Table 1

The effect of grain feeding on the colonic pH andE. coli counts of cattle fed various amounts of grain.

DietNumber of animalsColonic pHTotal E. coli (log cells/gram)Acid-resistantE. coli* (log cells/gram)
No grain
Hay67.2 ± 0.1 4.3 ± 0.5 <1.0
Pasture87.1 ± 0.1 5.0 ± 0.9 <1.0
Moderate grain
60% rolled corn316.9 ± 0.3 6.8 ± 0.7 4.4 ± 1.1
Mostly grain
≥80% rolled corn165.9 ± 0.6 6.9 ± 0.9 5.4 ± 0.7§
  • *  Acid-resistant E. coli are those that survived an acid shock (pH 2.0, Luria broth, 1 hour).

  •  Means within a column with different superscripts are significantly different (P < 0.05, Student's t test).