Plant-derived oils reduce pathogens and gaseous emissions from stored cattle waste

Carvacrol and thymol in combination at 6.7 mM each completely inhibited the production of short-chain volatile fatty acids and lactate from cattle was te in anoxic flasks over 23 days. Fecal coliforms were reduced from 4.6 x 1 0(6) to 2.0 x 10(3) cells per ml 2 days after treatment and were nondetecta ble within 4 days. Total anaerobic bacteria were reduced from 8.4 x 10(10) to 1.5 x 10(7) cells per mi after 2 days and continued to be suppressed to that level after 14 days. If the concentration of carvacrol or thymol were doubled (13.3 mM), either could be used to obtain the same inhibitory ferme ntation effect. We conclude that carvacrol or thymol may be useful as an an timicrobial chemical to control pathogens and odor in stored livestock wast e.