Studies On Molecular Evolution Of Domestic And Wild Bactrian And The Physical-chemical Properties Of Camel Milk

Changes in chemical compositions of milk during lactation and mitochondrial DNA sequences of Alxa Bactrian camels,Mongolian Gobi Red Bactrian camels and wild Bactrian camels were comparatively studied in this research. The experimental results showed that chemical compositions of milk and mitochondrial DNA were significantly different among the 3 kinds of Bactrian camel.The total solids, protein, fat and ash content in Alxa Bactrian camel colostrums, which was collected first time postpartum, were 20.16%, 14.23%, 0.27% and 1.22%, respectively. However, the content of these compositions were changed according to lactation time. The total solids content was17.46% to 17.42% from 2h to 30th d postpartum, but it was decreased to 14.31% at 90th d postpartum. The protein content was decreased to 8.06% in 24th h postpartum, and continually decreased to 7.45%, 4.87%, 4.34% and 3.56%, respectively, at 7th d, 30th d, 60th d and 90th d postpartum. The fat content was increased to 4.18% in 24th h postpartum and 6.91% in 30th d postpartum, but decreased to 5.65% in 90th d postpartum. The ash content was decreased to 0.90% at 24th h and stabilized during 0.82% to 0.98% in whole left lactation time. Variation in lactose content was small (4.24 to 4.71%) throughout the study period. The WPN, CN and NPN account for 58.74%, 38.57% and 2.69% in total N in first collected colostrums and 32.54%, 65.08% and 2.38% in 24th h colostrums postpartum, respectively. Percentages of caseins N increased steadily, whereas whey proteins N declined gradually until 3 month of lactation. Variation in NPN content was small (5.26 to 7.89%) throughout the study period. Gas liquid chromatography analysis of milk fat showed that the content of even-numbered saturated fatty acids(C_12:0-C_18:0) account for 57.54% in total fatty acids, and C_16:0, C_18:0, C_12:0 fatty acids account for 30.12%, 15.15% and 11.49% in total fatty acids, respectively. There was a considerable level of polyunsaturated fatty acids (mainly C18:1) in Alxa camel's milk fat. The levels of Ca and P were 222.58 and 153.74mg/100 g, respectively, in first time collected milk postpartum; The variation in Ca, P, Na, K and Cl levels in study period were 154.57¹86.87mg/100g, 116.82¹41.67 mg/100g, 59.5⁷9.5 mg/100g, 150.0¹91.0 mg/100g and 80.9¹52.0 mg/100g, respectively. The levels of vitamins A, C, E, B₁, B₂, B₆, and D were 0.97, 29.60, 1.45, 0.124, 1.24, 0.54 mg/L, and 640 IU/L, respectively, in Alxa camel milk at 90 d PP. Vitamin A and C contents were higher and vitamins E and B1 were lower than those in colostrum.The total solids, protein, fat and ash content in Mongolian Gobi Red Bactrian camel colostrums, which was collected first time postpartum, were 20.86%, 14.86%, 0.28% and 1.28%, respectively. However, the content of these compositions were changed according to lactation time. The total solids content was 17.86% to 18.32% from 2h to 30th d postpartum, but it was decreased to 14.49% at 90th d postpartum. The protein content was decreased to 8.15% at 24th h postpartum, and continually decreased to 7.44%, 4.92%, 4.51% and 3.56%, respectively, at 7th d, 30th d, 60th d and 90th d postpartum. The fat content was increased to 4.26% at 24th h postpartum and 6.85% at 30th d postpartum, but decreased to 5.71% at 90th d postpartum. The ash content was decreased to 0.92% at 24th h and stabilized during 0.82% to 0.98% in whole left lactation time. Variation in lactose content was small (4.35 to 4.65%) throughout the study period. The content of C_12:0, C_14:0,,C_{16: 0}, C_{18: 0}, C_{18: 1}, C_{18: 2} and C_{18: 3} fatty acids account for 3.2 mg/g fat, 49.3 mg/g fat, 165.0 mg/g fat, 158.6 mg/g fat, 161.0 mg/g fat, 12.3 mg/g fat and 7.6mg/g fat, respectively.The levels of Ca and P were 216 and 154.3mg/100 g, respectively, in first time collected postpartum; the variation in Ca, P, Na, K and Cl levels in study period were 156.3¹92.2 mg/100g, 126.8¹54.3mg/100g, 60.0⁸3.0 mg/100g, 126.8¹84.2 mg/100g and 85.6¹93.2mg/100g, respectively. The levels of vitamins A, E, B₁, B₂, B₆, C, and D were 1.07 mg/L, 1.41 mg/L, 1.57mg/L, 1.51mg/L, 0.68 mg/L, 33.55mg/L and 639.5 IU/L, respectively.The total solids, protein, lactose, fat, and ash content in wild Bactrian camel milk collected at 90th d postpartum were 16.47%, 4.47%, 4.58%, 6.39% and 0.92%, respectively. The levels of Ca, P, Na, K, Cl, S, Mg and Zn in regular milk of wild Bactrian camels collected at 90th d postpartum were 156.3 mg/100g, 135.5 mg/100g, 57.9 mg/100g, 185.0 mg/100g, 145.8 mg/100g, 39.9 mg/100g, 11.8 mg/100g and 0.7 mg/100g, respectively. The levels of vitamins A, E, B1, B2, B6, C, and D were 1.04 mg/L, 1.48 mg/L, 1.65mg/L, 1.44mg/L, 0.71 mg/L, 33.70mg/Land 638.33 IU/L respectively.The results of molecular evalution analysis showed that the length of mitochondrial gene group in the Domestic Bactrian Camel and Wild Bactrian Camel is 15,440 base pairs. The Domestic Bactrian Camel and Wild Bactrian Camel were differentied to two large branchs and became individent groups about six million years ago. The Wild Bactrian Camel has not only own ancient ancestry and pedigree but also the ancestor of the Demostic Bactrian Camel.