Linear Additivity of Multiple Concurrent Environmental Stressors' Effects on Chick Performance, Physiology, Histopathology, and Behavior
Mcfarlane, James Michael
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https://hdl.handle.net/2142/70051
Description
Title
Linear Additivity of Multiple Concurrent Environmental Stressors' Effects on Chick Performance, Physiology, Histopathology, and Behavior
Author(s)
Mcfarlane, James Michael
Issue Date
1987
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Culture and Nutrition
Abstract
Whether concurrent stressors synergize in affecting chicks was studied. Results suggest stressors affected chicks in similar fashion when acting singly or together; i.e., effects were additive. Experiment I. New Hampshire x Columbian chicks were studied via 2$\sp{4}$-factorial of aerial ammonia (A, O or 125 ppm), beak-trimming (B, sham or trimmed trial d 1), coccidiosis (C, O or 4 $\times$ 10$\sp{5}$ sporulated E. acervulina oocysts d 1), and heat (H, air 30.4 or 36.5 C). Five 7-d trials had 15 6-chick replicates of 16 treatments. All stressors decreased chick weight gain (G), feed intake (F), and G/F, except B for G/F; A x C for G was only interaction. A, C, and H increased s$\sp{2}$/x for G among chicks in treatment groups (CV-G). As stressor number (order) rose from 0 to 4, G, F, and G/F fell, and CV-G rose, linearly. D-7 heterophil %/lymphocyte % (h/l) rose due to all stressors and linearly with order. Only C affected blood total-cell fraction. Experiment II. Hubbard chicks were studied via 2$\sp{6}$-factorial of A and B (as Exp. I), C (0 or 6 $\times$ 10$\sp{5}$ oocysts as Exp. I), random electric shock (E, O or 3-10 mA), H (air 30.4 or 34.8 C), and continuous white noise (N, 80 or 95 dB). Four 7-d trials had 6 3-chick replicates of 64 treatments. All stressors but N decreased G, F, and G/F and increased CV-G; few interactions were found. As order rose from 0 to 6, G, F, and G/F fell linearly. No treatment affected d-7 plasma corticosterone. C increased carcass-water content and decreased chloroform/methanol-extract, A increased crude-protein, and C decreased carcass-energy; few interactions were found. Order did not affect composition. C increased standing and eating, H decreased drinking, times; few interactions were found. C damaged kidneys and duodenal mucosa; H mitigated the lesions. N caused, and synergized positively with C for, duodenal lesions. A caused, but H mitigated, hepatic lesions. Order affected no lesion score.
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