## 3 Results
### Serum Antioxidant Status  
The effect of experimental diets CV2% and SP2% on the blood antioxidant enzymes SOD, CAT, GSH, and TAC activity is presented within Figure 1. A significant increase (\(p\) < 0.001; \(p\) < 0.0001) of SOD concentration in serum of laying hens fed with microalgae was noticed compared to the CON group. Also, a highly significant difference (\(p\) < 0.001) was registered between experimental groups, where SP2% was characterized by an increased antioxidant activity which assumes a high antioxidant status of this group. The chlorella and spirulina powder diet supplements improved the enzymatic activity of CAT,  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameters**} & \multicolumn{3}{c}{**Dietary Treatments**} & \multirow{2}{*}{**SEM**} & \multirow{2}{*}{**\(p\)-Value**} \\ \cline{2-2} \cline{4-5}  & **CON** & & & **CV2\%** & \\ \hline \multicolumn{5}{c}{Antioxidant activity} \\ \hline Chlorophyll a, \(\mu\)g/g & 10.31 \({}^{\mathrm{c}}\) & 344.76 \({}^{\mathrm{b}}\) & 383.22 \({}^{\mathrm{a}}\) & 5.41 & \textless{}0.0001 \\ Chlorophyll b, \(\mu\)g/g & 2.77 \({}^{\mathrm{b}}\) & 40.93 \({}^{\mathrm{a}}\) & 38.92 \({}^{\mathrm{a}}\) & 1.44 & \textless{}0.0001 \\ Carotenes, \(\mu\)g/g & 31.45 \({}^{\mathrm{b}}\) & 84.92 \({}^{\mathrm{a}}\) & 81.70 \({}^{\mathrm{a}}\) & 1.08 & \textless{}0.0001 \\ Total polyphenols, mg/g GAE & 1.49 & 1.67 & 1.64 & 0.177 & 0.933 \\ Antioxidant capacity (DPPH \% inhibition) & 32.00 \({}^{\mathrm{c}}\) & 57.57 \({}^{\mathrm{b}}\) & 67.23 \({}^{\mathrm{a}}\) & 1.23 & \textless{}0.0001 \\ Antioxidant capacity (\(\mu\)M Trolox) & 5.19 & 6.25 & 5.79 & 0.403 & 0.620 \\ \hline \multicolumn{5}{c}{Fatty acid composition (\% of total fat)} \\ \hline \(\Sigma\)SFA & 29.03 \({}^{\mathrm{a}}\) & 19.72 \({}^{\mathrm{b}}\) & 22.44 \({}^{\mathrm{b}}\) & 0.893 & 0.001 \\ \(\Sigma\)MUFA & 47.42 \({}^{\mathrm{a}}\) & 37.06 \({}^{\mathrm{b}}\) & 40.12 \({}^{\mathrm{ab}}\) & 2.06 & 0.030 \\ \(\Sigma\) PUFA, from which: & 23.16 \({}^{\mathrm{b}}\) & 42.95 \({}^{\mathrm{a}}\) & 37.11 \({}^{\mathrm{a}}\) & 2.36 & 0.003 \\ \(\Sigma\) n-3 PUFA & 1.03 \({}^{\mathrm{b}}\) & 1.43 \({}^{\mathrm{a}}\) & 1.21 \({}^{\mathrm{ab}}\) & 0.06 & 0.007 \\ \(\Sigma\) n-6 PUFA & 22.14 \({}^{\mathrm{b}}\) & 41.52 \({}^{\mathrm{a}}\) & 35.90 \({}^{\mathrm{a}}\) & 2.32 & 0.003 \\ \(\Sigma\) n-6/\(\Sigma\) n-3 & 21.58 \({}^{\mathrm{b}}\) & 29.18 \({}^{\mathrm{a}}\) & 29.47 \({}^{\mathrm{a}}\) & 1.22 & 0.006 \\ \hline \hline \end{tabular}  
* Where: CON, conventional diet; CV2%, conventional diet supplemented with 2% chlorella powder; SP2%, conventional diet supplemented with 2% spirulina powder; \(n\) = 5 samples per group; SEM, standard error of the mean; \({}^{\mathrm{ab}}\) Mean values within a row with different letters are significantly different at \(p\) \(\leq\) 0.05. Abbreviations: \(\Sigma\)SFA, sum of saturated fatty acids; \(\Sigma\)MUFA, sum of monousmutated fatty acids; \(\Sigma\)PUFA, sum of polyunsaturated fatty acids; \(\Sigma\) n-3 PUFA = C18:3n-3 + C18:4n-3; \(\Sigma\) n-6 PUFA = C18:2n-6 + C20:2n-6 + C20:3n-6 + C20:4n-6.  
\end{table}
Table 3: Nutritional compounds of the feed (% as fed).  
increasing (\(p<0.01\)) its serum concentration value significantly compared to CON. There were no differences (\(p\geq 0.05\)) noticed between the two experimental groups.  
GSH serum concentration significantly increased (\(p<0.0001\)) in the SP2% and CV2% groups compared to CON. Also, significant statistically differences (\(p<0.05\)) were observed between the experimental groups. The same trend was noticed for total antioxidant capacity value from serum, but with highly statistical differences (\(p<0.001\)) between the two experimental groups.