Prevalence of Escherichia coli O157:H7 and Salmonella in beef steers consuming different forage diets.
OBJECTIVE
To compare the prevalence of faecal shedding of Escherichia coli O157:H7 and Salmonella in growing beef cattle consuming various forages.


RESULTS
In Experiment I, faecal samples were collected from steers grazing either endophyte-infected (E+) tall fescue or common bermudagrass (CB). Steers grazing E+ tall fescue were confined to a dry-lot pen and fed CB hay ad libitum for 10 days. In Exp. II, faecal samples were collected from steers grazing either E+ or novel endophyte-infected (NE) tall fescue and treated with one of two anthelmintics: ivermectin (I) or fenbendazole (F). In Exp. I, prevalence of E. coli O157:H7 was less in E+ tall fescue steers fed CB hay than steers grazing CB. More I-treated steers shed Salmonella than F-treated steers at 42-day postanthelmintic treatment but shedding of Salmonella was similar between anthelmintics at day 63 in Exp. II.


CONCLUSIONS
Faecal shedding of pathogenic bacteria was not affected by grazing E+ tall fescue. Alterations of forage diets may influence the prevalence of E. coli O157:H7, and anthelmintic treatment could affect faecal shedding of Salmonella.


CONCLUSIONS
Knowledge of factors that influence shedding of pathogenic bacteria in cattle is necessary to develop on-farm intervention strategies aimed at reducing pathogen shedding.
Looper
M L
ML
USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927, USA. mlooper@spa.ars.usd.gov
Edrington
T S
TS
Flores
R
R
Rosenkrans
C F
CF
Nihsen
M E
ME
Aiken
G E
GE
D000821:Animal Feed; D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000382:microbiology*; D031744:Cynodon; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000662:veterinary*; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology; D005273:Fenbendazole / Q000008:administration & dosage; D007559:Ivermectin / Q000008:administration & dosage; D006109:Poaceae; D015995:Prevalence; D012475:Salmonella / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000382:microbiology
D000871:Anthelmintics; D005273:Fenbendazole; D007559:Ivermectin