Methionine and Methyldonors for Mink (Mustela vison) in the Furring Period

Glem-Hansen (1976) showed, that methionine and cystine were the first limiting amino acids in typical Scandinavian mink feed. In following trials, to establish the requirement for sulphur containing amino acids in the growing period, dl-methionine was used (Glem-Hansen and Hansen, 1980). Investigations with other species have shown a varying degree of utilisation of dl- methionine. Teeter et al. (1978) concluded, that d-methionine was well utilised by cats. A calculation from their data indicates abt. 80 % of growth as compared to l-methionine. Due to the trial design, they could not quantify the degree of utilisation.
An alternative to methionine is the Methionine Hydroxy Analog (MHA). Teeter et al. (1978) tested MHA to growing cats. On a semipurified diet, the MHA group achieved a growth of about 78 % of that achieved by the group receiving l-methionine.
Besides being an essential amino acid in itself, methionine is converted to cystine and may cover the requirement for this amino acid. This process liberates methyl groups, which in themselves have metabolic functions.
Methyl groups may also be supplied by the vitamin choline chloride or betaine.
Børsting og Riis (2002) tested a partial substitution of methionine with betaine to mink in the growing and furring period. The results indicated a certain methionine sparing effect of betaine in the furring period. The following preliminary trial was carried out in order to clarify whether MHA or betaine may possibly substitute a part of the present methionine requirement (norm) to mink in the furring period.