Glycerol, a by-product of biodiesel production, is non-toxic to humans and environment. With the increase in demand for fuels obtained from biomass, the amount of glycerine waste increases. There are many ways to dispose it (pharmaceutical, cosmetics and chemical industry), but its utilization is still insufficient. Due to the fact that glycerine is a safe, cheap and easy to apply substance, the possibility of using it on a large scale in the aspect of chicken eggs storage seems to be possible.

This study was conducted to determine inner egg quality characteristics using external egg quality characteristics and to select variables in order to obtain the simplest model using ridge, LASSO and elastic net. The goodness of fit values of the regression estimating equations for egg yolk weight were 58.34 %, 59.17 % and 59.11 % using the ridge, LASSO and elastic net methods, respectively; for egg albumen weight they were 75.60 % for ridge, 75.94 % for LASSO and 75.81 % for elastic net.

It has been stressed that increasing the growth velocity and muscle mass in chickens possibly resulted in trade-offs regarding product quality. Therefore, this research aimed at comparing the breast meat quality of chickens with divergent growth rates. The results suggest that selection on high growth rates could be associated with increased pH when the body weight of fast-growing birds reaches about 40 to 60 % of their growth potential and, possibly, also with increased cooking loss.