Morphological and biochemical traits of pheasant Phasianus colchicus eggs in relation to embryo sex and egg laying date

摘要

Physical and biochemical characteristics of bird eggs depend on many factors. In turn, the biological quality of eggs influences hatchability and chick fitness. The aim of this study was to compare pheasant Phasianus colchicus eggs containing male and female embryos and laid in different months in terms of their morphology (egg weight, egg shape, yolk and white content, eggshell thickness) and biochemical traits (chemical composition, lysozyme content and activity, fatty acid profile as well as contents of macro- and microelements). The experimental material comprised eggs obtained from 1-year-old pheasants. Altogether 200 eggs were collected on April 7 and June 23 (100 eggs on each date). As some eggs were destroyed before and during measurements, numbers of eggs taken into account in the analysis of egg morphology traits were lower than numer of collected eggs. Egg homogenates were used in other analyses, sample size for each date ranged from 12-24. In conclusion, we stated that common pheasant eggs containing embryos of either sex did not differ in terms of morphology, basic chemical composition and a majority of other investigated traits, but eggs laid in April and June differed in terms of many studied traits (egg morphology, basic chemical composition, lysozyme content, some elements and fatty acids). Differences mentioned above can be explained by the egg laying date (female age), but environmental factors such as temperature and photoperiod might also affect egg traits.