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Title: Role of thyroid hormones, maternal antibodies, and antibody response in the susceptibility to colibacillosis of broiler genotypes
Authors: Ask, B ×
Decuypere, Eddy
van der Waaij, E. H #
Issue Date: Dec-2006
Publisher: Poultry science assoc inc
Series Title: Poultry science vol:85 issue:12 pages:2141-2148
Abstract: The purpose of this study was to investigate whether differences in susceptibility to colibacillosis are associated with maternal antibodies, antibody response, and alterations in thyroid hormones [triiodothyronine (T-3) and thyroxine (T-4)] and to investigate the effect of genotype on the changes in T-3 and T-4 during challenge and antibody response. A challenge experiment was executed in 2 trials. Per trial, 24 chicks per genotype were challenged, and 20 chicks per genotype were controls. At 7 d of age, challenged chicks were intratracheally inoculated with 0.3 mL of Escherichia coli O78K80 and controls with 0.3 mL of PBS. All chicks were euthanized at 14 or 15 d. Thyroid hormone plasma concentrations and E. coli-specific antibody titers (AB) were measured at 7 d (T-3 d7, T-4 d7, and AB(d7)) and 14 or 15 d (change from 7 to 14 or 15 d was analyzed: Delta T-3, Delta T-4, and Delta AB). Susceptibility was defined based on mortality, lesions, growth retardation, and eating behavior. There was a significant effect of challenge on T-3 d7; probably due to eating pattern in association with circadian rhythm. The challenge group was suggested to have functional hypothyroidism relative to the control group, indicating metabolic changes due to the challenge, and it was indicated that an antibody response was elicited. Differences in susceptibility were not significantly related to differences in T-3 d7, T-4 d7, Delta T-3, or Delta T-4 or to maternal antibodies (AB(d7)), but the antibody response tended to increase (decreasing Delta AB) with increasing susceptibility. There were indications of genetic variation in T-4 d7, Delta T-4, AB(d7), and Delta AB, but there was no observed effect of genotype on Delta T-3 and Delta T-4 during challenge or on the antibody response. Further, there were indications that selection for growth traits has resulted in alterations in Delta T-4 due to challenge, as indicated by a lower Delta T-4 in the challenge group relative to the control group for more intensively selected genotypes as opposed to a higher Delta T-4 for less intensively selected genotypes.
ISSN: 0032-5791
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Division of Livestock-Nutrition-Quality (-)
× corresponding author
# (joint) last author

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