Physiological and zootechnical variables of Japanese quails consuming macroalgae (Gracilaria birdiae) under different environmental conditions.

This research aimed to assess the physiological and zootechnical parameters of Japanese quails (Coturnix coturnix japonica) that were provided with diets containing varying amounts of the macroalga Gracilaria birdiae, all under different controlled climatic settings. A total of 864 female quails were utilized in a completely randomized design following a 4 × 3 factorial setup, which included four inclusion levels of the macroalga (0.0, 3.0, 6.0, and 9.0%) and three temperature settings (25.0, 29.0, and 33.0 °C). The evaluation of the birds focused on physiological metrics, zootechnical performance, and carcass traits. The results indicated that temperature had a significant impact on water and feed consumption, as well as on rectal temperature, respiratory rate, and live weight (P < 0.005). In conditions of heat stress (33.0 °C), the addition of 6.0 and 9.0% of the macroalga was effective in alleviating heat stress by lowering the rectal temperature of the birds. Additionally, relative carcass weight was found to be higher at 33.0 °C, indicating a metabolic adjustment to thermal stress. Nevertheless, no notable differences in feed conversion or weight gain were recorded across the different treatments (P > 0.005). Consequently, this study underscores the potential benefits of incorporating macroalgae into poultry diets in hot climates and highlights the necessity for further investigation to determine optimal inclusion rates and understand their mechanisms of action. The data reinforce that the inclusion of 6.0 to 9.0% Gracilaria birdiae can be a viable strategy to mitigate the impact of heat stress in Japanese quails, especially in high temperature conditions.