Mares, or female horses, produce milk that is vital for the survival and growth of their offspring, foals. Mare’s milk provides essential nutrients and immune support during a foal’s early life.
The Biology of Lactation in Mares
Lactation in mares is a complex physiological process regulated by hormones. A mare’s mammary glands are uniquely structured, with each half containing two separate gland complexes that drain into distinct teat cisterns and canals. Each teat typically has two separate openings.
The production of milk, or lactogenesis, is stimulated by the hormone prolactin, which promotes milk synthesis within the mammary glands. The release of milk, known as milk let-down, is triggered by oxytocin. These hormonal responses are largely initiated by the act of foaling and subsequently by the foal’s suckling.
Lactating mares can produce a significant volume of milk daily, ranging from 2% to 4% of their body weight, which translates to approximately 11 to 22 liters for a 545-kilogram mare. Peak milk production typically occurs during the first month of lactation, with a gradual decline thereafter. While mares under human management usually lactate for three to six months, in wild settings, this period can extend for over a year.
The Unique Composition of Mare’s Milk
Mare’s milk has a distinct nutritional profile compared to other mammalian milks, like cow’s milk. It has a high lactose content (7.73% to 7.93%) and relatively lower levels of fat (0.49% to 1.76%) and protein (0.93% to 2.3%). Composed of approximately 89.7% water, mare’s milk has a watery consistency.
Its protein composition is similar to human milk, with a whey-to-casein ratio of about 45% whey and 55% casein, classifying it as an “albumin-type milk.” This contrasts with cow’s milk, which is predominantly casein. Mare’s milk also contains beneficial components like lactoferrin, lysozyme, and immunoglobulins, along with vitamins (C, A, D3, E) and minerals (calcium, phosphorus, potassium, magnesium). It is rich in unsaturated fatty acids, including n-3 polyunsaturated fatty acids.
Vital Role for Foal Development
Mare’s milk is vital for foal growth and development, especially in their first months. The initial milk, colostrum, is a thick, yellowish fluid rich in antibodies, specifically immunoglobulins like IgG, IgM, and IgA. Foals are born without a developed immune system and do not receive antibodies through the placenta. They must ingest colostrum within 12 to 24 hours after birth to absorb these crucial antibodies, which provide passive immunity against diseases.
Beyond immune support, mare’s milk supplies nutrients for a foal’s rapid early growth, including amino acids, protein, energy, vitamins, and minerals. It also ensures hydration and acts as a natural laxative, aiding the foal in passing its first stool. Newborn foals consume 15% to 25% of their body weight in milk daily and may nurse 70 to 80 times per day. As foals mature, around two to three months of age, the milk’s nutrient concentration declines, indicating a need for supplemental feed to meet increasing nutritional demands.
Human Interaction with Mare’s Milk
Mare’s milk has a long history of human consumption, particularly in certain cultures. People in the grasslands of Mongolia consumed horse milk over 3,000 years ago. It remains a traditional staple in Central Asian diets, often fermented to produce beverages like kumis.
In modern times, mare’s milk occupies a niche market. It is sometimes used as a dietary supplement due to its nutritional profile and is recognized for being easier to digest than cow’s milk, attributed to its lower casein and higher whey protein content. Mare’s milk is also gaining recognition in the cosmetics industry, where its moisturizing, regenerating, and anti-aging properties are utilized in skin creams, lotions, and soaps. Some research also suggests potential therapeutic benefits for gastrointestinal issues and certain skin conditions. Despite these varied applications, its availability remains limited compared to other animal milks.