Abstract: Changes in chemical composition of Alax bactrian camels reared in the desert area of Alxa District of Inner Mongolia during lactation were investigated. Colostrum and milk samples from ten nomadic camel females at their first season of lactation were collected periodically from parturition until 90d post partum (PP). The average contents of gross composition were 14.23% protein, 4.44% lactose, 0.27% fat, 0.77% ash, and 20.16% total solids (TS) in colostrum at 2h PP, and the respective mean values were 3.55%, 4.24%, 5.65%, 0.87%, and 14.31% for normal milk on the 90th day. A fifteen-fold increase was shown by fat content during the first 24h, whereas a sharp decrease was shown during the first 12 h of lactation in protein, ash, and TS contents. Variation in lactose content were small (4.24%～4.71%) throughout the study period. Total N, non-protein N, casein N and whey protein N were found to be 2.23, 0.06, 0.86, and 1.31g/100ml of the colostrum at 2h PP; and 0.56, 0.04, 0.45, and 0.07g/100ml for the milk at 90d PP. Percentages of caseins increased steadily, while whey proteins declined gradually, until 3 months of lactation. Gas liquid chromatography analysis of milk fat showed that the content of even-numbered saturated fatty acids (C12:0～C18:0) in camel colostrum (2h～7d PP) was lower than that of normal milk (15～90d PP). The predominant saturatedfatty acids were C14:0, C16:0, and C18:0, regardless of the stage of lactation. There was considerable level of polyunsaturated fatty acids (mainly C18:1) in Alxa camel’s milk fat. The levels of Ca, P, Na, K and Cl were 222.58, 153.74, 65.0, 136.5, and 141.1mg/ 100g, respectively, at 2h PP; the values of the minerals were 154.57, 116.82, 72.0, 191.0, and 152.0mg/100g, respectively, for the normal milk on the 90th day. The levels of vitamins A, C, E, B1, B2, B6, and D were 0.97, 29.60, 1.45, 0.12, 1.24, 0.54mg/ L, and 640 IU/L respectively in Alxa camel milk at 90d PP. Vitamins A and C contents were higher and vitamins E and B1 were lower than those in colostrum.

Key words: Alxa bactrian camel milk, different lactation, chemical composition, analysis