Advanced Incubation and Embryology Ken Koelkebeck U of I Extension Poultry Specialist kkoelkeb@illinois.edu

The Life of a Chick Life begins with single cell formed by joining of two parent cells: ovum (yolk) and sperm = fertilization Fertilization occurs about 24 hours before egg is laid After fertilization, single cell beings to divide to 2, 4, 8, 16 cells and so on. This occurs on germinal disc/blastoderm

Chick Development Cells begin to divide into segments during incubation 3 segments - ectoderm - mesoderm - endoderm Ectoderm – skin, feathers, beak, claws, nervous system, eye, mouth

Chick Development Mesoderm – bone, muscle, blood, reproductive and excretory tracts Endoderm – lining of digestive tract, secretory, respiration organs

Chick Formation Extra-embryonic membranes of importance 1) Yolk sac 2) Amnion 3) Chorion 4) Allantois Yolk sac – tissue layer growing over the yolk – digests and absorb yolk material

Chick Formation Amnion Fluid filled sac that surrounds embryo and serves as protection Fluid allows embryo to move, change position, and shape Fluid keeps embryo parts from sticking together

Chick Formation Chorion Serves to contain both amnion and yolk sac No function at first, but then joins with allantois to form chorio-allantoic membrane Allows calcium reabsorption through capillaries of allantois from the shell

Chick Formation Allantois Serves as respiratory organ for embryo Holds excretions from embryo Absorbs albumen (nutrient protein) for embryo Absorbs calcium from shell for embryo Allantois origin within body of embryo

Embryonic Blood Vessels One – vitelline vessels carry yolk material to embryo Two – allantoic vessels – respiration and waste material

Hatching Days 19 & 20 - Abdominal wall surrounds yolk sac - Chick withdraws rest of yolk into body - Fluid decreases in amnion Day 21 - Chick forces egg tooth through air cell- head under right wing takes first breath – internal pipping – chick peeping inside

Hatching Day 21 - Egg tooth breaks through shell – external pipping Process last from 4 to 12 hr Chick emerges very wet, tired and rests for several hr After exiting shell, egg tooth (beak) dries and falls off

Thank You