In a modern egg-producing enterprise, taking care of the bottom line and reviewing the cost of production is critical, but the key element for the highest return on investment is sometimes forgotten: getting the best possible price for egg products. By determining which egg quality characteristics are important for your market, solutions can be implemented to yield the highest quality of egg products with the greatest return on investment for the producer. A high volume of saleable eggs at the highest quality, and therefore price, is key.

The formation of the egg is a natural but complex process. It requires the right nutrients at the appropriate levels and time, a sound reproductive system, a healthy hen and the right environment. While each main component of the egg (shell, albumen and yolk) has a well-defined structure, eggs will show many variations in shape, size, color of the shell and color of the yolk. These differences can be due to the breed of hens, the type of nutrition provided, the age of the flock or simply individual variations. In addition, once laid, the egg will change over time due to the exchange of gases within the environment and loss of moisture.

Although some attributes can disqualify an egg from being sold at top price, like off-odor, dirty shells, albumen, misshaped eggs or odd shapes and sizes that occur in practice, we will focus our attention on the most important ones, those that are evident to the table egg consumer such as freshness, eggshell strength (integrity) and egg yolk color.

Eggshell
Eggshell quality is the determining factor for what percentage of eggs are sold. This variable is quite important for table eggs since the consumer is not willing to accept damaged or broken eggs. In situations where eggs are sold in bulk, the packing protection is not present and, therefore, shell strength maximizes the value.

The eggshell is a structure designed to protect the egg contents and is composed mainly of calcium carbonate and proteins. For practical purposes, it provides an effective physical barrier with a very special design allowing the flow of air and water, while keeping outside bacteria at bay. Every egg contains around 2.2 g of calcium, independent of its size, and therefore the smaller the egg, in general, the stronger the shell. There is a linear relationship between egg size and hen size, wherein the bigger the hen, the bigger the egg. The shape of the egg gives natural strength to the shell and is important for the egg to not roll out of the nest (Stoddard et al., 2017). However, the specific shell strength for an individual egg is given by a combination egg size and structure of calcium crystals.

Hen age plays an important role on the eggshell structure or the way the crystals of calcium carbonate (calcite) are interlinked to provide strength. The process is regulated by more than 900 different proteins, acting in sequential order in a carefully orchestrated process that results in the perfect eggshell (Gautron et al., 2021). In a younger hen, the calcite crystals are shorter and therefore can be easily intertwined with each other to provide an ordinate and intricate wave that provides sturdiness to the structure. In an older hen, the crystals are elongated and therefore the wave became looser and not as intricated resulting in a weaker shell (Gautron et al., 2021). Older hens tend to be heavier and therefore tend to lay relatively larger eggs but with more cracks due to weaker shells. Furthermore, calcium absorption decreases significantly in older hens, requiring more

How to improve eggshell quality
The critical component for shell strength and integrity is the proper calcium and phosphorus metabolism and utilization. Addition of phytase to layer feed helps to increase available dietary phosphorus levels while also lowering feed cost. Furthermore, to maximize calcium absorption, especially in older birds, it is important to pay attention to the calcium and vitamin D sources provided. Increasing the levels of circulating vitamin D 25-OH D3 in serum helps to improve the utilization of serum calcium and phosphorus. Unlike traditional Vitamin D, vitamin D 25-OH D3 supplemented through feed bypasses the liver during Vitamin D metabolism, which aids in supporting liver health while also allowing more available circulating metabolite 25-OH D3, meaning stronger skeletons and healthier, more productive hens. The synergistic effect of providing both phytase and vitamin D 25-OH D3 together leads to optimal eggshell quality.

Yolk color
A golden yolk is always coming from a healthy hen. The color of the yolk is determined by the amount and kind of carotenoids present in the ovary at the time of ovodeposition. Carotenoids found in eggs are always from dietary origin and the most common sources are corn and derivatives (CGM and DDGS), marigold and marigold chemical extracts, paprika and synthetic canthaxanthin and Apoester. Therefore, to have a well pigmented yolk, carotenoids should be present in the diet in adequate quantities, and they must be absorbed efficiently and transferred to the liver and ovary via the lymphatic system.

Egg yolks contain almost all the vitamins that are considered essential for both birds and humans. There is a direct correlation between the vitamins fed to hens and the vitamins found in their eggs. So, to have vitamin-rich eggs, it is important to meet the vitamin requirements of hens through the feed. By providing the Optimal Vitamin Nutrition to laying hens, the nutrient accumulation in the eggs is beneficial for the health of the consumer.

How to improve yolk color
Carotenoids play an important role in animal feed. They are vital antioxidants and also vitamin A precursors. Also, dietary addition of vitamin D 25-OH D3 and carotenoids haven been proven to strengthen the yolk membrane and increase the antioxidants deposited. Vitamins provide optimal nutrition and supply what is exactly needed for the hen before, during, and after lay. A healthy gut in state of absorption is key to protect the investment on dietary carotenoids and vitamins. It is equally important to keep an eye on the mycotoxin risk levels in feed as they can not only affect egg production but also yolk quality. Products containing novel and comprehensive mycotoxin detoxification technologies help to manage the mycotoxin risk in feed effectively.

To quantify your yolk color improvement, you can use a handheld tool to measure the precise levels of carotenoids in your yolks to meet your target. There are digital yolk fans that connect to your smartphone, allowing for data collection and storage at the palm of your hand.

Freshness
This topic is at the top of mind for consumers, however few of them have defined criteria for a “fresh egg”. In the industry, we quantify the freshness of the egg based on measurements of the albumen thickness and yolk height (Marzec et al., 2019). This is because as the egg ages in storage, the structure of the protein starts to degrade, and the albumen becomes thinner while the yolk height decreases. The firmness of albumen can be measured in Haugh Units, which compares the egg size and the height of the thick albumen. For the yolk, the strength can be measured as breaking force kg/mm2 or by measuring the yolk index, which compares the height and the width of the yolk. The higher the yolk, the fresher it is. The strength of the yolk membrane is very important for the liquid egg industry since yolk contamination of albumen products is a constant problem for the industry.

The other measurement of freshness is the size of the air chamber, where air is exchanged between the egg and the environment. As the egg ages, it loses water, and the air chamber becomes enlarged.

How to improve egg freshness
Both Haugh units and egg yolk resistance can be preserved in refrigerated conditions for a longer period than at room temperature. It is also beneficial to store eggs in refrigerated conditions to reduce microbial growth, helping to maintain freshness. Egg freshness can be monitored at a commercial setting with various technical tools. At home, you can check your egg freshness by simply submerging it in water—a fresh egg will sink quickly while an older egg will float.

Conclusion
A healthy gut in state of absorption (as opposed of state of inflammation) supplying the plasma and lymph with Vitamins, Ca, P, and carotenoids is key to ensure proper skeletal, ovarian, and liver functions necessary to ensure a high-quality egg is produced throughout a longer production cycle. While Ca and P absorption and deposition should be upkeeped with the proper supplementation of phytase and Vitamin D3 metabolite to reduce the metabolic load of the liver and increase the absorption and deposition in eggshell and medullary bone. The quality of the carotenoids is also important to ensure the egg yolk nutrient density and color that are demanded by today’s consumer. For more information on egg quality, please check out the DSM Egg Quality Manual.