Effects of Essential Oils of Sagebrush on Deer Rumen Microbial Function

Investigations were conducted on the effects of essential oils of big sagebrush (Artemisia tridentata) on growth and metabolism of bacteria, including rumen microorganisms of mule deer (Odocoileus hemionus), and effects of the sagebrush feeding on appetite, rumen function, and rumen bacterial function of a fistulated steer. Sagebrush essential oils showed inhibitory action on several gram-positive and gram-negative bacteria, using the disc assay method. The addition of 0.05-ml amounts of essential oils of sagebrush inhibited the growth of deer rumen microorganisms in 9-ml amounts of agar media. The rate of cellulose digestion was decreased when 0.002-mil amounts of oils were added to 6 ml of cellulose broth and was apparently inhibited by 0.04 ml of oils. The addition of 0.1-ml amounts of oils added to 41 ml of deer rumen contents (sagebrush as substrate) decreased the rate of gas production and volatile fatty acid (VFA) concentrations. Appetite and rumen movements ceased completely following the introduction of 21 pounds of sagebrush in 7-pound daily portions through the rumen fistula of a steer.