Abstract: A pair of oligonucleotide primer was synthesized according to the invA gene nu-cleotide sequence within Salmonella specices. A new method of PCR was successfully developed by enrichment broth cultivation for the detection of Salmonella in laboratory animals. The DNA was extracted from 7 strains of Salmonella and 3 strains of nonsalmonella bacteria （by a rapid boiled-lysate technique）. All Salmonella yielded 284 bp specific band, while no specific product yielded in non-salmonella bacteria. As few as 50 CFU of salmonella in pure culture could be detected by PCR. Three sample-processing methods for mice feces, including low-and high-speed centrifugation, binding to glass powder,and selective enrichment cultivation, were used for the extraction of DNA template ,and the corresponding sensitivities of the methods were 2×10⁴,5×10³，10 CFU, respectively.One hundred and five laboratory animals were detected for the salmonella by enriched PCR procedure and conventional culture technique.The results suggested that the enriched cultivation-PCR have advangtages in rapid detection of Salmonella in a large number of laboratory animals.

Key words: Laboratory animals, Salmonella , Detection , Polymerase chain reaction, Culture