Expression of toll-like receptors and inflammatory cytokines in gut-associated lymphoid tissues in pigs subjected to cross-fostering

How comes that 13 piglets were euthanized on day 21 p.p while 8x3 (24 in total) piglet's intestinal organs were checked for the presence of "Toll-Like Receptors" ? Shmuel Marcus.

Twenty-four piglets were enrolled in the study. Piglets were randomly assigned to 1 of 3 treatments, according to colostrum source and postcolostral milk feeding for 21 day. However not all the piglets could be euthanized. This study was performed in a commercial during an PEDV epidemic outbreak. some pigs were grown to market

Thanks. Have a good Week End. Marcus.