Comparison of odd and branched chain fatty acids profiles of cow, yak, buffalo, Jersey cattle, goat, camel and horse milk fat

Abstract Text: To unravel the expression profile of odd and branched chain fatty acids (OBCFA) in cow (n=20), yak (n=20), buffalo (n=20), Jersey cattle (n=20), goat (n=20), camel (n=8) and horse (n=8) milk samples which were collected around the 4^th month of lactation for each species from February to April, 2013, composition and variation were detected by gas chromatography-mass spectrometry selected scan mode (GC-MS/SCAN) (7890N-5975C, Agilent Technologies Co., Ltd., USA). Descriptive statistics and Duncan's multiple comparison of OBCFA profiles were obtained by SAS 9.1 via GLM model (SAS Institute Inc., Cary, NC). All OBCFA data sets were analyzed by principal component analysis (PCA) using the Unscrambler 9.8 (CAMO SOFTWARE AS, Oslo, Norway) and submitted to further hierarchical clustering using Cluster 3.0 software (USA). Significant differences in milk OBCFA composition of different species were observed. In cow, yak, buffalo and Jersey cattle milk, the highest composition of OBCFA were iso-C15:0 and C15:0, in goat milk were C15:0 and anteiso-C17:0, while in horse and camel milk were iso-C15:0 and anteiso-C17:0, respectively. Among various species milk, anteiso-C13:0 accounted for the smallest percentage of OBCFA. Total OBCFA composition was highest in yak milk. Most of the individual OBCFA were significantly highest in yak milk, except for anteiso-C17:0 which was a little lower than in camel milk. However, most individual OBCFA and the total amount of OBCFA in horse milk were significantly lower than in other species’ milk. The cluster analysis result showed that cow, buffalo, Jersey cattle and yak milk samples comprised a major sample cluster, and goat milk added to this group yielded another cluster. Camel and horse milk were in another major cluster. In addition, principal component analysis (PCA) result could also be used to group different species according to OBCFA and demonstrate an effective way to distinguish between yak milk and others’ milk. It was concluded that milk from different species had its special OBCFA profile.

Keywords: odd and branched chain fatty acids, species milk, gas chromatography-mass