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Research on donkey milk · Study 100
Mannan oligosaccharides in the jennies’ feed: milk, foals
16 lactating Dezhou jennies received feed with or without 0.5 g/kg mannan oligosaccharides for 60 days. Milk fat (0.65 vs. 0.87 %) and milk protein (1.69 vs. 1.79 %) did not differ significantly; the foals tended to gain more weight (25.63 vs. 31.75 kg).
At a glance · tap the cards
The key figures
Study design
How it was studied
Sixteen lactating Dezhou jennies (2–3 years, 269.88 ± 31.84 kg) with their foals on a breeding farm in Shandong Province (China) were randomly allocated to two groups (eight jenny–foal pairs each) after three days of acclimatisation. The control group received the farm’s usual basal ration; the trial group received the same ration with 0.5 g/kg dry matter of mannan oligosaccharide (MOS, a prebiotic from yeast cell walls) mixed into the concentrate. The trial ran for 60 days; the foals suckled freely from the jennies. One milk sample per jenny was analysed for fat, protein, lactose and milk urea nitrogen. In the foals, body weight, blood serum values (proteins, liver enzymes, blood lipids) and the composition of the gut microbiota in the faeces (16S rRNA sequencing) were examined. Group comparisons used t-tests; the authors treated 0.05 ≤ p < 0.10 as a trend.
Interactive chart · values from the study
Milk composition with and without mannan oligosaccharides
Means (n = 8 per group) from Table 3; none of the differences shown is statistically significant (p = 0.134 / 0.157 / 0.224).
Second analysis
Body weight of the foals in the 60-day trial
Means (n = 8 per group) from Table 1; p = 0.512 / 0.133 / 0.091 – the gain counts only as a trend.
Results
What the study measured
Milk composition did not differ significantly between the groups. Milk fat in the MOS group was arithmetically 0.87 % compared with 0.65 % (p = 0.134), milk protein 1.79 % compared with 1.69 % (p = 0.157); the authors quantified this as a numerical increase of 33.85 % and 5.92 % respectively.
Lactose (6.95 % vs. 6.85 %, p = 0.224) and milk urea nitrogen (20.26 vs. 21.55 mg/dL, p = 0.474) also showed no significant difference.
The foals started with comparable weights (68.75 vs. 66.56 kg). After 60 days, final weight did not differ significantly (94.38 vs. 98.31 kg); total gain (25.63 vs. 31.75 kg) and daily gain (0.43 vs. 0.53 kg) tended to be higher in the MOS group (p = 0.091).
In the blood serum of the foals in the MOS group, total cholesterol (2.00 vs. 2.35 mmol/L) and LDL cholesterol (0.40 vs. 0.48 mmol/L) were lower and HDL cholesterol (1.56 vs. 1.27 mmol/L) higher. Total protein, albumin, liver enzymes and triglycerides did not differ; the authors themselves described the blood lipid findings as exploratory.
In the foals’ faecal microbiota, diversity indices (ACE, Chao1, Shannon, Sobs) and overall structure showed no significant group difference (PERMANOVA R² = 0.0825, p = 0.189). 1131 sequence variants occurred in both groups; by LEfSe analysis, ten taxa each were relatively more frequent in one of the two groups.
Authors’ conclusion: In the view of Li et al. (2026), supplementing lactating Dezhou jennies with 0.5 g/kg mannan oligosaccharide was associated with a tendency towards higher weight gain in the foals, altered cholesterol values in foal serum and individual shifts in the faecal microbiota; the milk constituents fat, protein and lactose did not change significantly. The authors saw this as a basis for further research on feeding lactating jennies; effects in humans were not examined.
Critical assessment
Strengths and limitations
Small groups, no milk effectsClear limitation
Only eight jenny–foal pairs from one farm per group were examined, with a single dose over 60 days. There was no significant difference in the classic milk constituents; the higher fat and protein values are purely arithmetical.
Title does not match the trialNote
The title refers to supplementation during pregnancy and improved development of the foals. According to the methods section, however, lactating jennies were fed for 60 days, and the foals’ weight gain reached only the level of a trend (p = 0.091).
Same animal trial as an earlier paperNote
Number of animals, age, weight (269.88 ± 31.84 kg), dose, duration and approval match Wang et al. (2025, Int. J. Mol. Sci.), which reports data on the jennies from the same trial. The two papers describe feeding times (8 am/6 pm vs. 7 am/7 pm) and housing (together with foals vs. individually) differently; in the present paper, the approval numbers in the methods section and the ethics statement also differ.
Milk sample barely describedNote
Only one milk sample per jenny was analysed; day of lactation, time, collection and milk yield are not given, nor is the age of the foals. Whether the dose refers to the dry matter of the concentrate or of the total ration remains unclear; the basal ration is only in the supplementary material.
Interpretations not tested directlyNote
The microbiota data are based on 16S sequencing and describe only composition, not metabolic activity; fatty acids in the faeces were not measured. A relationship between milk, microbiota and the foals’ blood lipids was not tested statistically. Effects in humans were not the subject of the study.
Randomised and transparently tabulatedStrength
The pairs were randomly allocated, means with standard deviations and p-values are tabulated, and the weight figures add up (final weight minus starting weight gives the gain). The authors themselves interpret non-significant findings cautiously in the discussion.
Editorial assessment: The study is a feeding trial in jennies and their foals. For the milk itself, it shows that the feed supplement tested did not measurably change fat, protein or lactose content under the trial conditions. No conclusions about commercial products or humans can be drawn from it. To the research archive.
Research question for DON DONKEY’S®
Do different amounts of mannan oligosaccharide over a whole lactation measurably change milk yield and the fatty acid and protein profile of donkey milk when samples are taken in a standardised way at several time points?
Original publication
Dietary Mannan Oligosaccharide Supplementation During Gestation Alters Milk Composition in Jennies and Improves Growth Performance, Lipid Metabolism, and Gut Microbiota in Dezhou Donkey Foals
Original title of the publication.
Li H., Luo J., Wen Z., Yin Y., Huang S., Shi D.
Microorganisms · 2026 · 14(10), 2409
College of Animal Husbandry and Veterinary Medicine, Jinzhou Medical University, Jinzhou; National Key Laboratory of Livestock and Poultry Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing; Laboratory of Feed Grain Safety and Healthy Poultry Farming, Beijing Jingwa Agricultural Science and Technology Innovation Center, Beijing, China
10.3390/microorganisms14102409: 10.3390/microorganisms14102409
Transparency: Chinese Universities Scientific Fund (2026RC021), Donkey Precision Nutrition and Healthy Production Project (CRP-DE-2025-268) and Modern Agricultural Industry Technology System of Hebei Province (HBCT2024280203). The authors declare no conflicts of interest. No product-related statement for DON DONKEY’S®.
Summarised and reviewed by the DON DONKEY’S editorial team on the basis of the original publication · as of October 2026
The study summarised above was carried out independently of DON DONKEY’S® and does not relate to our products. It serves solely to inform about the state of research.
DON DONKEY’S® donkey milk and donkey milk powder are foods. They are not intended to prevent, treat or cure any disease and do not replace medical advice.
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