Murray State Theses and Dissertations

Abstract

Stress has long been a topic of interest in the poultry industry due to its potential negative effects on chicken health and production of both eggs and meat. With increased global growth in egg and broiler production, more attention has been paid to the stressors that affect chickens in modern poultry operations, particularly environmental temperature and stocking density. Improving quantitative measurement of stress is always needed in poultry welfare research. In most studies, blood serum is measured for corticosterone, one of the biomarker hormones associated with stress in chickens. Methods of collecting blood serum are by their nature disruptive to the chicken and leave it with a higher level of stress than they previously experienced. Because of this, more research studies have been dedicated to evaluating different non-invasive ways to measure stress in poultry flocks. Fecal corticosterone levels are non-invasive and are used to quantify stress in wildlife. This method has been studied extensively in layer hens. Recent research has also focused on its use in broiler operations. This study investigated if fecal and serum corticosterone concentrations could be measured in a small flock of chickens managed with minimal control over environmental conditions. At 43 days of age (day 0), 24 male broilers were given either tap water or water treated with a corticosterone supplement (CORT, 20mg/L) for 48 hours. Blood was collected from one chicken per group (8 groups with 3 chickens per group) at -24, 6, 12, 24, 48, 72, and 96 h. Chickens were rotated between blood draws. Fecal samples were collected during the time of blood drawn from the bottom of each cage. Body weight was recorded for each group after blood was drawn. Data was analyzed using the Mixed procedure of SAS 9.4 with fixed effects of treatment and hour. CORT treatment reduced body weight at all time points. H:L (heterophil to lymphocyte) ratio increased until 12 h and then decreased. Average serum CORT concentration increased to peak at 6 h and returned to baseline values by 24 h after onset of treatment. Average fecal CORT concentration increased to peak at 12 h and returned to baseline concentrations by 72 h after onset of treatment. The results of this study were compared to a previously published study on a larger flock in a more controlled environment. The results from this study indicate that fecal CORT concentrations reflect serum CORT concentrations with a 6 h delay, as compared to previously published research where there was a 12 h delay. Both sample methods allow for the measurement of stress in broilers.

Year manuscript completed

2023

Year degree awarded

2023

Author's Keywords

Broiler, Physiological Stress, Corticosterone, Fecal, Serum, Well-being

Dissertation Committee Chair

Thomas Powell

Thesis Advisor

Thomas Powell

Committee Chair

Thomas Powell

Committee Member

Shea Porr

Committee Member

Barbie Papajeski

Committee Member

Kristie Guffey

Committee Member

Alyx Shultz

Committee Member

Debbie Reed

Document Type

Thesis

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