|Bauer, Nathan - FSIS|
|Schultz, Craig - FSIS|
|Chitko Mckown, Carol|
Submitted to: Journal of the American Veterinary Medical Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 10, 2004
Publication Date: April 15, 2005
Citation: Heaton, M.P., Keen, J.E., Clawson, M.L., Harhay, G.P., Bauer, N., Schultz, C., Green, B.T., Durso, L.M., Chitko Mckown, C.G., Laegreid, W.W. 2005. Use of bovine single nucleotide polymorphism markers to verify sample tracking in beef processing. Journal of the American Veterinary Medical Association 226(8):1311-1314. Interpretive Summary: Accurate food animal identification is essential for improving disease control and enhancing food safety. The aim of this study was to determine whether a selected set of 20 beef cattle DNA markers will verify sample tracking in a large, federally inspected, Northeastern slaughter facility that primarily processes culled dairy cows. Blood was collected from random animals just prior to slaughter and the purported corresponding liver samples were collected during beef processing. DNA tests were run on each sample and the results were compared. Results showed that the chance of a coincidental genotype match between 2 animals was estimated to be 1 in 23 million. DNA testing confirmed the matches for more than 90% of the purported blood-liver pairs and also revealed the mismatched samples. Thus, these DNA markers have sufficient power to verify accuracy of sample tracking in slaughter plants that process either beef or dairy cattle. These or similar SNP markers may facilitate high-throughput DNA-based traceback programs designed to detect tissue drug residue violations.
Technical Abstract: Objective - To determine whether a selected set of 20 beef cattle single nucleotide polymorphism (SNP) markers will verify sample tracking in a commercial slaughter facility that processes primarily culled dairy cows. Design - Prospective blinded validation study. Animals - 165 cows and 3 bulls from 18 states (82% Holstein, 8% other dairy breeds, and 10% beef breeds). Procedure - Blood was collected by venipuncture from random animals just prior to slaughter. The purported corresponding liver samples were collected during beef processing and genotype profiles were obtained for each sample. Results - Based on the SNP allele frequencies in these cattle, the average probability that 2 random individuals would possess identical genotypes at all 20 loci was 4 x 10^-8. Thus, the chance of a coincidental genotype match between 2 animals was 1 in 23 million. Genotype profiles confirmed the match of 152 of 168 purported blood-liver pairs (90.5%) and revealed 16 mismatched blood-liver pairs. In these 16 mismatched cases, 33 to 76% of the 20 SNP genotypes did not match (average of 52%). Genotype discordance attributed to genotyping error was estimated to be less than 1% based on results from split samples. Conclusions and Clinical Relevance - This selected set of 20 bovine SNP markers is sufficiently informative to verify accuracy of sample tracking in slaughter plants that process either beef or dairy cattle. These or similar SNP markers may facilitate high-throughput DNA-based traceback programs designed to detect tissue drug residues and control animal or food-borne diseases.