Characterization of the digestive proteinases of the redclaw crayfish Cherax quadricarinatus in response to different diets

SACRISTÁN, HJ; FERNÁNDEZ GIMENEZ, A.; CHAULET, A.; FENUCCI, J.; RODRÍGUEZ, E.M.; LÓPEZ GRECO, L.S.

Natal

Congreso; World Aquaculture 2011; 2011

World Aquaculture Society

The crayfish Cherax quadricarinatus is endemic to freshwater systems of northern Australia and southern Papua New Guinea. The biology of this species is well known and the culture techniques are well established, but its capacity to digest dietary nutrients, such as proteins, carbohydrates  and lipids is not yet completely understood. A better comprehension of  its nutritional  requirements  is  essential to ensure  profitable production and long-term sustainability  of the  culture. The aim of the present work was  to  determine the  enzymatic activities  of the  proteases  of juvenile  C. quadricarinatus  fed  two  fish-based  diets:  a commercial, non-specific diet usually used in cultures (Diet 1), and a diet formulated for this species (Diet 2).   The composition of  the  diets was: 16.03 and 4.40% of lipids, 3.85 and 37.45% of protein, 72.69 and 51.37% of carbohydrates, for Diet 1 and Diet 2, respectively. Juveniles of two sizes (7.07±1.13g and 1.35±0.32g) were fed both diets. Table shows that proteinase activity  and the percentage of trypsin inhibition were higher for individuals fed Diet 1, regardless of size. Trypsin activity was higher  in  the smaller juveniles fed with Diet  1  (lower  percentage of proteins). The  percentage of  specific trypsin inhibition  depended  on size and type of diet while the inhibition percentage of trypsin belonging to the serine class did not depend on diet or  size. Enzyme activity  varies with modifications to feeds  and its analysis  allows  a more accurate  definition of  an  animal´s  capacity  to utilize nutrients.