What animal's milk is closest to human milk?

November 15, 2025 •

4 min read

According to several studies, donkey milk is consistently cited as the animal milk most similar in composition to human breast milk. While no animal milk is a perfect substitute, donkey milk shares key nutritional and structural characteristics that set it apart from more common alternatives like cow's or goat's milk.

Quick Summary

Donkey milk is widely recognized as the animal milk most similar to human milk due to its balanced lactose-to-protein ratio and lower fat content. This makes it more digestible and potentially suitable for some with cow's milk protein allergies, though it requires specific fortification for infants.

Key Points

Donkey milk is the closest: Due to its macronutrient profile, donkey milk is consistently cited as the most similar animal milk to human breast milk.
High in Lactose, Low in Fat: Like human milk, donkey milk contains high levels of lactose and low levels of fat, though it requires fortification for infant nutrition.
Favorable Protein Profile: Donkey milk features a whey-dominant protein structure, similar to human milk, which is easier to digest than the casein-heavy protein in cow's milk.
Rich in Protective Components: It contains high levels of beneficial proteins like lysozyme and lactoferrin, offering antimicrobial and immunomodulatory benefits.
An Alternative for Allergies: Due to its high tolerance, donkey milk is sometimes used as a substitute for infants with cow's milk protein allergies, but only under medical guidance.
Mare's Milk is also comparable: As another equine milk, mare's milk shares similar characteristics like high lactose and low fat but has a different protein profile and higher mineral content.
Goat's Milk is easier to digest than cow's: The smaller fat globules and A2 casein in goat's milk make it more digestible than cow's milk, but its overall composition is less similar to human milk than donkey milk.

Understanding the Composition of Human Milk

Human breast milk is the nutritional gold standard for infants, uniquely tailored to support their growth, development, and immune system. Its composition is characterized by a high lactose and whey protein content, a moderate fat level, and a low casein content, resulting in a soft, easily digestible curd. This unique profile is the benchmark against which other milks are compared.

The Primary Contender: Donkey Milk

Research has shown that donkey milk most closely mirrors the nutritional profile of human milk, earning it the top spot among animal milk alternatives. Its resemblance lies in several key areas, from macronutrient ratios to specific protective proteins.

Key Compositional Similarities

High Lactose Content: Donkey milk contains a lactose level very similar to human milk, averaging around 6-7%. In comparison, ruminant milks like cow's milk have much lower lactose, making donkey milk sweeter and potentially better tolerated by some individuals.
Low Fat Content: The fat content in donkey milk is significantly lower than human milk, ranging from 0.3% to 1.8%. This means that for infant feeding, donkey milk would require enrichment to meet caloric needs. However, the structure of its fat globules is small and easily digestible, similar to human milk.
Favorable Whey-to-Casein Ratio: Human milk has a high whey-to-casein ratio (around 60:40), which promotes a soft, digestible curd. Donkey milk also has a whey-rich profile, with a ratio closer to human milk than cow's milk. Cow's milk, conversely, is casein-dominant, creating a dense curd that is harder for infants to digest.
Presence of Bioactive Proteins: Donkey milk contains notable levels of beneficial proteins like alpha-lactalbumin, lysozyme, and lactoferrin. Lysozyme, a powerful antimicrobial enzyme, is present in particularly high concentrations in donkey milk, exceeding even human milk levels, which helps protect against bacteria.

Other Notable Animal Milks

While donkey milk stands out, other animal milks have certain characteristics that make them more comparable to human milk than the ubiquitous cow's milk.

Mare's Milk

Mare's milk, from a horse, is also an equine milk and shares many compositional similarities with donkey milk and human milk. It is characterized by:

Low Fat and High Lactose: Similar to human and donkey milk, mare's milk has a low fat and high lactose content.
High Whey Protein: Its whey protein levels are also comparatively high, contributing to its digestibility.
Lower Casein: Like donkey milk, mare's milk is lower in casein than cow's milk, resulting in a softer curd.

Goat's Milk

Goat's milk is often cited as a closer alternative to human milk than cow's milk for a few reasons:

Easier Digestion: The fat globules in goat's milk are smaller and more naturally homogenized than those in cow's milk, allowing for easier digestion.
A2 Casein: Goat's milk is typically based on A2 casein, which is easier for some people to digest than the A1 protein found in most cow's milk.
Higher Minerals: It is richer in minerals like calcium, but this also means a higher mineral load for an infant's kidneys compared to human milk.

Comparison Table


Component	Human Milk	Donkey Milk	Mare's Milk	Goat's Milk	Cow's Milk
Fat (%)	3.5–4.0	0.3–1.8	0.5–2.0	4.9	3.5–3.9
Protein (%)	0.9–1.7	1.5–1.8	1.5–2.8	3.1	3.1–3.8
Lactose (%)	6.3–7.0	5.8–7.4	5.8–7.0	2.9–3.7	4.4–4.9
Whey/Casein Ratio	60:40	~50:50	~50:50	~20:80	~20:80

*Note: All values are approximate as milk composition can vary by breed, diet, and lactation stage.

Final Thoughts and Considerations for Infant Feeding

While donkey milk is compositionally the closest, it is not an identical match for human breast milk. A baby's mother's milk is always the ideal nourishment, containing a perfectly balanced array of nutrients, immune factors, and growth hormones specific to human development.

For infants with a confirmed cow's milk protein allergy (CMPA) who cannot be breastfed, donkey milk has been investigated as a hypoallergenic alternative. However, its low fat and energy content mean it must be fortified with oils and other nutrients to be suitable for infants. Critically, this should only be undertaken under strict medical supervision and is not a safe choice for newborns without professional guidance.

Conclusion: The Final Verdict

Research consistently identifies donkey milk as the animal's milk closest to human milk, primarily due to its similar levels of lactose, lower casein content, and rich whey protein profile. These characteristics make it a more digestible and hypoallergenic option compared to other commonly available milks. Mare's milk shares many of these traits, while goat's milk offers digestive benefits over cow's milk. Nevertheless, it is crucial to remember that no animal milk is a substitute for human breast milk, and any use for infant feeding must be done with medical oversight and proper nutritional adjustments to ensure a baby's health and safety. For more information on the compositional analysis of donkey milk, consult the International Dairy Journal at(https://www.sciencedirect.com/science/article/pii/S0958694618302267).

Frequently Asked Questions

Donkey milk is considered the closest due to its similar lactose and total protein content, as well as a more favorable whey-to-casein protein ratio that resembles human milk. It also contains valuable protective proteins and has smaller fat globules, aiding digestion.

No, you should not give a newborn baby donkey milk without explicit medical supervision. The World Health Organization and pediatricians do not recommend unfortified animal milk for infants under 12 months. Donkey milk is significantly lower in fat and calories than human milk and would not provide adequate nutrition without supplementation.

Donkey milk has been investigated as a potential hypoallergenic alternative for children with a confirmed cow's milk protein allergy (CMPA). However, this must be managed by a pediatrician, as the milk still requires fortification and monitoring to ensure proper growth and nutrition.

Mare's milk shares many similarities with human milk, including a low fat and high lactose content. It is another equine milk with a whey-rich protein profile, making it more digestible than ruminant milks like cow's or goat's milk.

In some aspects, yes. Goat's milk can be easier to digest than cow's milk because of its smaller fat globules and A2 casein protein composition. However, its overall macronutrient profile (higher protein, higher fat) is less similar to human milk than donkey or mare's milk.

Ruminant milks (cow, goat, sheep) are typically high in casein and fat, designed for rapid growth in their young. Equine milks (donkey, mare) are lower in casein and fat but higher in whey protein and lactose, which is better suited for a slower growth rate and easier digestibility, similar to human milk.

If an infant drinks unfortified donkey milk, they will receive inadequate fat and caloric intake necessary for proper growth and development. Additionally, they may be exposed to infections if the milk is not properly handled.