Analysis of the Reliability of Feather Sections for Corticosterone Measurement in Pekin Ducks.

Simple Summary: A widely used method for measuring stress in animals is to analyze corticosterone levels in the blood. However, blood sampling can cause pain and stress, which can negatively influence data precision. As an alternative, we measured corticosterone levels in feathers. However, a notable limitation of feather analysis is the variation in hormone levels across different feather sections, which can affect measurement reliability. Therefore, we evaluated the reliability of three feather parts (the whole feather, the rachis, and the vane) to identify the most suitable section for corticosterone assessment. Our results demonstrated that whole feathers provided the most consistent and reliable data despite lower corticosterone concentrations. While the rachis showed higher concentrations, its reliability was lower than that of whole feathers. The vane had the highest concentrations but showed no consistency across the samples. Based on these findings, we recommend using whole feathers to measure stress in individuals. This method offers reliable results with minimal stress to the animals and facilitates the sampling process by allowing the analysis of feathers without separation. These findings could improve the accuracy and efficiency of stress measurements in ducks, especially in field studies, and contribute to enhanced animal welfare. The aim of this study was to identify the feather section, among the whole feather, rachis, and vane, with the highest reliability for corticosterone measurement in 10 Pekin ducks aged 42 days. In total, 60 samples (i.e., 20 per section) were collected and each section was analyzed in duplicate. Corticosterone levels were measured using ELISA and statistical analyses were performed using ANOVA in SAS 9.2, and the intra-class correlation coefficient (ICC) was tested using IBM SPSS. The level in the whole feather (12.55 ± 4.41 pg/mg) was significantly lower (p < 0.001) than that in the rachis (18.12 ± 5.70 pg/mg). No significant differences were observed between the rachis and the vane (20.40 ± 3.04 pg/mg). ANOVA results confirmed substantial hormonal variability depending on the feather part analyzed. The ICCs for the whole feather, rachis, and vane were 0.923, 0.876, and 0.004, respectively. The vane section exhibited the highest concentration and lowest variance, whereas the whole feather exhibited the highest ICC. Although the whole feather had the lowest concentration, it exhibited greater consistency. Further research is necessary to improve the feather corticosterone analysis method for more accurate analysis. In conclusion, the whole feather provides the most reliable measure of corticosterone concentration among the three parts. [ABSTRACT FROM AUTHOR]