Submitted to: Pig Veterinary Society International Congress Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/20/2004
Publication Date: 7/1/2004
Citation: Hurd, H.S., Rostagno, M.H., McKean, J.D. 2004. Effect of pre-slaughter holding in abattoir pen or transport trailer on Salmonella prevalence [abstract]. Proceedings of the International Pig Veterinary Society. p. 684. Interpretive Summary:
Technical Abstract: Before slaughter, pigs are often held for at least two hours to recover from the stress of transport and to improve meat quality. However, recent research has shown that much pre-harvest Salmonella infection occurs immediately before slaughter during this rest period in the holding pen. Therefore, the objective of this study was to determine if resting pigs on their transport vehicle reduces Salmonella prevalence at slaughter. A total of 120 grower-aged pigs (~ 20 kg) were included in the experiment, divided in 4 replicates (30 pigs per replicate). On the farm, before loading, a 1-g fecal sample was collected from each pig using a fecal retraction loop. Pigs were loaded and immediately transported for 3-4 hours. Upon arrival at the abattoir, a 1-g fecal sample was again collected, and 15 randomly chosen pigs were unloaded, and moved to a holding pen, whereas the remaining 15 pigs stayed in the transport trailer. Before placement in the holding pen, five floor swabs (100 cm**2 gauzes) were collected to verify pre-existing contamination. After approximately 1.5 hours of resting, both groups were slaughtered, and samples collected. Samples collected included: distal ileum portion (10 cm), cecal content (10 g), and ileocecal lymph node. All samples were transported to the laboratory, and individually processed for the isolation and identification of Salmonella. Preliminary results from the first two replicates showed significantly higher Salmonella recovery rates from pigs held in the pens (44.8% vs. 16.7%). In both replicates, the pens were highly contaminated (5/5 and 4/5 positive samples) before placement of study pigs. Many believe that the number of pigs shedding Salmonella will be increased after transportation and its associated stress. However, there is no conclusive data showing a direct association between stress and increased shedding of Salmonella. So far, this study suggests that transportation of the pigs from farm to abattoir has no effect on Salmonella prevalence. However, further investigation is necessary to definitively fill this important gap of information. The preliminary results obtained in this study suggest that, except for unloading logistics, the possibility of resting pigs on the transport vehicle has the potential to decrease Salmonella levels entering the abattoir. Unloading logistics for large-scale pig slaughter (1,000 head per hour) may prevent truck holding. However, side-unloading trailers as opposed to rear-unloading trailers may allow for sufficiently rapid unloading.