In Vitro Ruminal Fermentation Profiles of Various Starch-Rich Food By-Products

This study evaluated nutritional content, gelatinisation rate and rumen fermentation of 13 starch-rich food by-products compared with grain feeds. Using in vitro rumen gas production rates over 24 h, feeds were classified into five clusters. Cluster 1 (corn grits) showed lower rumen fermentability due to low gelatinised starch. Cluster 2 included steam-flaked corn and barley, brown rice tea and barley tea. Cluster 3 (granola, pancake, bread crust, crepe wrapper) exhibited the highest initial gas production rate (p < 0.01), with high sugar and moderate starch. Cluster 4 (ice-cream cone, spring roll wrapper) showed the highest middle-phase gas production rate (p < 0.01), with high gelatinised starch and low sugar. Cluster 5 (ramen, rice cracker, dumpling wrapper, thin wheat noodle) showed slow initial fermentation, accelerating significantly in middle phase. While Clusters 4 and 5 showed the highest organic acid production over 24 h, Cluster 5 had less lactate accumulation in initial and middle phases and a smaller pH decrease compared with Clusters 3 and 4. By-products in Clusters 3, 4 and 5 demonstrated potential to supply more energy to ruminants compared with grain feeds but may increase the risk of ruminal acidosis due to rapid fermentation and subsequent pH reduction.