INFLUENCE OF PRE-INCUBATION STORAGE CONDITIONS AND CALIBRATION OF EGGS ON DIFFERENTIAL MORTALITY OF EMBRYOS OF DIFFERENT SEX
Abstract
The article highlights the importance of autosex poultry as a model object for scientific research due to its unique genetic and physiological characteristics. In particular, the issues of differential sex mortality are analyzed, which is an important aspect of studying the patterns of development of organisms. Poultry, especially chickens, are widely used as a model for analyzing the influence of external factors on ontogenesis. This applies to aspects such as sex ratio and embryo viability, which are key for fundamental biology and practical application in poultry farming. The study analyzed the sex ratio and mortality of chicken embryos under different conditions of pre-incubation storage and incubation of eggs. For this purpose, anatomical, Japanese, color-sex and federsex methods of sex determination were used, which ensured high accuracy of the results obtained. The studies covered a wide range of chicken breeds and hybrids, which made it possible to draw conclusions about the specifics of differential sex mortality in different genetic groups. The study analyzed the sex ratio of chicks depending on egg storage conditions, incubation regime and weight calibration. Under optimal incubation conditions, a secondary sex ratio close to 1:1 was confirmed. In seven batches of day-old chicks, the proportion of females was 49.71–53.49%, with an average value of 51.26%. Long-term storage of eggs (8–15 days) caused an increase in embryonic mortality (up to 28.1%) and the predominant death of male embryos, which led to a significant shift in the sex ratio in favor of females (61.7%). In contrast, short-term storage (1–7 days) did not affect the incubation indicators and ensured the expected equality of the sexes. The study of egg weight revealed that medium-weight eggs (group M0) provide the highest survival of embryos with an equal sex ratio. In small eggs (M-), the predominant death of male embryos was observed, while in large (M+) females died more often. Of the day-old chicks obtained from M- eggs, the proportion of females was 53.74–54.60%, and from M+ eggs, the proportion of males increased to 53.86–55.49%. Increased survival of embryos in the modal class of eggs (M0) is associated with their higher biochemical heterogeneity of protein proteins, which confirms the theory of genetic homeostasis. It was found that males are more sensitive to stress factors, which confirms the differential mortality of the sexes. The results obtained are consistent with the theory of bisexual evolution of V. A. Geodakyan. According to this concept, differential mortality of the sexes is an adaptive mechanism that allows the population to better adapt to stressful conditions. The study confirmed that under stress conditions caused by changes in egg storage or incubation conditions, male embryos die more often than female ones. This phenomenon was observed both in the embryonic and postnatal periods of development. Thus, the results of the work not only confirm the adaptive nature of differential mortality of the sexes, but also open new prospects for further study of the genetic and biochemical mechanisms that determine the development of embryos in different conditions. They are of great importance for optimizing breeding, incubation and reproductive management technologies in poultry farming.
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