Anti-nutritional potential of protodioscin and kinetics of degradation in Urochloa grasses

Abstract

This study aimed to evaluate the nutritional value of Urochloa exotic grasses to quantify aspects of anti-quality and to identify their correlation with quality grasses. We evaluated the grasses U. humidicola cv. Comum, U. humidicola cv. BRS Tupi, U. decumbens cv. Basilisk, D70 U. decumbens and U. ruziziensis ecotype R124, and we grouped them into summer, autumn, winter and spring. We determined the chemical composition, in vitro digestibility, levels of protodioscin and cumulative gas production from the leaves of grass materials in nature. Basilisk and D70 showed higher content protodioscin in all seasons, with the highest values (31.4 and 27.4 g kg-1, respectively) in spring. D70 had a crude protein content of 140.0 g kg-1 in summer and a better in vitro digestibility of dry matter (888.7 g kg-1). R124 had a higher cumulative gas production in the spring (16.44 mL gas 100 mg DM-1). U. humidicola (Comum and BRS Tupi) presented lower protodioscin concentrations (1.22 and 1.07 g kg DM-1, respectively), and U. decumbens (Basilisk and D70) presented higher concentrations (27.25 and 24.55 g kg DM-1, respectively). The presence of protodioscin interfered with in vitro digestibility results and cumulative gas production in vitro.