TABLE 1.

Fecal E. coli O157 in forage-fed cattlea

SubjectNo. of E. coli O157:H7 CFU/g of feces on day(s) postinoculationc:
01-35-78-1012-1415-1718-1921-2224-2628-2931-3335-38
Charolais/Herefordb
    CH102.5 × 1034.1 × 1055.0 × 1014.0 × 102E+dE+0E+E+00
    CH202.0 × 1035.0 × 103E+000000NDe
    CH301.5 × 1032.9 × 105E+E+E+E+E+E+E+00
    CH407.9 × 1035.0 × 101E+000000ND
Holsteinf
    H101.7 × 1052.0 × 104E+E+E+NDE+0E+00
    H202.0 × 1041.0 × 103000ND00000
    H30E+02.0 × 104E+E+NDE+0000
    H403.5 × 1041.9 × 105000ND2.5 × 1035.0 × 104E+E+0
    H50E+E+E+E+E+NDE+E+E+E+E+
    H601.0 × 102E+E+E+E+ND0E+E+0E+h
    H79.0 × 103g2.0 × 103E+E+E+1.0 × 103NDE+E+E+E+E+i
    H8E+gE+2.5 × 10404.5 × 104E+ND2.0 × 104E+E+E+1.0 × 103j
    H90E+5.0 × 1035.0 × 1035.0 × 102E+E+E+E+NDE+ND
    H100E+2.5 × 1031.5 × 1055.0 × 1021.5 × 10300E+ND1.4 × 104ND
    H1102.0 × 1030000000ND0ND
    H120E+1.0 × 1041.0 × 104E+E+E+E+E+NDE+ND
    H1300E+000000ND0ND
    H1405.0 × 1021.0 × 1041.4 × 103E+E+E+E+E+NDE+ND
  • a Cattle were inoculated with E. coli O157:H7 ATCC 43894 using a gastric tube placed directly into the rumen. CH1-4 and H1-8 received 4 × 1010 CFU of E. coli O157:H7. H9-14 received 3 × 108 CFU of E. coli O157:H7. Fecal samples were cultured on one of the days indicated.

  • b One-year old Charolais/Hereford heifers fed silage (see Materials and Methods).

  • c Results from nonenrichment culture.

  • d E+, fecal sample culture positive for E. coli O157 after enrichment culture but not by nonenrichment culture technique.

  • e ND, not determined.

  • f One-year-old Holstein steers. H1 to H8 were fed alfalfa, and H9 to H14 were fed grass hay (see Materials and Methods).

  • g Animals H7 and H8 were culture positive for E. coli O157 before experimental inoculation.

  • h Animal H6 remained E. coli O157 positive until day 69 by enrichment culture.

  • i Animal H7 remained E. coli O157 positive until day 56 by enrichment culture.

  • j Animal H8 remained E. coli O157 positive until day 69 by nonenrichment culture.