Research on donkey milk · Study 73

Probiotics in the feed: what measurably changed in the colostrum and milk of jennies

An Italian team added a probiotic to the feed of ten of twenty Ragusana jennies for 30 days. It then compared the small molecules of the milk and two enzyme activities – and also colostrum with mature milk.

Important: A feeding trial with 20 jennies and milk analysis. Metabolites and enzyme activities in the milk were measured – not any effect of donkey milk in humans.

Trial procedure · runs automatically

45 days on the tear-off calendar

Day of lactation0Foaling

Days 0–2
ColostrumSample within 48 hours of foaling. 20 clinically healthy Ragusana jennies, 5 to 10 years old; around 6 kg hay and 0.5 kg concentrate a day.
Day 15
Milk sample and startRandomly divided into two groups of ten. From now on, one group receives 18 g a day of a probiotic with eight bacterial strains (lactic acid bacteria and bifidobacteria).
Days 16–44
30 days of supplementAccording to Table 1, around 2,400 billion colony-forming units per daily dose in total (sum of the eight strains). The control group’s feed is unchanged.
Day 45
Last milk sampleMilked by hand in the morning between 9 and 10 am. Analysis by ¹H-NMR (metabolites) and two enzyme tests.

We deliberately do not name the probiotic or its manufacturer. The paper does not state whether the investigators knew which animals received it.

Result 1 · tap a tile

Colostrum versus milk: 18 differences

Colostrum
Day 15
p-value

All 20 animals, concentrations in mmol/L (Table 2). Percentages: calculated by us from the means. Of 76 identified metabolites, 18 differed significantly (p < 0.05). Dashed: values we do not consider plausible.

Result 2 · after 30 days of supplement

Twelve molecules that shifted

Milk on day 45, means in mmol/L, logarithmic scale. The arrow starts at the control group value and ends at the probiotic group value. The assignment of columns follows the methods section and text – in Table 3 the group labels are swapped. Set apart below: two further significant values not mentioned in the text.

Result 3 · enzyme tests

The spot plate turns yellow

6 / 10jennies with measurable
alkaline phosphatase

Alkaline phosphatase (ALP) was not detectable in colostrum, in the milk on day 15 or in the control group. In the probiotic group it was above the detection limit in six of ten animals: 0.97 to 11.73 U/mL. The test turns yellow when the enzyme is active. In cow’s milk, ALP serves as a test value for pasteurisation – in donkey milk it is usually absent (see Study 58).

Alkaline sphingomyelinase was higher in colostrum than in the milk on day 15 and, after 30 days of supplement, moderately but significantly higher than in the control group. The paper shows the values only as a graph.

Schematic: one well per animal. Enzyme activities are laboratory measurements, not a statement about an effect.

Critical assessment

Under the table magnifier

Editorial assessment: The authors draw connections to gut health, tumours and infant nutrition. None of this was examined. Donkey milk is not a substitute for breast milk or infant formula. According to the paper, no external funding and no conflicts of interest. Further feeding trials: Study 57 and Study 67.

Research question for DON DONKEY’S®

How strongly does feed shape the small molecules of milk?

The study suggests that sugars, fatty acids and amino acids in milk can shift with feed. How large such effects are with normal feeding – and how we can describe the feeding on our partner farms transparently – is something we want to keep following.

Document feedingColostrum: Study 63Await independent replication

Original publication

Donkey Colostrum and Milk: How Dietary Probiotics Can Affect Metabolomic Profile, Alkaline Sphingomyelinase and Alkaline Phosphatase Activity

Original title of the publication.

Laus F., Laghi L., Bazzano M., Cifone M. G., Cinque B., Yang Y., Marchegiani A.
Metabolites · 2023 · volume 13, issue 5, article 622 · open access
University of Camerino, University of Bologna, University of L’Aquila (Italy)

DOI: 10.3390/metabo13050622

Transparency: according to the paper, no external funding and 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

End of the study summary

Note on our products

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.

From our shop

DON DONKEY’S® donkey milk

100 % donkey milk · raw milk, frozen

On this page we report the findings of a published study. Independently of that, you will find our donkey milk here: 100 % donkey milk, frozen as raw milk.

Transparency: The study examined milk from Ragusana jennies in Italy – not the milk of our partner farms.

€24,90

100 ml bottle / 100ml · Unit price: €249,00 / 1 l · incl. VAT, plus shipping

View all sizes & purchase options →

Also in our shop

Donkey Milk Powder

Donkey milk in powder form

For anyone who prefers a longer shelf life: our donkey milk in powder form – easy to store and portion.

Transparency: The study examined fresh donkey milk, not our donkey milk powder.