Research on donkey milk · Study 41

Breast milk in the digestion simulator

In 2024, Giribaldi et al. simulated in the laboratory how a preterm infant digests fortified breast milk. The question: does it change which protein fragments – so-called peptides – are formed when the fortifier comes from donkey milk instead of cow's milk?

Important: A purely laboratory experiment with an experimental clinical human milk fortifier – not a study in children and not donkey milk for drinking. Donkey milk is not a substitute for breast milk or infant formula.

View data Study results

Publication

Giribaldi et al.
2024 · Food Chemistry

Study type

Laboratory experiment
(in vitro digestion)

Model

Preterm infant,
4 weeks old

Peptides

over 2,200
identified

What it's about

What protein becomes during digestion

Very small preterm infants often receive breast milk with a fortifier – an additive that supplies extra protein and nutrients. Fortifiers made from cow's milk whey, whose protein is already pre-digested, are standard. In the Italian FortiLat series (studies 12 to 15 and 40), a donkey-milk-based fortifier with intact proteins was tested.

This work looks one level deeper: during digestion, protein breaks down into peptides. The scientific literature attributes certain properties to some of these fragments. The researchers wanted to know whether the peptide pattern changes depending on the fortifier.

What exactly was studied?

Basispooled preterm breast milk from 5 donors

ComparisonDonkey milk fortifier vs. cow's milk fortifier

Modeldynamic digestion (DIDGI®), 3 runs

AnalysisMass spectrometry (LC-MS/MS)

ResultPeptides from breast milk largely the same

Limitationlaboratory only, no measurement in the infant

Briefly explained

The terms used in this study

Clinical productFortifier

An additive that enriches breast milk for very small preterm infants with protein and nutrients.

Building blockPeptide

A short protein fragment formed during digestion – here 6 to 50 amino acids long.

MethodPeptidomics

Capturing as many of the peptides in a sample as possible at once – by mass spectrometry.

ModelIn vitro digestion

A device simulates the stomach and intestine with enzymes and acid – without an infant or animal.

Step 01Mixing

Breast milk was fortified with each fortifier to the same protein and energy content.

Step 02Digesting

The model simulated the stomach and small intestine of a four-week-old preterm infant.

Step 03Sampling

Samples were taken at seven time points – three in the stomach, four in the intestine.

Step 04Analysing

Each peptide was identified, assigned to its protein of origin and compared with databases.

Interactive · The data at a glance

2,214 fragments, few differences

How was the experiment run, where do the peptides come from, when do they appear – and what does the database comparison show? Switch between the views.

1Breast milkpooled from 5 donors, pasteurised (Turin milk bank)

2Two fortifiersDonkey milk with intact proteins · cow's milk whey, pre-digested

3Equally fortified+1 g protein and 18 kcal per 100 ml

4Simulated digestionPreterm infant, 4 weeks old · 3 runs each

Figures from the original publication, rounded. A deviation of more than ±10 % at p < 0.05 was considered a difference.

Key findings

What the researchers report

Overall result

Breast milk peptides hardly changed

1,254 peptides from breast milk

The amount and type of peptides from the breast milk were very similar with both fortifiers. Only around one in ten shared peptides differed in frequency – mainly in the simulated intestine.

Individual proteins

Lactoferrin fragments remained longer

lactoferrin · α-lactalbumin

With the donkey milk fortifier, fragments of the breast milk protein lactoferrin were more often detectable until the end of the intestinal phase. Certain α-lactalbumin peptides, on the other hand, appeared somewhat later than with the cow's milk fortifier.

Donkey milk peptides

914 additional fragments

5 matches in the database comparison

914 peptides of its own came from the donkey milk fortifier. Five of them match sequences to which the literature attributes antioxidant or ACE-inhibiting properties – this was not tested here.

The authors see the donkey milk fortifier as a possible alternative to the cow's milk fortifier and formulate this as a hypothesis for the clinical nutrition of preterm infants. One co-author is a co-inventor of a patent on the donkey milk fortifier studied; the other authors declare no conflicts of interest.

Critical assessment

Basic research in the test tube

What the study shows

✓

In the digestion model, almost the same peptides were formed from breast milk with both fortifiers.

✓

Small differences mainly concerned lactoferrin and α-lactalbumin in the simulated intestine.

✓

The donkey milk fortifier supplied a large number of peptides of its own because its proteins were still intact.

What it does not show

No effect in the body – digestion took place only in the device, nothing was measured in infants.

No proven bioactivity – the properties of the peptides come from databases, not from the study's own tests.

No statement on drinking donkey milk – a clinical fortifier was studied; only one pooled breast milk sample.

Research question for DON DONKEY’S®

What happens to donkey milk protein during digestion?

The study shows how precisely it is possible to track which protein fragments are formed during digestion. For us, a prompt to learn more about the protein structure of our milk – without any promise of effects.

01 · LITERATURECollect digestion studies on donkey milk comprehensively.

02 · ANALYSISHave the protein profile of our raw milk documented.

03 · COMPARISONCompare fresh milk and powder.

04 · EXCHANGEGet in touch with food research in Turin.

Original publication

Peptidomic profile of human milk as influenced by fortification with different protein sources: An in vitro dynamic digestion simulation

Giribaldi M., Nebbia S., Briard-Bion V., Jardin J., Ménard O., Dupont D., Coscia A., Cresi F., Lamberti C., Cavallarin L., Deglaire A.
Food Chemistry · online 2024 · volume 462 (2025), article 140886

DOI: 10.1016/j.foodchem.2024.140886
Full text: CNR (IRIS), open access

A laboratory experiment with an experimental specialty product for preterm infants – no product-related statement for DON DONKEY’S®.

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 infant food or a substitute for breast milk, 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 by Giribaldi et al. examined an experimental human milk fortifier in the laboratory, not DON DONKEY’S® donkey milk. Our donkey milk is a food and not infant food.

€24,90

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

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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 an experimental human milk fortifier, not our donkey milk powder. Our donkey milk powder is a food and not infant food.