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

Abstract

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 C 3 plants only and had different values of O ratios in plasma were the most powerful variables for the discrimination among the dietary treatments.

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

“…Day 1 represents the first day of stall feeding; however, as the blood was sampled before feed supplying, the blood collected on day 1 reflects the pasture diet of the previous 75 days of grazing. Blood samples were taken individually from the jugular vein, collected in tubes and immediately centrifuged (3000 g , 15 min, 4 °C) to separate plasma and erythrocytes . All the experimental procedures were approved by the University of Catania (Catania, Italy) and were in accordance with national regulations concerning animal care and use.…”

“…The 18 O/ 16 O ratio in feed (≈0.8 mg) was measured using a DELTA XP isotope ratio mass spectrometer (Thermo Scientific) coupled with a pyrolyser (TC/EA, high‐temperature conversion elemental analyzer (Thermo Scientific)). Further details of the analytical procedures adopted have been reported in previous papers . The 18 O/ 16 O ratio in plasma was determined in 2 mL of defrosted samples after equilibration with CO 2 using an ISOPREP 18 (VG Isotech, Middlewich, UK) online preparation system that allows CO 2 /H 2 O equilibration, interfaced with a SIRA II isotope ratio mass spectrometer (VG Isogas, Middlewich, UK), employing the water equilibration method described for wine in the OIV method (MA‐AS2‐12: R2009).…”

“…As a consequence, the stable isotope ratios of animal tissues can be used with varying degrees of success to verify the diet and/or the change of diet in animals . However, in the specific case of pasture‐fed lambs there is one 'hurdle' that needs to be cleared, as in meat production it is common practice to make use of finishing diets based on concentrates, even for those animals previously raised on pasture …”

“…determined the half‐life of δ 13 C values in whole blood of lambs fed with leguminous plants or corn silage and found that the 167 days of the experiment were not sufficient to reach isotope equilibrium. Recently, Biondi et al . determined the δ 13 C, δ 15 N, and δ 18 O values in plasma and erythrocytes from lambs raised on different diets for 89 days.…”

Elemental and Isotopic Mass Spectrometry

“…Origin authentication of pork was through differences in δ 13 C and δ 15 N values [282]. Muscle 13 C/ 12 C and 34 S/ 32 S and plasma 13 C/ 12 C and 18 O/ 16 O ratios reveal the feeding changes of lambs [283]. Authentication of PDO dried-cured hams according to their origin, breeding and processing conditions was by 2 H/ 1 H, 13 C/ 12 C, 15 N/ 14 N, 18 O/ 16 O, and 34 S/ 32 S ratios [284].…”