1. Reproduction and Incubation
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58 Terms
Due to __________ hens will lay eggs regardless of whether the eggs are fertilized
selective breeding
How many eggs to modern hens lay?
300 eggs
How many eggs do the red jungle fowl lay a year?
12
Shell
a hard, porous, protective structure around the egg
Yolk
a structure full of nutrients which feeds the embryo
albumen
protein-rich egg white
Germinal disc
a region that contains embryonic cells, organelles, and RNA
Air cell
formed when the cooling egg contracts and pulls the innter and outer shell membrane apart
LABEL EGG PARTS AND REPRO TRACT
vitelline membrane
the membrane around the yolk
Chalaza
spiral bands of tissues that suspend the egg yolk in the albumen
cuticula
a protein-based membrane around the eggshell that protects against bacteria
Egg shells have _______ that are very small holes
pores
pores
allow movement of water, oxygen, and CO2 but can be invaded by bacterial pathogens
What element are egg shells mostly made of
calcium
What are egg shells often colonized by?
salmonella
improper egg handling =
salmonella food poisoning
What is the egg yolk composed of?
triglycerides and other lipids like cholesterol, phosphoproteins, lipoproteins, and nutrients binding proteins, hormones, immune cells, and vitamins and minerals
Hormones and immune cells are _____________________ to ensures proper development before the embryo has a mature endocrine and immune system
deposited by the hen
color of the yolk is determined by…
the hen’s diet (beta-carotene and lutein)
Majority of the albumen is ______
ovalbumin
what can the albumen be broken down into
amino acids for the embryo
albumen _______ when refrigerated
liquifies
when the albumen is refrigerated what happens?
pH goes from neutral to basic, aids in gas and nutrient diffusion during incubation, and lowers incubation time
Where does fertilization by a sperm cell occur
germinal disc
what does the germinal disc contain
embryonic cell organelles, proteins and mRNA associated with fertilization, proteins and mRNA associated with early division
What is used by the chick to hatch
air cell
what is great for determining if humidity levels are incorrect during incubation
air cell
vitelline membrane allows…
the yolk to be attached to the shell and suspended in the albumen by the chalaza
what does the chalaza prevent
it prevents the yolk from sticking to the shell or embryonic membranes
cuticula is mainly composed of…
protein
The cuticula can prevent ___________ but can be_______
the cuticula can prevent bacterial adhesion and penetration but can be scrubbed away
what are the two ways eggs can be incubated?
natural (hen setting) and artificial
why do we care about incubation?
not all eggs are fertile, not all chicks will hatch successfully, so we want to maximize hatchability.
Hatchability
the number of eggs hatched divided by the number of eggs set (chicks hatched/fertile eggs) x 100
How do we maximize hatchability
proper incubation and hatch conditions!
Critical parameters for incubation and hatch
temp, humidity level, position, oxygen level, CO2 level
Day 1-19 of embryonic development…the ideal shell temp is
99.8 degrees F
Embryos will die if…
<96 degrees F
>103 degrees F
cooler temp =
slower metabolism
when in doubt…
play it cool
Day 19 to hatch what is the incubator temp?
98.8 degrees F
Day 1 -1 of embryonic development humidity should be
50%-55%
humidity levels affect what
air sac size
high humidity =
small air sac and chick might drown at hatch
low humidity =
big air sac and chick cannot turn
Day 19 to hatch the humidity should be
70%
Mitigates water loss at 70% humidity
hatching is very metabolically intensive
Eggs should be turned ______ per day
3 to 5x
Why should eggs be turned?
prevents embryonic membranes from adhering to the shell membrane and aids air circulation in incubator
eggs must be ______________ or on their sides
large end up
why does the large end need to be up or on their sides
this ensures the embryo’s head is not upside-down. By day 15-16 the embryo’s head is near the air sac
embryos need ________ to develop
oxygen
embryos produce ________ as a byproduct
CO2
Proper ventilation =
no suffocation
why is proper ventilation good
needed to remove excess heat, as chicks get bigger, they produce more heat
ideal oxygen level
21%
Ideal CO2
0.5%