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.

In two Polish conservative flocks of Miniduck (K2) and Pekin (P33), registered by FAO as domestic genetic resources (World Watch List, 2000) the mean values of physical (tissue components) and qualitative traits of meat (pH 15 , pH 24 , colour of meat) were determined. The experimental flocks showed significant variations in body weight at 7 weeks of age (1540 vs 2088 in drakes and 1395 vs 1986 g in ducks), in the proportion of breast and leg muscles and skin with subcutaneous fat in eviscerated carcass. K2 ducks are characterized by outstanding musculature of breast and P33 ducks by that of lower leg and by low fatness. pH 15 values of breast and leg muscles in K2 and P33 birds were greater than pH 24 of these muscles. In both flocks pH 15 values of 6.09 to 6.33 and pH 24 values of 5.90 to 6.05 in breast muscles were lower than in leg muscles (6.33 to 6.46 and 6.12 to 6.37, respectively). A significantly lower L* value (darker colour) of breast muscle was characteristic of K2 birds (43.7 in males and 40.5 in females) compared to P33 males and females. Furthermore, breast muscles of K2 drakes and ducks had significantly higher redness (a*) and yellowness values (b*) than P33. In pectoralis superficialis muscle of K2 and P33 females, a significantly lower diameter was found for white muscle fibres (αW) (30.0 to 30.5 µm) and for red muscle fibres (βR) (16.9 to 17.6 µm) than in biceps femoris muscle (αW from 48.3 to 54.2; βR from 36.0 to 37.1 µm). Muscle fibres of K2 compared to P33 ducks were characterized by significantly greater diameters of βR muscle fibre in pectoralis superficialis muscle, and by lower αW and βR fibre diameters in biceps femoris muscle. The experiment showed that meat of ducks from the conservative flocks studied is valuable from the consumer's point of view.

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%).

The aim of this study was to evaluate the reproductive traits and physical traits of the eggs of three-breed crosses of geese -White Kołuda (WK) × Slovakian (Sl) × Graylag (Gr) -in terms of the direction of crossing of the parents, and to determine differences in the chemical composition of eggs at the beginning and at the end of the reproductive period. The highest egg production (37 eggs), egg weight (192.4 g) and body weight (males 7491 g, females 6507 g) were characteristic of the crossbreds Sl'GrWK. The eggs of these geese had high density and a high yolk index, as well as a higher Haugh unit value, compared to those of geese from the other groups. The mutually crossed hybrids WKGr´Sl, which had the lowest body weight (males 5804 g, females 5763 g), had the highest egg fertility (77.3%) and hatchability of goslings from set (67.1%) and fertilized eggs (86.9%). In addition, they had the highest Haugh unit value and the greatest number of pores in the shell. The egg yolks of WKGr´Sl crossbreds contained the highest amount of ash at the end of egg production and the highest amount of water in albumen at the beginning of egg production. During the egg production period, water and ash content increased, and the fat content of the egg yolks of the geese decreased regardless of the direction of crossing of the parents. A statistically significant interaction (time × groups) occurred only for percentage of ash in yolk. During the same period, the levels of water, protein and ash increased in the albumen of the eggs, but time × groups interactions were only found for water and ash percentage.

In eviscerated carcasses of ducks from Khaki Campbell (Kh1) and Pekin (P8) conservative flocks, percentages of breast muscles, leg muscles, skin with subcutaneous fat and abdominal fat, as well as meat quality traits (pH 15 , pH 24 and colour) and muscle fibre microstructure were determined. Statistically significant differences were detected in body weights at 7 weeks of age (1383 and 2292 g in Kh1 and P8 males, 1396 and 2177 g in Kh1 and P8 females, respectively).pH 15 values of breast and leg muscles of Kh1 and P8 ducks were higher than pH 24 values of these muscles. Meat of ducks from both flocks showed lower pH 15 and pH 24 values in breast muscles (from 6.07 to 6.52 and from 5.84 to 6.14) compared to leg muscles (from 6.27 to 6.60 and from 6.15 to 6.38, respectively). Birds from both flocks were characterized by a similar colour of breast muscle (L) -46.90 and 44.01 in Kh1 males and females; 44.69 and 44.34 in P8 males and females, respectively. Breast muscles of Kh1 birds of both sexes were characterized by a significantly greater yellowness (b) compared to the muscles of P8 ducks. In Pectoralis superficialis muscle of ducks of both flocks, the diameters of white (αW) and red fibres (βR) were lower than in Biceps femoris muscle. Muscle fibres of Kh1 compared to P8 ducks were characterized by lower βR and αW fibre diameters in Pectoralis superficialis (31.3 and 16.6 μm) and Biceps femoris muscles (46.0 and 32.7 μm, respectively).