User's Manual

AE21 GB Issue 02
6
5.2 There are three methods available to bird breeders to achieve correct humidity levels:
a) Follow the manufacturer’s guidelines for water and ventilation levels (see below).
b) Measure humidity levels and adjust to match published guidelines for different species (see below).
c) Monitor egg weight loss which varies as a direct result of humidity and correct against published weight
loss figures for the species.
a) As a general guide for poultry set the ventilation control to about half open and maintain water
in one of the water channels. If the incubator is not full reduce the ventilation level
accordingly. If the incubator is full of parrot (and parrot like species) eggs the ventilation
control should be about 2/3rds open. If fewer eggs are incubated reduce the ventilation level
accordingly.
For all species ensure there is water in all channels for the last two days of incubation. Higher
humidity levels are needed for hatching to prevent membranes drying too quickly. Do not
close the vent below 1/3
rd
when hatching.
The above guidelines make no provision for different ambient conditions and are necessarily
rather generalised but they are simple and often effective.
b) If measuring humidity levels directly be cautious of readings from low cost analogue or digital
hygrometers.
Generally accepted incubation RH levels for species groups:
During incubation Poultry 40-50% RH
Waterfowl 45-55% RH
Parrots 35-45% RH
Hatching All species 65% RH or more
For more specific information on particular species’ requirements check the relevant literature.
c) Eggs lose moisture through their shells and the rate of evaporation depends on the humidity
levels around the eggs and the shell porosity. During incubation eggs need to lose a fixed
amount of water which corresponds to a loss in weight of around 13-16% depending on
species. By weighing eggs periodically during incubation it is possible to monitor and, if
necessary, correct humidity levels to achieve the correct weight loss.
Weigh the eggs on the day they are set in the incubator, take the average weight and plot this
on a graph (see example below). The ideal weight loss line can be plotted by joining the point
representing initial average weight with the ideal hatch weight (13-16% less depending on
species) with the x-axis representing the incubation period (in days).
By measuring actual average weights every few days the actual weight loss can be plotted and
compared to the ideal weight loss line and corrections can be made. For example if the actual
weight loss was greater than ideal (see graph below) then the air has been too dry and humidity
levels need to be increased to compensate.
Typical ideal weight losses for species groups:
Poultry 13%
Parrots 16%
Waterfowl 14%