
fertility (48 and 24 per cent, respectively). Significant 
differences in hatchability were also observed at these levels, 
Glycarbylamide did not have any effect on the fertility of the 
rooster. The authors believed that the sperm in the oviduct 
of medicated hens may be killed by contact with glycarbylamide 
in the albumen lining the lumen of the magnum or that the drug 
imparts a gametocidal effect directly on the hen. fhe birds ree 
turned to normal after four days from the removal of the drug. 
Other factors may affeet the composition or oharacter- 
istics of the laid eggs, thus affecting directly or indirectly 
fertility, hatchability and the subsequent performance of the 
mature bird. Some components of the rations affect the formation 
of the egg more than others. It should be mantioned that the 
level of calcium, phosphorus and vitamin D in the diet affect 
to different degrees not only egg production in general but 
also the overall amounts of these components in the egg affect- 
ing hatehability in the long run, 
31 
