 The outside of the egg counts for fewer overall points than the interior. Let's review what you can do to ensure that your entry has good interior quality. First, what is the difference between a blood spot and a meat spot? A blood spot is a little dot of blood on the inside of the egg. It forms when the yolk first enters the ovaduct. Check your 4-H avian bowl manual under Avian Systems for a detailed explanation about the hen's reproductive tract. A meat spot is a little bit of tissue instead of blood. To detect a blood spot or meat spot, you will need to candle the egg. Candling is done by holding an egg up to a strong light source. This allows you to see the egg's interior. You can also see the air cell and the yolk shadow. Use these two factors to select your highest quality eggs. When candling an egg, you can see the size of a blood spot or a meat spot and whether it is scattered or a single spot. In this example, we have a small meat spot. This makes the egg grade B because the spot is less than 1 eighth of an inch in diameter. A large spot is easier to identify and helps you determine if the spot is a meat spot or blood spot. Blood spots are reddish in color. A large spot makes the egg inedible and it cannot be sold. The yolk shadow can be used to assess the quality of the egg's proteins. As an egg ages, proteins in the egg white, or albumin, break down reducing the egg white's ability to hold the yolk centered. A fresh egg with high quality proteins will hold the yolk in the middle of the egg, preventing the yolk from hitting the side of the egg. This is important because if the egg could contain a growing embryo, you would not want to hurt it by having it hit the shell. When you candle an egg, spin it slightly to rotate the yolk. This is a grade AA egg. This is an example of a grade B egg with a prominent yolk shadow. Observe the obvious yellow color and how close the yolk gets to the shell. This is a grade A egg with a yolk shadow between that of the AA and B grade eggs. Finally, check the size of the air cell. The larger it is, the lower the quality of the egg's interior. As moisture is lost to aging, the air cell grows larger. This is an air cell for a grade B egg. This is an air cell for a grade A egg. Measuring devices like an egg air cell gauge will help you learn the difference between air cell sizes. Your county 4-H agent has a gauge or you may order a gauge directly from the USDA. This is an example of a grade AA air cell. After you check the air cell and yolk shadow and determine if there are any blood or meat spots present, then you must make your overall grading decision. If you have a AA yolk shadow but an A sized air cell, then you must go with the lower grade. Another example would be an egg with AA grade for yolk shadow and air cell but with a large meat spot. It would be considered inedible because the meat spot contributes the lowest grade. The lowest grade determines the egg's overall grade.