Dissertação
Otimização do processo de extrusão de ração padrão para tilápias do nilo (Oreochromis niloticus)
Fecha
2020-03-13Autor
Dalcin, Marina Osmari
Institución
Resumen
This study aimed to evaluate different extrusion conditions, temperature and humidity of
standard feed containing corn starch and fish meal as macro nutrients, as well as the physical-
chemical and technological properties of the extrudates in addition to the evaluation of
apparent digestibility in Nile tilapia. . The best extrusion condition was established using a
central rotational composite design with outlet temperature (92 - 138 ° C) and humidity (15 -
39%) as independent variables, and buoyancy and available starch content as an answer.
Through this experimental planning, 11 tests were carried out. The highest content was found
in experiment 1, in which 100°C was used as the outlet temperature and 15% humidity.
Through the images obtained by scanning electron microscopy, the presence of pores of
different sizes is noted, with a predominance of pores of small diameter, indicating good
expansion and development of starch. Subsequently, the apparent digestibility coefficients of
dry matter (DM), crude protein (CP), mineral matter (MM), organic matter (OM) and ether
extract (EE) of two diets were determined, one in extruded form and the other, pelleted for
Nile tilapia specimens, both diets with the same nutritional composition. Digestive indexes
and digestive enzyme activities were evaluated. Twelve specimens of Nile tilapia were
randomly distributed in six incubators (200 L), the experimental design was completely
randomized, with two treatments and three replications. The data were subjected to analysis of
variance and the means compared by Student's t test (P<0.05). There was no statistical
difference in the parameters evaluated, except in the centesimal composition of the diets (DM,
MM and EE) and feces (CP), and the apparent digestibility coefficient of ether extract. In
short, both diets, both extruded and pelleted using the same procedures employed, can be used
for Nile tilapia, without interfering with the evaluated parameters. It is worth emphasizing that
the extrusion process, under the conditions tested, improved the digestibility of the protein,
reducing the excretion of this nutrient through the feces compared to the pelleted diet.