Nw. Darby et al., EFFECTS OF DIET ON UNGULATE EXCRETION OF ENTEROCOCCUS SPP, STREPTOCOCCUS-BOVIS, AND STREPTOCOCCUS-EQUINUS IN FECES, Journal of environmental quality, 24(4), 1995, pp. 719-724
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-ta
iled 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 arie
s), and horses (Equus caballus) grazing separate grass paddocks of sim
ilar 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 (4) pasture. The FS were isolated from ungulate
species in each group using the membrane filter technique. Filters wer
e plated on KF streptococcus agar and all pink to red colonies were co
unted. The FS composition was determined by randomly selecting 20 colo
nies from each filter and then identified by using growth characterist
ics and C source utilization. Forage samples were analyzed for crude p
rotein (CP) and neutral detergent fiber (NDF). Ungulates did exhibit s
ome differences in FS quantities and composition, however, all FS spec
ies were present in most all ungulates and occurrences were highly var
iable. Nutritive quality of ungulate diets on grazed forage did not gr
eatly affect the quantities and composition of FS excreted, but trends
were difficult to discern because of the high variability of FS sampl
es. Botanical composition of ungulate diets altered both PS quantities
and composition. The FS quantities from cattle were greatest when cat
tle were fed grain rations and smallest when rattle consumed hay or pa
sture forage. Streptococcus bovis proliferated in feces of cattle fed
grain and silage rations while S. equinus and Enterococcus durans domi
nated on pasture and hay diets. We concluded that the use of FS as ind
icators of fecal pollution from specific ungulates is unreliable in mo
st cases because of the effects of forage nutritive quality and botani
cal composition.