Changes in Thickness and Weight of Shell Portion of Egg and in Weight and Size of Whole Egg during the Stay in the Uterine Part of the Oviduct (Shell Gland) in the Guineafowl: Comparison with White Leghorn Hens

Abstract

The thickness and weight of the shell portion (shell with shell membrane) of eggs at various times during the stay in the uterus and at oviposition were found to be greater in the guineafowl than those in the chicken (White Leghorn). A greater increase in the thickness and weight of the shell portion was found in the guineafowl during the stay in the uterus. The weight of the whole egg at 2 hours of stay in the uterus did not differ between the guineafowl and the chicken. In both the guineafowl and the chicken, the weight of the whole egg showed an increase at 8 hours of stay and almost no change thereafter. The amount of the increase in the weight of the whole egg was less in the guineafowl than that in the chicken. The size of the egg, as estimated by the length of the long and short axes, showed a minor enlargement at 8 hours of stay in the uterus in the guineafowl, whereas marked enlargement was observed in the chicken at the same time point. These results suggest that (1) the greater thickness and weight of the shell portion in the guineafowl egg is due to a larger amount of minerals deposited on a thicker shell membrane, (2) the size of egg in both the guineafowl and the chicken is determined by 8 hours of stay in the uterus, and (3) the smaller egg size and the smaller amount of albumen in the guineafowl egg is due to less extensive of plumping during the first 8 hours after entering the uterus.

Keywords

• guineafowl
• shell gland
• eggshell formation
• egg size