Effects of Diet on Ungulate Excretion of Enterococcus spp., Streptococcus bovis, and Streptococcus equinus in Feces
1995
Darby, Neal W. | Mosley, Jeffrey C. | Davitt, Bruce B. | Bohach, Gregory A.
We compared fecal streptococci (FS) quantities and species composition excreted by native and domestic ungulates that were consuming various feed rations. Group 1 was comprised of elk (Cervus elaphus), white-tailed deer (Odocoileus virginianus), and bighorn sheep (Ovis canadensis) fed alfalfa (Medicago sativa) hay. Group 2 consisted of elk, cattle (Bos spp.), mule deer (Odocoileus hemionus), domestic sheep (Ovis aries), and horses (Equus caballus) grazing separate grass paddocks of similar botanical composition. Group 3 had four subgroups of cattle each fed a different feed ration: (1) grain and silage; (2) hay, grain, and silage; (3) hay; and pasture. The FS were isolated from ungulate species in each group using the membrane filter technique. Filters were placed on KF streptococcus agar and all pink to red colonies were counted. The FS composition was determined by randomly selecting 20 colonies from each filter and then identified by using growth characteristics and C source utilization. Forage samples were analyzed for crude protein (CP) and neutral detergent fiber (NDF). Ungulates did exhibit some differences in FS quantities and composition, however, all FS species were present in most all ungulates and occurrences were highly variable. Nutritive quality of ungulate diets on grazed forage did not greatly affect the quantities and composition of FS excreted, but trends were difficult to discern because of the high variability of FS samples. Botanical composition of ungulate diets altered both FS quantities and composition. The FS quantities from cattle were greatest when cattle were fed grain rations and smallest when cattle consumed hay or pasture forage. Streptococcus bovis proliferated in feces of cattle fed grain and silage rations while S. equinus and Enterococcus durans dominated on pasture and hay diets. We concluded that the use of FS as indicators of fecal pollution from specific ungulates is unreliable in most cases because of the effects of forage nutritive quality and botanical composition. Contribution no. 745 of the Idaho Forest, Wildlife and Range Exp. Stn., Univ. of Idaho, Moscow, ID 83844.
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