Equid Milk: Chemistry, Biochemistry and Processing

The characteristics of equid milk of interest in human nutrition include a high concentration of polyunsaturated fatty acids, a low cholesterol content, high lactose and low protein levels, as well as high levels of vitamins A, B and C. Compared to bovine milk, the protein fraction of equid milk contains proportionally less casein and more whey proteins. The low fat and unique fatty acid profile of both equine and asinine milk result in low atherogenic and thrombogenic indices. The high lactose content of equid milk gives good palatability and improves the intestinal absorption of calcium that is important for bone mineralisation in children. The renal load of equid milk, based on levels of protein and inorganic substances, is equal to that of human milk, a further indication of its suitability as an infant food. The concentration of lysozyme, lactoferrin and n-3 fatty acids is exceptionally high in equid milk, suggesting a potential anti-inflammatory effect. Equine and asinine milk can be used for their prebiotic and probiotic activity and as alternatives for infants and children with cow milk protein allergy and other food intolerances. While the gross composition of equine and asinine milk has been reasonably well established and the caseins have been fractionated and well characterised, the presence of κ-casein remains a contentious issue and there is little or no information on the physicochemical properties of equid milk. The only significant product from equine milk is the fermented product, koumiss. The composition of equid milk suggests a product with interesting nutritional characteristics with potential use in dietetics and therapeutics, especially in diets for the elderly, convalescent and newborns, but the lack of scientific research must be addressed to develop the potential of equine and asinine milk in the health and nutritional markets.