Prevalence and characterization of Salmonella present during veal harvest

Authors: Bosilevac, Joseph - Mick; ZHILYAEV, SAMSON - Virginia Polytechnic Institution & State University; Wang, Rong; LUEDTKE, BRANDON - Former ARS Employee; Wheeler, Tommy; KOOHMARAIE, MOHAMMAD - Institute Of Environmental Health Laboratories And Consulting Group

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2018
Publication Date: 4/15/2019
Citation: Bosilevac, J.M., Zhilyaev, S., Wang, R., Luedtke, B., Wheeler, T.L., Koohmaraie, M. 2019. Prevalence and characterization of Salmonella present during veal harvest. Journal of Food Protection. 82(5):775-784. https://doi.org/10.4315/0362-028X.JFP-18-478.
DOI: https://doi.org/10.4315/0362-028X.JFP-18-478

Interpretive Summary: Veal products can be contaminated by Salmonella, a bacteria that causes gastroenteritis. There are two commonly harvested types of veal. Bob veal, calves that are days old; and formula-fed veal, calves raised on a milk replacer formula for about 20 weeks. The Food Safety Inspection Service reported that they find Salmonella more often in bob veal than formula fed veal. The objective of this work was to survey five veal processing plants and assess the frequency, levels and kinds of Salmonella found in bob and formula fed veal in different stages of processing. Results showed bob veal products are at higher risk of Salmonella contamination than formula fed veal. The subtypes of Salmonella from bob veal were mostly types not often seen in human illness, while the opposite was found for formula-fed veal. Some processors have already made changes that should improve the safety of veal but further efforts are necessary from both bob and formula-fed veal processors.

Technical Abstract: Beef, and veal products have been vehicles implicated in the transmission of Salmonella enterica, a gastroenteritis causing bacteria. Recent regulatory samples collected from veal have indicated bob veal, or calves harvested within days of birth, have higher rates of Salmonella than samples collected from formula-fed veal, or calves raised 20 weeks on milk-replacer formula before harvest. To investigate this problem we collected samples from veal calf hides, pre-evisceration and final carcasses, at 5 veal processors that harvested bob and/or formula-fed veal. Prevalence and levels of Salmonella were determined, then the isolates characterized for serovar and antibiotic susceptibility. Salmonella was more prevalent (P<0.05) among bob veal than formula-fed veal hides, pre-evisceration and final carcass (84.2 vs. 15.6%, 62.8 vs. 10.1%, and 12.0 vs. 0.4% respectively). Concentrations of Salmonella could be estimated using regression order statistics on hides and pre-evisceration carcasses at two veal plants; one harvesting bob veal and the other bob and formula-fed veal. The concentration of Salmonella on bob veal hides at the plants was 1.45±0.70 and 2.04±1.00 log CFU/100cm2, greater (P<0.05) than on formula-fed veal hides, which was 1.10±1.51 log CFU/100cm2. Concentrations on carcasses however were very low, but mixed. Seventeen Salmonella serovars were identified among 710 isolates. Serovars London, Cerro and Muenster were most common to bob veal and made up 50.7, 18.7 and 6.3% of the isolates respectively, while serovar Montevideo (6.8% of isolates) was most common to formula-fed veal. Although bob veal had increased prevalence and concentrations of Salmonella, formula-fed veal was found to harbor human disease related antibiotic resistant Salmonella serovars Heidelberg and monophasic Typhimurium(1,2 null). Some processors have already made changes that should improve the safety of veal but further efforts are necessary from both bob and formula-fed veal processors.