Variations in stable isotope ratios in lamb blood fractions following dietary changes: a preliminary study.

RATIONALE: In meat production it is common practice to use finishing diets based on concentrates, even for those animals previously raised on pasture. No studies have investigated the variations of stable isotope ratios in lamb plasma and erythrocytes, following a switch from pasture to a concentrate-based diet during the last days before slaughter. For meat traceability it is important to verify how and whether these parameters are affected in blood fractions. METHODS: Blood of ten male Italian Merino lambs, whose diet was switched from pasture to concentrate, was sampled 8 times (days 1, 2, 3, 4, 5, 6, 7 and 14) in the last 14 days before slaughter. The variations in the δ(13)C, δ(15)N, δ(18)O and δ(34)S values of blood plasma and erythrocytes were investigated. The stable isotope ratios of the samples were measured using a stable isotope mass spectrometer coupled with an elemental analyser (C, N, S) and a CO2/H2O equilibration system (O(plasma)). RESULTS: The δ(13) C(plasma), δ(18)O(plasma) and δ(34)S(plasma) values were shown to be different 7 days after the abrupt variation in the diet. The comparison between erythrocytes and plasma stable isotope ratios could be suitable for verifying whether the animal was actually pasture-raised and could merit a higher price. The erythrocytes isotopic signature was not affected by very short finishing periods in previously grazed animals and maintained the pasture-raised fingerprint, while the analysis of plasma could detect very short finishing periods with concentrate and hay. CONCLUSIONS: The present study has demonstrated that the combination of blood plasma and erythrocytes stable isotope ratios of carbon, nitrogen, oxygen and sulphur can be used to infer the dietary background of lambs and thus offers a tool for the authentication of the animal production system.

Stable isotope ratios of blood components and muscle to trace dietary changes in lambs.

Multielemental stable isotope ratio (SIR) analysis was used in lamb plasma, erythrocytes and muscle to detect the switch from a pasture- to a concentrate-based diet, with the aim of verifying the possibility to trace the change of feeding in animal tissues. During 89 days of experimental feeding, lambs were subjected to four dietary treatments: pasture (P), pasture followed by concentrate in the stall for either 14 days (P-S14) or 37 days (P-S37) or concentrate in the stall (S). Pasture and concentrate diets comprised C3 plants only and had different values of 13C/12C, 18O/16O, 2H/1H and 34S/32S ratios. Muscle 13C/12C and 34S/32S and plasma 13C/12C and 18O/16O ratios in P, P-S14 and P-S37 lambs were significantly different. A multivariate analytical approach revealed that 13C/12C and 18O/16O ratios in plasma were the most powerful variables for the discrimination among the dietary treatments.

Exposure to pesticides residues from consumption of Italian blood oranges.

This paper reports the results of a 5-year study to evaluate pesticide levels, derived from orchard activities, on Italy's most common orange cultivar (Citrus sinensis, L. Osbeck, cv. Tarocco). Using a Bayesian approach, the study allowed both the qualitative (number) and quantitative distributions (amount) of pesticides to be determined with its own probability value. Multi-residue analyses of 460 samples highlighted the presence of ethyl and methyl chlorpyrifos, dicofol, etofenprox, fenazaquin, fenitrothion, imazalil, malathion and metalaxil-m. A total of 30.5% of samples contained just one pesticide, 2.16% two pesticides and 0.65% of samples had three pesticides present simultaneously. The most common residue was ethyl chlorpyrifos followed by methyl chlorpyrifos. Estimated daily intake (EDI) values for ethyl and methyl chlorpyrifos, as well as the distance from the safety level (non-observed adverse effect level, NOAEL), were calculated. The risk was differentiated (1) to take account of the period of actual citrus consumption (180 days) and (2) to discriminate the risk derived from eating oranges containing a certain level of chlorpyrifos from unspecified pesticides. The most likely EDI values for ethyl chlorpyrifos derived from Italian blood orange consumption are 0.01 and 0.006 mg/day calculated for 180 and 365 days, respectively. Considering the probability of the occurrence of ethyl chlorpyrifos, these EDI values are reduced to 2.6 x 10(-3) and 1.3 x 10(-3) mg/day, respectively. For methyl chlorpyrifos, the most likely EDI values are 0.09 and 0.04 mg/day, respectively; considering the probability of its occurrence, the EDI values decrease to 6.7 x 10(-3) and 3.4 x 10(-3) mg/day, respectively. The results confirmed that levels of pesticides in Italian Tarocco oranges derived from a known controlled chain of production are safe.