Transmission of Salmonella typhimurium among Feedlot Cattle after Oral Inoculation

Fifteen six-eight month old steers and bulls weighing approximately 160 kg were inoculated orally with a virulent strain of Salmonella typhimurium. Three or four inoculated animals were confined in each of four pens, immediately after inoculation, with approximately 22 uninoculated cattle. The pen size in the experimental feedlot was 23 x 46 m. The 15 intentionally inoculated animals all became infected and excreted Salm. typhimurium in their faeces. Two of them died of salmonellosis and more than half the cattle penned with the inoculated animals became infected within 8 d after exposure. Twenty-four of the animals were still excreting salmonellas 71 d after initiation of the experiment.