Effects of cinnamaldehyde, eugenol, and capsicum on fermentation of a corn-based dairy ration in continuous culture

Abstract

A 12-unit continuous culture system was used in a complete randomized design to study the effects of no oil (CON), cinnamaldehyde oil (CIN), eugenol oil (EUG), and capsicum oil (CAP) (500 mg L-1 d -1) with a 45:55 forage:concentrate ratio (dry matter basis) ration on rumen fermentation. Dry matter digestibility did not differ among treatments. Organic matter digestibility tended to decrease with CIN. Digestibility of neutral detergent and acid detergent fiber tended to be highest with CAP. Crude protein digestibility and bacterial nitrogen flow was depressed with CIN and EUG. CIN tended to decrease microbial protein synthesis and increase effluent ammonia nitrogen. Total volatile fatty acid production did not differ among treatments; however, isovalerate production tended to be highest with CAP. CIN and EUG had higher mean pH, spent fewer hours per day and had smaller area under the curve at pH < 5.6 and 5.8. CAP had smaller area under the curve at pH < 5.6. Supplementation with these oils at the current dose had limited effects on rumen fermentation, with the majority of effects observed being mainly attributable to the very high dosage of oil used. Key words: Dairy cow, essential oil, continuous culture, rumen fermentation, rumen pH