The effects of various diets on chitinase and ß‐glucosidase activities and the condition of cod, Gadus morhua (L.)

Groups of cod, Gadus morhua (L.), were fed exclusively on fish, crustaceans, or crustacean shells for a period of 3 weeks. Chitinase and ß‐glucosidase activities were measured in enzyme extracts of stomach contents, stomach tissue, pyloric caeca, intestinal contents, and intestine tissue, and compared to the enzyme activities of control fish starved over the same period. Fulton's condition factor K, liver lipid content and liver water content were determined to estimate the effects of the diets on the condition of cod. general, the highest chitinase activities were measured in samples of cod that had been fed on whole crustaceans. In this feeding group, there was also a remarkable increase of activity by a factor of four to eight in the pyloric caeca, compared to the group fed on fish and the control group, respectively. Measurements of ß‐glucosidase activity revealed no similar dependence on food quality, ß‐glucosidase occurrence seemed to be mainly restricted to the pyloric caeca and the intestine of cod.