Assessing the safety and quality of foods of animal origin
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abstract
In general, published data concerning carriage of Salmonella in bovine lymph nodes are limited, especially those pertaining to the management of live beef cattle. Most studies have been designed to capture prevalence rates of Salmonella in bovine lymph nodes at harvest (2, 3, 4, 9, 10, 11). With regard to feedlot environment, previous studies have focused on the presence of anaerobic bacteria (15) and Salmonella (3, 8) in the feces of feedlot cattle, but not the potential impact of management practices on Salmonella prevalence in the feedyard environment and associated cattle.Additionally, prior work has shown differing levels of Salmonella prevalence in bovine lymph nodes due to seasonality, geographic location, and feedyard environment. Specifically, the Texas meat industry faces increased Salmonella challenge due to southern geography and warm, coastal climate. Little is known about when the bovine lymphatic system originally acquires the pathogen, or if cattle are able to rid their system of the pathogen over time. To address these issues, we would like to investigate Salmonella in bovine lymph nodes from cattle raised in commercial feeding environments unique to south Texas. By tracking calves at different stages in the feeding process, we may be able to determine if they enter the feedyard with the pathogen sequestered in their lymphatic system, and whether the calves retain the pathogen or shed it over the course of their feeding program. Conversely, we may be able to determine if cattle enter the feedyard without the pathogen in their system, but later acquire it during the feeding period. By overlaying Salmonella prevalence in bovine lymph nodes with general beef production, we can better plan for future research and intervention development and implementation.With regards to Salmonella prevalence in pork, previous studies have focused on a variety of non-edible tissues/surfaces, including lymph nodes inherent to the gastrointestinal tract. However, limited literature is currently available on Salmonella prevalence in porcine PLNs, which, like bovine PLNs, are imbedded in the fat between muscles. While sanitary dressing plays an important role in the prevention of pathogen transfer during the conversion of a live animal into a carcass, it is important to acknowledge the potential role of Salmonella in PLNs. Due to their close association with muscle tissue, PLNs can be exposed during fabrication, or incorporated in ground products. While a number of large PLNs can easily be removed during normal fabrication practices, some pork carcasses and cuts are often cooked intact, not always providing an opportunity for the removal of PLNs. Salmonella harbored in PLNs and exposed during the carving/serving of these products can become a concern in situations where proper internal temperatures are not reached during cooking, as was suspected in the outbreak mentioned previously. By estimating the current prevalence levels of Salmonella spp. in porcine lymph nodes, in addition to the specific attributes of any salmonellae present, the pork industry will gain a better understanding of the food safety implications posed by Salmonella-positive lymph nodes in pork...........
