Abstract. A total of 60 drakes out of three flocks of conservative Miniduck (K2), Polish Pekin (P33), native Pekin population type A3 and two breeding strains (A55, P66), aged seven weeks, were used for comparison. The content of protein, lipids, moisture, essential amino acids, fatty acids and cholesterol were estimated. There were differences among flocks in all biochemical parameters. The muscles of A55 and P66 comprised more protein and less moisture than P33 and A3 muscles. The P33 breast muscles comprised the least of lipids (0.8% v/s 1.16–1.32%), however A55 of cholesterol (71.21mg/100g v/s 82.23–111.82 mg/100g). The isoleucine (ILE) and valine (VAL) were amino acids which limited the biological value of meat proteins from breast muscles of A3, P33 and K2, however tryptophan (TRP) for A55, P66 muscles. The unsaturated fatty acids (UFA) were predominant for all flocks (50.12–60.64%), the P66 muscles contained the most of UFA and P33 the most of saturated fatty acids (SFA). The highest level of polyunsaturated fatty acids (PUFA) was established in K2 muscles. The PUFA/SFA and n-6/n-3 PUFA ratios were 0.63–0.84 and 3.22–5.85 respectively. The lipids of A55 were characterized by the best fatty acid profile among the investigated muscles. Taking into consideration the nutritive value of proteins, cholesterol content and profile of fatty acids, A55 breast muscles appeared to be the most favourable from the human health point of view.

Recently, transgenic potato plants were created with overexpression of the 14-3-3 protein derived from Cucurbita pepo. Detailed analysis of those plants suggested that the function of the isolated 14-3-3 isoform is in the control of carbohydrate and lipid metabolism in the plants. 14-3-3 protein overexpression gave rise to an increase in soluble sugar and catecholamine contents in both leaves and tubers. It is proposed that 14-3-3 protein affects carbohydrate metabolism in potato plants via regulation of catecholamine synthesis. Furthermore, genetically modified potato tubers with 14-3-3 protein overexpression showed changes in lipid content and composition. The transgenic potato tubers contained 69% more total fat compared to the wild-type plant. Separation of tuber lipids into polar and nonpolar fractions revealed that the transgenic potato tubers contained almost 3 times more nonpolar lipids than the control. Analysis of fatty acid composition, conducted by the means of gas chromatography, showed that linoleic acid was the main fatty acid present in the tubers of both modified and control potato plants. In the nonpolar fraction of the fat of the transgenic tubers the unsaturated fatty acids exhibited a higher participation in the sum of all fatty acids.

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Abstract. The study was carried out on eggs of two-year-old Orpington ducks (O1) and crossbred ducks Khaki Campbell×Orpington (KhO). Eggs for analysis were collected in the 6th and the 22nd week of egg laying. The eggs of KhO ducks had greater weight (72.45 g), specific gravity (1.083 g/cm3) and a thicker shell (0.67 mm) in comparison to eggs of the O1 population (70.64 g, 1.081 g/cm3 and 0.65 mm, respectively). Eggshell content accounted for 9.53% and 7.85% of egg weight in KhO and O1 ducks, respectively. Eggs of KhO ducks were characterized by a lower egg white index (0.07), yolk content (39.48%) and protein content of egg white as well as lower L* parameter of yolk than eggs of O1 ducks. In KhO eggs, yolk lipids contained more C 18:1 cis-9, C 20:4, C 22:6 and C 20:5 and less α C 18:3 and C 18:1 trans-11 fatty acids than those of O1 eggs. The eggs laid in the 6th week had greater weight (by 3.61 g), specific gravity (by 0.01 g/cm3), egg white content (by 2.26%), eggshell thickness (by 0.04 mm), strength (by 10.70 N) and deformation (by 0.90%), and lower yolk content (by 2.34%) than the eggs laid in the 22nd week of laying. Furthermore, the eggs laid at the beginning of the second laying period were characterized by higher protein content of egg white and yolk (by 0.26% and 0.49% respectively) and pH value of egg white and yolk, lower lightness of yolk (L*), higher unsaturated fatty acids (UFA) content of yolk (especially polyunsaturated fatty acids – PUFA, by 2.53%), and lower saturated fatty acids (SFA) content of yolk (by 3.10%) and total cholesterol content (by 2.38%).