According to Gram Research analysis, goats fed a diet with 60 percent Terminalia brownii tree leaves ate the most, gained weight faster, and produced the lowest methane readings in a 90-day trial of 25 goats published in 2026. Blood health stayed within a normal range, though the small study needs larger follow-up.
A Gram Research analysis of a 2026 study in Veterinary Medicine and Science looked at whether tree leaves can replace some of the grain-based feed given to goats. Researchers divided 25 male goats into five groups and fed each group a different mix of commercial concentrate feed and leaves from Terminalia brownii, a tree. After 90 days, goats eating the highest share of leaves, 60 percent of their diet, ate more, gained weight faster than goats on grain-heavy diets, and produced less methane, a gas released during livestock digestion that contributes to climate change. Their blood tests stayed within a healthy range, which suggests the leaves did not harm their health. The study was small and short, and it did not measure costs, so these results are not yet a complete guide for farmers. Still, the findings point to tree leaves as a possible lower-cost feed option in regions where feed is scarce.
Key Statistics
A 2026 randomized trial of 25 male goats published in Veterinary Medicine and Science found that a diet with 60 percent Terminalia brownii leaves produced the lowest methane reading of the five diets tested, at 34.84 ppm-m.
In the same 90-day study, goats fed 60 percent Terminalia brownii leaves gained an average of 63.4 grams per day, compared with 59.0 grams per day for goats fed 45 percent leaves.
The 2026 goat study reported that goats on the 60 percent leaf diet consumed an average of 779.24 grams of dry matter, the highest intake among the five feeding groups.
The Quick Take
- What they studied: Can leaves from the Terminalia brownii tree replace part of the concentrate feed given to goats, and does this help their growth, blood health, and methane output?
- Who participated: 25 male goats with an average starting weight of about 19 kilograms. The goats were randomly placed into five groups of five, and all of them also ate natural pasture hay.
- Key finding: Goats eating a diet with 60 percent tree leaves ate the most feed, gained about 63.4 grams per day, and produced the lowest methane readings of the five groups. Their blood health stayed in a normal range. Because the groups were small, these differences need confirmation in larger studies.
- What it means for you: If you raise goats, tree leaves may be a practical way to stretch or partly replace expensive grain feed. Think of this as an early sign, not a proven plan. Talk with a local veterinarian or animal nutritionist before changing your herd’s diet.
The Research Details
Researchers wanted to know whether swapping some of a goat’s grain-based feed for tree leaves would change how much the animals ate, how fast they grew, their blood health, and the methane they released. They started with 25 young male goats of similar size and used random assignment to place them into five feeding groups of five goats each. Random assignment means chance decided which goats went into which group, which helps prevent the groups from being different in ways that could skew the results.
One group ate only the standard concentrate feed. The other four groups received mixes in which the leaves made up 15, 30, 45, or 60 percent of the concentrate portion. Every goat also had access to natural pasture hay. The feeding period lasted 90 days. Near the end, the team ran a seven-day test to measure how well the goats digested their food, which shows how much of each nutrient the body actually absorbs.
To measure methane, the researchers used a laser-based detector, a tool that can estimate the gas released by an animal. Blood samples were analyzed to check the goats’ overall health, and the team recorded weight gain and how efficiently each goat turned feed into body weight. The data were analyzed with standard statistical software, which is the normal way to compare groups in an experiment like this.
Randomly assigning the goats to groups is a strong design choice because it makes it fairer to attribute differences to the feed itself rather than to pre-existing differences between animals. Measuring intake, digestion, growth, blood work, and methane together gives a fuller picture than looking at only one outcome. A 90-day feeding period is long enough to see real changes in growth and blood health, which short tests often miss.
The random assignment and the use of several different types of measurements are strengths. However, the study used only five goats per group, which is a small number. Small groups can produce results that look bigger or smaller than they really are, and a single unusual goat can shift the average. The study was also conducted on animals rather than people, so its findings apply to goats first. Readers should look for larger follow-up studies before treating these results as settled.
What the Results Show
The goats fed the highest share of tree leaves, 60 percent, ate more feed than the other groups. They consumed an average of 779.24 grams of dry matter and 181.06 grams of crude protein, which is the portion of feed that contains protein. More food and more protein are both important for growth, which helps explain why this group performed well.
These goats also gained weight faster than the groups on grain-heavy diets. Their average daily gain was 63.4 grams, while the group eating 45 percent leaves gained 59.0 grams per day. The study reported that both of these leaf-heavy groups grew faster than the control group and the groups with less leaf. In plain terms, the more leaves the goats ate, up to a point, the better they grew in this study.
Methane was the third major finding. Goats eating 60 percent tree leaves produced the lowest methane readings, at 34.84 ppm-m, which is lower than the other groups. Methane from livestock is a meaningful source of greenhouse gas, so a feed that lowers it could matter for the environment. However, the measurement was taken at a single point during the study, so the size of this effect should be read cautiously.
The blood tests showed that the goats eating tree leaves did not experience harmful changes. The group eating 60 percent leaves had the highest hemoglobin levels, which is the protein in red blood cells that carries oxygen. The researchers concluded that replacing concentrate feed with leaves did not negatively affect blood health.
Digestion of two fiber measures, neutral detergent fiber and acid detergent fiber, did not differ significantly among the groups. This means the goats were able to break down the fiber in the leaves about as well as the fiber in the standard feed. That is useful because it suggests the leaves do not make the diet harder to digest.
Blood immune cell counts also varied across groups. The group eating 60 percent leaves had the highest lymphocyte percentage at 61 percent, while the group eating 45 percent leaves had the lowest at 36.5 percent. Lymphocytes are white blood cells that help fight infection. The group eating 45 percent leaves had the highest neutrophil count, another type of white blood cell. These variations are interesting, but they do not show a clear pattern of better or worse health, and the small group sizes make it hard to interpret them confidently.
The authors also noted that future studies should look at costs. Harvesting and processing tree leaves takes labor and time, and the study did not show whether the gains in growth and methane reduction are worth those expenses.
Researchers have long known that goats and other ruminant animals can use leaves from trees and shrubs as a feed source, especially in dry seasons when grass is scarce. This study adds to that knowledge by testing a specific tree species at several replacement levels and measuring methane at the same time. Many feed studies focus only on growth, so the methane measurement makes this work more relevant to the climate conversation. Still, the findings should be seen as a starting point, since most similar studies in this area are also small and short.
The most important limitation is the small number of goats, five per group. Small studies are more easily affected by chance, so the differences between groups may not hold up in larger groups. The feeding period was 90 days, which is useful, but it does not show what happens over a full year or across multiple breeding cycles.
The methane measurement used a single tool at a single point in the study, so it may not capture how methane changes over the course of a day or across seasons. The study also did not calculate costs, which means it cannot tell whether using tree leaves saves money overall. Finally, these were male goats, so results may differ for females, kids, or breeds not included in the study.
The researchers themselves noted that cost-benefit analysis is still needed. This is an honest acknowledgment that the practical value of the approach has not yet been fully tested.
The Bottom Line
Based on this single small study, tree leaves appear to be a promising partial substitute for concentrate feed in goats. Confidence is moderate for the finding that goats eat and grow well on a leaf-heavy diet, and lower for the methane result, which needs confirmation. Confidence that the blood profile is not harmed is moderate, given the study measured several blood markers. Farmers should consider trying small-scale trials on their own animals and tracking results before changing whole herds.
Goat farmers and smallholders in regions where grain feed is expensive or hard to get may find this research useful. Animal nutritionists, agricultural extension workers, and researchers studying livestock and climate impacts should also pay attention. People who keep goats only as pets, or who have access to affordable commercial feed, probably do not need to change their routine based on this study alone.
Based on the 90-day feeding period in this study, changes in feed intake and growth could be visible within a few months of starting a similar diet. Blood changes and methane effects would need longer or more careful monitoring to confirm. Any benefits to cost or herd productivity would depend on local conditions and would take a full growing season or more to judge reliably.
Frequently Asked Questions
Can goats eat tree leaves instead of grain feed?
A 2026 study of 25 male goats found that replacing part of the grain feed with Terminalia brownii leaves supported growth and kept blood health normal. The best results came at 60 percent leaves, though the study was small and did not measure costs.
Do tree leaves reduce methane from goats?
In a 90-day study of 25 goats, the diet with 60 percent Terminalia brownii leaves had the lowest methane reading, at 34.84 ppm-m. The result is promising, but it was measured at one point in time and needs confirmation in larger studies.
How much weight do goats gain on tree leaf diets?
Goats fed 60 percent Terminalia brownii leaves gained about 63.4 grams per day in a 2026 trial, slightly more than the 59.0 grams per day seen with 45 percent leaves. Growth results come from a small group of five goats per diet.
Are tree leaves safe for goat blood health?
Researchers found no harmful effects on blood profiles when tree leaves replaced concentrate feed in a 90-day trial. The 60 percent leaf group had the highest hemoglobin levels, which carry oxygen in the blood. Owners should still check with a veterinarian first.
Want to Apply This Research?
- Weigh each goat once a week at the same time of day and record the result. Log the daily amount of each feed type offered and what is left over. Together these two records let you calculate weekly weight gain and approximate feed intake for each animal.
- Start with a small trial. Replace a modest share of concentrate, such as 15 percent, with safe tree leaves for two to four weeks, then compare weight gain and feed consumption with a control group. Use the app to note any changes in appetite, energy, or stool quality, and stop the trial if you see signs of illness.
- Keep a running log for at least one full season. Record weight, feed amounts, and any veterinary check results every month. Review the data every three months to see whether the trends hold, and consult a veterinarian before making major changes to a herd’s diet or adding new blood tests.
This article summarizes a small animal study of goats and is intended for general information only. It is not veterinary or farm management advice. The results come from one short trial with five goats per group and may not apply to other breeds, ages, climates, or herd conditions. Consult a licensed veterinarian or animal nutritionist before changing any animal’s diet.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.