Studies On Molecular Traceability Of The Species Origin Of Sheep And Goat Meat Products

This study reviewed the status of current technologies available for the identification of species origin of raw meats for different meat products. The quality and quantity of genomic DNAs extracted using three methods of phenol-coloruform, salting out and kit were assessed. A septenary multiplex PCR system to identify DNAs of pig, cattle, sheep, goat, chicken, horse and yak was established and used to evaluate nine fresh and 10 highly processed meat products of sheep and goat purchased in the supermarkets in Beijing. DNA sequencing information was used for a further validation of the results. Finally, a simple PCR-RFLP procedure for differentiating the 472 bp Cyt b gene fragments amplified using the universal primers from goat, sheep and duck was developed for the fast identification of these three species. The major results and conclusions were as follows:1. The quality and quantity of genomic DNAs recovered using the three methods were very similar and the procedure of DNA extraction kit required relatively short time as an advantage.2. Routine agarose gel electrophoresis was sufficient to differentiate the septnary multiplex PCR products of mtDNA Cyt b gene ranging from 175 bp to 517 bp and differing by at least 41 bp each other, indicating that this septenary multiplex PCR method can be used for a rapid, accurate and simultaneous identification of the seven species, in particular for three species of cattle, yak and goat at a sensitivity of 2.5 ng DNA.3. Among the 19 products evaluated using the septenary multiplex PCR method, five of them did not match to what was declared in the packages with two highly processed meat products adulterated with some or completely beef, one freshly minced meat product adulterated with some chicken meat, and the remaining two declared fresh sheep meat products to be a mixture with some goat meat.4. A 472 bp long fragment of mtDNA Cyt b gene were amplified from sheep, goat and duck DNAs using a pair of universal primers and then digested using Bsu36I and SpeI restriction enzymes that resulted in different fragments as 95 bp and 377 bp for the duck Cyt b gene and 146 bp and 326 bp for both sheep and goat Cyt b genes, respectively. The results indicated that this PCR-RFLP procedure was simple and reliable for the fast and accurate identifications of duck meat from the sheep or goat meat.