Abstract

Effects of feeding modified cassava chip and corn seed as energy source inclusion in diet were investigated on growth performance, rumen fermentation, and blood metabolites in early fattening bulls. Thirty-six 1-year-old Charolais crossbred bulls with initial weight 270 ± 50 kg were randomly assigned into 6 groups with different experimental rations as cassava-based concentrates including non-modified cassava chip (Cass-Con), with 15 % of alkaline-treated cassava chip (Cass-Alkaline), with 15 % of steam-treated cassava chip (Cass-Steam) and corn-based concentrates including non-modified corn seed (Corn-Con), with 15 % of alkaline-treated corn seed (Corn-Alkaline), and with 15 % of steam-treated corn seed (Corn-Steam), according to completely randomized design (CRD). Results showed that feed intake and digestibility were not significantly different among treatments, while digestible dry matter and organic matter intake of Cass-Steam and Corn-Alkaline were higher than those of the other diets (P < 0.05). Ruminal pH post-feeding was highest in Corn-Alkaline and lowest in Cass-Con (P < 0.05). Blood glucose was similar among treatments. However, blood insulin at 4 h post-feeding was higher in Cass-Steam, Corn-Alkaline, and Corn-Steam than in the others. Blood insulin in bulls fed corn-based concentrate was higher than in bulls fed cassava-based concentrate (P < 0.01). Body weight gain and average daily gain were significantly higher (P < 0.05), while feed conversion ratio was lower in Cass-Steam, Corn-Alkaline, and Corn-Steam as compared with in Cass-Con, Cass-Alkaline and Corn-Con. Results indicated that using a modified energy source can improve growth performance in early fattening beef bulls. An appropriate method to modify cassava chip was steam method, while alkaline method for corn seed was superior.