## 3 Results and Discussion
In the industrial system of growing, a wide variety of feed ingredients are used for the pig's diet: flaked barley, fish meal, flaked maize, potato protein, full-fat soya, ground micronized wheat, whey powder, maize starch, etc. These values are similar to those reported by [PERSON] et al. (2018) [8] for Spanish conventional pork meat samples, which varied from \(-23.0\) to \(-22.3\)% (mean value \(-22.6\)%). For the swine coming from the yard-rearing system, the isotopic fingerprint of \({}^{13}\)C varied from \(-20.1\) to\(-14.2\)%. These swine are grown in a semi-open system, moving outdoors. The feed consists of a boiled mixture of herbs and plants that grow in that geographical area, these plants being different throughout the year, with each season having its own specific plants [12]. Furthermore, these farm-raised animals are fed boiled potatoes and corn, a rich corn-based diet that is an old Romanian tradition for pig yard rearing systems in rural areas. Thus, they form their own fat deposits to help them cope with low temperatures during the cold season. This kind of rearing system leads to a special taste in pork meat, which is very appreciated by consumers. A similar trend of results was obtained by [PERSON] et al. (2020) [7], with significantly lower \(\delta^{13}\)C values for conventional pork as compared to organic pork from the same area. _Content of macro-, micro-, trace-, and toxic elements in chicken and pork meat_  
Figure 3: \(\delta^{13}\)C versus \(\delta^{2}\)H for investigated meat samples. ICP-MS represents one of the most advanced and accurate analytical methods used for multi-element determinations. A total of 28 elements, namely, macro- (K, Na, Mg, and Ca); micro- (Fe, Zn, Rb, Cu, Cr, B, Ni, Ba, Mn, Se, Mo, Li, and Sr); trace elements (V, Co, La, Nb, Pd, and In); and metals with toxic potential (Pb, Sn, Sb, As, and Pb) were determined from the chicken and pork meat samples. The minimum, maximum, and mean concentrations of these elements are presented in Table 1.  
For the _chicken meat_, the most abundant mineral was K, with a mean value of 4513.4 mg/kg (fresh weight), followed by Na, Mg, and Ca, with mean values of 1037.9 mg/kg (fresh weight), 804.7 mg/kg (fresh weight), and 80.2 mg/kg (fresh weight), respectively. [PERSON] et al. (2022) [19] obtained the same decreasing order for macroelements in chicken breast from conventional and sustainable farms in Korea. The values of macroelements (in mg/kg) in chicken meat samples, presented in other studies, ranged between: 4250 and 5140 [19], 2425 and 3236 [20], 3621 and 4010 [21] for K; 280 and 470 [19], 312.03 and 4036 [20] for Na; 260 and 310 [19], 220.75 and 292.62 [20], 278 and 330 [21] for Mg; and 50 and 80 [19], 39.08 and 88.30 [20], 41-77 [21] for Ca, respectively. In the present study, based on the mean values, the concentrations were reported in descending order as follows: Fe > Zn > Rb > Cu > Cr > B > Ni > Ba > Mn > Se > Mo > Li > Sr (for microelements); V > Co > La > Nb > Pd > In (for trace elements); and Pb > Sn > As > Sb > Cd (for potentially toxic elements). The mean concentrations (in mg/kg fresh weight) of some essential microelements obtained from investigated chicken meat were: 2.02 (Cu), 7.12 (Fe), 0.17 (Mn), 0.10 (Se), 3.73 (Zn), and 0.05 (Mo). For these essential minerals, the values reported in the literature [19; 20; 21; 22] for _chicken meat_ (in mg/kg) were: Brazil (2.2 and 6.0 for Cu, 19.8 and 42.1 for Fe, 0.326 and 0.470 for Mn, 0.421 and 0.455 for Se, 51 and 108 for Zn, and 0.206 and 0.120 for Mo, in confined chicken and free range chicken, respectively), South Korea (0.23 and 0.22 for Cu, 0.15 for Mn, 0.036 and 0.043 for Se, and 3.83 and 4.33 for Zn in meat from conventional and sustainable chicken farms), Brazil (1.99 for Cu, 3.95 for Fe, and 7.72 for Zn in a chicken breast sample), and Croatia (0.36 for Cu, 0.32 for Mn, 0.19 for Se, and 7.6 for Zn).