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A team from Jiangnan University in Wuxi and the Chinese company Dong’e Ejiao gave mice donkey milk or a sugar fraction derived from it for 30 days and then allowed the animals to swim. Swimming time until exhaustion, as well as blood and tissue values, were measured. In several groups, the mice swam longer than the control animals. However, the study has significant limitations, and three authors work for the donkey milk supplier.
Animal study on mice – no statement about an effect in humans. Swimming time, blood and tissue values are the measured parameters of this mouse model. Donkey milk is a food.
Study at a glance
| Feature | Information |
|---|---|
| Original title | Anti-Fatigue Effects of Donkey Milk and Its Polysaccharides in a Mouse Swimming Model |
| Authors | Wang T., Sun Y., Wang K. et al. |
| Journal | Foods, 15(14): 2568 |
| Year | 2026 |
| Country | China |
| Study type | Animal study on mice (swimming test) plus test tube tests |
| Sample | 210 male BALB/c mice, 7 groups of 30 (3 subgroups of 10 each) |
| DOI | 10.3390/foods15142568 |
What question did the researchers ask?
The researchers wanted to know whether mice that had previously received donkey milk or a sugar fraction derived from it for 30 days differed from untreated animals in the swimming test and laboratory values. They also described the composition of this fraction, which they call "polysaccharides," i.e., molecules composed of many sugar building blocks.
How it was investigated
- Groups: One control group without administration, three groups with donkey milk (2.08, 4.16 or 8.32 ml per kg of body weight) and three groups with the sugar fraction (0.625, 1.25 or 2.5 g/kg).
- Administration: Once daily via gavage for 30 days, standard feed and water freely available.
- Three swimming tests: 10 animals per group swam with a lead weight until exhaustion, another 10 for 90 minutes without weight (afterwards blood, liver, muscle), another 10 for 10 minutes for lactate measurement.
- Laboratory values: Liver glycogen (stored sugar), ATP (cellular energy carrier), lactate, urea nitrogen, enzymes and messengers in the serum.
The results
According to the paper, all six treatment groups swam statistically longer than the control. The text only provides figures for three groups. There was no difference in body weight between the groups. The dose groups behaved inconsistently regarding the laboratory values: For example, the MDA marker for oxidatively modified fats in the liver decreased only in the group with the lowest donkey milk dose.
| Measured parameter | Control | Donkey milk, high dose (HDM) | Fraction, low dose (LDMP) |
|---|---|---|---|
| Swimming time until exhaustion | 51.50 ± 1.05 min | 116.67 ± 6.50 min | 115.33 ± 1.03 min |
| SOD activity in serum | only as a graphic | 168.50 ± 22.31 U/ml | 146.30 ± 17.53 U/ml |
| TNF-α in serum | only as a graphic | 330.70 ± 2.86 pg/ml | 260.90 ± 17.31 pg/ml |
| IL-1β in serum | only as a graphic | 2.17 ± 0.19 pg/ml | 2.14 ± 0.10 pg/ml |
Mean ± standard deviation, n = 10. According to the analysis, the sugar fraction consisted of 53.89 mol% galactose, 28.27% glucose and 9.12% N-acetylglucosamine. In the test tube, donkey milk scavenged the test radical DPPH more strongly than the fraction; in the second test (FRAP), the fraction came out ahead.
In the mouse model, animals given donkey milk or the fraction swam longer, and several laboratory values differed from the control. No statement about humans can be derived from this.
Critical assessment
- No resting control group: All animals swam. The authors themselves cite this as a limitation.
- Unclear fraction: Yield, purity, residual protein and lactose were not determined. Galactose and glucose are also the building blocks of lactose.
- Small amounts: According to our calculation, the highest donkey milk dose corresponds to around 0.2 ml per day in a 25 g mouse.
- Conspicuous figures: The spread in the exhaustion test is unusually small (51.50 ± 1.05 min). The IL-1β percentage figures result in two different control values. The summary calls the fraction antioxidatively "stronger," while in the DPPH test it was the other way around.
- Inconsistent dose groups: Sometimes the lowest dose came out ahead, sometimes the highest; a clear dose-response relationship is missing.
- Transferability: According to the authors, the mouse swimming model can only be transferred to humans to a limited extent.
Funding, conflicts of interest and level of evidence
The work was funded by programs from the provinces of Shandong and Jiangsu as well as the Chinese National Natural Science Foundation. Three authors (Jie Yu, Yangen Sun, Chuanliang Ji) were employed by Dong’e Ejiao Co., Ltd.; Jie Yu is one of the two corresponding authors. The donkey milk was supplied by Shandong Dong’e Ejiao Food Co., Ltd. According to the paper, the company had no influence on the design, data collection and evaluation.
Level of evidence: preclinical (animal model on mice plus test tube tests) – no statement about effects in humans.
What does this mean for donkey milk as a food?
The study describes a sugar fraction from donkey milk and measured values in a mouse model. The authors propose their fraction as a "functional ingredient" – we do not adopt this classification. No recommendation can be derived from this for donkey milk as a food.
Our research question: Which sugar building blocks are in donkey milk besides lactose – and how can they be reliably measured separately?
Frequently asked questions
What is the "sugar fraction"?
A powder that the researchers obtained by heating donkey milk, centrifuging, precipitating with alcohol and freeze-drying. How pure it is was not determined.
How much donkey milk did the mice receive?
Depending on the group, 2.08, 4.16 or 8.32 ml per kilogram of body weight per day – so only fractions of a milliliter for a mouse.
Can this be transferred to humans?
No. It is an animal study with a special swimming model. The results describe measured values in mice.
You can find all measured values, interactive graphics and the complete critical assessment on our research page: Study 83: Donkey milk in the swimming test on mice. Further studies in the research archive.
Wang T., Sun Y., Wang K. et al. (2026). Anti-Fatigue Effects of Donkey Milk and Its Polysaccharides in a Mouse Swimming Model. Foods, 15, 2568. DOI: 10.3390/foods15142568
Summarized and reviewed by the DON DONKEY'S editorial team based on the original publication · As of: October 2026. This summary does not replace the original work.
End of the study summary. The study was conducted independently of DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.
