Changes in eggshell conductance after transfer of hens from an altitude of 3,800 to 1,200 m

Hens acclimated to an altitude of 3,800 m (PB 480 Torr) were transferred to 1,200 m (PB 657 Torr). Eggs were collected before departure and daily after the transfer so that changes in eggshell conductance could be studied. Over the next 2 mo eggshell conductance increased 30%, presumably to compensate for the 37% reduction (from 657 to 480 Torr) in gas diffusivity at the lower altitude. Measurements of shell thickness and number of pores in the shell allow one to calculate that most of the change in total pore area occurred by an increase in cross-sectional area of individual pores.