Abstract: The objective of this study was to investigate the regulation and variation of milk amino acids composition from different dairy animals. Milk samples from cows,goats,yaks and buffalos(n=20 for each species) were obtained from the local farm of Beijing,Shanxi,Yunnan and Qinghai province,respectively.Amino acids were extracted by hydrolyzed with 7.8 mol/L HCl for 24 h,and concentrations of amino acids were determined by high speed amino acid analyzer.Data was performed statistical analysis with the SAS 9.0 and principal component analysis with The Unscrambler 9.8 software. The results showed that concentrations of all tested amino acids in yak milk were significantly higher than those of buffalo,goat,high-protein and low-protein cow milk(P<0.05). Except for Thr,Ser,Val and Tyr,other amino acids of buffalo milk were significantly higher than those of goat,high-protein and low-protein cow milk(P<0.05).Thr,Ser,Val,Met,Phe and Tyr of goat milk were significantly higher than those of cow milk(P<0.05).Except for Met,amino acids in high-protein cow milk were significantly higher than low-protein cow milk(P<0.05). Amino acids of the cow,yak,buffalo and goat milk were significantly different(P<0.05).According to the PCA scores and loading plots,goat milk with Ser,Thr,Val and Tyr contents were different from the cow,buffalo and yak milk, which were grouped together. It was concluded that the different specials showed distinct amino acids profiles and had a certain species.

Key words: species; milk; amino acids