Donkey milk
Donkey milk is the milk from the domesticated donkey. It has been used since antiquity for cosmetic purposes as well as infant nutrition.
History
Donkey milk has been used by humans for alimentary and cosmetic purposes since Egyptian antiquity. Doctors recommended it to treat several afflictions because of its supposed healing and cosmetic virtues.Hippocrates was the first to write of the medicinal use of donkey milk and prescribed it for numerous conditions, including poisoning, fevers, infectious diseases, edema, wounds, nose bleeds, and liver trouble. In the Roman era, donkey milk was a recognized remedy; Pliny the Elder in his encyclopedic work, Naturalis Historia, wrote extensively about its health benefits, i.e. to fight fever, fatigue, eye strain, weakened teeth, face wrinkles, poisonings, ulcerations, asthma, and certain gynecological troubles. However, it was not until the Renaissance that the first real scientific consideration was given to donkey milk. Georges-Louis Leclerc the Comte de Buffon mentions the benefits of donkey milk in his Histoire naturelle and Pauline Bonaparte, Napoleon's sister, is reported to have used donkey milk for skin care. In France in the nineteenth century, Dr. Parrot of the Hospital des Enfants Assistés spread the practice of bringing motherless babies directly to the donkey's nipple. Donkey's milk was sold until the twentieth century to feed orphaned infants and to cure delicate children, the sick, and the elderly. For this reason, there were many donkey farms in Italy, Belgium, Germany, and Switzerland. In the twenty-first century, donkey milk is largely used in the manufacture of soaps and moisturizers, but evidence shows it has possible medical uses to treat infants and children with cow's milk protein allergy as a natural "formula" for infants.
Production
The donkey is considered a seasonal polyestrous animal. However, the latitudinal location of the farm can greatly impact the reproduction cycle. The female is normally pregnant for about 12 months.Donkey milk production differs greatly from that of conventional dairy species, especially in terms of milk supply, which is much more limited. The equid mammary gland has a low capacity and a part of the milk production should be left to the foal. Milking may be carried out two or three hours after separation from the foal. Donkeys should be milked three times a day from 20 to 90 days after foaling. A female produces between 0.5 and 1.3 litres of milk a day for about 6–7 months. The variability of donkey milk production is due to many factors, such as individual milkability, nutrition, genetics and management of reproduction, in addition to milking management.
Generally, a donkey farm for milk production is small, and has rarely more than ten heads or so. The largest donkey farm in Europe is found in northern Italy. The Montebaducco donkey farm in Quattro Castella, a comune in Emilia Romagna, Italy, has 800 donkey heads.
Composition
Gross composition
Published data on donkey milk's gross composition confirm the close resemblance to breast milk for lactose, protein, and ash levels when compared with cow, sheep and goat milk. Despite the high lactose content of donkey milk, the average fat content is lower. When used in infant nutrition, donkey milk is usually supplemented with vegetable oil to conform to human milk energy.| Composition | Donkey | Mare | Human | Cow |
| pH | 7.0–7.2 | 7.18 | 7.0–7.5 | 6.6–6.8 |
| Protein g/100g | 1.5–1.8 | 1.5–2.8 | 0.9–1.7 | 3.1–3.8 |
| Fat g/100g | 0.3–1.8 | 0.5–2.0 | 3.5–4.0 | 3.5–3.9 |
| Lactose g/100g | 5.8–7.4 | 5.8–7.0 | 6.3–7.0 | 4.4–4.9 |
| Total Solids g/100 g | 8.8–11.7 | 9.3–11.6 | 11.7–12.9 | 12.5–13.0 |
| Casein Nitrogen g/100 g | 0.64–1.03 | 0.94–1.2 | 0.32–0.42 | 2.46–2.80 |
| Whey protein g/100 g | 0.49–0.80 | 0.74–0.91 | 0.68–0.83 | 0.55–0.70 |
| NPN g/100 g | 0.18–0.41 | 0.17–0.35 | 0.26–0.32 | 0.1–0.19 |
| Casein Nitrogen % | 47.28 | 50 | 26.06 | 77.23 |
| Whey protein % | 36.96 | 38.79 | 53.52 | 17.54 |
| NPN % | 15.76 | 11.21 | 20.42 | 5.23 |
The casein to whey protein ratio in donkey milk was lower compared to the value in cow milk.
Non-protein nitrogen accounts for an average of 16% of total nitrogen in donkey milk, which is close to values reported for human milk but higher than those of domestic ruminants.
The amino acid profile of the donkey milk proteins shows a very similar percentage of essential amino acids than in human milk proteins.
Functional and bioactive components
Among the functional proteins detected in donkey milk, there are molecules active in antimicrobial protection such as lysozyme and lactoferrin. The lactoferrin content of donkey milk is intermediate between the lower values of cow milk and the higher values of human milk. Lactoferrin inhibits the growth of iron-dependent bacteria in the gastrointestinal tract. This inhibits certain organisms, such as coliforms and yeast, that require iron. Lysozyme in donkey milk is present in large amounts, and ranges from 1.0 mg/mL to 4 mg/mL, depending on the analytical method used ; This substance is present also in humans but only in trace amounts in cow and goat milk. Lysozyme in donkey milk is highly thermo-stable and is very resistant to acid and protease and may play a significant role in the intestinal immune response.In donkey mammary secretion, defatted or not, growth factors and hormones have also been determined. Donkey mammary secretions contain human-like leptin at levels close to human milk. The bioactive peptides insulin-like growth factor 1, ghrelin, and triiodothyronine were also found in frozen donkey milk. These molecules and many others present in human milk, are increasingly receiving attention from a nutraceutical point of view because of their potential direct role in regulating food intake, metabolism, and infant body condition.
Nutritional use
Natural hypoallergenic milk for infants with cows' milk protein allergy
Pasteurized donkey milk is used as a natural hypoallergenic milk because it is tolerated by about 90% of infants with food allergies, e.g., cows' milk protein allergy, a common food allergy in childhood with a prevalence of approximately 3% during the first 3 years of life. However, an infant's tolerance to donkey milk must be evaluated under medical supervision, and after carrying out specific allergy tests. Natural hypoallergenic formula is preferred over those of soy or produced from protein hydrolysates because it has a pleasant taste and may not cause allergies in people who also have allergic reactions to soy proteins or protein hydrolysates.Natural "infant formula"
Donkey's milk is similar to human milk for its lactose, proteins, minerals, and amino-acid content.In terms of energy, donkey milk has a high lactose content but a low average fat content. To use it in infant nutrition before weaning, donkey milk should be fortified with a source of fat ; particular attention must also be given to essential fatty acids. Omega‐3 and omega‐6 fatty acids, particularly docosahexaenoic acid, are known to play an essential role in the development of the brain and retina. Intakes in pregnancy and early life affect growth and cognitive performance later in childhood, ensuring adequate intakes of fat, essential fatty acids, and DHA through these life stages is crucial. Cost-effective dietary sources of these fatty acids are needed to ensure adequate essential fatty acid and DHA intakes in these populations. The integration of these substances can take place with supplements of essential fatty acids and vegetable oil certified for babies. It is important to exclude spores that can pass the gastric mucosa in the first 4 months. For children who are not allergic to cow or goat milk, a part of the fat can be compensated naturally by adding 1–2% of cow or goat butter. In any case, the integration of fats and essential fats can be done through the integration of donkey milk with artificial formulas for infants.
From the point of view of hygienic-sanitary safety, like all milk, donkey milk and its ingredients must be pasteurized before taking. The process of pasteurizing donkey milk deactivates bacterial and viral contaminants.
Donkey milk contains immune-enhancing compounds to help protect infants from disease. In addition, the flavour and appearance of donkey milk are attractive to children.
Diet supplement
Donkey's milk is recommended for countering stomach acid, promoting the growth of intestinal flora, calming coughs and pertussis, and for use in the treatment of immune-mediated disorders.Commercial forms
Raw donkey milk
After collection, donkey milk is cooled to refrigeration temperature. According to European legislation, like all milk of animal origin, it must be pasteurized before being used, i.e. it must be heated up to about 90 °C for at least 2 minutes.Raw milk can be kept for 3 days at refrigerator temperature starting from the day of milking. To prolong conservation, raw milk can be frozen for up to 2–3 months. In any case, it must be thawed in the refrigerator and pasteurized before use.