Pellets from each strain were resus-
pended in 0.1% peptone water (BD, Sparks, MD) and combined
together to obtain a final inoculum concentration of approximately
109 CFU/ml. A 1-ml aliquot was used to measure the cell concen-
tration in the inoculum. Pet food kibbles were inoculated within 1 h
of inoculum preparation.