Effects of Gracilaria birdiae supplementation on physiological parameters and carcass quality of laying quails in different thermal environments

This study evaluated the physiological responses and carcass traits of Japanese quails (Coturnix coturnix japonica) fed diets supplemented with the macroalga Gracilaria birdiae across different thermal environments. A completely randomized 4 × 3 factorial design tested four macroalgae inclusion levels (0, 3, 6, and 9%) and three temperatures (25, 29, and 33 °C). Cloacal temperature (CT), respiratory rate (RR), and surface temperature (ST) were not significantly influenced by algal inclusion (P = 0.1413 and P = 0.9616, respectively). On the other hand, RR decreased significantly in quails receiving macroalgae (P = 0.0002), indicating improved heat dissipation. No interaction between dietary algae levels and temperature was detected for absolute or relative organ weights (P>0.05). Inclusion of 9% Gracilaria birdiae in the diet of female Japanese quails was safe and effective at 29 °C, maintaining live weight, carcass quality, and organ development. At 33 °C, however, breast yield decreased significantly, highlighting the importance of heat-stress management strategies.