What egg defects should I look for in my pastured poultry operation?
Answer: Eggs need to be inspected both internally and externally to determine that they are wholesome and suitable for consumers. Conduct an external inspection by looking at the shell. Discard eggs with cracks in the shell, or leaking albumen (commonly referred to as “leakers”), and do not sell them to consumers. These defects pose a health risk to consumers, as bacteria have an easier pathway into the internal contents of the egg. Remove any foreign material on the shell, including feces, feathers, or bedding, and clean the egg.
Other external defects include excess calcium deposits and “body checks.” A body check is a defect that occurs where the egg was broken inside the hen but then repaired with extra calcium. The shell will appear thinner in these areas, also referred to as “water windows.” Excess calcium can build up on the egg and show up as small bumps or ridges over the eggshell’s surface. These are only structural deficiencies in the eggshell and these eggs are still fine for human consumption. Defined ridges on the eggshell or misshapen eggs can occur as well. While these eggs are also safe, their appearance may raise questions with consumers. However, these defects are usually very rare.
Internal defects present much more of a risk, as their appearance alone will turn consumers away. Internal inspection can be done by candling eggs. To candle, hold an egg up to, or over, a light source to see the internal contents. There are various candlers available on the market, but homemade ones can be made out of something as simple as a small, bright flashlight. To candle, hold an egg up to a light source, quickly turn it one-quarter revolution, and then stop. This spins the internal contents so that they can all be seen as they pass. There are two major defects to look for that will deem an egg to be inedible. The first is blood in the egg. While all eggs will have an orange glow under a candler, blood will show up as being bright red. Tissue or foreign objects can also appear in eggs. This defect occurs when a part of the hen’s reproductive tract is caught within the internal development of the egg. These show up as small or large spots inside of an egg that are dark red or black in color and unmistakable. Although these eggs pose no health threat to consumers, selling them could seriously diminish consumer perception of the quality of eggs coming from a particular farm. Remove and discard eggs with internal defects.
Eggs can be given a grade based on their internal quality, as indicated by the air cell. The air cell is the area in the large end of an egg, where the two interior membranes do not lay flat on top of each other. It’s possible to determine the quality of the egg by assessing the size of the air cell because it directly correlates to quality of the albumen and yolk. As an egg ages, water evaporates through the shell. This degrading of the egg is indicated by the air cell growing larger. For eggs free of interior or exterior defects, the three main grades are AA, A, and B. Each internal-quality grade depends on the size of the air cell when the egg is candled. The following standards are from the USDA Agricultural Marketing Service:
• AA: 1/8 inch or less
• A: 3/16 inch maximum
• B: 3/8 inch or larger
You can purchase cards with air-cell sizes and gauges to assist in grading eggs accurately.
Egg size is another factor in labeling. USDA regulations do not allow sale of ungraded eggs, so eggs of similar sizes should be grouped together for sale. These sizes are Peewee, Small, Medium, Large, Extra Large, and Jumbo. Use an egg scale to determine the size of each egg. Specific scales are meant to deal with the average weight of eggs and will denote the size immediately. For more information on egg sizes and handling, refer to the ATTRA publication Small-Scale Egg Handling.
You can learn much more about egg production in the ATTRA publication Pastured Poultry: Egg Production. This publication examines many of the risk factors that beginning poultry farmers should consider before acquiring a pastured laying flock. It addresses animal-management issues including breed selection, housing, nutrition, predator control, and natural-resource management. It also discusses processing and marketing of the end product, table eggs.