Cornish breed chicken embrios development depending on hen age at egg laying

The results of studies have been presented in the paper on morphologic and biochemical and hatching properties of eggs of layers of cross “Smena 9” father parent form in dependence of layer age. Morphologic and biochemical egg composition changes have been proved depending on layer age that is significant egg mass increasing, egg white relative mass decreasing and yolk relative mass increasing. Worst hatching egg quality from 40 week age layers have been determined with low vitamin A content in yolk and low vitamin B2 content in egg white, with minimal egg white index and Haugh units values and low protein level. All these factors have determined early and end embryonic death and high per cent substandard chicks.