Organ development in relation to egg-laying capacity in the fowl

Abstract

Eighty-nine Fayomi pullets were classified into three major classes High, Medium and Low according to the intensity of egg laying. Six birds in each class were slaughtered. The major body organs were dissected and weighed. The number and diameter of the visible oocytes were recorded. The dressing out percentage was obtained. The results were as follows: 1. During the first year of laying, the averagenumber of eggs laid per day was 0·50, 0·42 and 0·24 eggs for the High, Medium and Low classes respectively. 2. There were significant differences in the ovarian weight, length and weight of oviduct, these being highest in the High class. 3. The number of visible oocytes was some 200 in all classes. There were, however, differences between classes in the maturation rate of the oocytes as measured by the differences in the diameter of successive ones. 4. The weight of blood, feathers, head, wings and legs were higher in the Low than in the High; these are all early maturing organs. 5. The weights of the full alimentary canal and the empty gizzard were higher in the High than in the Low, this might be accounted for by a greater appetite and to intake of feed induced by the higher egg production. 6. There were no significant differences in the weight of the circulatory, excretory and respiratory organs which are needed for the physiological welfare of the birds. 7. The dressing out percentage was higher in the Low and Medium than in the High. This may be due to the greater drainage of nutrients required for high egg production.