The Effect of Egg Laying on Feather and Plasma Corticosterone Concentrations in Turkey (Meleagris gallopavo) Hens

Abstract

Phenological differences in energy demand (i.e., reproductive status) might influence the measurement of corticosterone. The objective of this study was to compare corticosterone concentrations in feathers (FCORT) and plasma (PCORT) for turkey hens before and during egg laying. Secondary feathers 1 and 3, and a plasma sample were collected from 50 hens at 30 weeks (before egg laying) from two purebred lines. The hens were reexamined during lay (45 weeks) to collect regrown feathers and plasma samples. Corticosterone concentrations were measured using an ELISA. Linear mixed models were used to assess the effect of genetic line (A vs. B) and period (pre-lay vs. lay) on FCORT and PCORT levels. An increase in FCORT during lay was detected for line B (p < 0.0001), but not line A (p = 0.3076). An increase in FCORT during lay was detectable in both feather types, but there was a difference between secondary 1 and 3 in FCORT concentration within each line studied. Conversely, PCORT decreased between the pre-lay and lay periods for both lines, although the decrease was more substantial for line A (p < 0.0001). Differences in metabolic investment in egg production between the two genetic lines may explain the different FCORT response during lay. The results from this study provide insight into how periods of high energy demand may influence corticosterone which should be considered when interpreting results.

Comparison of stress biomarkers in laying hens raised under a long-term multiple stress condition

“…The reason may be related to an inherently large variation in feather CORT concentrations of poultry ( Weimer et al, 2018 ). In particular, the variation in MC treatment was greater than in NC treatment, which appears to be reasonable because of the greater individual variation in feather CORT accumulation rate of hens exposed to stress conditions than normal conditions ( Leishman et al, 2021 ). In addition, it should be noted that feather CORT concentrations in laying hens may also vary with stage and extent of feather growth because growing feathers are more responsive to changes in blood CORT levels than full-grown and inert feathers ( Bortolotti et al, 2008 ; Lattin et al, 2011 ; Jenni-Eiermann et al, 2015 ).…”

“…Moreover, our observation is also likely related to the general physiology of laying hens. Leishman et al (2021) reported that a female-line turkey had greater feather CORT concentrations than a male-line turkey. Bortolotti et al (2008) also reported that the feather CORT concentrations were highly and positively correlated to the number of laying eggs.…”

Genetic parameters of feather corticosterone and fault bars and correlations with production traits in turkeys (Meleagris gallopavo)

“…Previously, we showed that FCORT levels differ between different turkey genetic lines which may indicate underlying genetic differences 29,30 . Heritability of FCORT or fault bars has yet to be estimated; however, several estimates exist for plasma corticosterone in various domestic and wild bird species.…”