Eggshell Appearance Does Not Signal Maternal Corticosterone Exposure in Japanese Quail: An Experimental Study with Brown-Spotted Eggs

Abstract

Reproduction is a critical period for birds as they have to cope with many stressful events. One consequence of an acute exposure to stress is the release of corticosterone, the avian stress hormone. Prolonged stress can have negative impacts on the immune system, resulting in, for example, increased oxidative stress. Through maternal effects, females are known to modulate their investment in eggs content according to their own physiological condition. Less is known about maternal investment in eggshells, especially in pigments. The two main eggshell pigments may possess opposite antioxidant properties: protoporphyrin (brown) is a pro-oxidant, whereas biliverdin (blue-green) is an antioxidant. In Japanese quail, we know that the deposition of both pigments is related to female body condition. Thus, a chronic stress response may be reflected in eggshell coloration. Using female Japanese quails that lay brown-spotted eggs, we explored whether physiological exposure to corticosterone induces a change in female basal stress and antioxidant factors, and eggshell pigment concentration, spectrophotometric reflectance, and maculation coverage. We supplemented adult females over a 2 week period with either peanut oil (control) or corticosterone (treatment). We collected pre- and post-supplementation eggs and analysed the effect of corticosterone treatment on female physiology and eggshell appearance parameters. Except for corticosterone-fed birds which laid eggs with brighter spots, supplementation had no significant effect on female physiology or eggshell pigment concentration, reflectance and maculation. The change in eggshell spot brightness was not detected by a photoreceptor noise-limited color opponent model of avian visual perception. Our data confirms that eggshell reflectance in spotted eggs varies over the laying sequence, and spot reflectance may be a key factor that is affected by females CORT exposure, even if the changes are not detected by an avian visual model.

Repeated subcutaneous administration of PT150 has dose-dependent effects on sign tracking in male Japanese quail.

“…Male quail were maintained at 85% body mass whereby grain was provided 2–3 hr after conditioning. The resulting body mass closely matched previously defined bird methods of food deprivation (Duval et al, 2013; Duval, Cassey, Mikšík, Reynolds, & Spencer, 2013; Shousha, Nakahara, Nasu, Sakamoto, & Murakami, 2007). Quail were weighed daily and following the establishment of their mean free-feeding body weight; 18% of their body weight was calculated to provide minimum caloric intake in grams of feed to sustain 85% body mass throughout conditioning (e.g., Lejeune & Nagy, 1986).…”

Intramuscular Route of Administration Increases Potency in Eliciting Cocaine-Induced Behavioral Sensitization

“…Quail were maintained at 85% body mass, where food was available from 10 AM to 6 PM daily. This closely matches previously defined avian measures [29–31]. …”

Effects of food limitation on the intensity of blue‐green and brown eggshell coloration: an experimental study with the canary

“…ABCG2 in the case of protoporphyrin; Samiullah et al 2015), are affected by factors related to the nutrient availability. Food restriction may also lead to elevation in stress hormone levels (Astheimer et al 1992, Giuliano et al 1996, Saino et al 2003, which may affect eggshell pigmentation, although no support for this hypothesis was found in Japanese quails (Duval et al 2013b).…”