Designing and evaluation of urea microcapsules in vitro to improve nitrogen slow release availability in rumen

BACKGROUND There is a growing interest in the development of novel and innovative vehicles for controlled release of urea into the rumen, aiming to provide ammonia‐N for the biosynthesis of proteins of bacterial origin and to prevent urea intoxication by direct feeding to livestock. Urea microencapsulation is a system that can control the release of urea to be slow and steady. RESULTS The amount of encapsulated urea was 69% of CSU (calcium silicate + urea + Eudragit RS100® + dichloromethane) and 71% of ACU (activated charcoal + urea + Eudragit RS100® + dichloromethane) groups (p > 0.05) The buoyancy of the microcapsules was over 50% after 12 h of agitation in both groups (CSU and ACU), producing significant differences in the volume of the organic phase factor, which was 20 mL at the lowest value (p = 0.0005). The morphology of the microcapsules produced with CSU and ACU showed no significant differences in microcapsule morphology (p > 0.05). The lower temperature (35 versus 40 °C, p = 0.035) retained better morphology of the microcapsules. Regarding the in vitro ammonia‐N release kinetics, unprotected urea reached a maximal peak after 6 h, while CSU and ACU took more than 24 h to reach ammonia‐N released concentration. CONCLUSIONS We stabilized the physical factors in the microencapsulation of urea that can allow slow release of rumen fluid. © 2018 Society of Chemical Industry