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This study analyzes the National Residue Program (NRP) of the Food Safety and Inspection Service (FSIS), United States Department of Agriculture (USDA), data for the years 1983-1998 to determine the effectiveness of all three microbiological screen tests that were developed and used by the FSIS to control antimicrobial residues in food animals. The Swab Test On Premises (STOP) was the first screen test introduced in slaughterhouses, followed by the Calf Antibiotic Sulfonamide Test (CAST) and the Fast Antimicrobial Screen Test (FAST). The data for STOP indicates that during 1983-1998, the rate of food animal carcasses with violative levels of antimicrobial residues reduced from 2.33% to 0.45% under the monitoring plan and under the surveillance plan, the rate reduced from 55.1% to 0.56%. Similarly, the data for CAST indicates that the rate of calf carcasses with violative levels of antimicrobial residue also declined significantly during those years. Because of its higher sensitivity and shorter analytical time, the use of FAST started in 1995. By 1999, it had practically replaced the use of STOP and CAST in bovine species. The use of only one test such as FAST instead of different tests has removed confusion for testing different species of food animals and thereby has enhanced the efficiency of the NRP.

Recovery results of Staphylococcus aureus ATCC 6538 treated with phenolics and quaternary ammonium compounds on Dey and Engley (D/E) neutralizing medium at various time intervals were compared by the use of two commonly used media. Two recovery processes were utilized. In one, the chemically treated organisms were plated directly onto an agar medium. In the other, the aliquot was first put in broth and then was plated with agar. By either process, the numbers and the time period for recovery of organism were greater on D/E medium.

The visible/near-infrared spectra of 300 chicken livers were analyzed to explore the feasibility of using spectroscopy to separate septicemic livers from normal livers. Three strategies involving offset, second difference, and functional link methods were applied to preprocess the spectra, while principal component analysis (PCA) was utilized to reduce the input data dimensions. PCA scores were fed into a feed-forward back-propagation neural network for classification. The results showed no obvious difference in classification accuracy between offset and non-offset data when no other preprocessing method was applied. The full 400-2498 nm wavelength region produced better results than the 400-700 nm, 400-1098 nm, and 1102-2498 nm sub-regions when more than 30 PCA scores were used. In general, the classification accuracy was improved by increasing the number of scores of input data, but too many scores diminished performance. The functional link test showed that using functional-link spectra selected at every third point with 60 scores achieved the same classification accuracy as that obtained when using all the data points with 90 scores. The best classification model used offset correction followed by second difference (g = 31) and 60 scores. It achieved a classification accuracy of 98% for normal and 94% for septicemic livers.