A method of preparing a feed additive composition comprising: (a) admixing at least one proline tolerant tripeptidyl peptidase predominantly having exopeptidase activity wherein said proline tolerant tripeptidyl peptidase is capable of cleaving tri-peptides from the N-terminus of peptides having (i) (A)Proline at P1； and (B) An amino acid selected from alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, valine or synthetic amino acids at P1； or (ii) (a') Proline at PV； and (b') An amino acid selected from alanine, arginine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, serine, threonine, tryptophan, tyrosine, valine or synthetic amino acids or amines at PV； and one or more ingredients selected from the group consisting of a salt, polyol including sorbitol and glycerol, wheat or a wheat component, sodium acetate, sodium acetate trihydrate, potassium sorbate Talc, polyvinyl alcohol (PVA), benzoate, sorbiate, 1,3-propane diol, glucose, parabens, sodium chloride, citrate, metabisulfite, formate or a combination thereof； and (b) optionally packaging as well as uses of such proline tolerant tripeptidyl peptidases, feed additive compositions, feed additive kits, feeds or feedstuffs and/or premixes.Un método de preparación de una composición de un aditivo para piensos, caracterizado porque comprende: (a) mezclar al menos una tripeptidil-peptidasa que tolera la prolina, que tiene predinantemente actividad exopeptidasa, donde la tripeptidil-peptidasa que tolera la prolina es capaz de escindir tripéptidos del N-terminal de péptidos que tienen (i) (A) prolina en P1； y (B) un aminoácido seleccionado de alanina, arginina, asparagina, ácido aspártico, cisteína, glutamina, ácido glutámico, glicina, histidina, isoleucina, leucina, lisina, metionin
