Analytical Methods for Comprehensive Characterization

In this study, ethanol and hydrochloric acid (HCl) were purchased from Aladdin Biochemical Technology Co., (Shanghai, China). The guarantee reagents of copper sulphate, potassium sulphate, sulfuric acid, boric acid were purchased from Sinopharm Chemical Reagent Co., LTD., China. Standards for the determination of amino acids: aspartic acid (Asp), threonine (Thr), serine (Ser), glutamic acid (Glu), glycine (Gly), alanine (Ala), valine (Val), methionine (Met), isoleucine (Ile), leucine (Leu), tyrosine (Tyr), phenylalanine (Phe), lysine (Lys), histidine (His), arginine (Arg), proline (Pro), cysteine (Cys) and tryptophan (Trp) were all purchased from Anpu Experimental Technology Co., (Shanghai, China). Standards for the determination of fatty acids were purchased from Sigma co., United States. Protease, trehalase and lipase kits were all purchased from Qingdao Sci-tech Innovation Quality Testing Co., LTD. (Qingdao, China). DNA kits and Polymerase chain reaction (PCR) amplicons kits for intestinal contents samples were purchased from Omega Bio-Tek Co. (Norcross, GA, United States) and Invitrogen Co., (Carlsbad, CA, United States), respectively.