Donkey Milk Study: Comparison of Milk Fat from Nine Species (Chen 2026)

683 lipids were identified in milk from nine species. In the triglycerides of donkey milk, polyunsaturated fatty acids accounted for 26.90 mol% (human milk 29.96, cow milk 3.17 mol%).

The study in brief

• Original title: Lipidomics and fatty acid positional distribution in milk from nine mammalian species
• Authors: Chen M., Lu S., Song L. et al.
• Journal: npj Science of Food, 10, 329 (2026)
• Country: China · Study type: Laboratory study

How it was investigated

Mature pooled milk from Holstein cow, buffalo, yak, goat, sheep, camel, mare, and donkey, as well as pooled human milk (18 donors, 3–6 months postpartum) from China, was investigated, with three biological replicates each. The donkey milk came from a cooperative's collection tank; each replicate included milk from approximately 10–20 lactating animals. The lipid molecules were identified using liquid chromatography-tandem mass spectrometry.

Important figures

• 9 – milk types, three pooled replicates each
• 10–20 – donkeys per pooled sample (cooperative tank)
• 683 – lipid molecules identified in 25 subclasses
• 67.5 % – proportion of glycerolipids in the lipid count (461 molecules)
• 157 – differential lipids donkey milk vs. human milk
• 40.05 mol% – even-numbered saturated fatty acids in donkey milk triglycerides (human milk 37.62, cow 69.87)

Results

A total of 683 lipid molecules from five main categories and 25 subclasses were identified; by count, glycerolipids dominated (67.5 %), followed by glycerophospholipids (17.3 %), sphingolipids (6.7 %), free fatty acids (4.5 %) and sterolipids (4.0 %). In all milk types, triglycerides were the most common subclass.

In the principal component analysis, ruminant milks overlapped, while camel, mare, donkey, and human milks formed separate groups; mare and donkey milk were close together. Compared to human milk, donkey milk contained 157 differential lipids, predominantly with a higher relative amount in the animal milk.

In the triglycerides of donkey milk, even-numbered saturated fatty acids accounted for 40.05 mol%, thus close to human milk (37.62 mol%), significantly below Holstein and goat milk (69.87 and 69.63 mol%, respectively). Polyunsaturated fatty acids reached 26.90 mol%, almost entirely linoleic acid (25.67 mol%); α-linolenic acid was 0.83 mol% (mare milk 16.75 mol%).

Limitations of the study

• Three pooled samples per species: Only three pooled samples were available for each milk type, with donkey milk from a cooperative with 10–20 animals per sample. Breed, lactation stage, and feeding are not specified, and it remains unclear which of the three mentioned regions of origin the donkey milk belongs to.
• Abstract deviates from Table 3: According to the abstract, long-, medium-, odd-, and branched-chain fatty acids prefer the sn-2 position. According to Table 3, however, long-chain fatty acids in donkey, human, mare, goat, and camel milk preferentially occupied the outer position (donkey 31.80 % at sn-2, below the chance value of 33.3 %). In addition, palmitic acid was also found at sn-2 more often than expected in cow, buffalo, yak, and goat milk (36.62–48.56 %), although the abstract describes the opposite pattern for ruminants.
• Similarity index described unclearly: The results text speaks of six groups, while the methods section mentions three evaluation groups. For the overall value, ruminants are only given as a range. The index mathematically describes the fat composition and says nothing about tolerance or suitability for infants.
• Relative lipid amounts: Lipidomics is based on relative signal intensities; the fatty acids are given as mol% of the triglycerides, not as content per liter of milk. The raw data is only available upon request.
• Functional interpretations not tested: The authors' statements about fat absorption, calcium availability, or development in infants are based on literature and were not investigated in this study.

Level of evidence: Basic research (laboratory) – describes the properties of milk, no statement about effects in humans.

Our assessment

The study provides comparative measured values for the fat composition and the position of fatty acids in triglycerides for donkey milk and eight other milk types. The similarity index is a purely mathematical comparison of compositions. Statements about effects, the nutrition of infants, or individual commercial products cannot be derived from this.

Source: Chen M., Lu S., Song L., Zhang J., Qi Y., Zhao X., Zheng N., Zhang Y., Wang J. (2026). Lipidomics and fatty acid positional distribution in milk from nine mammalian species. npj Science of Food. DOI: 10.1038/s41538-026-00954-w · Summarized by the DON DONKEY'S editorial team, as of October 2026.

End of the study summary. The study was conducted independently by DON DONKEY'S® and does not refer to our products. Our donkey milk is a food.