Nutritional and nutraceutical Amiatina donkey milk quality.

Recently, a project aimed to the creation of a donkey milk chain from Amiatina native breed has been developed in Tuscany. In a second step of the project, the use of donkey milk in the diet of children with allergy to the cow's milk proteins (CMA) has been evaluated. At the same time, nutritional, nutraceutical, hygienic and safety milk characteristics were tested. Furthermore, another topic of the project was to promote the biodiversity and the economy of Tuscany productions and to provide products having a constant quality. Every month bulk milk samples underwent physical and chemical analysis. The results showed dry matter content of 10 g/100 ml of milk and total protein and fat content of 1.6 and 0.5 g/100 ml, respectively. In donkey milk the protein fraction was more similar to human milk than ruminant milk, with low amounts of casein (0.8 g/100 ml). Whereas whey protein content was about a half of the total proteins (51.1%). The main whey protein fractions were beta-lactoglobulin and alpha-lactalbumin (0.35 and 0.30 g/100 ml, respectively). In addition, the lysozyme content was high (0.15 g/100 ml) and represented about the 9% of the total proteins; this enzyme has antimicrobial activity [1]. Fat content significantly differed from human milk, thus it would require an energetic integration when is used in infant feeding. By contrast, the milk showed a fatty acid composition of nutritional interest, especially for the unsaturated fatty acid content (45 g/100 g of fatty acids). In particular, the unsaturated/saturated fatty acid ratio and the ω6/ω3 ratio were 0.82 and 1.65 respectively. Oleic, linoleic, alpha linolenic and eicosapentanoic acids were respectively 17%, 14%, 8% and 0.13% of the total fatty acids. These polyunsaturated fatty acids are known for their beneficial properties on human health. In addition, milk fat globules showed a mean diameter of 1.92 micron, smaller than the diameter reported for other milks. The smaller globule diameter may promote the digestibility of donkey milk fat [2]. The high lactose content (7.1 g/100 ml) is also of nutritional interest because of its contribution on milk palatability that makes the milk acceptable by children. Ash content was lower than cow milk and was about 0.36 g/100 ml. With regard to individual minerals, the amount of calcium (70 mg/100 ml), phosphorus (60 mg/100 ml), potassium (60 mg/100 ml) and sodium (20 mg/100 ml) were more similar to human milk. The Amiatina donkey milk had also a high content of vitamin D (2.3 µg/100 ml; 92 IU/100 ml on the average), higher in summer than in winter. In conclusion, the similarities with human milk were high, except for the fat content. This finding highlights the need for energy integrations especially when the milk is used in early childhood. Moreover, donkey milk use could be extended to obese people and to the elderly.