Natural faecal fluorophores and the potential of chlorophyll based markers to optimise fluorescence as a real-time solution for the detection of faecal contamination on carcasses

More accurate and sensitive visualisation of faecal contamination in the abattoir would significantly reduce
the risk posed by harbouring pathogenic micro-organisms. We carried out a preliminary investigation of the
range of fluorophores found naturally in faeces from typical ruminant diets. Sixteen ewes were offered
either: i) fresh forage (FF), ii) grass silage (GS), iii) grass hay (GH) or iv) concentrate and barley straw (CB).
Animals offered FF diets had a greater concentration (Pb0.001) of chlorophyll based compounds in their
faeces and subsequent fluorescent emission spectra. In a second experiment we investigated a range of
fluorescent markers against a basal concentrate and barley straw diet. Ten Cheviot sheep were split into five
treatment groups during a duplicate 5 × 5 Latin square design. Four of the groups received a chlorophyll
based marker at a rate of 2 g/d: i) Mg–Chlorophyllin (MgC), ii) Fe–Chlorophyllin (FeC), iii) Zn–Chlorophyllin
(ZnC) or iv) Spirulina (Chlorophyll a extract from blue green algae, Sp). The last group received no
supplement as the control (Con). The appearance of chlorophyllin markers and their derivatives in faeces
was similar with mean concentrations of 3.1 and 7.2 μg/g DM, respectively. The most intense fluorescent
signal was shown with MgC followed by ZnC, FeC, Sp and Con at 685 nm. The use of markers in pre-slaughter
diets would improve the accuracy of faecal detection as a result of greater fluorescence and specific emission
wavelengths which do not overlap with natural meat components to help with visualisation