Effect of exogenous glucoamylase on ruminal in situ and in vitro dry matter and starch degradability of cereal grains in beef cattle

Abstract

Objective: To evaluate the effects of glucoamylase on ruminal in situ and in vitro dry matter degradability (DMD), in vitro starch degradability (IVSD), volatile fatty acids (VFA), gas production and methane production using cereal grains as substrates in beef cattle. Methods: Six substrates (4 mm; 0.70 g per F57 bag) including sorghum (micronized and whole), barley (whole and steam-flaked), and corn (dry-rolled and steam-flaked); were incubated with exogenous glucoamylase (from Trichoderma reesei; 0.25 mg/g substrate DM) and buffered rumen fluid in six replicates per run in 3 independent runs. In vitro dry matter degradability (IVDMD), In vitro starch degradability (IVSD), In situ DMD (ISDMD), VFA, and methane production was measured after 7, and 12 h of incubation. In situ ruminal DMD (I