Page 88 - Hand rearing birds second

Incubation 71

“Blood Ring” on Candling:
BWE = blastoderm without embryo – membranes and blood only;
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ED = early dead embryo (see below).
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Obvious Dead Embryo on Candling:
ED = early dead embryo – H&H stage 1–19 (≤3 days in chick embryo);
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MD = mid‐dead embryo – H&H stage 20–39 (3–14 days in chick embryo);
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LD = late dead embryo – H&H stage 40–45 (≥14 days in chick embryo).
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All embryos should be examined to determine if they are normal for their developmental stage
and whether that stage is consistent with the number of days of incubation. Positioning of very late
dead embryos, those near hatching with little or no free fluid in the egg, should be noted as either
normal or one of seven recognized malpositions:
1) head between the thighs (normal early pre‐hatch position);
2) head in the small end (upside down);
3) head under left wing;
4) beak directed away from the air cell;
5) leg over head;
6) head over right wing (should hatch normally);
7) crosswise in egg (spine aligned with short axis).
These embryos may be dissected for more detailed gross and histological examination as would
be done for a newly hatched chick.
Hatching failures due to obvious causes, such as insufficient egg weight loss, are easy to diagnose
with individual eggs, and often easy to prevent in the future. Most causes of poor hatchability will
be subtle and difficult to detect, so careful analysis of data over time will prove invaluable. For exam-
ple, if there is a high incidence of mortality during mid‐incubation, it may be traced back to a nutri-
tional problem with the breeding birds or to a source of infection of the eggs. The problem may be
as simple as a malfunctioning turning mechanism on a particular incubator. Diligent and detailed
record keeping followed by objective data analysis is the best way to ensure optimum hatchability.

Sources­of Products­Mentioned

A.B. Incubators: Unit 1, Church Farm, Chelmondiston, Ipswich, Suffolk, IP9 1HS, United
Kingdom, +44(0)1473‐780‐050, www.abincubators.co.uk.
Avey Incubators/Precision Incubators: P. O. Box 279, Hugo, Colorado 80821, (719) 297‐7010,
https://www.precisionincubators.com.
Brinsea Products, Inc., 704 North Dixie Avenue, Titusville, Florida 32796, (321) 267‐7009, (888)
667‐7009, http://www.brinsea.com.
Cole‐Parmer, 625 East Bunker Court, Vernon Hills, Illinois 60061, (800) 323‐4340, (847) 549‐7600,
sales@coleparmer.com,www.coleparmer.com.
Dremel, 1800 West Central Road, Mount Prospect, Illinois 60056‐2230, (800) 437‐3635, www.dremel.com.
Fenix Lighting, Littleton, Colorado, (888)775-9996, customerservice@fenixlighting.com, https://
www.fenixlighting.com.
Fisher Scientific Worldwide, One Liberty Lane, Hampton, New Hampshire 03842, (800) 766‐7000,
http://www.fishersci.com/us/en/home.html.