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Determination of amino acid profile of mare milk produced in the highlands of the Kyrgyz Republic during the milking season

Mazhitova, A.T., Kulmyrzaev, A.A.
Journal of dairy science 2016 v.99 no.4 pp. 2480-2487
amino acid composition, derivatization, glutamic acid, grazing, high performance liquid chromatography, highlands, leucine, lysine, mare milk, mares, milk, milk composition, milking, ornithine, pastures, statistical analysis, Kyrgyzstan
This study was carried out to determine the influence of milking season on amino acid (AA) profile and chemical composition of milk samples from Kyrgyz native breed mares under traditional pasture conditions. Milk samples were collected monthly from May to August 2014 from mares grazing at 2,200m above sea level. The AA composition was determined by precolumn derivatization with diethyl ethoxymethylenemalonate in HPLC and 18 AA were determined in mare milk. The analytical parameters of linearity (0.01–4μg/mL), precision of the method (0.26–4.88% relative standard deviation), derivatization procedure (0.82–2.80% relative standard deviation), and instrument precision (0.08–1.00% relative standard deviation) were determined. The most abundant AA were glutamic acid (0.393–480g/100g of milk), leucine (0.192–0.230g/100g of milk), and lysine (0.192–0.230g/100g of milk). The amount of ornithine was small (0.002–0.015g/100g of milk). The percentages of essential AA in the protein of mare milk were 46, 46, 51, and 48% for May, June, July, and August, respectively, which demonstrate the high biological value of milk during the whole milking season.