*2.8. Culture*

Samples were kept in 4 oz WHIRL-PAK® bags and homogenized by a stomacher blender (Seward Limited, Worthing, West Sussex, United Kingdom for 30 s at 265 rpm. A series of 10-fold dilutions were performed into Butterfield's dilution tubes, plated onto tryptic soy agar (Becton Dickinson and Company, Franklin Lakes, NJ, USA) and incubated for 24 h at 37 ◦C.

For lab trials 1 and 2 the addition of Xylose-Lysine-Tergitol 4 (XLT4; Becton Dickinson and Company, Franklin Lakes, NJ, USA) plates were used to evaluate Salmonella bacterial recovery and were plated from the same Butterfield's dilution tubes then incubated for 48 h at 37 ◦C. Sample WHIRL-PAK® bags were incubated for 24 h at 37 ◦C then 100 μL of each sample were transferred into corresponding Rappaport-Vassiliadis (RV) Salmonella enrichment broth(Becton Dickinson and Company, Franklin Lakes, NJ, USA). The RV tubes that were incubated for 24 h at 37 ◦C were then struck onto XLT4 plates and incubated for 24 h at 37 ◦C to determine how many positive samples were detected through selective enrichment.

## *2.9. Scanning Electron Microscopy*

Transport coop flooring was cut into approximately 18 mm squares and then thoroughly washed and cleaned in 100% ethanol. Squares were then packaged and sterilized by ethylene oxide gas sterilization. Sterilized squares were individually placed in 50 mL conical centrifuge tubes containing 45 mL of tryptic soy both inoculated with 10 μL from an overnight culture of *Enterococcus faecalis* and incubated overnight at 37 ◦C on a horizontal shaker. After overnight incubation, squares were removed and preserved by emersion in 25 mL of a fixative containing 3% glutaraldehyde prepared in 50 mM phosphate buffer, pH 7.4, with 50 mM sucrose. After a 60 min incubation, squares were post-fixed in a solution of 1% osmium tetroxide in 100 mM phosphate buffer, pH 7.4, with 100 mM sucrose for an additional 60 min. Following osmication, squares were rinsed in distilled water, dehydrated in a graded ethanol series and critical point dried using CO2. Squares were then mounted on aluminum stubs, sputter-coated with gold and examined using a scanning electron microscope (JEOL 6400, JEOL USA, INC, Peabody, MA, USA). Control squares were un-inoculated pieces of cage material that were placed on aluminum stubs and examined in the scanning electron microscope.
