Research shows that replacing 2% of corn with dried citrus pomace in older laying hens did not reduce egg production or egg quality over four weeks. The same study found significantly lower intestinal oxidative damage, according to Gram Research analysis of a 2026 Poultry Science trial with 48 hens.
Gram Research analysis of a 2026 study in Poultry Science found that swapping 2% of the corn in older laying hens’ feed with dried citrus pomace, the pulp and peel left after juice is pressed, did not hurt egg production or egg quality. The hens also showed lower levels of a marker of cell damage in the lower intestine, along with healthier-looking intestinal lining and changes in genes linked to gut barrier strength and immune defense. Egg production and egg quality stayed about the same, so the feed change appears safe at this level. The study was small, lasted only four weeks, and did not show a clear change in overall gut bacteria, so these results should be seen as early signs rather than proof. Larger and longer studies are needed before farmers or consumers can count on these benefits.
Key Statistics
A 2026 study of 48 late-phase laying hens published in Poultry Science found that replacing 2% of corn with dried citrus pomace significantly reduced malondialdehyde, a marker of oxidative damage, in the lower intestine.
In the same four-week trial, hens fed 2% dried citrus pomace showed no significant change in laying performance or egg quality compared with hens on a standard corn-based diet.
The 2026 Poultry Science trial also found that citrus pomace-fed hens had significantly shorter intestinal crypts and higher villus-to-crypt depth ratios, patterns linked to a healthier gut lining.
The Quick Take
- What they studied: Can replacing part of the corn in laying hens’ feed with dried citrus pomace, a leftover from orange and other citrus processing, affect egg production, antioxidant defenses, and gut health?
- Who participated: 48 healthy Hy-Line Brown hens, about 450 days old (roughly 15 months), split into two groups. Each group had 12 small pens with 2 hens each.
- Key finding: Egg production and egg quality did not change in a meaningful way. Hens eating 2% citrus pomace had significantly lower levels of a damage marker called MDA in their lower intestine, and their intestinal lining looked healthier, with shorter crypts (the small pockets that produce new lining cells) and taller villi (the finger-like folds that absorb nutrients).
- What it means for you: This is early evidence that citrus pomace may be a safe, low-level feed ingredient that could help protect the gut. It does not show that eating eggs from these hens is better for you, and the results come from a short study in one breed of hen.
The Research Details
Researchers randomly divided 48 older laying hens into two groups for four weeks. One group ate a standard diet (the control group). The other group ate the same diet, except 2% of the corn was replaced with dried citrus pomace, an ingredient made from the pulp, peel, and seeds left after citrus juice is pressed.
During the trial, the team tracked egg production and egg quality, including how thick the egg white was. They also took blood samples to measure protein levels and oxidative stress, which is a type of cell damage caused by unstable molecules in the body. At the end of the study, they examined the lower part of the small intestine (the ileum) to look at tissue structure, gene activity, and the bacteria living there.
Because the hens were randomly assigned to groups and the researchers measured many outcomes in the same way, the comparison between the two groups is fairly fair. The team used standard statistical tests to decide whether differences were likely real or due to chance.
Random assignment helps make sure the two groups start out similar, so any differences seen at the end are more likely caused by the feed change. Measuring both the outside results (eggs) and the inside results (gut tissue and genes) gives a fuller picture of whether the ingredient is safe and whether it might offer benefits beyond egg production.
The study used a randomized design and measured several outcomes in a consistent way, which are strengths. However, each group had only 12 pens of 2 hens, so the total group sizes were small. The study ran for only four weeks, and it was published in a peer-reviewed poultry science journal. Many of the results were close to the cutoff for statistical significance, so some findings may not hold up in larger studies.
What the Results Show
The main finding was that adding 2% dried citrus pomace did not change how many eggs the hens laid or the overall quality of the eggs. This is an important safety signal, since a feed ingredient that lowers egg output would not be practical for farms.
The clearest change was in the intestine. Hens eating citrus pomace had significantly lower levels of MDA, a marker of oxidative damage, in the lining of their lower small intestine. Their intestinal tissue also showed shorter crypts and a higher ratio of villus length to crypt depth. In plain terms, the lining looked more like a healthy, well-structured surface that is better at absorbing nutrients.
The team also found that two genes linked to gut defense, TJP1 and IL22, were more active in the citrus group. TJP1 helps build tight junctions, which are seals between cells that keep unwanted substances out of the body. IL22 supports the gut lining and its immune defenses. OCLN, another barrier-related gene, showed a trend toward higher activity, but this result was not statistically clear.
Some blood and egg results also leaned in a favorable direction without reaching clear statistical significance. Egg white height tended to increase, and blood MDA tended to decrease. Blood total protein tended to go down slightly. These trends are worth watching in future studies but should not be treated as firm results.
Overall gut bacteria communities looked similar between the two groups, meaning the feed did not clearly reshape the whole microbial population. One group of bacteria, from the Bacillus family, was more common in the control group. This suggests the citrus feed may influence specific microbes, but the practical meaning of this shift is still unclear.
The antioxidant and immune changes point toward a possible protective effect against cell stress in the gut. Since oxidative stress is linked to inflammation and aging in tissues, reducing it may help older hens maintain intestinal health. However, the study did not measure long-term health outcomes such as disease rates or flock lifespan.
Citrus by-products are rich in plant compounds such as flavonoids and fiber, which earlier research has linked to antioxidant activity and gut support in both animals and people. This study adds to a growing body of work exploring food processing leftovers as useful feed ingredients. It fits with the idea that natural plant-based antioxidants may help protect intestinal tissue, but it is one of the early studies testing this specifically in older laying hens.
The study was small, with only 48 hens and a four-week timeline, which makes it hard to know whether the effects would last or apply to larger flocks. Only one hen breed was studied, and the diet included a single level of citrus pomace (2%), so results may differ with other amounts or breeds. Several findings were trends rather than clear results, meaning they might have occurred by chance. The study also did not measure long-term health, disease resistance, or nutrient content of the eggs in detail. Finally, citrus pomace can vary in composition depending on how it is processed, which may affect results.
The Bottom Line
Based on this study, adding about 2% dried citrus pomace to the diet of older laying hens appears safe, since egg production and quality held steady (moderate confidence). The reduction in intestinal oxidative damage and the healthier gut lining are promising (low to moderate confidence) and need confirmation in larger, longer trials before producers should rely on them. Farmers should consider the feed change as a possible option to test rather than a proven improvement.
Poultry producers, feed formulators, and researchers working on sustainable feed ingredients should pay attention, especially those looking to use citrus industry byproducts. Consumers interested in how animal diets affect egg quality may find it useful background. People who are not involved in poultry farming or feed decisions do not need to change anything based on this study alone.
This study only tracked changes over four weeks, so it cannot show how long-term use would affect hens or their eggs. Any gut or antioxidant benefits would likely take several weeks to appear and would need months of consistent feeding to confirm. Longer studies over a full laying cycle would be needed to know whether these effects last.
Frequently Asked Questions
Does adding citrus pomace to chicken feed affect egg production?
In a four-week study of 48 older laying hens, replacing 2% of corn with dried citrus pomace did not significantly change egg production or egg quality. Egg white height tended to increase, though this trend was not statistically clear.
What is citrus pomace and why is it used in animal feed?
Citrus pomace is the leftover pulp, peel, and seeds from pressing citrus fruit for juice. It is studied as a feed ingredient because it is a low-cost byproduct that contains plant compounds with antioxidant activity.
Can citrus pomace in hen feed improve gut health?
A 2026 study found that 2% dried citrus pomace significantly reduced oxidative damage in the lower intestine of laying hens and improved intestinal tissue structure. Researchers say larger, longer studies are needed to confirm these gut health benefits.
How long did the citrus pomace hen study last?
The study ran for four weeks and included 48 Hy-Line Brown hens, about 450 days old, divided into two diet groups. Its short duration means researchers cannot yet say whether the effects would continue over a full laying cycle.
Want to Apply This Research?
- For a flock or backyard coop, record daily egg count, the percentage of eggs with normal shell and yolk quality, and weekly feed intake for each group. If testing citrus pomace, compare these numbers against a control period of at least four weeks using the same measurements.
- Users who keep laying hens can talk with a poultry nutritionist before changing feed. If a small trial is considered, replace no more than 2% of the corn with dried citrus pomace, and make the change gradually over several days to allow the flock to adjust.
- Track egg production, egg weight, and shell quality monthly, and note any changes in droppings, feather condition, or activity levels. Over several months, review these records alongside feed changes to see whether any patterns emerge. Consult a veterinarian if there are unexplained drops in egg output or signs of illness.
This article summarizes a single animal study on laying hens and is intended for general information only. The results do not show that citrus pomace affects human health or that eggs from these hens are healthier. The study was small and short, so its findings are preliminary. Anyone making decisions about poultry feed or flock management should consult a qualified veterinarian or poultry nutritionist.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.