OLIVEIRA, A. G.; http://lattes.cnpq.br/4285867711243914; OLIVEIRA, Airton Gonçalves de.
Resumo:
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.