The Effects Of Different Amino Acid Pattern On α-Casein Synthesis And Hormones Secretion And Fat Synthesis In Cows

The effects of different amino acid pattern on proli -feration of mammary epithelial cells of dairy cattle,α-casein synthesis, hormone(sIGF-I,GH,PRL)and trigalloyl glycerol (TG) secretion, activities of lipogenic key enzymes (FAS,ME,G-6-PDH) in mammary epithelial cells were studied in this paper. Results were shown below:(1) The amino acids ratio were adjusted (Met,Lys,Leu) with Amino Acid Balance Index(AABI), to design the different groups. The mammary gland tissue were cultured 15 days in vitro . The results showed that: while the number of cultured days increased ,the number of cells increasd. The number of cells increased to its maximum on the tenth day and declined afterward. Mammary epithelial cell growth curve"S"shape. The different amino acid pattern had significant impact on cell growth of mammary epithelial cells. Compared with the amino acid imbalance, amino acid balance, the ideal group to better promote cell growth. The differences between the groups were significant(P<0.05).(2) The test proved that the cultured mammary epithelial cells normally secret of milk protein. The amino acid pattern had significant impact onα-casein synthesis of mammary epithelial cells, experimental group is higher than that of the control group. Among the experimental groups, groupⅠsecreted the highest.The differences between the groups were significant(P<0.05).This indicated that amino acid pattern regulatedα-casein synthesis and secretion by increasing the number of epithelial cell .(3)The results showed that the different amino acid pattern had significant impact on hormones(IGF-I,GH,PRL)synthesis of mammary epithelial cells. Among the experimental groups, GroupⅤwas most highest. It showed that hormone secretion was regulated by different amino acid pattern. This result in turn proving that different amino acid balance status can directly affect Insulin synthesis and secretion(4) Experiment results showed that the different amino acid pattern had significantly impact on enzyme activity of key enzymes involved in lipid metabolism and trigalloyl glycerol secretion of mammary epithelial cells. The differences between groups were significant(P<0.05).Group I was significantly higher than the other groups. Increased enzyme activity of key enzymes involved in lipid metabolism, increased trigly-ceride secretion and thus promoted fat synthesis. In conclusion, the number of mammary epithelial cell were the most in the 9d or 10d, the hormones secretion level,α-casein synthesis ,Trigly -ceride secretion , and enzyme activity of key enzymes involved in lipid metabolism were the highest in different amino acid pattern. Medium with different amino acid pattern affects not only theα-casein synthesis, also increased enzyme activity of key enzymes involved in lipid metabolism, increased trigly-ceride secretion and thus promoted the fat synthesis. amino acids is the main precursor substances in milk protein synthesis and a primary role milk composition.The results were best but only with the numbers and proportion of the other two precursors sufficient and appropriate , the metabolisms of nutrients in mammary were synergy and overall.