Research Note: A sip of stress. Effects of corticosterone supplementation in drinking water on feather corticosterone concentrations in layer pullets

Abstract

The measurement of feather corticosterone concentrations ( fCORT ) is a comparatively new method for the evaluation of stress in wild and captive birds and may be a useful indicator in animal welfare research. The aim of this study was to assess the suitability of fCORT as an indicator of stress, and for this purpose a prolonged stress period was experimentally simulated by oral intake of corticosterone via drinking water and corticosterone concentrations were analyzed in feathers grown during this period. Layer pullets of both a control group (n = 20) and a CORT group (n = 20) were offered drinking water ad libitum throughout the entire experimental phase. The drinking water of the CORT group was supplemented with corticosterone at a concentration of 20 mg/l from the 64th to the 114th day of life. The vaned parts of the primaries 5 ( P5s ) were clipped on d 114 and fCORT was analyzed by ELISA after extraction. Body weights increased from day 64 until d 114 in both groups, however, at the end of the experiment, mean body mass in the CORT group was significantly lower than in the control group ( P < 0.001). Pullets of the CORT group also showed shorter and lighter P5s as well as a retarded molt of the primaries. The supplementation of drinking water with corticosterone increased the average fCORT in the P5s of the CORT pullets compared with the control group (median: 110.3 pg/mm [interquartile range (IQR): 47.2] vs. 10.0 pg/mm [IQR: 2.5], P < 0.001). The results show that experimentally increased systemic corticosterone concentrations over a period of seven weeks in layer pullets are reflected in corticosterone concentrations of feathers grown during that time. This indicates that the measurement of fCORT may be a useful and minimally invasive tool for the evaluation of long-term stress in chicken and provides the basis for further investigations on its use in animal welfare research.

The effects of transport of 18-day old hatching eggs on physiology and behaviour of slow growing broiler chicken

“…Research has shown that CORT deposition in feathers can provide a representation of stress during feather growth in birds (Bortolotti et al, 2008;Jenni-Eiermann et al, 2015) and that exposing layer hens to CORT through drinking water, increases CORT as measured in feathers (Bartels et al, 2021). High stocking density during rearing also increased CORT levels measured in feathers in layer hen pullets (von Eugen et al, 2019).…”

Heat stress and poultry production: a comprehensive review

“…Glucocorticoids in the blood and heterophil to lymphocyte ratio ( HLR ) are considered to be the most commonly measured biomarkers of HS in poultry due to their reliability. Glucocorticoids can be measured in the blood, feces, egg, and feather ( Weimer et al, 2018 ; Bartels et al, 2021 ; Kim et al, 2021 ; Lee et al, 2022 ; Oluwagbenga et al, 2022 , 2023b ). Although measurement of cortisol as biomarker of stress has been ignored for over 2 decades, recent studies reported an increase in circulating cortisol following exposure to HS or ACTH in poultry thereby showing its importance as an index of stress ( Sohail et al, 2010 ; Kim et al, 2022b ; Mirsaiidi Farahani and Hosseinian, 2022 ; Oluwagbenga et al, 2022 ; Tetel et al, 2022a , b ).…”