The feeding-stimulatory effects of extracts of the mantle muscle of squid
Todarodes pacificus on the young yellowtail
Seriola quinqueradiata were studied by applying the extracts in starch pellets.
Pellets containing an extract of the muscle and those containing a synthesized chemical substitute were completely eaten within a short period. However, the stimulatory effectiveness of the natural extract and the synthetic mixture rapidly decreased with decreasing concentration and in both one-tenth dilution resulted in a marked diminution in the number of swallowed pellets.
Omission tests for the constituents of the synthetic mixture were performed by dividing them into five groups, A
1) amino acids having a stimulatory effect on the taste receptors, A
2) those ineffective for the taste receptors, B) betaine, N) nucleotides, and O) organic bases. Omission of A
1 individually or together with other groups from the synthetic mixture resulted in a serious reudction in the feeding stimulant activity of the synthetic mixture. A
1 showed a high feeding stimulant activity when applied individually. Omission of A
2 did not yield any appreciable effect. Omission of N, B or 0, all of them were more or less effective for the taste receptors, also decreased the feeding stimulant activity of the synthetic mixture to a small extent. N was rarely accepted when applied individually, but when added to A
1, enhanced the effectiveness of A
1.
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