Milk Properties and Morphological Characteristics of the Donkey Mammary Gland for Development of an Adopted Milking Machine—A Review

Donkey milk (DM) has been known in the world for 5000 years for its benefits for human nutrition and health. Nowadays, DM has become more and more attractive as a commercial product. DM contains several physiologically functional components, including high-quality whey proteins, vitamins, important minerals, unsaturated fatty acid and bioactive components. Therefore, it is not only consumed as food but also as a remedy. The average daily milk yield of a female donkey over the entire lactation season was 1.57 ± 1.12 kg/day and fluctuated between 0.20 and 6.00 kg/day. Average milk concentrations (±SD) of fat, protein, lactose, total solids and ash in DM were 0.63 ± 0.41%, 1.71 ± 0.24%, 6.34 ± 0.37%, 9.11 ± 0.95% and 0.39 ± 0.04%, respectively. Interestingly, DM is similar in composition to mare’s milk, and both are similar to mother’s milk. The anatomical and morphological properties of the mammary gland of the female donkey are special and can be compared with those of mare udders. However, the cistern cavity of the mammary gland of female donkeys is characterized by the presence of multiple pockets that open directly into the teat, instead of a single cistern cavity. Therefore, the mammary gland capacity in donkey mare is low and milking technique and routine are of most importance. So far there is no special milking machine for female donkeys and mares. The milking machines used nowadays were initially designed for smaller sheep and goat udders. The company Siliconform, Germany, has set itself the task of developing an optimized milking machine for donkey mares, which is adapted to the anatomical and morphological properties of the donkey mammary gland. Furthermore, it should achieve a physiologically ideal milking process meeting high animal welfare standards for increased milk production with high quality standards.