophil/lymphocyte as a measurement of stress in chickens. Avian Diseases 27: 972979CrossRefGoogle ScholarPubMed
Gross, W.B. and Siegel, P.B. (1986) Effect of initial and second period of fasting on heterophil and lymphocyte ratios and body weight. Avian Diseases 30: 345346CrossRefGoogle ScholarPubMed
Gross, W.B. and Siegel, P.B. (1993) General principles of stress and welfare. In: Livestock, Handling and Transport (Ed. Grandin, T.), CAB International, Wallingford, UK, pp. 2134.Google Scholar
Gross, W.B., Dunnington, E.A. and Siegel, P.B. (1984) Environmental effects on the wellbeing of chickens from lines selected for responses to social strife. Archives für Geflugelkunde 48: 37Google Scholar
Hale, E.B. (1969) Domestication and the evolution of behavior. In: The Behavior of Domestic Animals (Ed. Hafez, E.S.E.), Williams and Wilkins, Baltimore, MD, pp. 2242Google Scholar
Hall, R.D., Gross, W.B. and Turner, E.C. Jr. (1979) Population development of Ornithonyssus sylvarium (canestrini and fazango) on Leghorn roosters inoculated with steroids and subjected to extremes of social interaction. Veterinary Parasitology 5: 287297CrossRefGoogle Scholar
Han, P.F.S. and Smyth, J.R. Jr. (1972) The influence of restricted feed intake on the response of chickens to Marek's disease. Poultry Science 51: 986990CrossRefGoogle ScholarPubMed
Harvey, S., Klandorf, H. and Pinchasov, Y. (1983) Visual and metabolic stimuli cause adrenocortical suppression in fasted chickens during refeeding. Neuroendocrinology 37: 5963CrossRefGoogle ScholarPubMed
Harvey, S., Phillips, J.G., Rees, A. and Hall, T.R. (1984) Stress and adrenal function. Journal of Experimental Zoology 232: 633645CrossRefGoogle ScholarPubMed
Huston, T.M. and Edwards, H.M. (1961) The effect of environmental temperature upon growth and feed efficiency of domestic fowl. Poultry Science 40: 1417 (abstract)Google Scholar
Jones, R.B. (1987) Social and environmental aspects of fear. In: Cognitive Aspects of Social Behaviour in Domestic Fowl (Eds Zayan, R. and Duncan, I.), Elsevier, Amsterdam, pp. 82149Google Scholar
Katanbaf, M.N., Dunnington, E.A. and Siegel, P.B. (1989) Restricted feeding in early and late feathering chickens. 1. Growth and physiologial responses. Poultry Science 68: 344351CrossRefGoogle Scholar
Klasing, K.C. (1988) Influence of acute feed deprivation or excess feed intake on immunocompetence of broiler chicks. Poultry Science 67: 626634CrossRefGoogle ScholarPubMed
Kowalczyk, T. (1969) Etiologic factors of gastric ulcers in swine. American Journal of Veterinary Research 30: 393400Google ScholarPubMed
Levine, S. (1962) Plasma-free corticosteroid response to electric shock in rats stimulated in infancy. Science 135: 795796CrossRefGoogle ScholarPubMed
Levins, S. (1971) Stress and behavior. Scientific American 224: 2631CrossRefGoogle Scholar
Lindgren, D. (1972) The temperature influence on the spontaneous mutation rate. Hereditas 70: 165178CrossRefGoogle ScholarPubMed
Marsh, J.T., Lavender, J.F., Chang, S.S. and Rasmussen, A.F. (1963) Poliomyelitis in monkeys: decreased susceptibility after avoidance stress. Science 140: 14141415CrossRefGoogle ScholarPubMed
Marsteller, F.A., Siegel, P.B. and Gross, W.B. (1980) Agonistic behavior, the development of social hierarchy and stress in genetically diverse flocks of chickens. Behavioural Processes 5: 339354CrossRefGoogle ScholarPubMed
Marx, J.L. (1983) Surviving heat shock and other stresses. Science 221: 251253CrossRefGoogle ScholarPubMed
Mauldin, J.M. and Siegel, P.B. (1979) ‘Fear’, headshaking and production in five populations of caged chickens. British Poultry Science 20, 3944CrossRefGoogle Scholar
Maxwell, M.H. (1993) Avian blood leucocyte responses to stress. World's Poultry Science Journal 49: 3443CrossRefGoogle Scholar
Maxwell, M.H., Robertson, G.W., Spence, S. and McCorquodale, C.C. (1990) Comparison of hematological values in restricted- and ad libitum-fed domestic fowls: red blood cell characteristics. British Poultry Science 31: 407413CrossRefGoogle Scholar
Maxwell, M.H., Hocking, P.M. and Robertson, G.W. (1992) Differential leucocyte responses to various degrees of food restriction in broilers, turkeys and ducks. British Poultry Science 33: 177187CrossRefGoogle ScholarPubMed
May, J.D., Deaton, J.W. and Branton, S.L. (1987) Body temperature of acclimated broilers during exposure to high temperature. Poultry Science 66: 378380CrossRefGoogle ScholarPubMed
McBride, G. (1980) Adaptation and welfare at the man-animal interface. In: Behavior in Relation to Reproduction, Management and Welfare of Farm Animals. Reviews in Rural Science IV (Eds Wodzicka-Tomaszewska, M., Edey, T.N. and Lynch, J.J.), University of New England, Armidale, New South Wales, pp. 195198Google Scholar
McFarlane, J.M., Curtis, S.E., Shanks, R.D. and Carmer, S.G. (1989) Multiple concurrent stressors in chicks. 1. Effect on weight gain, feed intake, and behavior. Poultry Science 68: 501509CrossRefGoogle ScholarPubMed
McLean, J.G. (1973) Equine paralytic myoglobinuria (azoturia). A review. Australian Veterinary Journal 40: 4143CrossRefGoogle Scholar
Mench, J.A. (1988) The development of aggressive behavior in male broiler chicks: a comparison with laying-type males and the effects of feed restriction. Applied Animal Behavior Science 21: 233242CrossRefGoogle Scholar
Mench, J.A., Van Tienhoven, A., Marsh, J.A., McCormick, C.C., Cunningham, D.L. and Baker, R.C. (1986) Effects of cage and floor pen management on behavior, production, and physiological responses of laying hens. Poultry Science 65: 10581069CrossRefGoogle ScholarPubMed
Moberg, G.P. (1985) Biological responses to stress: key to assessment of animal suffering and well-being. In: Animal Stress (Ed. Moberg, G.P.), Waverly Press, Baltimore, MD, pp. 2750CrossRefGoogle Scholar
Mowbray, R.M. and Sykes, A.H. (1971) Egg production in warm environmental temperature. British Poultry Science 12: 2529CrossRefGoogle Scholar
Munck, A. and Guyre, P.M. (1991) Glucocorticoids and immune function. In: Psychoneuroimmunology (Eds Ader, R., Felten, D.L. and Cohen, N.), Academic Press, San Diego, pp. 447493CrossRefGoogle Scholar
Munck, A., Guyre, P.M. and Holbrook, N.J. (1984) Physiological functions of glucocorticoids in stress and their relation to pharmacological actions. Endocrine Reviews 5: 2544CrossRefGoogle ScholarPubMed
Nicol, C.J. and Guilford, T. (1991) Exploratory activity as a measure of motivation in deprived hens. Animal Behavior 41: 333341CrossRefGoogle Scholar
Nir, I., Yam, D. and Perek, M. (1975) Effect of stress on the corticosterone content of the blood plasma and adrenal gland of intact and bursectomized Gallus domesticus. Poultry Science 54: 21012110CrossRefGoogle ScholarPubMed
North, M.O. and Bell, D.D. (1990) Commercial Chicken Production Manual. Chapman and Hall, New YorkGoogle Scholar
O'Sullivan, N.P., Dunnington, E.A., Smith, E.J., Gross, W.B. and Siegel, P.B. (1991) Performance of early and late feathering broiler breeder females with different feeding regimes. British Poultry Science 32: 981995CrossRefGoogle Scholar
Parsons, P.A. (1988) Evolutionary rates: effects of stress upon recombination. Biological Journal of Linnean Society 35: 4968CrossRefGoogle Scholar
Proudfoot, F.G., Hulan, H.W. and Ramey, D.R. (1979) Effect of four stocking densities on broiler carcass grade, the incidence of breast blisters and other performance traits. Poultry Science 58: 791793CrossRefGoogle Scholar
Raup, D.M. and Boyajian, G.E. (1988) Patterns of generic extinction in the fossil record. Paleobiology 14: 109125CrossRefGoogle ScholarPubMed
Reece, F.N., Deaton, J.W. and Kubena, L.F. (1972) Effects of high temperature and humidity on heat prostration of broiler chickens. Poultry Science 51: 20212025CrossRefGoogle ScholarPubMed
Rees, A., Harvey, S. and Phillips, J.G. (1985) Adrenocortical responses to novel stressors in acutely and repeatedly starved chickens. General and Comparative Endocrinology 59: 105109CrossRefGoogle ScholarPubMed
Rice, P.L. (1987) Stress and Health. Brooks/Cole Publ. Co., Monterey, CAGoogle Scholar
Robbins, K.R., McGhee, G.C., Osei, P. and Beauchene, R.E. (1986) Effects of feed restriction on growth, body composition, and egg production of females through 68 weeks of age. Poultry Science 65: 22262231CrossRefGoogle ScholarPubMed
Root, T. (1988) Environmental factors associated with avian distributional limits. Journal of Biogeography 15: 489505CrossRefGoogle Scholar
Rushen, J. (1991) Problems associated with the interpretation of physiological data in the assessment of animal welfare. Applied Animal Behaviour Science 28: 381386CrossRefGoogle Scholar
Sapolsky, R.M. (1992a) Neuroendocrinology of the stress response. In: Behavioral Endocrinology (Eds Becker, J.B., Breedlove, S.M. and Crews, D.), MIT Press, Cambridge, MA, pp. 287324Google Scholar
Sapolsky, R.M. (1992b) Stress, the Aging Brain and the Mechanism of Neuron Death. MIT Press, Cambridge, MAGoogle Scholar
Satterlee, D.G. and Johnson, W.A. (1988) Selection of Japanese quail for contrasting blood corticosterone response to immobilization. Poultry Science 67: 2532CrossRefGoogle ScholarPubMed
Selye, H. (1937) Studies on adaptation. Endocrinology 21: 169188CrossRefGoogle Scholar
Selye, H. (1976) The Stress of Life. McGraw-Hill Book Co., New YorkGoogle Scholar
Selye, H. (1980) The stress concept today. In: Handbook of Stress and Anxiety (Eds Kutash, I.L., Schlesinger, L.B. and associates), Jossey-Bass Publisher, San Francisco, pp. 127143Google Scholar
Shea, M.M., Mench, J.A. and Thomas, O.P. (1990) The effect of dietary tryptophan on aggressive behavior in developing and mature broiler breeder males. Poultry Science 69: 16641669CrossRefGoogle ScholarPubMed
Siegel, H.S. (1971) Adrenal, stress and the environment. World's Poultry Science Journal 27: 327349CrossRefGoogle Scholar
Siegel, H.S. (1980) Physiological stress in birds. Bioscience 30: 529534CrossRefGoogle Scholar
Siegel, H.S. (1983) Effects of intensive production methods on livestock health. Agro-Ecosystem 8: 215230CrossRefGoogle Scholar
Siegel, P.B. (1979) Behavior genetics in chickens. World's Poultry Science Journal 35: 919CrossRefGoogle Scholar
Siegel, P.B. (1984) The role of behavior in poultry production: a review of research. Applied Animal Ethology 11: 299316CrossRefGoogle Scholar
Siegel, P.B. and Dunnington, E.A. (1990) Behavioral genetics. In: Poultry Breeding and Genetics (Ed. Crawford, R.D.), Elsevier, Amsterdam, pp. 877896Google Scholar
Siegel, P.B., Haberfeld, A., Mukherjee, T.K., Stallard, L.C., Marks, H.L. and Dunnington, E.A. (1992) Jungle fowl-domestic fowl relationships: a use of DNA fingeprinting. World's Poultry Science Journal 48: 147155CrossRefGoogle Scholar
Smith, A.J. (1973) Some effects of high environmental temperatures on the productivity of laying hens. Tropical Animal Health and Production 5: 259271CrossRefGoogle ScholarPubMed
Warren, D.C. and Schnepel, R.L. (1940) The effect of air temperatures on egg shell thickness in the fowl. Poultry Science 19: 6772CrossRefGoogle Scholar
Webster's New Collegiate Dictionary (1981) G and C Merriam Co., Springfield, MAGoogle Scholar
Wiens, J.A. (1974) Climatic instability and the ‘ecological saturation’ of bird communities in North American grasslands. Condor 76: 385400CrossRefGoogle Scholar
Williams, N.S. (1984) Stress and the behavior of domestic fowl. World's Poultry Science Journal 40: 215220CrossRefGoogle Scholar
Wilson, H.R., Armas, A.E., Ross, I.J., Dorminey, R.W. and Wilson, C.J. (1966) Familial differences of Single Comb White Leghorn chickens in tolerance to high ambient temperature. Poultry Science 45: 784788CrossRefGoogle ScholarPubMed
Wilson, H.R., Wilcox, C.J., Voitle, R.A., Baird, C.D. and Dorminey, R.W. (1975) Characteristics of White Leghorn chickens selected for heat tolerance. Poultry Science 54: 126130CrossRefGoogle ScholarPubMed
Zayan, R. (1990) Perspectives in the study of social stress. In: Social Stress in Domestic Animals (Eds Zayan, R. and Dantzer, R.), Kluwer Academic, Norwell, MA, pp. 3169Google Scholar
Zulkifli, I., Dunnington, E.A., Gross, W.B., Larsen, A.S., Martin, A. and Siegel, P.B. (1993) Responses of dwarf and normal chickens to feed restriction, Eimeria tenella infection, and sheep red blood cell antigen. Poultry Science 72: 16301640CrossRefGoogle ScholarPubMed
Zulkifli, I., Dunnington, E.A., Gross, W.B. and Siegel, P.B. (1994a) Food restriction early or later in life and its effect on adaptability, disease resistance, and immunocompetence of heat-stressed dwarf and nondwarf chickens. British Poultry Science 35: 203214CrossRefGoogle ScholarPubMed
Zulkifli, I., Dunnington, E.A., Gross, W.B. and Siegel, P.B. (1994b) Inhibition of adrenal steroidogenesis, food restriction and acclimation to high ambient temperatures in chickens. British Poultry Science 35: 417426CrossRefGoogle ScholarPubMed
Zulkifli, I. and Siegel, P.B. (1994) Heterophil to lymphocyte ratios during perinatal and neonatal stages in chickens. British Poultry Science 35: 309313CrossRefGoogle ScholarPubMed