## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{3}{c}{**Chicken Meat**} & \multicolumn{3}{c}{**Pork Meat**} \\ \cline{2-7}  & **Min** & **Max** & **Mean** & **Min** & **Max** & **Mean** \\ \hline \multicolumn{7}{c}{**\%o**} \\ \hline \(\delta^{13}\)C\({}_{\text{VPDb}}\) & \(-22.3\) & \(-12.8\) & \(-19.3\) & \(-24.1\) & \(-14.2\) & \(-19.0\) \\ \(\delta^{2}\)H\({}_{\text{VSMOW}}\) & \(-58.1\) & \(-29.1\) & \(-46.3\) & \(-74.7\) & \(-25.9\) & \(-49.5\) \\ \(\delta^{18}\)O\({}_{\text{VSMOW}}\) & \(-6.6\) & \(-0.5\) & \(-4.6\) & \(-9.6\) & \(-3.7\) & \(-6.1\) \\ \hline \multicolumn{7}{c}{**Concentration (mg/kg fresh meat)**} \\ \hline
**K** & 774.8 & 7818.7 & 4513.4 & 1093.1 & 4161.3 & 2724.1 \\
**Na** & 253.2 & 2621.2 & 1037.9 & 303.3 & 5681.1 & 837.7 \\
**Mg** & 261.1 & 1756.5 & 804.7 & 123.1 & 405.9 & 272.3 \\
**Ca** & 4.7 & 206.8 & 80.2 & 19.2 & 405.0 & 59.0 \\
**Fe** & 0.40 & 25.02 & 7.12 & 5.48 & 70.75 & 27.24 \\
**Zn** & 0.01 & 28.71 & 3.72 & 6.85 & 63.74 & 19.19 \\
**Rb** & 0.38 & 7.55 & 2.43 & 0.90 & 6.20 & 2.72 \\
**Cu** & 0.25 & 22.99 & 2.02 & 0.26 & 5.32 & 1.05 \\
**B** & 0.01 & 0.99 & 0.56 & LOQ & 0.76 & 0.19 \\
**Ba** & 0.04 & 0.79 & 0.18 & 0.01 & 0.63 & 0.09 \\
**Se** & 0.04 & 0.41 & 0.10 & 0.01 & 0.44 & 0.26 \\
**Cr** & 0.004 & 8.64 & 1.70 & 0.37 & 5.48 & 1.79 \\
**Ni** & 0.003 & 1.45 & 0.36 & 0.13 & 3.41 & 0.48 \\
**Mn** & 0.001 & 0.68 & 0.17 & 0.09 & 2.06 & 0.23 \\
**Mo** & \textless LOQ & 0.14 & 0.05 & LOQ & 0.20 & 0.04 \\
**Li** & LOQ & 0.34 & 0.03 & LOQ & 0.37 & 0.02 \\
**Sr** & LOQ & 0.16 & 0.03 & 0.01 & 0.23 & 0.04 \\
**V** & LOQ & 0.06 & 0.02 & 0.001 & 0.08 & 0.02 \\
**Co** & LOQ & 0.03 & 0.01 & 0.001 & 0.14 & 0.02 \\
**La** & LOQ & 0.13 & 0.004 & LOQ & 0.10 & 0.003 \\
**Nb** & LOQ & 0.01 & 0.004 & LOQ & 0.01 & 0.002 \\
**Pd** & LOQ & 0.05 & 0.003 & LOQ & 0.21 & 0.01 \\
**In** & LOQ & 0.01 & 0.001 & LOQ & 0.01 & 0.0006 \\
**Pb** & LOQ & 4.12 & 0.60 & 0.02 & 1.05 & 0.27 \\
**Sn** & LOQ & 0.16 & 0.05 & LOQ & 0.17 & 0.04 \\
**Sb** & LOQ & 0.01 & 0.001 & LOQ & 0.001 & 0.0005 \\
**As** & LOQ & 0.52 & 0.02 & LOQ & 0.05 & 0.005 \\
**Cd** & LOQ & 0.05 & 0.002 & LOQ & 0.01 & 0.002 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The minimum, maximum, and mean content of determined elements in chicken and pork meat samples. Figure 2: Isotopic composition (\(\delta^{2}\)H versus \(\delta^{18}\)O) for investigated meat samples. As it can be observed in Figure 3, there is a very good separation between the animals grown in different systems. The \(\delta^{13}\)C range of variation for chicken grown in conventional systems is very narrow, between \(-22.3\) and \(-21\)% (mean value \(-21.5\)%), proving a similar diet among farms, a mix of C3 (barley, oats, rye, and wheat) and C4 (corn) plants. [PERSON] et al. (2010) [18] obtained a mean value of \(\delta^{13}\)C = \(-20.75\)% for commercially grown corn-fed chickens, reporting that a calibration of the \(\delta^{13}\)C analysis versus the corn proportion in the diet produced a linear relation. Thus, by their developed method, [PERSON] et al. (2010) [18] proposed a critical value \(\delta^{13}\)C = \(-22.5\)% of chicken meat that could assign (\(>\)97.5%) chicken as non-corn fed if the diet contains no more than 23.3% corn. The \({}^{13}\)C isotopic values of chicken meat samples obtained through a yard rearing system were higher than those obtained through a conventional growth system. For 30 of the 33 chickens raised in the yard, \(\delta^{13}\)C values ranged from \(-20.4\) to \(-17.3\)%. These values demonstrate that the feed was based on a combined C3 and C4 diet, with an important proportion of corn. For the other three samples, the mean isotopic composition of \({}^{13}\)C was \(-13.2\)%, confirming the fact that chickens were exclusively fed corn. Regarding pork meat samples, the \(\delta^{13}\)C range of variation for pigs grown in conventional systems is between \(-24.1\) and \(-20.0\)% (mean value \(-21.8\)%).