Shell Deposition Rates in Birds Selected for Thick and Thin Eggshell Production

The purpose of this experiment was to visualize and compare the shell deposition rates of two lines of White Leghorns selected for thick- and thin-shell production. Eggs were expelled by hormone injection at 4, 8, 12, 16, and 20 hr after entry into the shell gland, and percent shell was calculated. Results indicate that the thick-shell line exhibits a greater increase in shell weight and percent shell per unit of time in the shell gland than does the thin-shell line. Selection has produced two lines differing in eggshell quality due to different rates of shell deposition.