Sex‐specific effects of dietary restriction on physiological variables in Japanese quails

Abstract Nutritional limitation is a common phenomenon in nature that leads to trade‐offs among processes competing for limited resources. These trade‐offs are mediated by changes in physiological traits such as growth factors and circulating lipids. However, studies addressing the sex‐specific effect of nutritional deficiency on these physiological variables are limited in birds. We used dietary restriction to mimic the depletion of resources to various degrees and investigated sex‐specific effects on circulating levels of insulin‐like growth factor 1 (IGF‐1) and triglycerides in Japanese quails (Coturnix japonica) subjected to ad libitum, 20%, 30% or 40% restriction of their daily requirement, for 2 weeks. We also explored the association of both physiological variables with body mass and egg production. While dietary restriction showed no effects on circulating IGF‐1, this hormone exhibited a marked sexual difference, with females having 64.7% higher IGF‐1 levels than males. Dietary restriction significantly reduced plasma triglyceride levels in both sexes. Females showed more than six‐fold higher triglyceride levels than males. Triglyceride levels were positively associated with body mass in females while showed not association in males. Overall, our findings revealed sex‐specific expression of physiological variables under dietary restriction conditions, which coincide with body size.