Dead-in-Shell / Embryo Mortality (Death)
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Causes ... Signs of Deficiency in the Embryo Nutrient
Unsuccessful hatches can be caused by infertile eggs or embryo mortality. Each of these conditions can be diagnosed by Candling Eggs. (Click here for an alternative way to check for embryo mortality.) It is important to examine eggs that do not hatch to estimate whether infertility or embryo death is the basis for hatch failure.
Embryo death predominately occurs at two periods during incubation:
- within the first 3 days of incubation and within the last 3 days immediately before a hatch.
- early embryo death occurs during formation of embryonic organs.
Death immediately before a hatch occurs during the transition between living in an egg to living on the outside. The chick can have difficulty positioning for pipping, absorbing the yolk sac, or changing to breathing air. Sometimes humidity control can be implicated in some of these problems.
- Nutritional Deficiencies
- Bacterial or viral infection (sanitary and dry environment will help prevent this)
- Egg being chilled (interruption of incubation process)
- Dehydration (misting the eggs with warm water may help)
Signs of Deficiency in the Embryo Nutrient:
| Nutrient | Deficiency Signs: |
| Vitamin A | Death at about 48 hours of incubation from failure to develop the circulatory system; abnormalities of kidneys, eyes and skeleton |
| Vitamin D | Death at about 18 or 19 days of incubation, with malpositions, soft bones, and with a defective upper mandible prominent. |
| Vitamin E | Early death at about 84 to 96 hours of incubation, with hemorrhaging and circulatory failure (implicated with selenium). |
| Vitamin K | No physical deformities from a simple deficiency, nor can they be provoked by antivitamins, but mortality occurs between 18 days and hatching, with variable hemorrhaging. |
| Thiamin | High embryonic mortality during emergence but no obvious symptoms other than polyneuritis in those that survive. |
| Riboflavin (Vitamin B2) | Mortality peaks at 60 hours, 14 days, and 20 days of incubation, with peaks prominent early as deficiency becomes severe. Altered limb and mandible development, dwarfism and clubbing of down are defects expressed by embryo. |
| Niacin | Embryo readily synthesizes sufficient niacin from tryptophan. Various bone and beak malformations occur when certain antagonists are administered during incubation. |
| Biotin | High death rate at 19 days to 21 days of incubation, parrot beak, chondrodystrophy, several skeletal deformities and webbing between the toes. Perosis. |
| Pantothenic acid | Deaths appear around 14 days of incubation, although marginal levels may delay problems until emergence. Variable subcutaneous hemorrhaging and edema; wirey down in poults. |
| Pyridoxine | Early embryonic mortality based on antivitamin use. |
| Folic acid | Mortality at about 20 days of incubation. The dead generally appear normal, but many have bent tibiotarsus, syndactyly and mandible malformations. In poults, mortality at 26 days to 28 days of incubation with abnormalities of extremities and circulatory system. |
| Vitamin B12 | Mortality at about 20 days of incubation, with atrophy of legs, edema, hemorrhaging, fatty organs, and head between thighs malposition. |
| Manganese | Deaths peak prior to emergence. Chondrodystrophy, dwarfism, long bone shortening, head malformations, edema, and abnormal feathering are prominent. Perosis. |
| Zinc | Deaths prior to emergence, and the appearance of rumplessness, depletion of vertebral column, eyes underdeveloped and limbs missing. |
| Copper | Deaths at early blood stage with no malformations. |
| Iodine | Prolongation of hatching time, reduced thyroid size, and incomplete abdominal closure. |
| Iron | Low hematocrit; low blood hemoglobin; poor extra-embryonic circulation in candled eggs. |
| Selenium | High incidence of dead embryos early in incubation. |
| Source / Reference: http://gallus.tamu.edu/Extension%20publications/b6092.pdf | |
Kate Ison offers an "easier and less intrusive way to find out if the embryo in a cold and neglected egg is dead or alive:"
To find out if the embryo in a cold and neglected egg is dead or alive:
- IMPORTANT: Warm the egg to brooder temperature first. As long as you are sure the egg hasn't pipped externally (if it has just pipped internally it wont harm it). Gently place the egg in a small but deep bowl of water at 100f for up to 20 seconds. If the embryo is still alive the egg will bob up and down and generally wobble around, take it out and dry it on a tissue or the chick could become chilled, put it back in the brooder. It will not harm the chick and may in some cases help a chick in trouble to eventually get out. It causes no shock to an embryo and presents no danger of the chick bleeding to death or becoming dehydrated or infected as it sits in an open egg waiting for the blood vessels to recede.
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