Donkey Milk Study: Comparison of Odd-Chain Fatty Acids (Carta 2022)

In eight donkey milk samples, odd- and branched-chain fatty acids accounted for 2.36 g/100 g of fatty acids—less than in ruminants (3.33–4.51) and more than in human milk (1.34). Undecanoic acid (C11:0) reached 0.895 g/100 g.

The Study in Brief

• Original title: Comparison of Milk Odd- and Branched-Chain Fatty Acids among Human, Dairy Species and Artificial Substitutes
• Authors: Carta S., Correddu F., Battacone G. et al.
• Journal: Foods, 11(24), 4118 (2022)
• Country: Italy · Study type: Laboratory study

How the Study Was Conducted

Laboratory comparison of 282 individual samples: 8 donkey milk samples (Sarda breed), 70 cow, 61 buffalo, 69 goat, and 55 sheep milk samples from previous surveys in Sardinia (buffalo from Campania), 11 donated human milk samples, and 8 commercially available infant formulas. All samples were stored at −20 °C. After fat extraction and esterification, the fatty acid methyl esters were determined by gas chromatography with flame ionization detection and reported as g/100 g of total fatty acid methyl esters.

Key Figures

• 282 – individual samples examined from seven types of milk
• 8 – donkey milk samples (Sarda breed, Sardinia)
• 0.39 % – mean fat content of donkey milk (SD 0.207)
• 2.359 g/100 g – total OBCFA in donkey milk (based on fatty acid methyl esters)
• 4.513 g/100 g – total OBCFA in sheep milk (highest value)
• 1.342 g/100 g – total OBCFA in human milk

Results

The fat content in donkey milk was 0.39% and in human milk 1.08%, thus significantly lower than in ruminant milk (cow 3.75%, buffalo 7.58%). All eleven fatty acids examined were detectable in donkey, buffalo, goat, and sheep milk.

The total OBCFA was higher in ruminants than in donkey, human, and infant formula: sheep 4.51, buffalo 3.78, cow 3.38, goat 3.33, donkey 2.36, human milk 1.34, and infant formula 0.18 g/100 g of fatty acid methyl esters.

Linear odd-numbered fatty acids in donkey milk (1.62 g/100 g) were at the same level as in cow, buffalo, and goat milk. Undecanoic acid (C11:0) was higher in donkey milk at 0.895 g/100 g than in all other types of milk; C15:0 (0.374) and C17:0 (0.353) corresponded approximately to the values in human milk.

Limitations of the Study

• Few donkey milk samples: Only eight samples of one breed from an existing sample collection were available for donkey milk; the stage of lactation, feeding, and management are not described. The milk types come from different surveys and regions, so differences do not necessarily stem solely from the animal species.
• Discrepancies between text and table: The discussion states 40% C11:0 and 6.5% anteiso-C13:0 for OBCFA in donkey milk; according to Table 2, it is 37.9% C11:0, and the 6.5% refers to anteiso-C13:0 (iso-C13:0: 1.1%). According to the abstract, iso-C17:0 is the most common iso-fatty acid except in donkey and buffalo, but according to Table 1, iso-C15:0 is higher in infant formula.
• Contradictions in the evaluation: In the results, sheep and buffalo milk have positive values on the first principal component, while the discussion lists sheep and goat as the first group. The table footnote states p < 0.001 as the significance threshold, while the methods section states p < 0.05.
• Relative data: All values refer to the fatty acid content, not the milk volume. At 0.39% fat in donkey milk, the proportions correspond to very small absolute amounts; human milk was obtained as only a single sample, and its fat content was below literature values.
• Interpretations not verified: The introduction and conclusion refer to literature on the health effects of these fatty acids; only the composition was examined. The marker proposal C11:0/anteiso-C13:0 is based on eight samples; an earlier study on Chinese donkeys found C15:0 and C17:0 to be the most common OBCFA.

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

Our Assessment

The study describes the fatty acid pattern of a small number of donkey milk samples in a species comparison. Statements about health effects, suitability for specific groups of people, or individual commercial products cannot be derived from it.

Source: Carta S., Correddu F., Battacone G., Pulina G., Nudda A. (2022). Comparison of Milk Odd- and Branched-Chain Fatty Acids among Human, Dairy Species and Artificial Substitutes. Foods. DOI: 10.3390/foods11244118 · 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.