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Title:Linear Additivity of Multiple Concurrent Environmental Stressors' Effects on Chick Performance, Physiology, Histopathology, and Behavior
Author(s):Mcfarlane, James Michael
Department / Program:Animal Science
Discipline:Animal Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(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.
Issue Date:1987
Description:376 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.
Other Identifier(s):(UMI)AAI8721710
Date Available in IDEALS:2014-12-15
Date Deposited:1987

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