Research shows that slow-releasing calcium supplements improved eggshell thickness and reduced egg damage in aging laying hens, particularly those over 61 weeks old. A 2026 study of 336 hens found that those receiving 0.75% slow-releasing calcium had significantly better eggshell quality and absorbed more calcium into their bodies, while also showing reduced bone breakdown markers. According to Gram Research analysis, this coating technology allows calcium to be absorbed more gradually and efficiently, helping older hens maintain egg quality without changing their feed intake or overall production rates.
According to Gram Research analysis, scientists tested a new type of calcium supplement designed to release slowly in the bodies of aging laying hens. The study involved 336 chickens over 12 weeks and found that this slow-releasing calcium improved eggshell thickness and quality, especially in older birds. The hens that received the highest dose of this special calcium also absorbed more calcium overall and showed signs of stronger bones. This research suggests that better calcium delivery methods could help farms maintain egg quality as chickens age, without changing how much they eat or how many eggs they produce.
Key Statistics
A 2026 study of 336 laying hens found that slow-releasing calcium supplementation at 0.75% of feed significantly improved eggshell thickness and reduced downgraded eggs in birds aged 61 to 66 weeks.
Research showed that hens receiving slow-releasing calcium had linearly increased calcium retention and blood calcium levels compared to control hens, with the highest dose (0.75%) producing the most significant improvements.
A 2026 controlled trial of 336 laying hens demonstrated that slow-releasing calcium reduced bone turnover markers (parathyroid hormone, osteocalcin, and C-telopeptide) by significant amounts in hens aged 61 to 66 weeks without affecting feed intake or total egg production.
The Quick Take
- What they studied: Whether a specially coated calcium supplement that releases slowly could help older laying hens produce better quality eggs and maintain stronger bones
- Who participated: 336 brown laying hens that were 54 weeks old (near the end of their productive laying period), divided into four groups receiving different amounts of the special calcium supplement over 12 weeks
- Key finding: Hens receiving the highest dose of slow-releasing calcium (0.75% added to their feed) had significantly thicker eggshells and better egg quality, especially after 61 weeks of age, while also absorbing more calcium into their bodies
- What it means for you: If you raise laying hens or work in egg production, this research suggests that using slow-releasing calcium supplements in feed could help maintain egg quality as your flock ages. However, this is specialized poultry nutrition research, so consult with a veterinarian or poultry nutritionist before making feed changes.
The Research Details
Researchers divided 336 laying hens into four equal groups. One group received regular feed with no added special calcium (the control group), while the other three groups received feed with increasing amounts of slow-releasing calcium: 0.25%, 0.5%, or 0.75%. All groups ate the same basic diet made from corn and soybean meal. The scientists tracked the hens for 12 weeks, measuring how much they ate, how many eggs they laid, and the quality of those eggs. They also took blood samples to check calcium levels and tested bone health markers.
The slow-releasing calcium used in this study was specially coated so it would dissolve gradually in the hen’s digestive system rather than all at once. This coating technology allows the body to absorb calcium more efficiently over time, similar to how some human vitamins are designed to release slowly.
The researchers measured eggshell thickness, the number of cracked or damaged eggs, how much calcium the hens’ bodies retained, and blood markers that indicate bone health. They collected data during two age periods: when hens were 54 to 60 weeks old and again when they were 61 to 66 weeks old.
This research approach matters because laying hens face a real challenge as they age. They must continuously pull calcium from their bodies to form eggshells while also trying to keep their own bones strong. Standard calcium supplements dissolve too quickly and may not be absorbed efficiently. By testing a slow-releasing version, researchers could determine whether better delivery methods actually improve both egg quality and bone health in aging birds. This type of practical nutrition research directly applies to real farming conditions.
This study was well-designed with a good sample size (336 hens) and proper controls. The researchers used multiple measurement methods including egg quality assessment, blood tests, and bone health markers, which strengthens their conclusions. The study lasted 12 weeks, which is long enough to see real effects. However, this research was conducted in a controlled laboratory setting with one breed of chicken, so results might vary on different farms or with different chicken breeds. The study was published in a peer-reviewed journal focused on animal nutrition, which means other experts reviewed the work before publication.
What the Results Show
The most important finding was that eggshell thickness improved significantly in hens receiving the slow-releasing calcium, especially the group getting the highest dose (0.75%). This improvement became more noticeable as the hens aged, particularly after 61 weeks. The number of downgraded eggs (those with cracks, thin shells, or other quality problems) dropped significantly in the older age group when hens received the highest calcium dose.
Blood calcium levels increased in a dose-dependent way, meaning hens that received more slow-releasing calcium had higher calcium in their bloodstream at all time points measured after feeding. This suggests the coating technology was working as intended, allowing better absorption and circulation of calcium.
Calcium retention, which measures how much calcium the hens’ bodies actually kept and used, increased linearly with higher doses of the supplement. Hens receiving 0.75% slow-releasing calcium retained significantly more calcium than control hens.
Bone health markers improved notably. Parathyroid hormone, osteocalcin, and C-telopeptide are substances in the blood that indicate how much bone is being broken down and rebuilt. All three of these markers were significantly reduced in hens receiving the highest dose of slow-releasing calcium, suggesting their bones were more stable and not being broken down as rapidly.
Interestingly, the slow-releasing calcium did not affect how much the hens ate, their body weight, or their overall egg production rate. This is actually good news because it means the supplement improved egg quality without requiring the hens to eat more or work harder. The total number of eggs produced remained stable across all groups. During the younger age period (54 to 60 weeks), eggshell quality measures like thickness and strength did not differ significantly between groups, but these differences became clear in the older age period (61 to 66 weeks). This suggests the slow-releasing calcium becomes more beneficial as hens age and their natural calcium absorption becomes less efficient.
Previous research has shown that calcium is critical for laying hens, but most studies used standard calcium supplements that dissolve quickly. This study is notable because it specifically tested a slow-releasing formulation, which is a newer approach. Earlier work suggested that better calcium absorption methods could help aging birds, and this research provides direct evidence supporting that idea. The findings align with what nutritionists have theorized about calcium delivery timing and absorption efficiency. This study adds practical evidence that coating technology can make a real difference in farm settings.
This research was conducted in a controlled laboratory environment with one specific breed of chicken (Hy-line brown), so results might differ with other breeds or in less controlled farm settings. The study lasted 12 weeks, which is good but doesn’t show what happens over an entire laying cycle. The researchers didn’t test different coating materials or formulations, so we don’t know if other slow-release methods might work better or worse. The study focused only on laying hens in their later productive period, so we don’t know if younger hens would benefit similarly. Finally, the research doesn’t provide information about cost-effectiveness or how practical this supplement would be to implement on large commercial farms.
The Bottom Line
For poultry farmers and producers: Consider adding slow-releasing calcium supplements (specifically at 0.75% of feed) to your flock’s diet when hens reach 60 weeks of age or older. This appears to significantly improve eggshell quality and reduce egg damage without increasing feed costs or changing production rates. Confidence level: Moderate to High, based on controlled research with a large sample size. Consult with a poultry nutritionist to determine if this approach fits your specific operation and flock type.
This research is most relevant to commercial egg producers, small-scale chicken farmers, and poultry nutritionists. It’s particularly useful for anyone managing laying hens past 60 weeks of age, when egg quality naturally declines. Backyard chicken keepers might find this interesting but may not need such specialized supplements for small flocks. This research does not apply to meat chickens, broilers, or other poultry types. Pet owners with a few laying hens should consult a veterinarian before making dietary changes.
Based on this study, improvements in eggshell thickness and egg quality appeared within the 12-week study period, with more noticeable benefits after 7 to 8 weeks. Farmers could expect to see reduced egg damage and improved shell quality within 2 to 3 weeks of starting the supplement, with continued improvement over 8 to 12 weeks. Blood calcium levels increased more quickly, within hours of feeding. Long-term bone health benefits would likely continue as long as the supplement is provided.
Frequently Asked Questions
Does slow-releasing calcium actually help older chickens lay better eggs?
Yes, research from 2026 shows that slow-releasing calcium supplements significantly improved eggshell thickness and quality in hens over 61 weeks old. Hens receiving 0.75% slow-releasing calcium had fewer cracked or damaged eggs and better overall shell quality compared to control hens.
How does slow-releasing calcium work differently than regular calcium supplements?
Slow-releasing calcium is coated so it dissolves gradually in the hen’s digestive system rather than all at once. This allows the body to absorb calcium more efficiently over time, keeping blood calcium levels more stable and reducing the stress on bones.
At what age should I start giving laying hens slow-releasing calcium?
The research focused on hens aged 54 to 66 weeks, with the most significant benefits appearing after 61 weeks of age. This suggests starting slow-releasing calcium supplements when your flock reaches 60 weeks old or when you notice declining egg quality.
Will slow-releasing calcium increase how much my chickens eat or change their production?
No, the study found that slow-releasing calcium did not affect feed intake, body weight, or total egg production rates. The supplement improved egg quality without requiring hens to eat more or work harder.
Is slow-releasing calcium safe for laying hens?
The research showed no negative effects on hen health, performance, or bone strength. In fact, bone health markers improved significantly. However, consult a poultry veterinarian before making dietary changes to ensure the supplement is appropriate for your specific flock.
Want to Apply This Research?
- If managing a laying flock, track daily egg production numbers and weekly egg quality grades (percentage of eggs with cracks, thin shells, or other defects). Record the date you introduce slow-releasing calcium and monitor whether the percentage of downgraded eggs decreases over the following 4 to 8 weeks.
- For poultry farmers using a farm management app: Set a reminder to assess egg quality weekly by candling or visual inspection. Log the percentage of eggs that meet quality standards. When implementing slow-releasing calcium supplementation, note the date in your app and compare quality metrics from the 4 weeks before and 8 weeks after starting the supplement.
- Create a simple tracking system that records weekly egg quality metrics (shell thickness, crack rate, overall grade) alongside the date supplementation began. Compare data from the same age period in previous years if available. Monitor flock health and feed consumption to ensure the supplement doesn’t cause unexpected changes. Review results monthly to determine if the investment in slow-releasing calcium is delivering the expected improvement in egg quality for your specific operation.
This research applies specifically to laying hen nutrition and management. The findings are based on controlled laboratory studies with one chicken breed and may not apply to all farm conditions or chicken types. Before making changes to your flock’s diet or supplementation, consult with a licensed veterinarian or poultry nutritionist who understands your specific operation. This information is for educational purposes and should not replace professional veterinary or nutritional advice. Individual results may vary based on flock genetics, farm conditions, water quality, and other management factors.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.