The Effect of Trace Elements on Eggshells

Eggs are the most convenient and quickest way to supplement protein and are one of the most indispensable foods in the daily diet of people all over the world. This means that egg-laying hen farms around the world need to provide enough eggs, and the quality of the eggs needs to meet standards. However, during the collection, grading, packaging, transportation, storage, and processing of eggs, they are inevitably affected by external factors, leading to cracked and broken eggshells, which represents a significant economic loss for farmers and wholesalers.

Therefore, for poultry farms, ensuring egg production is one priority, but continuous monitoring of eggshell hardness, color, and appearance is also necessary. Insufficient eggshell hardness does 

not necessarily indicate a calcium deficiency in the feed. Eggshell formation requires the participation of various trace elements and vitamins. Even if the diet contains sufficient minerals, if nutrients are not fully absorbed, soft-shelled eggs, thin-shelled eggs, broken eggs, rough shells, and abnormal colors can still occur.

Therefore, improving eggshell quality requires attention to various nutritional components, as well as comprehensive consideration of feed formulation, trace element sources, nutrient absorption, laying hen age, and the rearing environment. Understanding the role of different trace elements helps farmers analyze problems more accurately and develop more reasonable nutritional management plans.

1. What are Some Common Eggshell Problems?

Common eggshell problems include: cracked eggs , split eggs , thin-shelled eggs , soft-shelled eggs , rough-shelled eggs, and wrinkled eggs. Some eggs may also have color variations. So what causes these eggshell problems? We will explain them one by one below.

1.1 Insufficient Eggshell Strength

Cracked and broken eggs are typical results of insufficient eggshell strength. To address this, the calcium-to-phosphorus ratio needs adjustment, vitamin D supplementation needs to be increased, and manganese deficiency should be investigated. Environmental stress should be reduced, repeated transfers of laying hens should be avoided, and the laying environment should be kept as consistent as possible.

1.2 Abnormal Eggshell Formation

Thin-shelled eggs have brittle shells that break easily with slight impacts, while soft-shelled eggs cannot form a hard enough shell and are therefore unsellable. The main causes of thin-shelled and soft-shelled eggs are insufficient calcium in the diet, an imbalance in the calcium-to-phosphorus ratio, environmental stress, and disease . They may also be caused by a deficiency in zinc and an imbalance in the ratio of manganese.

1.3 The Eggshell Surface is Not Smooth

Scrunch-shelled eggs have a rough , granular surface, while wrinkled eggs have an uneven or wrinkled shell . Both types of eggs have poor appearance and are unsuitable for market sale. A major reason for the appearance of scrunch-shelled and wrinkled eggs is a deficiency of zinc and copper in the laying hens. Zinc primarily promotes eggshell calcification, while copper primarily promotes the formation of collagen and elastin in the eggshell membrane.

1.4 Eggshell Color Change

The appearance and color of eggs are influenced by a variety of factors, such as the breed of the hen, its age, health status, lighting, and feeding management. Iron is involved in the physiological process of pigment formation in the eggshell. When the hen is deficient in iron, the eggshell color may become lighter, and the gloss of the eggshell will also be affected. When the hen's supply of zinc and manganese is insufficient, or when the season changes, the eggshell color may also change slightly.

2. The Effects of Common Trace Elements on Laying Hens

The relationship between trace elements and eggshell quality is clearly evident from the figure and table above.

2.1 Zinc Promotes Eggshell Calcification

Zinc, known as the "element of life " is one of the essential trace elements for eggshell formation. It is a major component of carbonic anhydrase , playing a crucial role in eggshell calcification. Zinc deficiency in laying hens reduces carbonic anhydrase activity, thus affecting eggshell formation, resulting in lighter eggshells and reduced eggshell luster.

Zinc is a component of ALP and may play a regulatory role in certain phosphorylated proteins in the eggshell matrix, thereby directly or indirectly affecting calcium carbonate deposition and leading to soft-shelled, thin-shelled, and broken eggs . Therefore, proper zinc supplementation should not only focus on the appearance of the eggshell but also on its strength and overall structure.

However, zinc deficiency can lead to decreased egg quality in laying hens, but this doesn't mean that adding more zinc will have a better effect. Excessive calcium in the diet, or components like phytic acid, can still affect zinc absorption and utilization. In actual formulation, it's necessary to consider the basal diet, other mineral levels, and the laying hen's production stage to rationally select the source and amount of zinc. If you are unsure about this, you can consult Polifar. Polifar is a feed additive supplier with long-term partnerships with major factories and possesses a variety of excellent formulations, which can provide you with better and more reasonable formulation optimization suggestions. Polifar can supply trace elements such as zinc sulfate, zinc oxide, and zinc carbonate on a long-term basis.

2.2 Manganese Element Enhances Eggshell Thickness and Hardness

Most studies have shown that manganese and zinc need to be added to the laying hen diet simultaneously to achieve better results ( Holder, 1978; Huntley, 1978). Manganese can catalyze glycosyltransferases and alkaline phosphatases, which can build the organic structure of the eggshell, helping to form a more complete and stable eggshell.

Laying hens have a high manganese requirement, but traditional inorganic manganese has low absorption and utilization rates, so supplementing poultry with inorganic manganese is not recommended. When the manganese content in feed is insufficient, eggshells become thinner, and the proportion of cracked and broken eggs increases. Furthermore, egg production and hatchability both decrease. Eggshell quality is optimal when the manganese level in the diet is increased to 55-60 mg/kg. Studies on Hy-Line Brown laying hens have shown that adding 100 mg/kg of manganese to the diet significantly improves eggshell quality , including increasing eggshell strength, thickness, and fracture toughness.

While researching the subject of this article, Polifar found that feeding animals at night during hot seasons can effectively prevent a decline in eggshell quality. Nighttime feeding ensures a continuous release of calcium from the digestive tract, thereby improving eggshell quality (Lowe, 1996; Hecher, 1996).

Similar to zinc, excessive manganese can interfere with the absorption and metabolism of other nutrients, such as calcium. When feeding laying hens, other nutritional factors such as zinc, manganese, calcium, and phosphorus should be assessed simultaneously to select a more balanced nutritional regimen. Manganese sulfate and manganese oxide are common manganese feed additives; Polifar can be considered if needed.

2.3 The Effect of Iron on Eggshell Appearance

Iron is also one of the trace elements needed by laying hens. Iron participates in the formation of hemoglobin and eggshell pigments. The source of iron for laying hens is their daily feed, and they need about 1.1 mg of iron per egg. When there is insufficient iron in the feed, laying hens will develop iron-deficiency anemia, which will affect the color and luster of the eggshell.

However, a lighter eggshell color is not the only indicator of iron deficiency. Factors such as hen breed, age, disease, lighting, and season can also affect eggshell color. If the eggshell color differs from previous batches after ordering new laying hens, the feed should be checked promptly, and adjustments made dynamically based on the test results. Ferrous sulfate monohydrate/heptahydrate is a common ingredient in feed iron supplements.

2.4 Copper Helps Maintain the Integrity of The Eggshell Membrane

Copper plays a vital role in the membrane inside the eggshell. Insufficient copper in the feed of laying hens can lead to an increased rate of deformed eggs. Copper is also a component of many enzymes, including cytochrome oxidase, lysine oxidase, ceruloplasmin, and superoxide dismutase . These enzymes participate in metabolism, promoting the formation of stable connections between collagen and elastin in the eggshell membrane and reducing membrane rupture.

Experiments have shown that adding copper to the drinking water of older chickens can effectively improve eggshell quality and reduce abnormal and broken eggs . Polifar, as a copper sulfate supplier, recommends adding 30 mg/kg of copper to feed to promote optimal eggshell strength and thickness. Anhydrous copper sulfate and copper sulfate pentahydrate are the most frequently asked copper products by customers.

2.5 Effects of other Trace Elements on Eggshell

Besides the effects of zinc, manganese, iron, and copper on eggshells, trace elements such as magnesium , fluorine , iodine , chromium , and selenium also play a significant role in the normal physiological activities and production performance of laying hens .

Magnesium participates in various physiological processes. Generally, a dietary magnesium content of 0.1%-0.3% is sufficient to meet the growth and egg production needs of laying hens. Excessive magnesium can lead to changes in eggshell thickness and strength. Fluorine levels exceeding 5 ppm in feed or drinking water significantly reduce eggshell quality; therefore, excessive addition should be avoided.

Iodine primarily affects thyroid function in laying hens; long-term deficiency can impair egg production and embryonic development. Eggs from severely iodine-deficient hens have extremely low hatchability, and the embryos are of lower weight. Even if chicks hatch, they are often weak and suffer from problems such as goiter. From a hatching perspective, the maximum allowable iodine intake in laying hen feed is 50 mg/kg.

Chromium primarily helps reduce cholesterol content in egg yolks. Jenson (1978) reported that adding 5 mg/kg of chromium significantly improved egg quality . Adding 0.6–0.7 mg/kg of chromium to the diet of laying hens significantly reduced yolk cholesterol content (Li et al., 1999) .

Selenium can effectively promote the conversion of methionine to cysteine in laying hens , reducing decreased egg production and weight , and decreasing liver bleeding caused by fatty liver. Selenium works synergistically with vitamin E to maintain the body's resistance to disease and stress. The selenium content in protein is approximately 0.20 mg/kg; the dosage is very small, with 2 mg/kg causing a decrease in egg production. Selenium is inexpensive, making it easy to recoup costs, and supplementing laying hen diets with selenium can improve the nutritional content of eggs. However, selenium is a highly toxic element and must be used in strict accordance with safety guidelines.

The above clearly demonstrates that micronutrient management requires ensuring the supply of various elements within appropriate ranges and paying attention to potential sources in feed and drinking water to promote better and faster absorption by animals, rather than simply adding everything. You can find all the micronutrients you need, such as magnesium oxide, calcium formate, potassium iodide, and sodium selenite, at Polifar – all in one place!

3. Eggshell Problems Did Not Improve after Supplementing with Trace Elements

3.1 Laying Hens Failed to Fully Absorb and Utilize the Nutrients

The trace elements contained in feed formulations do not equal the amount actually absorbed and utilized by laying hens . Antagonistic interactions between mineral elements and with other substances can lead to competition for absorption sites . Furthermore, ionic mineral elements readily bind with anti-nutritional factors such as phytic acid, oxalic acid, and tannic acid in feed, reducing the absorption and utilization rate of trace elements and resulting in mineral deficiencies . High calcium and phosphorus levels in laying hen diets inhibit the absorption of copper, iron, zinc, and manganese, thus leading to low absorption and utilization rates of inorganic trace elements in the laying hen diet.

3.2 Trace Element Sources

Micronutrients such as zinc, manganese, and copper from different sources may vary in stability, solubility, and absorption. Organic micronutrients may have advantages in utilization under certain dietary conditions, but their actual effectiveness still depends on the specific product, the level of addition, and the feed composition. When selecting suitable micronutrient products, factors such as quality stability, nutritional utilization, formulation suitability, and overall cost should be considered.

3.3 Differentiation at the Production Stage

The nutritional needs of laying hens change at different growth stages. In the later stages of egg production, the body's nutrient reserves are gradually depleted, and eggshell quality problems worsen. It is necessary to adjust the nutritional plan in a timely manner based on the egg production rate, breakage rate, eggshell thickness, and diet.

FAQ

Q1: What are Some Common Feed-Grade Trace Elements?

A1: Commonly used: iron, copper, zinc, manganese, selenium, iodine, cobalt; raw material forms include inorganic salts (sulfates, oxides), chelated/hydroxyl trace elements, which can be added alone or made into compound premixes.

Q2: Where can I Buy Trace Mineral Premix?

A2: You can contact Polifar to provide you with high-quality premix formulations based on your actual needs. We have premixes for trace elements, vitamins, amino acids, and other ingredients.

Q3: Can You Provide Samples and Testing Procedures?

A3: Yes. We can provide small batches of samples with a Certificate of Account (COA); we can also develop simplified feeding trial protocols tailored to your poultry breed and growth stage for verifying breeding effectiveness.

Q4: What is Sodium Selenite?

A4: Feed-grade sodium selenite is an inorganic selenium source additive. As a raw material for selenium in feed, it enhances the antioxidant capacity and immunity of animals. It is highly toxic and cannot be added directly. It must be made into a premix before use.

Q5: What are the Nutritional Advantages of Organic Trace Elements?

A5: Organic trace elements can first meet the basic metabolic needs of animals, ensure basic growth, and prevent deficiency diseases, while also taking into account commercial traits such as fur and eggs. Beyond this, they improve feed conversion rate, production and reproductive performance, and enhance product quality. Furthermore, they strengthen antioxidant capacity and immunity, optimize the intestinal environment, and achieve disease prevention and health maintenance effects.

Conclusion

Micronutrient supplementation is crucial for eggshell quality. In actual feed formulation, micronutrients need to be added scientifically, paying attention to synergistic and antagonistic interactions . Zinc, manganese, iron, and copper should be rationally balanced according to the laying hen's growth stage, diet composition, elemental forms, and environmental conditions. Excessive magnesium and fluorine intake should be avoided, and iodine, chromium, and selenium should be used scientifically. This approach effectively improves eggshell quality, reduces egg production losses, and enhances economic benefits.

Polifar, as a one-stop feed additive supplier, provides comprehensive services to global buyers. We tailor our services to meet specific customer needs, providing all necessary certifications and high-quality support. Our products and services are exported to over 200 countries and regions worldwide, and our reputation for quality and service is well-deserved. Contact us now!