To prepare a growth promoting agent capable of markedly improving the growth of a Decapnda such as a Penaeus excellent in digestion and absorption and nutritient effect by using an aliphatic ester of a cholesterol having a specific structure as an active ingredient.
The subject agent contains, as an active ingredient an aliphatic ester of a cholesterol of the formula (RCO is a 8-22C linear saturated or unsaturated aliphatic acid residue). This ester is preferably prepared from cholesterol and a fatty acid by carrying out the ester synthesis using a lipase. The cholesterol obtained from wool fat is preferred as the raw cholesterol. Palmitic acid or oleic acid or soy been oil containing them in plenty is preferred as a raw aliphatic acid. When this growth stimulator is formulated to the feed for prawn sea farming, its amount is preferably 0.1-1wt.% based on the weight of the feed.
NAKAJIMA JUN
TEJIMA SHINICHI
