Guanidinoacetic acid (3c372)

What it is. Guanidinoacetic acid is a feed additive produced by chemical synthesis, marketed as a powder with a minimum content of 98% guanidinoacetic acid (dry matter basis). It is the direct metabolic precursor of creatine and may contain cyanamide as an impurity, controlled at maximum levels set in the regulation.

What it is for. This additive belongs to functional group 3c (amino acids, their salts and analogues) and is authorised for chickens for fattening, weaned piglets and pigs for fattening. It supports creatine metabolism, which is relevant to energy status in muscle tissue. An associated study illustrates its use in broilers under chronic cyclic heat stress, examining effects on oxidative status and creatine metabolism; this remains an illustration and not a usage recommendation.

Points to watch. Maximum content in complete feed is set at 1200 mg/kg (minimum 600 mg/kg) for the authorised species. Particular attention should be paid to the presence of methyl donors other than methionine in the animal's diet when this additive is used. Moisture content must be indicated on the additive label, and handling requires inhalation risk control measures, including personal protective equipment where necessary. Authorisation expires on 25 October 2026.