• Normal hatching: on time and without help required (B42).

Hatching problems associated with incorrect incubation conditions:

• Sticky, difficulty in final push after successful rotation, or difficulty in final rotation: low hatcher humidity, or low humidity during incubation (B42, B106).
• Large/swollen chick: humidity too high during incubation (B42, B106).
• Early hatch: slightly high incubator temperature. May be small, weak chicks, may have incompletely absorbed yolk sac, and minor malformations such as crooked toes. also associated with splay leg (B42, B106).
• Late hatch: slightly low incubator temperature, temporary chilling during incubation, low hatcher humidity (B42). Low temp also associated with large, soft chicks and some malformations such as crooked legs or wry neck (B106).
• Small weak chicks and large percentage dead in shell - low initial period humidity.
• Large soft chicks, sticky with albumen, and unhatched pipped eggs requiring assistance  - excess initial humidity.
• Low hatcher humidity causes problems in hatching, pieces of shell stuck (B106).
• Inadequate ventilation may produce soft swollen chicks gasping for air (B106).

(B42, B106).

Hatching assistance:

• It is very important to insure that the membranes are kept moist at all times. The hatcher humidity must be kept high, remembering that opening the hatcher to assist a chick inevitably decreases the humidity, and the membranes should be moistened with sterile saline.
• Assistance should take place in stages. Stopping after each stage of assistance gives the chick a chance to complete the hatching by itself, if the problem has been overcome, and reduces the chance of problems associated with premature hatching. (B41, B115.4.w1).
  • Assistance too early may lead to excessive blood loss as the external vessels are still functional and care must be taken not to remove a chick from the egg when it has not yet absorbed the yolk sac. 
  • If a hole is to be made in the membranes this must be made in an area free from active blood vessels. 

(B41, B115.4.w1).

• If a chick has failed to break the inner membrane into the air space and appears to be weakening, it may be malpositioned.
  • A malposition may be visible on candling, with the tip of the bill visible near the air space, or the shell may be opened cautiously and the membrane moistened, which may reveal the position of the bill. (B115.4.w1)
  • Radiography may also be used to show the position of the chick. (B115.4.w1)
• If the bill is located away from the air space (malpositioning) it may be possible to remove a piece of shell from over the bill and make a small incision through the membrane (care not to cut active blood vessels). The bill is then pulled through the shell so that the nares are exposed, and fluids are removed from the airways if necessary. The chick may then be left with a loose cover over the area of missing shell and the humidity kept high. Further assistance should wait one to two days for yolk sac absorption and blood vessel contraction to occur. (B115.4.w1)
• If pipping has occurred but hatching does not progress as expected, assistance may be required. Initially the shell over the airspace may be removed and the membrane between the chick and the aircell moistened carefully. If the blood vessels are pale and empty the membrane may be peeled back a little at a time, with pauses to allow the chick to emerge by its own efforts if possible. (B40, B108, B115.4.w1)
• Just lifting the head from under the wing and gently extending it may be sufficient to allow the chick to complete hatching (B41).
• If the yolk sac has been absorbed and the blood vessels are contracted but the chick is weak, with oedema around the back of the head and neck and is failing to progress, further assistance may be required. (B115.4.w1)
• N.B. Opinions differ as to whether and how much a chick should be assisted to hatch. A chick may be unable to hatch due to genetic problems resulting in malpositioning or general weakness, in which case assistance may promote the survival of birds with deleterious genes. However, hatching difficulties may also result from deficiencies in incubation - a man-made problem - with a chick which is genetically viable, or an abnormally thick shell which may be related to nutrition.

(B40, B41, B108, B115.4.w1, V.w5)

• Hatching assistance may be required for chicks which are taking a long time to hatch

• Assisting hatching may result in bleeding from blood vessels in the membranes.
• Chicks assisted to hatch too early may not have fully absorbed the yolk sac.
• In assisting hatching there is a risk that a bird will be allowed to survive which has genetic problems which were the cause of its failure to progress normally at hatching.

• Sterile saline for keeping membranes moist.
• Scissors suitable for incising membranes.

• The decision as to when to intervene and how fast to progress with assistance is not simple and there are no hard rules. Experience with the normal range of times taken to hatch for different species is helpful.

• No special costs are involved

• N.B. Opinions differ as to whether and how much a chick should be assisted to hatch. A chick may be unable to hatch due to genetic problems resulting in malpositioning or general weakness, in which case assistance may promote the survival of birds with deleterious genes. However, hatching difficulties may also result from deficiencies in incubation - a man-made problem - with a chick which is genetically viable, or an abnormaly thick shell which may be related to nutrition.