Ureia microparticulada em matriz de pectina cítrica para liberação gradual na dieta de ruminantes.

Abstract

This study aimed to obtain microspheres containing urea by extrusion/ionic gelation, obtained by three microencapsulated systems with fixed ratios of encapsulant (5% pectin solution) and concentrations of 10%, 20% and 30% of urea (wt%, considering the weight of urea and pectin solution), referred as UM1, UM2 and UM3, respectively. After previous testing, microencapsulated systems were characterized for their morphology, microencapsulation yield (MY), urea content (load capacity), microencapsulation efficiency (ME) and by thermogravimetry (TG), derived thermogravimetry (DTG) and differential scanning calorimetry (DSC). In situ degradability kinetics were also evaluated, using three fistulated male Santa Inês sheep, with an average weight of 30.4 ± 6 kg and age 28 ± 2 months. The in situ test was performed using nonwoven bags [(TNT100g/ m2 (polypropylene)] with 4.5x4.5 cm, containing 1 g of sample and the incubation times were 0, 1/4 , 1/2, 1, 3, 6, 12, 24 and 48 h. Analyzes were carried out for ruminal and blood parameters, including protozoa counting, pH and rumen temperature, urea and electrolyte measurement. Preliminary, the retained urea content was higher as the pectin concentration decreased, with values (%) of 72.6 ± 4.4; 69.6 ± 0.5 and 56.8 ± 0.1 for formulations with 3, 4 and 5% of pectin, respectively, defining, among those tested, the formulation with 5% of pectin. In the definitive test, the formulations UM1, UM2 and UM3 showed urea content effectively retained of 26.2, 43.5 and 49, 2%, respectively. All systems (UM1, UM2 and UM3) presented a high percentage of yields, with values greater than 92%. The thermal analyzes and micrographs obtained revealed that UM1 and UM2 had more effective protection against thermal degradation probably due to the particle microstructure (more regular and thick). The degradation kinetics demonstrated that the use of slowrelease urea provided an increase in the effective degradability of microencapsulated urea, increasing the microbial population and providing adequate values of pH, temperature and biochemical constituents of the blood. Thus, pectin can be considered a suitable encapsulant to protect urea, especially UM1 and UM2. Among them, the UM2 system is recommended, considering it can favor the use of higher amount of urea to ruminants without impairing their metabolism.