Donkey Milk Study: Fat and Fatty Acids over 210 Days (Martemucci 2012)

In nine Martina Franca donkeys, the milk fat content decreased from 0.72% (day 15) to 0.42% (day 210), and the energy value from 1857.3 to 1645.6 kJ/kg. The proportion of saturated fatty acids fell from 62.88% to 41.54% by day 180.

The study in brief

• Original title: Fat content, energy value and fatty acid profile of donkey milk during lactation and implications for human nutrition
• Authors: Martemucci G., D’Alessandro A.G.
• Journal: Lipids in Health and Disease, 11, 113 (2012)
• Country: Italy · Study type: Laboratory study

How the study was conducted

Nine healthy, multiparous Martina Franca donkeys (6–12 years, 320 ± 30 kg) with similar foaling dates (± 7 days) were kept semi-extensively in the southeastern Murgia region (Apulia, Italy): 7–10 hours of grazing on natural scrub vegetation daily, plus 2.0–2.5 kg of oats per animal per day. The foals remained with the donkeys and were separated 3 hours before milking; they were milked twice daily by machine. Individual milk samples (morning and evening milk pooled) were taken on days 15, 30, 45, 60, 90, 120, 150, 180 and 210 after birth.

Key figures

• 9 – multiparous Martina Franca donkeys, sampled over 210 days of lactation
• 0.72% – milk fat on day 15; day 210: 0.42%
• 1857.3 kJ/kg – gross energy on day 15; day 210: 1645.6 kJ/kg
• 1748.5 kJ/kg – average energy value according to the results section (Abstract: 1719.2 kJ/kg)
• 51.98% – saturated fatty acids on average during lactation
• 62.88 → 41.54% – saturated fatty acids from day 15 to day 180 according to the text

Results

The milk fat content averaged 0.54% and was highest on day 15 (0.72%) and day 30 (0.71%); it gradually decreased to 0.42% on day 210, becoming significant only compared to this final time point. The calculated gross energy value followed the fat and decreased from 1857.3 to 1645.6 kJ/kg; the authors estimate the decrease at 10%.

On average during lactation, the milk fat consisted of 51.98% saturated, 28.00% monounsaturated, and 20.02% polyunsaturated fatty acids. The most common individual fatty acids were oleic acid, palmitic acid, and linoleic acid; caprylic, lauric, myristic, and capric acids were each in the range of several percent, stearic acid below 2%.

According to the text, the proportion of saturated fatty acids fell from 62.88% on day 15 to 41.54% on day 180. Lauric acid (−59%) and myristic acid (−54.5%) decreased the most, capric acid fell from 13.46% (day 30) to 5.82% (day 180). Monounsaturated fatty acids increased from 23.58% to 34.40% on day 180, driven mainly by oleic acid (17.55 to 27.57%).

Limitations of the study

• Small group, one management system: Nine donkeys of one breed were studied under pasture management in one region. Feed and pasture availability changed throughout the year, so the lactation stage and feeding cannot be separated.
• The averages in the text differ from Table 4: After editorial recalculation, Table 4 gives an average of 12.39% for linoleic acid, while the text states 18.38% – more than the highest individual value in the table (17.20%) and not compatible with 20.02% total PUFA. The text averages for caprylic, capric, lauric, and myristic acids are also around 10–15% above the table averages.
• Inconsistent energy and fat data: The Abstract states 1719.2 kJ/kg, the results section 1748.5 kJ/kg as the average energy value; according to Table 1, the decrease is around 11% instead of 10%. The average fat content is stated as 0.54%, while the average of the table values is 0.57%. For day 45, a fat value is missing, and the protein and lactose contents, which were included in the energy calculation, are not reported.
• Minor discrepancies: For day 180, the text states 41.54% saturated fatty acids, while the sum from Table 4 is 40.56%. The ratio of unsaturated to saturated fatty acids is partly given in percentages, and the stated geographic longitude of the location (60° East) does not match Apulia.
• Far-reaching interpretations by the authors: The discussion derives statements about nutrition and health in children and adults from the fatty acid pattern and literature. These were not investigated in the study; only milk analyses were collected.

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

Our assessment

The study provides measured values for the fat, energy, and fatty acid pattern of raw milk from a southern Italian donkey breed under pasture management. Health effects in humans were not investigated and cannot be derived from this data.

Source: Martemucci G., D’Alessandro A.G. (2012). Fat content, energy value and fatty acid profile of donkey milk during lactation and implications for human nutrition. Lipids in Health and Disease. DOI: 10.1186/1476-511X-11-113 · 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.