Hartmut Siegel

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The number of lymphocytes in chicken blood samples decreased and the number of heterophils increased in response to stressors and to increasing levels of corticosterone in the chicken feed. The ratio of heterophils to lymphocytes was less variable than the number of heterophil or lymphocyte cells, and the range of values for this ratio was greater than the(More)
Chickens from third generation matings of lines of chickens selected for high (HA) and low (LA) antibody production to sheep red blood cells (SRBC) and typed for MHC genotypes B13/13, B13/21, and B21/21 were used in this study. Chickens from both lines carried all the three genotypes B13/13, B13/21, and B21/21. To study T- and B-lymphocytes mitogenic(More)
A RIA for mammalian adrenocorticotropic hormone (ACTH) was modified and validated to measure chicken ACTH. The assay was capable of detecting an increase in chicken plasma ACTH following treatments known to increase plasma ACTH. Both splenic and peripheral blood leukocytes stimulated with corticotropin-releasing factor (CRF) showed a significant increase in(More)
1. Stress describes the bird's defence mechanisms and a stressor is the situation that elicits the defence response. 2. As the environment can be viewed as a composite of interacting stressors, the bird's success in coping with its environment depends on the severity of the stressors and the physiological ability to respond properly and thus maintain(More)