Research reviewed by Gram found that a feed blend of licorice root extract, woad leaf extract, and Bacillus subtilis at 25 grams per kilogram of feed helped protect young sheep from colon inflammation. Lambs also gained more weight and showed lower inflammation signals in this 2026 PLOS ONE animal study of 45 lambs.
Young sheep often develop diarrhea and gut inflammation when they are weaned, and farmers are looking for safe alternatives to antibiotics. According to research reviewed by Gram, a feed blend made from licorice root extract, woad leaf extract, and a helpful bacterium called Bacillus subtilis appeared to support gut health in lambs. In a 2026 study published in PLOS ONE, lambs fed 25 grams of the blend per kilogram of feed gained more weight, and their immune markers and gut-lining proteins improved. When the researchers gave the lambs a chemical that irritates the intestines, the blend reduced damage to the colon and lowered several inflammation signals. The findings are promising, but they come from animal experiments, so more research is needed before this approach is used widely on farms.
Key Statistics
A 2026 animal study of 45 lambs published in PLOS ONE found that feeding 25 grams of a licorice, woad leaf, and probiotic blend per kilogram of feed reduced colon damage caused by an irritant.
In the same 2026 PLOS ONE study, lambs fed 25 grams of the blend per kilogram of feed showed lower levels of several inflammation signals, including IL-1β, IL-6, and IFN-γ, while gut-barrier genes became more active.
According to research reviewed by Gram, the blend slowed the growth of E. coli and Staphylococcus aureus in laboratory tests, though the helpful bacterium Bacillus subtilis was not promoted by the plant extracts alone.
The Quick Take
- What they studied: Can a blend of licorice root extract, woad leaf extract, and a beneficial bacterium protect young sheep from gut inflammation and help them grow, as a substitute for antibiotics?
- Who participated: The study used 45 healthy male Hu lambs, about 45 days old and weighing roughly 16 kilograms. The lambs were split into separate groups for a growth test and a gut-protection test. This was an animal study, so the results do not directly apply to people.
- Key finding: Lambs given 25 grams of the blend per kilogram of feed gained more weight each day. When the lambs were given a chemical that causes colon inflammation, the blend reduced colon damage and lowered several inflammation signals, with the strongest effects at the 25 gram dose.
- What it means for you: If you raise sheep, this research suggests a plant and probiotic feed blend may help young lambs stay healthier during weaning. Because this was a small study in animals, farmers should talk with a veterinarian before changing feed programs.
The Research Details
The researchers began with lab tests to see how the ingredients affected bacteria. They found that the blend slowed the growth of two harmful bacteria, E. coli and Staphylococcus aureus, while the individual plant extracts did not change the growth of the helpful bacterium on their own.
Next, the team ran a feeding trial with 27 lambs divided into three groups of nine. One group ate a normal diet, and two groups ate diets with the blend added at 25 or 30 grams per kilogram of feed. The researchers tracked weight gain and took blood and tissue samples to measure immune markers.
Finally, a separate group of 18 lambs was split into three groups of six. One group was fed normally, one group was given a chemical called dextran sulfate sodium (DSS) to irritate the colon, and a third group ate the blend for a week before receiving the same irritant. This setup let the researchers compare protection against gut damage directly.
Comparing a normal diet, an irritant-only group, and a blend-plus-irritant group shows whether the blend itself caused the protective effect. Measuring both growth and detailed gut markers also reveals whether improvements in weight and in gut health happened together.
The study used randomized groups, which helps reduce bias, and it included a control group for comparison. It also measured results in several ways, including growth, immune markers, gene activity, and tissue examination. However, each group was small, with only six to nine animals, and the study was done in one breed under controlled conditions. Results like these need to be repeated in larger studies on working farms before they can be considered reliable.
What the Results Show
The blend did not promote the growth of the helpful bacterium Bacillus subtilis, but it did slow the growth of E. coli and Staphylococcus aureus in laboratory tests. This suggests the combination may help limit harmful microbes in the gut, although lab results do not always translate directly to a living animal.
In the feeding trial, lambs given the 25 gram dose gained more weight each day than lambs on the normal diet. Both blend doses also increased levels of immune proteins in the blood and in the lining of the colon. These proteins help the body fight infections and defend the gut surface.
The most notable results came from the 25 gram dose. It lowered several inflammation signals, including IFN-γ, IL-1β, and IL-6, which are chemical messengers that drive inflammation. At the same time, it raised IL-4 and IL-10, which help calm inflammation. The blend also increased the activity of genes that build the gut’s protective barrier, such as ZO-1, occludin, Muc2, and α-catenin. Together, these changes were linked to less damage in the colon of lambs exposed to the irritant.
The researchers also measured secretory immunoglobulin A, an antibody that coats the gut surface and acts as a first line of defense against microbes. Lambs receiving either blend dose showed higher levels of this antibody. Because the blend affected several immune pathways at once, the researchers suggest it may support the gut in a balanced way rather than simply suppressing the immune system.
Farmers and researchers have been searching for alternatives to antibiotics in livestock feed, since antibiotic use can contribute to antibiotic resistance. Licorice root compounds, traditional herbs, and beneficial bacteria have each been studied for gut health in animals. This study adds to that work by testing them together, and it suggests the combination may work better than any single ingredient, though this specific comparison was not directly tested.
The study was conducted in sheep, not humans, so the results cannot be directly applied to people. The groups were small, and the experiments lasted a short time, so it is unclear whether the benefits continue over months or affect meat or milk production. The researchers also used a chemical irritant to cause gut inflammation, which may not match the natural causes of weaning-related diarrhea on farms. The study does not report the exact percentage of improvement for most measures, so the size of the benefit remains uncertain.
The Bottom Line
Based on this early animal research, adding about 25 grams of the blend per kilogram of feed may be worth considering for young lambs during weaning. Confidence is moderate for the immune and gut-protection effects seen in this study, but low to moderate for real-world benefits, since the findings have not yet been tested on working farms or across different sheep breeds.
Sheep farmers, feed companies, and veterinarians who manage weaning-age lambs may find this research useful. Pet owners, people looking for supplements for their own health, and anyone seeking medical treatment for human gut conditions should not apply these findings directly, since the study did not involve people.
In this study, changes in weight and gut markers were measured over a few weeks of feeding. Farmers should expect that any benefits would appear during the weaning period, but long-term effects on growth, health, and productivity have not been established and would require longer studies.
Frequently Asked Questions
Can a licorice and probiotic feed blend help sheep with gut problems?
A 2026 PLOS ONE study found that lambs fed 25 grams of a licorice root, woad leaf, and Bacillus subtilis blend per kilogram of feed had less colon damage and lower inflammation signals. These results come from a small animal study and need further testing on working farms.
What is DSS-induced colitis in sheep?
DSS-induced colitis is an inflammation of the colon caused by giving animals dextran sulfate sodium, a chemical that irritates the intestinal lining. Researchers use it to model gut damage in a controlled way. In the 2026 study, this model helped test whether the feed blend could protect lambs from intestinal injury.
Are herbal feed additives a safe alternative to antibiotics for lambs?
Research reviewed by Gram suggests herbal and probiotic feed additives may support lamb gut health without antibiotics, but evidence is still early. The 2026 study in 45 lambs showed promising immune and gut benefits at 25 grams per kilogram of feed, and researchers called the blend a potential safe option.
How does a probiotic like Bacillus subtilis help the gut?
Bacillus subtilis is a beneficial bacterium that may support digestive health by helping maintain a balanced gut environment. In this study, it was combined with licorice and woad leaf extracts, and the blend was linked to higher immune antibodies and stronger gut-lining proteins in lambs.
Want to Apply This Research?
- For farm use, record each lamb’s weight once a week, along with the daily feed amount and any signs of diarrhea, such as loose stools, dehydration, or lower appetite. Tracking these measurable signs can show whether the feed blend makes a difference in your flock.
- If you raise sheep, log the blend dose in grams per kilogram of feed and make sure it is mixed evenly into the diet. Check with your veterinarian before starting, and note any changes in weight gain or stool quality in the app so you can review them later.
- Keep weight and health records for each lamb over several months, including weaning, growth milestones, and any treatment history. Review these records with your veterinarian each season to decide whether the feed blend is worth continuing, and compare results against a control group if possible.
This article summarizes an animal study conducted in sheep and does not provide veterinary or medical advice for people. Results may not apply to other animals or to humans. Farmers should consult a licensed veterinarian before changing feed or treating livestock, and anyone with a digestive condition should speak with a qualified healthcare professional.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.