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Research on donkey milk · Study 50
What lives in raw donkey milk? An inventory
A team from the Cyprus University of Technology monitored the raw milk of a donkey farm microbiologically over eight months and identified the bacteria of eleven jennies by genetic analysis. The result is a profile of the bacteria in the milk of this farm.
What it's about
Two views of the same milk
Classic milk checks grow bacteria on culture media and count the colonies. But this only finds what grows well in the laboratory. Genetic sequencing, on the other hand, reads a piece of bacterial DNA from the sample and thus also shows bacteria that cannot be cultured.
The Cypriot team combined both: regular culture checks over eight months and sequencing of the milk of individual jennies. Fat, protein and dry matter were also determined.
What exactly was studied?
Briefly explained
Tools of microbiology
A gene section that all bacteria carry. Its variations reveal which genus it is.
All bacteria that grow on a standard culture medium – given as log CFU per millilitre.
A large phylum of mostly gram-negative bacteria that includes many environmental bacteria.
A measure of diversity: the higher it is, the more different bacteria in balanced proportions.
One sample per week from the herd's daily milk, for eight months.
Total bacterial count and a targeted search for E. coli, Listeria, Bacillus cereus and others.
Milk from 11 jennies: bacterial DNA read and assigned to genera.
Proportions of genera, diversity and differences between the jennies.
Interactive · The data at a glance
A profile of the milk bacteria
How the samples were collected, what the bacterial count showed, which genera dominated, how few lactic acid bacteria were among them – and how diverse the samples were. Switch between the views.
0 %25 %50 %
Proteobacteria such as Sphingomonas and Pseudomonas made up the majority. Lactic acid bacteria averaged only 2.42 %.
The authors suspect the high lysozyme content of donkey milk, which tends to affect gram-positive bacteria, as one possible reason. They did not measure this.
Values from the freely available version of the study (arXiv preprint). The journal version appeared in the Journal of Dairy Science.
Key findings
What the researchers report
Low bacterial counts on this farm
avg. 3.80 log CFU/mLOver eight months, bacterial counts remained low. E. coli, Listeria monocytogenes and Bacillus cereus were not detected in any of the 33 samples.
Environmental bacteria shape the picture
Sphingomonas up to 47 %Proteobacteria such as Sphingomonas, Mesorhizobium and Pseudomonas accounted for the largest share. In two jennies, Acinetobacter was conspicuously frequent.
Only a small proportion
1–4 % · Ø 2,42 %Lactobacillus and Streptococcus were present, but rare. The authors see this as confirming that donkey milk contains mainly gram-negative bacteria.
According to the authors, it remains open where the bacteria come from – the environment, skin, udder or the animal itself. They recommend further studies with more samples.
Critical assessment
A profile, not a seal of quality
What the study shows
What it does not show
Research question for DON DONKEY’S®
What is the microbial profile of our raw milk?
This study shows how the bacterial pattern of donkey milk can be recorded precisely. For us, it is a model of transparency: regular laboratory testing documents the microbiological quality of raw milk.
Original publication
Investigation of donkey milk bacterial diversity by 16S rDNA high-throughput sequencing on a Cyprus donkey farm
Papademas P., Kamilari E., Aspri M., Anagnostopoulos D. A., Mousikos P., Kamilaris A., Tsaltas D.
Journal of Dairy Science · online 2020 · volume 104, pp. 167–178
A microbiological examination of a farm in Cyprus – no product-related statement for DON DONKEY’S®.
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.
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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.
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Donkey milk in powder form
For anyone who prefers a longer shelf life: our donkey milk in powder form – easy to store and portion.
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