The Pan-European Strategy on Biological and Landscape Diversity has encouraged the institution of new protected areas of regional and of national parks aimed to safeguard the extensive agriculture and the sustainable rearing of autochthonous breeds in order to reduce the abandon of rural areas. These areas, which include parks, reserves and marginal areas, have an economy mainly based on agriculture, livestock production and forestry.
Among these activities, livestock production in general and the raising of autochthonous livestock breeds in particular contributed significantly to create traditional agricultural landscapes supporting a greater variety of plants and wild animals. Therefore, to maintain and valorise this biodiversity, it is fundamental to preserve and/or reintroduce autochthonous breeds into these areas. This, in turn, may have positive implications for protecting and conserving the natural heritage of these areas.
In this context, the pastoral activity and semi-extensive farming of donkey, if properly managed, may exert a positive influence on biodiversity. Donkeys are grazers as well as browsers, their teeth and lips allow them to graze close to the ground; thus, they can efficiently graze short vegetation. These animals are non-selective grazers, preferring thistles, rushes and other coarse vegetation to more palatable grasses. Thus, donkeys are capable of controlling some invasive plant species and those with less appetite (Cosentino et al., 2012). In recent years, there has been a renewed interest towards the products (milk and meat) and social practices (rural tourism, onotherapy, etc.) that this species can offer, although donkey’s breeding is still poorly widespread.
Concerning milk production, it is well known that donkeys provide milk that shows the closest similarity to human milk (Polidori et al., 2009). Thanks to its nutritional characteristics, donkey milk has several applications: in paediatric sphere, in patients affected by cow’s milk protein allergy and intolerance, as best alternative to human milk in infant food and in geriatric field for the treatment of ageing diseases; Polidori et al., 2015). According to the literature, this milk has low levels of casein allergens and high levels of lactose, of unsaturated fatty acids (linoleic and linolenic) and of lysozyme. This enzyme is practically absent in other species, such as cow, goat, sheep, human (Vincenzetti et al., 2008) and has important physiological functions like inhibition of certain microorganism growth, anti-inflammatory and antitumor activity and increase of defence system in early childhood.
Another promising valorisation strategy of donkey milk is the use of this product in cosmetic preparations. Nowadays, the cosmetic trade is mainly focused towards products made with natural ingredients, and it is oriented to a sustainable consumption without preservatives addition. This has led many companies to increase the use of natural ingredients in existing preparations or to create new products (Cosentino et al., 2015). Because of their natural origin, milk components correspond in many fields to the needs of cosmetology.
In cosmetic preparations, donkey milk is often used as basic constituent. Minerals, vitamins, fatty acids, bioactive enzyme and coenzyme, lactose and whey proteins contained in donkey milk prevent skin-ageing process, thanks to the hydrating and restructuring action of the dermal intercellular substance. It is known that these properties are principally due to the high lysozyme and to the antioxidant action of fatty acids contained in donkey milk.
FEEDING LACTATING DONKEY
For most of the year donkeys are fed on crop residues and mature bush grasses of poor nutrient quality, each being low in N and with high fibre content (Pearson et al., 2001). In order to determine the quantity of nutrients donkeys can obtain from both poor- and good-quality forages, it is important to know how much they consume and how well they digest these feeds when given them either ad libitum or when they receive a restricted ration.
Comparative studies (Pearson & Merritt, 1991) of the voluntary food intakes of donkeys and ponies fed moderate- or poor-quality roughage diets (meadow hay and barley straw respectively) have shown that donkeys tend to consume less DM/d. As a result, they have a slower rate of passage of digesta through the gastrointestinal tract and, as a consequence, have a higher apparent digestibility of both organic matter and fibre fractions than has been measured in ponies.
The better apparent digestibility of nutrients by donkeys on forage diets compared with that of ponies enables them to compensate fairly successfully for their lower intakes of feed (Pearson et al., 2001). The donkey appears more “ruminant-like,” with longer retention times of feed in the tract, lower intakes and better apparent digestibility of nutrients. In situations where the forage supply is limited, the donkey would exploit the nutrients available more effectively than the pony could.
Donkeys may require dietary supplementation with hay or haylage during the winter or when pregnant, lactating or growing in order to supply extra energy. Hay or haylage for donkeys must be selected carefully as forage made for horses or other livestock is often too rich and may lead to dietary upset or laminitis. Hay or haylage should be late cut, high in fibre, low in sugar and will be visibly coarse. High fibre haylage may be appropriate for donkeys when late cut hay is not readily available as sugar levels are reduced through partial fermentation. Pregnant or lactating donkeys should be provided with ad libitum hay or haylage during the last trimester of pregnancy and the first 3 months of lactation.
During lactation, donkey has a low but constant daily production (Polidori et al., 2009). Production level is influenced by several aspects, such as stage of lactation, milking technique, presence of the foal and foaling season (Salimei et al., 2004). In particular, during milking, the presence of foal and the stage of lactation influence fat and protein content. Moreover, lactose content is constant during lactation, being independent of breed, milking time and stage of lactation.
Requirements are basically determined by factorial method; for maintenance, requirements are determined using balance experiments and then appropriate nutrients conversion rates for calculation (Martin-Rosset et al., 2006). For pregnancy, requirements are determined using weight gain and accretion of nutrients, estimated with the appropriate method and then nutrients conversion rates if these are known.