Risk of Salmonella and Campylobacter contamination of cattle during transport to slaughter

Abstract

This study evaluated the effect of typical production practices during transport of cattle on the resulting incidence of pathogenic bacteria in cattle and their resulting carcasses. Various factors, including type of animal, body condition score, breed, age, time of feed/water withdrawal, contamination level of transport vehicle at the feedlot/farm, transport time/distance, contamination level of the holding pen, and time held in holding pen, were evaluated for their effect on the incidence of Salmonella and Campylobacter in feedlot cattle and adult beef cattle. Four groups of feedlot cattle and four groups of adult cattle were sampled on different days. Samples were collected from the cattle both prior to transport and after transport (rectal and hide swabs) as well as from the carcasses derived from these cattle. Furthermore, environmental samples were collected from the transport vehicles, holding pens, and knock boxes at the slaughter facility. Following sample collection, microbiological examination was conducted to provide a characterization of the incidence of Salmonella and Campylobacter within the segment of the farm-to-table continuum in Texas related to the transport of cattle from feedlots/farms to the slaughter plants. The intestinal carriage rate of Salmonella for feedlot cattle decreased from 5.0% prior to transport to 3.0% after transport whereas the intestinal carriage rate for adult cattle increased from 1.0% prior to transport to 20.8% after transport. Although the adult cattle were shedding more Salmonella overall, hide contamination with Salmonella was very similar for both feedlot and adult cattle (an increase from approximately 19.0% prior to transport to 55.0% after transport). Carcass contamination with Salmonella was 19.0% for feedlot cattle and 54.2% for adult cattle. The intestinal carriage rate of Campylobacter for feedlot cattle increased from 64.0% prior to transport to 68.0% after transport whereas the intestinal carriage rate for adult cattle increased from 6.3% prior to transport to 7.3% after transport. Campylobacter contamination of hides and carcasses in both feedlot and adult cattle was minimal. Regression analysis indicated that there were no relationships between the aforementioned risk factors and subsequent fecal shedding, hide contamination, and carcass contamination.