Milk fat chemical composition of yak breeds in China

The present study was undertaken to evaluate the fatty acid composition, conjugated linoleic acid (CLA) and cholesterol contents in the milk from three yak breeds, Maiwa yak (n = 24), Zhongdian yak (n = 16) and Gannan yak (n = 16) and two yak crossbreeds. Maiwa yak x yellow cattle (n = 16) and Gannan yak x yellow cattle (n = 16). Statistically significant differences (P < 0.05) in the proportions of individual milk fatty acids were observed among the three yak breeds. The proportion of saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs) did not differ statistically (P > 0.05) among the three yak breeds. However, the percentage of total polyunsaturated fatty acids (PUFAs) in Zhongdian yak milk (4.82%) was significantly higher (P < 0.01) than in Maiwa (3.99%) and Gannan (3.68%) yak milks. The contents of a-linolenic acid (C18:3) and cis-9. trans-11 conjugated linoleic acid (CLA) were significantly different (P < 0.05) among the three yak breeds. The total SFAs, MUFAs and PUFAs were not significantly different (P > 0.05%) between the two yak crossbreeds. The cholesterol contents in milk samples from yak breeds and yak crossbreeds were found to be in the range 12.32-16.17 mg/100 g. Cholesterol contents in milk samples from yak breeds and yak crossbreeds were positively correlated with their fat contents. (C) 2010 Elsevier Inc. All rights reserved.