Gęsi Zatorskie jako populacja należąca do krajowych zasobów genetycznych drobiu
AbstractThe Zatorska breed of geese, originating from four indigenous Polish goose varieties, was developed during 1956-1961 in the Research Institute of Animal Breeding at Zator with the aim to form a new home variety of better performance and good fit to local environmental conditions. In the years 1967-1985 the Zatorska goose population of 650-700 birds, kept at that time at the Ostrow Szlachecki research farm of the Agricultural University of Krakow, belonged to the national pedigree breeding stock, then it was classified as a gene pool flock. In 1996 the geese were moved to the Rząska research station and since then, with the population size diminished to 250 birds, they have been included in the country's waterfowl genetic resources. The present work provides a brief description of the body phenotype and plumage characteristics of the Zatorska goose breed. Data on the age structure of the population, the number of mating pens and the age of sires and dams are given. Special reference is made to the concept of breeding work in a closed flock which was introduced in 1962. Later on, in 1967, a compromise was found between the closed flock selection programme for body weight and egg laying and the attempts to maintain genetic variation in the population. Matings between close relatives, such as sibs or cousins, were avoided to reduce the rate of inbreeding. Pedigreed weekly hatches were used and efforts were made to maintain one surviving son from each sire family in every generation. Such measures reduced both the variance in the sire family size and the inbreeding rate. The sire pedigree lines presented in this study (since 1962) show three or four male ancestors of the population. Individual records on body weight, number of eggs, age of sexual maturity, egg weight, egg fertility and hatchability were used to analyse the performance of the population undergoing selection for over 30 years in changing environmental conditions. After five years of initial improvement at the Koluda Wielka farm, the rate of improvement decreased slightly when the flock was transferred to the Ostrow Szlachecki farm; this was due to the lack of adaptation of geese to worse and unstable environmental conditions. Later on, at the Rząska research farm, the performance generally improved (except for egg hatchability). The body weight of geese aged 8 and 20 weeks showed a downward time trend in the years 1970-1988 while the 11-week body weight in 1989-2001 and the body measures displayed an upward trend. The egg laying in the first and second season, despite an initial decline, showed a positive time trend in 1970-2001, and the age of sexual maturity of geese decreased by more than 20 days during that period. Also the number of days between 1 January and the date of first egg followed a positive trend and increased by 20 days. There was a decreasing time trend for egg weight in the first season of laying and an increasing trend in the second season of production. In older geese the mean weight of eggs consecutively laid during the laying season decreased by 0.23 g per egg, with the biggest decrease being in 4-year-old birds. No change in egg weight was observed in geese during their first season of laying. Egg fertility in the general flock displayed a negative time trend over 30 years. However, there had been no substantial change in this trait for first 25 years before egg incubation was moved to hatcheries out of the goose farm. Hatchability in both the selection flock and the general flock showed negative time trends. As suggested by the level of genetic variance in the performance characteristics studied during 30 years, there was no change or slow depletion of variation for some traits. Slight downward trends were observed for the heritability coefficients (h2s) of the number of eggs, the age of sexual maturity and the fertility and hatchability from eggs set. The average level of inbreeding in the population remained low. The mean coefficient of inbreeding in the flock during 35 years varied between 0.4 and 3.29%. The average increase in inbreeding was less than 0.1% per generation, which indicates that even in a small closed population the avoidance of matings between relatives and the maintenance of a high effective population size may prevent an undesirable rise in inbreeding. The possible adverse effect of inbreeding on geese performance was estimated by calculating the coefficients of linear regression of some traits on the inbreeding coefficients in 33 generations. A one-percent growth in inbreeding may reduce the 8-week body weight by 3 g, the egg laying performance by 0.02 to 0.12 eggs, the mean egg weight by 0.21 to 0.49 g, the gosling hatchability from eggs set by 0.09 to 0.13%, and the hatchability from fertile eggs by 0.16 to 0.18%. Comparative karyotypic studies revealed that the Podkarpacka, Suwalska and Pomorska varieties of geese have a karyotype typical ofAnser anser, while the Garbonosa variety possesses a karyotype typical of Anser cygnoides. After 35 years of breeding work in a closed population, 8.57% of individuals carry metacentric chromosome 4, typical ofAnser cygnoides, and 91.43% of birds have submetacentric chromosome 4, characteristic of Anser anser. Research carried out on early goose embryos revealed 5.84% of individuals with metacentric chromosome 4. The frequency of chromosomal numerical aberrations in goose embryos was low (5.6-6.1%) and the initial sex ratio did not diverge significantly from the expected ratio of 1 : 1. As indicated by embryopathological analysis and the diagram of embryonic mortality, among the embryos of different karyotypes those carrying metacentric chromosome 4 exhibited a greater mortality during the first and second critical peak. Several experiments on the inheritance of chromosomal polymorphism in the population of Zatorska goose showed that the frequency of Fi individuals, both embryos and birds, carrying metacentric chromosome 4 is markedly smaller than expected. It is likely that the difference in morphology between the homologous chromosomes of the fourth pair might hamper the normal reproduction process, thus adding to the genetic factors responsible for deteriorated hatchability. In summary, the present study convincingly demonstrated that the flock of Zatorska goose has a unique structure and due to its origin and long breeding records makes a valuable population to be used in research on cytogenetics and genetic variation by methods including molecular techniques. It also confirmed validity of the decision to put this breed on the FAO list of the preserved genetic resources of poultry. Together with the other nine indigenous groups of geese in Poland the Zatorska goose adds to the country's cultural heritage which deserves protection.
|Other language title versions||Zatorska goose population as a part of the Polish genetic resources of waterfowl|
|Publisher||Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW |
|Publishing place (Publisher address)||Kraków|
|Book series /Journal (in case of Journal special issue)||Zeszyty Naukowe Uniwersytetu Rolniczego im. Hugona Kołłątaja w Krakowie. Rozprawy, ISSN 1899-3486, (0 pkt)|
|Publication size in sheets||8|
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