Compared with strain A44, male and female ducks of strain A55 showed significantly higher body weights at 7 weeks of rearing. They did not differ only in shank length and breast muscle thickness. Dressing percentage and percentage of tissue components were similar in both strains. Only the percentage of skin with subcutaneous fat and weight of abdominal fat were lower in A55, which is a favourable result. The weights of breast and leg muscles were found to be positively and significantly correlated with the lengths of trunk with neck, trunk, sternum and shank. The percentage of skin with subcutaneous fat combined with abdominal fat was significantly and negatively correlated with trunk and sternum length and with chest and shank circumference. Trunk and sternum length can be used in selection for high weight of breast and leg muscles and decreased fatness, while shank length can be employed in the selection for decreased fatness. pH 15 and pH 24 values in strains A44 and A55 were similar to those found in other studies. The water holding capacity of breast and leg muscles was high and higher in A55, whereas the water content of muscles was similar in both strains. Percentages of protein and ash were higher in breast muscles and those of fat in leg muscles. In other Polish and foreign studies the proportions of protein, fat and ash in the muscles were greater. The meat quality of A55 ducks was superior to that of A44 ducks.

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.

Commercial geese breeding in Poland is based on two strains of White Italian geese (W11 and W33). The crossbreeds W33 (paternal line) and W11 (maternal line) are distributed in Poland under the commercial brand of White Ko³uda® goose. However, there are several breeds which are covered by the animal genetic resources conservation program and kept as conservative flocks. These breeds proved invaluable to commercial geese breeding to stabilize body weight, improve muscling and decrease the amount of fat in the carcass of the crossbreeds. Therefore, this study analyzed the reciprocal crossbreeds of White Ko³uda® geese with the individuals from conservative flocks. DNA polymorphism (RAPD-PCR) of the crossbreeds as well as the phenotypic effect of crossbreeding was evaluated. PCR amplification of five RAPD markers resulted in obtaining 14.25 band/crossbreed group. The genetic similarity of the crossbreeds expressed as band sharing frequency (BS) ranged from 0.44 to 0.97. The direction of crossing of the W33 goose with one of the individuals from the conservative flock strongly affected the genetic similarity estimates. The body weight in the 17 JD or 24 JD week of life and the percentage of leg muscle weight in the 24 JD week of life differed significantly depending on the crossbreed genotype. A similar relationship was demonstrated for egg fertilization and number of nestlings per goose. As the lines were differentiated only by origin of the Z chromosome, the background of the differences in genetic polymorphism and the phenotypic records is hypothesized as (i) the linkage of some production traits with sex chromosomes; (ii) the impact of selection on W33 individuals resulting in lower performance of geese with a W33-derived Z chromosome; (iii) genetic imprinting displayed as the effect of either maternal or paternal origin of the Z chromosome.

In 80 Mulard ducks (crossing of Muscovy drakes with Pekin ducks) at 9-and 12-weeks of age the relationships between alive body measurements and live body weight and percentage content of breast and legs muscles, skin with subcutaneous fat, abdominal and intestinal fat and bones in the carcass were determined.According to the multiple regression equations the following parameters are useful for estimating the percentage of meat in 9-and 12-week-old living Mulard ducks: thorax lenght, shank length, breast circumference and breast muscle thickness. The fat content can be estimated on the basis of body weight, arm length, thorax length, sternum crest length and breast depth.