SUMMARY
An experiment was conducted to assess the impact of vitamin D3, on laying hens' performances, egg yolk fatty acid profile (FA), antioxidant compounds and vitamin transfer in the eggs. For that, one hundred twenty, 34 weeks old Lohmann Brown laying hens, were allocated to completely randomized block arrangement of three dietary treatments: T1, control (C) with 2500 IU/kg vitamin D3; T2 with 3000 IU/kg vitamin D3 and T2, with 3200 IU/kg vitamin D3. All diets had identical basal diet structure containing 17.50% crude protein and 2780 kcal/kg, metabolizable energy, being isocaloric and isonitrogenous. Feed intake and feed conversion ratio were significantly (p<0.05) lower in T2 and T3 groups compared to T1, without any impact on average egg weight. Egg production was significantly (p<0.05) higher only in T2 group, compared with T1 and T3. No significant (p>0.05) contribution of vitamin D3 supplementation was observed on total saturated fatty acids (SFA), unsaturated fatty acids (UFA) or monounsaturated fatty acids (MUFA) classes determined in egg yolk. From the sum of cis FA, significantly (p<0.005) higher was palmitoleic FA in T1 egg yolk compared with T2 and T3 egg yolks. On the other hand, from the total trans group, nervonic FA was significantly (p<0.05) higher in eggs belonging to higher vitamin D3 supplement groups. Total polyunsaturated fatty acids (PUFA), were significantly (p<0.05) higher in T2 and T3 egg yolks compared with T1 egg yolk. However, n-3 increase significantly only in T3 yolks being with 43.92% higher compared with T1 yolk and with 35.51% higher compared with T2 yolk. From the antioxidant compounds, total polyphenol content, total antioxidant capacity, lutein and zeaxanthin, vitamin A and vitamin E registered slightly higher values in T2 and T3 eggs versus T1 eggs, but without significant (p>0.05) effect. Vitamin D3 transfer in eggs increased significantly (p<0.05) in T3 compared with T1 and T2 eggs, as a main effect of supplemental vitamin D3 in laying hens' diets.