ARTIFICIAL INCREASE OF EGGSHELL CONDUCTANCE IMPROVES HATCHABILITY OF EARLY LAID GOOSE EGGS

1. The purpose of this work was to test the possibility of increasing the hatchability of goose eggs with low mass specific eggshell gas con ductance (G(sp)), by drilling holes through the eggshell into the air cell, and thus solving both the low water loss rate and low oxygen ava ilability problems. 2. A linear relationship was found between the are a of a hole drilled and the apparent increase in eggshell gas conducta nce (G). Drilling more than one hole increased apparent G 3.6 times mo re than one hole only, of the same total area. 3. Hole-drilling did no t increase egg contamination. The drilling of a 5 mm(2) hole on day 17 of incubation increased hatchability both in laboratory tests and in commercial hatcheries (6.1% and 10.5% respectively). 4. Drilling holes on days 15 to 22 of incubation increased hatchability when the predic ted mean water loss was lower than 14%. Drilling on day 25 did not hav e a significant effect, and drilling on day 11 of incubation was too e arly. 5. Drilling a hole into the aircell (during the second half of i ncubation) may increase hatchability of low conductance eggs, although oxygen pressure under the eggshell should then be checked in order to evaluate oxygen availability to the embryo.