A comparison of three highly fermentable carbohydrate sources (corn, cassava powder or cassava pulp) on in vitro digestion

Cassava powder and pulp contain high levels of carbohydrate and variable starch; thus, they have the potential as substitutes for corn grain in cattle rations. This study aims to determine whether cassava (powder and pulp) can replace corn as an energy source in rations. Using a completely randomized design, rations were formulated using three corn, cassava powder or cassava pulp; and palm kernel cake as a protein source with a ratio of 60:40 (carbohydrate:protein source). Cassava powder and cassava pulp in the diet increased (P<0.05) VFA concentration over that from corn (14.6 and 18.2 vs. 11.3mM, respectively) and decreased NH₃-N (4.73 and 4.55 vs. 8.26mg/100mL, respectively) in the rumen fluid compared to corn (P<0.05). pH did not change and ranged from 7.10-7.24. Rations containing cassava pulp showed the greatest microbial N concentration (P<0.05) compared to rations containing corn or cassava (5.85 vs. 4.52 and 1.43mg/100mL, respectively). Dry matter digestibility of the ration with cassava powder is higher (P<0.05) than corn and cassava pulp (62.4 vs. 59.4 and 50.6, respectively). It may be concluded that cassava powder and cassava pulp can substitute corn in ruminant rations with a positive effect on the characteristics of rumen fermentation.