Profil proteina i sastav masnih kiselina mleka magarice balkanske rase tokom perioda laktacije / Protein profile and fatty acid composition on donkey milk of the balkans breed

Nutritional quality of Balkan donkey milk during lactation was investigated within this thesis. The mean content of dry matter, fat and lactose in the Balkan donkey milk was 9.26%, 0.61% and 6.50%, respectively. Protein content during lactation period ranged from 1.40% to 1.92%. Content of the analyzed minerals: Ca, Na, K, Mg, Zn and P increased during the lactation period and reached their maximum value at 170th day. The protein profile of Balkans donkey milk was Doktorska disertacija Jasmina Gubić defined by application of capillary electrophoresis when the following protein fractions: s1-kazein, s2- kazein, -kazein (A, F), -laktalbumin (A, C), - laktoglobulin, lysozyme, lactoferrin, serum albumins and immunoglobulins, whose content decreases during lactation period,were identified. -lactalbumin contents ranged from 3090 mg/l to 1990 mg/ and lysozyme varies between 1040 mg/l to 2970 mg/l. These two protein fractions were the most abundant in the Balkan donkey milk, while lactoferrin and immunoglobulin were at least represented. The fatty acid composition of Balkan donkey milk was determined using gas chromatography/mass spectrometry. The share of the essential linoleic (C18: 2 n6) and  - linolenic (C18: 3 n3) acid rangred from 7.08 % to 9.69% and from 5.85 % to 7.83 %. Nutritional quality of Balkan donkey milk has been compared with the nutritional quality of human milk during the 40th and 90th day of lactation. Significant differences in the protein content of milk, fat and minerals were found. The ratio of casein and whey protein ranged from 0.68 to 0.75 in the Balkan donkey milk, while in human milk this value varies from 0.59 to 0.70. The share of -linolenic acid (C18:3 n3) is around 2.5 times higher in donkey than in human milk. The main conclusion is that Balkan donkey milk has specific and unique nutritional quality which depend on the feed composition and on the analyzed period of lactation.