Potential of chlorophyll-rich feed ingredients to improve detection of fecal contamination in the abattoir.

The use of fecal fluorescence to improve detection of contamination of carcasses in the abattoir was previously reported. However, incidents of false negatives can result when animals are offered diets that contain little chlorophyll (e.g., concentrate). Here, we investigated the potential of incorporating a high-chlorophyll-containing feed ingredient (concentrated alfalfa extract; CAE) into the diets of sheep and cattle to improve fecal fluorescence intensity. The sheep experiment evaluated the fecal fluorescence of animals from pasture, when fed a concentrate-barley straw diet and when the concentrate diet incorporated CAE (100 g of dry matter a day). Fecal chlorophyll and metabolite content was highest on the pasture-fed animals and increased significantly over the concentrate diet when CAE was included. Subsequently fluorescent intensity was increased from 15,000 to 36,000 arbitrary units for concentrate and CAE-concentrate diets, respectively, compared with 59,000 for the pasture-fed animals. The cattle experiment investigated the potential of CAE to improve fluorescence of feces from a concentrate diet as well as a silage diet at two levels of incorporation (75 and 150 g CAE/kg of dry matter intake). This study also determined the fluorescence of digesta and carcass contamination in the abattoir on a subset of carcasses. In agreement with the sheep study, CAE significantly improved fluorescence of feces and digesta when added to a concentrate diet, but had little effect on improving fecal fluorescence from the silage-fed animals. This was thought to be related to greater chlorophyll degradation in the rumen or/and the dark nature of the silage feces acting as a quencher of emitted fluoresced light. Incorporating high-chlorophyll-containing plant ingredients into ruminant concentrate diets will improve detection of fecal contamination by reducing false-negative readings. However, they will have little effect on false-positive readings due to the range of wavelengths emitted by natural chlorophyll and its metabolites. Implications and potential solutions for this are discussed.

Effect of oxygen concentration on photo-oxidation and photosensitizer bleaching in butter.

The effect of headspace oxygen concentration and color of light on photo-oxidation and degradation of photosensitizers in butter was studied. Butter samples were stored under 0%, 0.4%, 0.8%, 1.6%, 3.0%, 5.0%, 21% oxygen, and exposed to violet, green or red light. Storage time was 36 h. Degree of photo-oxidation was measured by a trained sensory panel. Photobleaching of six different photosensitizers was estimated based on front face fluorescence excitation and emission landscapes and spectral curve resolution (parallel factor analysis). The higher oxygen concentration, the more sensory degraded were the samples. Violet light resulted in slightly higher degrees of photo-oxidation than green and red light for low oxygen concentrations. Bleaching rate and course as function of O(2) concentration differed between the photosensitizers. It is suggested that the rate of photobleaching is a balance between type I and type II photoreactions.