Air cell - The air space between the inner
and outer shell membranes. Usually found
at the broader end of the egg.
Albumen - The white of the egg.
Antagonist - An anti-nutritional factor present in feed which reduces its nutritional value.
Calcification - See Shell calcification.
Cannibalism - The vice of eating other birds.
Chalazae - White, twisted, rope-like structures attached to the thick albumen which anchor the yolk in the centre of the egg.
Cloaca - The common external opening for the digestive, urinary and reproductive tracts.
Cull - To remove unprofi table or otherwise unwanted birds from the flock.
Cuticle - The outer membrane covering the egg shell which gives the shell a bloom.
Filler - A moulded tray for packing eggs in an upright position.
Follicle - A sac-like structure in the ovary containing a developing ovum.
Germinal disc - A small, circular, white patch on the upper surface of the yolk, containing cells from which the chick develops if the egg is fertilised.
Grading - The process of classifying eggs by quality and by weight.
Infundibulum - A funnel-shaped section of the oviduct, about 6 to 8 cm long, which collects the ovum as it is released from the ovary.
Isthmus - A section of the oviduct about 12 cm long which secretes the shell membrane and some albumen.
Light programme - The schedule of artificial lighting for poultry flocks. Day length and light intensity are regulated to improve egg production.
Magnum - Part of the oviduct, immediately after the infundibulum. It is about 30 cm long and secretes about 40% of the egg’s albumen.
Ovary - The female reproductive organ in which the ova (yolks) develop. Only the left ovary is functional in hens.
Oviduct - A long, tubular organ which adds the egg white, shell membranes and shell to the yolk as it passes through.
Ovulation - The release of a mature ovum from an ovarian follicle. Ovum (plural ova) - An egg at the stage when it is a yolk without any white (albumen).
Oxidising agent - A substance which brings about chemical changes involving oxygen. In the case of poultry feed, these changes can result in loss of potency or nutritional value.
Premix - A blend of micro-ingredients, usually vitamins or trace minerals and including a carrier substance, added to feed during the mixing process.
Prolapse - The irreversible protrusion of the cloaca.
Pullet - A female bird in her fi rst laying season.
Roll-out tray - An extension of the cage fl oor on which eggs accumulate for collection.
Shell calcification - The process of shell formation during the period the egg is in the shell gland (uterus). Shell membranes - Inner and outer membranes that together line the inside of the shell and adhere very closely to it.
Uterus (shell gland) - Part of the oviduct, about 12 cm long, which secretes water into the albumen and forms the shell.
Vagina - Part of the oviduct, after the uterus, in which the shell cuticle is formed.
Vent (anus) - The external opening of the cloaca.
Vent picking - The vice of pecking other birds around the vent.
Vitelline membrane - A thin, transparent membrane which surrounds and contains the yolk.
© The State of Queensland, Australia (through its Department of Primary Industries and Fisheries) and DSM Nutritional Products Ltd., 2007. No part of this publication may be reproduced, copied or transmitted save with prior written permission of Director, Intellectual Property Commercialisation Unit, Department of Primary Industries and Fisheries, GPO Box 46 Brisbane, Queensland, Australia 4001, and DSM Nutritional Products Ltd.