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B. Healthy stock
It is important that eggs from only a healthy flock are used for hatching, as some diseases can be
transmitted through the egg. The egg-transmittable diseases to be most aware of are salmonella infections,
fowl typhoid and Mycoplasma gallisepticum.
Eggs laid by birds infected with disease may fail to hatch. Of those that do hatch, some birds may die during
brooding, and the survivors may act as carriers and infect healthy chicks.
Do not add eggs from unknown sources to make up numbers, as you risk infecting your flock.
Breeding stock nutrition
The egg provides a complete food store for proper embryo development except gaseous oxygen, which
enters the egg through pores in the shell. Breeding stock must be fed a well-balanced diet to fully meet the
embryos' nutrient requirements.
The deficient nutrients are usually vitamins or minerals. A deficiency of these in the breeders' diet may not
show any ill effects in the breeders, though hatchability may be affected, which is why different categories
are fed specific diets. Nutritional deficiencies, such as a lack of riboflavin, are the main causes of embryo
mortality during the middle stage of incubation (i.e. between the 12th and 14th days).
Hens' vitamin and mineral requirements for laying eggs are lower than those of breeders. The breeder's diet
should begin six to eight weeks before hatching eggs are required, with particular attention to vitamin A, D3,
riboflavin, pantothenic acid, biotin, folic acid, vitamin B12 and the mineral manganese.
Deficient nutrient Result
Riboflavin
Leads to poor hatchability with a high incidence of malformed embryos, which are
excessively moist
Pantothenic acid
Lowers hatchability and causes a high incidence of apparently normal embryos to die
over the last two or three days of incubation
Biotin, choline and
manganese
Leads to abnormal development of the embryo and a condition known as enlarged
hock/slipped Achilles tendon
B12
Leads to a rapid decrease in hatchability and a progressively poorer survival of chicks
that do hatch
C. Age of breeding stock
If the male bird is active, not too large or overweight, and fertile, then his age has little or no effect on
hatchability or the vigour of the chicks. The older the cock bird, the fewer hens he can mate effectively without
loss of fertility. Fertility and hatchability also decrease, as the hen's egg production drops with age, and is highest
during her first and second laying season.
D. Hatching eggs selection
It is important to consider the size, shape and shell texture when selecting eggs for hatching. Best results are
obtained by setting eggs that are around the average egg weight for the type of poultry.
Since egg size is highly heritable, the rejection of small eggs will help to maintain good egg size in the progeny.
Extra large or small eggs are a handicap in the incubator. The egg shape is hereditary, so continual use of badly
shaped eggs perpetuates and increases this fault.
Only eggs with good shell texture should be used for hatching. Shell texture is not heritable; however, weak-
shelled eggs may crack, enabling bacteria to enter or excessive moisture to be removed from the egg. Porous-
shelled eggs increase the rate of moisture loss during storage and incubation. Hair cracks that are too small for
the naked eye to detect can be found by placing a strong light behind the egg. Egg colour does not affect
hatchability.
E. First Season Eggs
Any fertile egg will hatch in the right conditions but "best practice" is to only hatch hen eggs of 12 months and
older, even 12 month old hen eggs can be smallish depending on when she hatched. If a chook is hatched in
August, Sept Oct, it will produce hatchable eggs at a younger age than one hatched in January Feb Mar. They will
have matured and got their pullet size eggs over and done with through winter, whereas a January hatched pullet
is too young to have started laying before winter therefore their pullet eggs won't start until Spring, BUT because
they are older and stronger when they come into lay, their eggs get bigger quicker if that makes sense. Pullet eggs
will produce small chicks and more often than not these will become smaller hens, who will in turn have smaller
eggs who will have smaller chicks and so on.
In saying that the chicks seem to be just as healthy and if the eggs are a reasonable size I would just go for it, start
adding meat bird crumble to their starter crumble at about 4 weeks old and that will give them a really good
protein boost and they will grow better. Just don't hatch any very petite eggs.
