In Vitro Digestibility and Rumen Fermentation of Grass or Rice Straw Basal Diet With or Without Complete Rumen Modifier Supplementation

An in vitro study was conducted to evaluate the supplementation of complete rumen modifier (CRM) to elephant grass or rice straw basal diet. CRM is feed additive consisting of a mixture of defaunator, methanogenesis inhibitor and bacterial growth factors. The diet was formulated in iso energetic and iso protein contained CP 16% and ME 2.3 MJ/kg. The diet was fermented for 48 hours under anaerobic condition at 39 °C. Experiment was conducted in a completely randomized design in 2×2 factorial arrangement using 2 levels of type of basal diet (Napier grass and rice straw) and 2 levels of CRM supplementation (0 and 2%). The parameters recorded were apparent digestibility of grass substrate, gas production, methane production and bacterial and protozoal counts. Total gas and methane produced during incubation was recorded at 2, 4, 8, 12, 16, 24, 36 and 48 hours. Results from the study show that DM and OM digestibility, bacterial and protozoal population were significantly affected by the interaction between CRM supplementation and type of basal diet. CRM supplementation in rice straw basal diet increased DM and OM by 27% and 23,48% respectively, but it did not increase in grass basal diet. Bacterial population was increased by CRM supplementation in grass basal diet, in contrast, in rice straw basal diet, CRM supplementation decreased bacterial population. Whereas protozoal population was decreased both in grass and rice straw basal diet, the decreased was about 63.26% and 64% respectively for grass and rice straw basal diet. Methane production tended (P<0.07) to decrease by CRM supplementation in rice straw basal diet. From this study, it can be concluded that CRM supplementation was able to improve the fermentability of rice straw basal diet and tended to decrease proportion of methane production. CRM supplementation did not have any effect on grass basal diet.