Incidents of foodborne illness associated with consuming undercooked or raw chicken are often linked to two causative pathogens: Campylobacter spp. or Salmonella spp, according to Michael Lee from Aberystwyth University.

In a paper published in Poultry Science with co-authors there and at the University of Bristol, they report that numerous studies have shown that contamination of carcasses results when pathogens are transferred from the intestinal tract or faecal material on feet and feathers to the dressed carcass.

Ultraviolet spectral imaging to detect surface faecal and ingesta contamination on poultry carcasses may provide a solution to aid detection. However, poultry diets do not provide sufficiently high levels of natural fluorophores for this system to be reliable.

Their study investigated the potential of chlorophyll-based feed additives to improve fluorescence of the faeces and narrow the excitation and emission wavelengths to aid in the development of a simple visualization system.

Twenty-four hens (Gallus gallus domesticus) were allocated at random to one of four treatments:

• control (C, no marker)
• Zn chlorophyllin
• Mg chlorophyllin, or
• Fe chlorophyllin.

All markers were incorporated into mash before pelleting at a rate of 1g per kg of dry matter.

The experiment consisted of two 4×4 Latin squares with each period consisting of two weeks.

Feces were collected and extracted in acetone:water (50:50; vol/vol) with faecal fluorescence emission spectra determined using a Jasco FP-6200 Spectrofluorometer with excitation at 382nm.

A main peak evolved at wavelength 670nm with the total area under the peak used as fluorescence intensity.

Following seven days of marker supplementation, the three markers improved the fluorescence intensity by ×14.8, 12.8, and 6.9 for Fe, Mg and Zn chlorophyllin, respectively, compared with the control.

The addition of faeces containing Mg chlorophyllin to chicken carcass increased detection of the faeces compared with faeces with no marker.

Lee and co-authors added that, due to the plain background of chicken skin, a simple image at 675nm with appropriate thresholds would allow detection of contaminated carcasses at the current slaughter line speed without the need of expensive hyperspectral imaging.

Reference

Lee M.R.F., D. Leemans, V.J. Theobald, H.R. Fleming and A.P. Gay. 2013. The development of chlorophyll-based markers in poultry diets to aid detection of fluorescent fecal contamination. Poult. Sci. 92(12):3251-3258. doi: 10.3382/ps.2013-03310