Effects of some egg characteristics on the mass loss and hatchability of ostrich (Struthio camelus) eggs

Abstract

1. This study was conducted to examine some egg characteristics and determine the effects of eggshell thickness and eggshell porosity on water loss and hatchability of eggs in ostriches. 2. Shell thickness did not correlate significantly with hatchability. However, eggs of low shell thickness lost more mass (13·03%) than those with intermediate (11·22%) and high (10·36%) shell thickness. Mass loss during incubation was higher in hatched (11·98%) than unhatched eggs (11·09%). Shell thickness was negatively correlated to egg mass loss (r = −0·65). 3. The pore density was correlated with hatchability. Hatchability was 50% lower in eggs with low pore densities (40·93%) than with high densities (80·94%). Pore density was positively correlated with egg mass loss (r = 0·63). Incubation mass losses of hatched and unhatched eggs were not significantly different. 4. Mean eggshell water vapour conductance (G) value and shell conductance constant (k) were 87·77 ± 4·21 mg H2O/d/Torr and 2·44 respectively (n = 15). 5. Because of eggshell functional properties and resulting low egg mass loss hatchability is low when ostrich eggs are artificially incubated. The mass of eggs used in the experiment was relatively high and their eggshell water vapour conductance was low. As a result, egg incubation mass loss was lower than it should be. It is concluded that incubator humidity should be low (25%) to allow enough mass loss during incubation from the eggs.