Egg Incubation Info: Weight Loss During Incubation

1. General Tips About Egg Incubation
2. Waterfowl Considerations
3. Incubating with Surehatch Egg Incubators
4. Incubation Facilities
5. Incubation Temperature
6. Weight Loss During Incubation
7. Turning of the Eggs
8. Ventilation of the Egg Incubator
9. Monitoring Egg Development
10. Hatching Facilities
11. Keeping Records
12. Incubation and Embryology Frequently Asked Questions
13. Incubating Your Eggs
14. Frequently Asked Questions on Candling

Weight loss during incubation

• Eggs normally lose a total of 18% of their weight during incubation, due to loss of water vapour which diffuses across the egg shell . Eggs should lose 15% of their weight from the start of incubation to the start of hatching (internal pipping). Monitoring and if necessary manipulation of their weight loss may be used to improve hatching success.

• For ideal results, each egg should be weighed individually on an accurate balance and the actual weight loss plotted on a graph and compared with the ideal weight loss for that egg. This may be done by hand or using an appropriate computer programme.

• Weight loss may be too fast due to thin shells or low incubator humidity. Weight loss may be too slow due to thick shells or high incubator humidity.

• If weight loss is too fast or too slow, it may be manipulated. N.B. Correcting the rate of weight loss after the first third of incubation is much more difficult.

• The correct rate of weight loss early in incubation appears particularly important for hatchability; incorrect early rates of weight loss may be fatal to the embryo despite later correction giving the required overall weight loss.

• If several incubators are kept at slightly different relative humidities, an egg may be moved into an incubator at higher humidity if it is losing weight too fast, or lower humidity if it is not losing weight sufficiently fast. Other methods involve altering the porosity of the egg shell:

  • Porosity (and therefore water loss) may be increased by careful thinning of the eggshell using sandpaper.

  • Conversely, part of the eggshell may be painted over with nail varnish to decrease water loss through the shell.

  • In extreme cases of excessive weight loss, rehydration may be used. This involves completely submerging the egg in cold (approximately 10°C, 50°F) sterile water for up to five minutes daily or even more frequently, with accurate weighing to monitor the uptake of water during the procedure. The cold temperature causes the egg contents to contract, drawing water into the egg. The frequency and duration of dipping should be varied according to the degree of weight loss and the stage of incubation. Care must be taken not to over stress the embryo by dipping for too long. Dipping in antibiotic solution has been described for the first dip (3mg tylosine tartrate (Tylan Soluble, Elanco Animal Health) in 1 litre sterile 0.9% saline giving 3000 parts per million tylosin solution). N.B. in general, eggs which are normally incubated in very damp conditions are likely to require a higher level of humidity during incubation than eggs which would be incubated in the wild in very dry conditions.

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