Donkey milk (or ass milk, or jenny milk) is the milk from the domesticated donkey (Equus asinus). 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 (460–370 BC) 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.Hippocrates. The Genuine Work of Hippocrates. Vol. 1. Sydenham Society 1843 In the Roman era, donkey milk was a recognized remedy; Pliny the Elder (23–79 AD) 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.Pliny the Elder. The Natural History. Book XXVIII "Remedies derived from living creatures". John Bostock 1855.
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 (1707–1788) mentions the benefits of donkey milk in his Histoire naturelleLeclerc GL. L’Histoire naturelle, générale et particulière, avec la description du Cabinet du Roy. Tome Cinquième. P. Duménil 1835; 40. and Pauline Bonaparte (1780–1825), 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 (Bulletin de l’Académie de médicine, 1882). 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 (CMPA) 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.Sewell, Sybil E. "Foaling out the Donkey Jennet," Alberta Donkey and Mule.com. Web page accessed March 4, 2008
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 (max 2.5 L) 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.Doreau M (1991) Le lait de jument. INRA Productions Animales 4 :297–302. Donkeys should be milked three times a day from 20 to 90 days after foaling.Doreau M, Martin-Rosset W (2011) Animals that produce dairy foods – horse. In Encyclopaedia of dairy sciences (2nd ed.), Fuquay JW, Fox PF & McSweeney PLH, eds., San Diego, CA, USA: Academic Press, volume 1, pp. 358–364. 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 (4 mL per 100 mL of milk) to conform to human milk energy.
+ Composition of donkey's, mare's, human and cow's milk (g/100 g) 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 (TS) g/100 g 8.8–11.7 9.3–11.6 11.7–12.9 12.5–13.0 Casein Nitrogen (CN) 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 (CN) % 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 (NPN) accounts for an average of 16% of total nitrogen in donkey milk, which is close to values reported for human milk (20%) but higher than those of domestic ruminants (5%).
The amino acid profile of the donkey milk proteins shows a very similar percentage of essential amino acids (36.7 to 38.2 g amino acid /100 g protein) than in human milk proteins (40.7 g amino acid /100 g protein).
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 (chemical or microbiological); This substance is present also in humans (0.12 mg/mL) 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 (3.35 e 5.32 ng/mL 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 (CMPA), 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 (sunflower oil); particular attention must also be given to essential fatty acids. Omega‐3 and omega‐6 fatty acids, particularly docosahexaenoic acid (DHA), 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 (omega-3; omega-6) 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 (in particular lysozyme and lactoferrin) 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 (a.k.a. whooping cough), and for use in the treatment of immune-mediated disorders.
Commercial forms
Raw donkey milk After collection, donkey milk is cooled to refrigeration temperature.
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.
EU regulations dictate that it must be pasteurized before being used, i.e. it must be heated up to about 90 °C for at least 2 minutes.
Pasteurized donkey milk Donkey milk is pasteurized in a closed circuit of pasteurization and bottling (aseptic) at least 72 °C for 15 seconds or equivalent times and temperatures. In the case of pasteurization in discontinuous systems, the temperature must be higher depending on the method used and the type of plant and destination.
Freeze drying (lyophilized) Donkey milk can be freeze-dried to preserve the biological quality of the milk, and so preserve its nutritional, functional, and cosmetic properties. This is possible because in freeze drying the milk is frozen and brought under vacuum at low temperatures. During this process, the water is removed by sublimation. The result is approximately ten percent of dry matter that is called lyophilized (or freeze-dried) donkey milk. This powder is easy to reconstitute. The lyophilized product has to be packaged without any oxygen. It has a shelf life of two years. Normally it is produced from pasteurized donkey milk so it is ready to use.
Analysis of freeze-dried donkey's milk has demonstrated that the natural colour, flavours, nutrients, and bioactive substances of fresh donkey milk are retained. Spray-drying is another way to dry products, in which the milk is heated and vitamins and other important bioactive substances may get lost. In contrast, Freeze-drying does not require chemical preservatives and can be either consumed directly or re-hydrated easily. However, this method for is costly, and is practiced only by a few companies.
This product is easy to find in Italy, where it was for the first time put on the market.
Cosmetic use
Cosmetics with donkey milk