4-H Embryology Day 7 Candling Classroom Presentation
Calvin DeVries and Vicki Jedlicka
Author
04/02/2020
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Description
This is Nebraska Extension in Lancaster County’s candling presentation given 7 days after eggs are placed in incubators in local classrooms as a part of the 4-H Embryology school enrichement program. After answering students’ questions, the room lights are turned off and presenter has small groups of students come to the incubator to see eggs be candled. The class keeps track of how many winners, quitters and yolkers are in their incubator. Quitters and yolkers are removed so they don’t rot.
Note: the last half of this video is the same footage as our YouTube video “Candling Chick Eggs at Day 7.”
You may watch eggs hatch on 4-H EGG Cam at lancaster.unl.edu/eggcam!
Locally, the 4-H youth development program is a partnership between Nebraska Extension and Lancaster County government. Learn more about the Lancaster County 4-H program at lancaster.unl.edu/4h.
Searchable Transcript
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- [00:00:00.000]Hello, my name is Calvin DeVries and I
- [00:00:02.481]specialize in the 4-H Youth Development
- [00:00:04.419]program for Nebraska Extension in
- [00:00:06.330]Lancaster County and today I'm going to
- [00:00:08.527]talk with you about the candling
- [00:00:10.115]presentation performed for 4-H embryology.
- [00:00:12.622]Candling is the process of shining a light
- [00:00:15.752]through the air cell checking for
- [00:00:17.774]freshness or fertility inside of an egg.
- [00:00:20.649]So the air cell is located on the top end
- [00:00:24.347]or the wider part of the egg. So when you
- [00:00:27.494]shine your light through the air cell you
- [00:00:30.721]are able to project an image to see the
- [00:00:32.590]structures developing or checking for
- [00:00:34.627]freshness on the inside of your egg.
- [00:00:37.596]A phone light can also be used as a
- [00:00:40.141]supplemental light to preform candling
- [00:00:42.210]at home. So while candling in the
- [00:00:44.807]embryology project we are able to
- [00:00:46.447]recognize three different types of eggs
- [00:00:48.634]being a winner, quitter, and a yolker.
- [00:00:52.898]So inside of a
- [00:00:54.526]winner we will have a developing embryo
- [00:00:57.352]as it was a fertilized egg. So you're
- [00:01:00.189]going to recognize all sorts of different
- [00:01:02.204]red lines going to the center that closely
- [00:01:04.918]resemble a red spiderweb and those are
- [00:01:07.620]going to be connected to the yolk and
- [00:01:09.856]albumin absorbing that as it's source of
- [00:01:12.182]nutrition or food and water as it grows
- [00:01:15.533]and develops. But on day seven of candling
- [00:01:18.318]which would be performed in classrooms
- [00:01:20.540]we would recognize the eye as one of the
- [00:01:22.597]main structures at just seven days of
- [00:01:24.740]development the eye will be almost fully
- [00:01:27.783]developed. Now that we can have winners we
- [00:01:30.996]can also have quitters. At one point in time
- [00:01:34.183]this quitter was actually a winner but for
- [00:01:36.644]lots of variety of reasons that I can't
- [00:01:38.790]explain it decided to absorb into the
- [00:01:41.420]center creating a cloud shape or the blood
- [00:01:44.134]ring. This is due to the fact that it
- [00:01:46.287]would never be strong enough to thrive and
- [00:01:49.480]hatch and thrive on the farm. We can also
- [00:01:52.130]have yolkers. So this egg would closely
- [00:01:55.785]resemble an egg that you would buy from
- [00:01:58.376]the regular grocery store. But similar to
- [00:02:00.744]all the winners and quitters, this egg
- [00:02:03.583]came from a farm that has both hens and
- [00:02:05.764]roosters so had the opportunity to be
- [00:02:07.834]fertilized but just like drawing a name
- [00:02:09.748]out of a hat, it wasn't selected. Alright,
- [00:02:12.960]so now let's go candle some eggs.
- [00:02:17.476]This is day seven of development of a
- [00:02:21.400]white leghorn chicken embryo. As you can
- [00:02:24.263]see if I rotate the egg, the eye is a very
- [00:02:27.918]recognizable at this stage of development
- [00:02:30.835]that is the black or dark spot that
- [00:02:33.493]continues to emerge as I rotate the egg.
- [00:02:36.936]Throughout the egg connecting the embryo
- [00:02:40.560]to the yolk and albumin or egg white are
- [00:02:42.695]red spiderweb looking blood vessels and
- [00:02:46.740]veins. Those are responsible for absorbing
- [00:02:49.790]the nutrients from the yolk and albumin
- [00:02:52.643]throughout the development process of the
- [00:02:55.703]embryo. The candling light is shown
- [00:02:58.932]through the air cell of the egg to show
- [00:03:03.120]a clearer picture. You can see clearly
- [00:03:08.213]some red spiderweb pattern of blood
- [00:03:11.519]vessels and veins. Day seven is a good
- [00:03:16.435]time to check for fertility in your eggs
- [00:03:20.305]as you are able to recognize beginning
- [00:03:22.617]structures such as the eye.
- [00:03:24.787]If you wain until later
- [00:03:27.717]stages such as like day 14 the embryo will
- [00:03:31.849]begin to fill the good portion of the egg
- [00:03:35.593]and certain structures will be harder to
- [00:03:38.038]see. This one is a quitter. There is a
- [00:03:41.136]very recognizable blood ring going
- [00:03:44.198]throughout the egg. And as you can see on
- [00:03:53.491]the back side here the crack could be the
- [00:03:57.143]reason why this egg no longer continued
- [00:04:00.779]to develop as added bacteria are able to
- [00:04:04.603]enter the shell when hairline cracks are
- [00:04:07.967]found on the eggshell. Here we have a
- [00:04:14.510]yolker. There's no signs of blood vessels
- [00:04:17.206]or structures developing on the inside of
- [00:04:19.416]this egg but you can clearly see the air
- [00:04:21.931]cell at the top of the end of the egg here
- [00:04:25.036]and the yellow spot in the middle is the
- [00:04:28.185]yolk and you can see pores covering the
- [00:04:31.714]outside of the shell and the clear liquid
- [00:04:34.953]inside of the egg is the egg white or
- [00:04:37.677]albumin. This is a quitter. You can
- [00:04:44.178]identify it by the red blood ring on the
- [00:04:46.744]outside here. Looks like it made it a few
- [00:04:49.277]days into development as you rotate it and
- [00:04:51.634]you see the indication of an eye or the
- [00:04:54.185]black spot at the middle of the egg but
- [00:04:56.969]you can know it's a quitter due to the red
- [00:04:59.671]blood ring located on the outside of the
- [00:05:02.922]egg. This is coming off of a mechanical
- [00:05:07.515]egg turner. If you are doing incubation of
- [00:05:13.162]eggs by hand they are most commonly placed
- [00:05:16.124]on the side so the embryo would be toward
- [00:05:21.309]the top end or closer to my flashlight and
- [00:05:24.120]the yolk and albumin or egg white would be
- [00:05:26.828]towards the bottom and as you rotate the
- [00:05:29.215]egg it will naturally move as you rotate
- [00:05:32.909]the egg when you need to move it three
- [00:05:35.275]times a day but as it came out of a
- [00:05:37.662]mechanical turner the air cell will be
- [00:05:39.883]facing up so naturally the embryo is
- [00:05:43.842]towards the air cell.
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