Variáveis fisiológicas e zootécnicas de codornas japonesas na fase de corte e postura sob conforto e estresse térmico consumindo macroalga (Gracilaria Birdiae).

Abstract

This research aimed to evaluate the influence of adding the macroalga Gracilaria birdiae on the zootechnical performance, physiological variables, and carcass quality of Japanese quails when subjected to three controlled environments (climatic chambers with air temperatures of 25, 29, and 33°C) in two phases: 14–42 days and 49 112 days. A total of 864 female quails were used in the first phase and 576 in the second phase, distributed in a completely randomized design with a 4 × 3 factorial scheme, consisting of four levels of macroalga inclusion (0.0, 3.0, 6.0, and 9.0%) and three temperatures (25.0, 29.0, and 33.0°C). Physiological variables, zootechnical performance, and carcass characteristics were evaluated. Temperature significantly influenced water and feed intake, as well as variables such retaly temperature, respiratory rate, and live weight (P<0.005). Under heat stress conditions (33.0°C), the inclusion of 6.0 and 9.0% of macroalgae helped mitigate the effects of heat, reducing the birds' cloacal temperature. The relative carcass weight was higher at 33.0°C, suggesting a metabolic adjustment to heat stress, but there were no significant differences in feed conversion and weight gain between treatments (P>0.005). The evaluated physiological parameters included cloacal temperature (CT), respiratory rate (RR), and surface temperature (ST) of the quails. Live weight, feed intake, cloacal temperature, surface temperature, and respiratory rate were influenced by environmental temperature (P<0.05), with higher values observed at 33°C. Productive performance, carcass yield, and organ weights (liver and heart) showed no significant differences due to macroalgae inclusion (P>0.05). Even at the highest level (9%), the relative carcass weight was higher under heat stress conditions, suggesting a metabolic adjustment of the birds. Thus, the study reinforces the potential use of macroalgae in poultry diets for hot climates, highlighting the need for further studies to adjust inclusion levels and explore their mechanisms of action. The inclusion of up to 9% Gracilaria birdiae in the diet of laying quails aged 49–112 days is recommended.