In vitro Manipulation of Rumen Fermentation Efficiency by Fumaric acid – Bentonite Coupled Addition as an Alternative to Antibiotics

Short term in vitro incubations were used to evaluate the effect of fumaric acid - bentonite coupled addition onrumen fermentation effeciency. Ruminal contents from five steers were used for preparation of inoculums ofmixed rumen microorganisms that were used in generatation of three treatment systems, negative control, fumaric acid treated, and fumaric acid – bentonite coupled treated. The fermentation pattern revealed that, thiscoupled addition was associated with an additional increase in propionic acid production and fermentationefficiency and was related to an additional decrease in methanogenesis and VFAs utilization index. Furthermore, it increased total VFAs concentrations and decreased pH value, ammonia nitrogen (NH3–N) concentrations andbutyrate proportions. Meanwhile, it did not alter the proportions of long chain VFAs or cellulase activity. Conclusively, this coupled addition would improve the impact of fumaric acid on rumen fermentation patternand can be appropriate alternative for antibiotic feed additives in improving ruminants feed efficiency