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 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 or amines at P1′； 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.
