Reliable animal models are critical for reproducing infectious disease in experimental
settings. Frequently used models for pigs include the conventional specific pathogen free
(SPF) model, cesarean-derived colostrum-deprived (CDCD) model, and gnotobiotic model.
Conventional SPF models are not always suitable for highly prevalent pathogens because the
presence of maternal antibodies precludes challenge or vaccination of very young pigs. Both
CDCD and gnotobiotic models require surgery to deliver piglets and sterile compartments in
which they are raised. As gnotobiotic pigs are raised entirely in sterile compartments, the
duration of experiments is limited because pigs may outgrow the allotted space. Further,
gnotobiotic pigs fail to produce serum immunoglobulin (Ig)G and IgM antibodies to T-cell
dependent and type-2 T-cell independent antigens, whereas pigs colonized by a single strain
of Escherichia coli produce antibodies [1]. Accordingly, gnotobiotic pigs differ from
conventional pigs immunologically. This raises questions regarding the applicability of
gnotobiotic pig experiments to field situations. It was in this context that we optimized a
previously published snatch-farrowed porcine colostrum-deprived (SF-pCD) pig model [2,3]
to achieve 100% survival. This provided an alternative model for infectious disease research
[4]. SF-pCD pigs were raised on a bovine-colostrum-based liquid diet before weaning, and a
post-weaning diet that was free of porcine byproducts