Heritable load in the geese in the process of creating a dimorphic population

Abstract

The paper presents the results of determining the spectrum and frequency of hereditary genetic defects in embryo development on a wide range of geese. They were the original family forms (Large Gray breed, Rhine breed) of geese, descendants of the first and third generations and the created dimorphic population. At the end of the incubation process among the waste incubation of eggs were selected dead embryos, the so-called "dead". Visual examination of embryos revealed morphological disorders in the structure of the skeleton, as well as various disproportions of individual parts of the body. Morphological and anatomical hereditary defects of embryos were established during pathological and anatomical examination of incubation waste. The level of genetic load in each studied group of birds was determined as the proportion of detected abnormalities in the development of embryos to the total number examined. In geese of a Large Gray breed among the examined dead embryos, one of them had a double anomaly, the frequency of which was 0.65 %. It is obvious that individual-family selection, which is carried out with this bird for a long time, does not contribute to the accumulation and consolidation in its gene pool of "harmful genes". In the Rhine breed geese during all three years of monitoring, hereditary defects in their development were found among the examined dead embryos. The magnitude of the hereditary load was in the range of 1.52-4.00 %. As the difference in this indicator over the years was unbelievable, the fluctuations in the level of genetic load are due to small sawtooth fluctuations in the frequency of lethal genes relative to the average population level in a limited number of Rhine breed geese. No genetic abnormalities were found in the F₁ offspring among the examined dead embryos. In the offspring of the second generation among the examined dead embryos were diagnosed with two genetic developmental defects with a frequency of 0.79 % each. The level of genetic load is low and amounted to 1.59 %. It can be assumed that the lethal genes in F₁ hybrids were in a heterozygous state and therefore did not appear in them, and in the descendants of F₂ some of them went into a homozygous recessive state and showed their effect by the appearance of hereditary defects of embryos. In third-generation geese, one anomaly was diagnosed among the examined embryos, the frequency of which was 1.25 %. It can be assumed that the gene that causes this defect in embryonic development was inherited by F₃ geese from a previous generation bird. In geese of the created dimorphic population the level of genetic load is low (2.50 %) and does not represent threat for poultry breeding.