STUDIES ON THE DIGESTIVE ENZYMES OF RAINBOW TROUT-I

Abstract

The enzymatic actions of the extracts from the digestive organs were investigated on various growth stages of rainbow trout for the purpose of obtaining some useful knowledge on the culture of the fish. And in this paper the following results are presented. (1) The activities of amylase and α-glucosidase were recognized in the extracts but not β-glucosidase, α-galactosidase, β-h-fructosidase and cellulase.-(Table 2) (2) The remarkable hydrolytic action on starch was observed in the digestive organs of the younger stages (body weight less than 4g.). It seemed that the hydrolytic activity increases with the growth of the fish in the early stages, but decreases contrarily after the middle stage (body weight about 100g.), in which the highest activity was found. The activity in the later stage (body weight about 1, 000g.) was considerably low.-(Table 3 and 4) (3) However, the difference of the starch hydrolytic activity with growth was not so much as that of the proteolytic activity which will be described in the following paper3). (4) Optimal temperatures of the amylases were relatively low (20°-25°C), and even at a lower temperature (at 5°C) the enzymes did not lose most of their activities.-(Fig. 2)