The present study evaluated two previously developed methods for amplification
of bovine mtDNA segments of 109 and 271 base pairs (bp) by real-time
polymerase chain reaction (PCR). Beef samples were sterilised experimentally at
different temperatures (1268C, 1298C, 1328C and 1358C). These experimentally
sterilised beef samples and nine commercial meat and bone meals (MBM) were
mixed to a reference plant concentrate in strengths of 50%, 10%, 5%, and 1%.
The results of the following PCR showed that the Bos-109 real-time PCR assay
was able to detect all the experimental beef samples with exception of the mixtures
of beef heated experimentally to 1358C. In mixtures of industrial MBM bovine
DNA were always found. Comparatively, the beef sterilised at 1358C and 1328C
(and their respective mixtures) and the mixture containing 1% of beef sterilised at
1298C were not detectable with the PCR assay amplifying a target of 271 bp.
Using this PCR mixtures of industrial MBM were only weakly detected. The low
concentrated mixtures of the extremely processed MBM-1 and MBM-2 even
reported negative. These results indicate that the detectability of bovine DNA is
strongly influenced by the degree of the thermal treatment. Only the PCR assay
amplifying relatively short fragments of a multi-copy mitochondrial target was
reliable for the detection of correctly heated MBM in mixed feed.