Effects of black cumin and grape powder mix on growth performance and hepatopancreas histology in third instars of Pontastacus leptodactylus

This study investigated the effects of dietary supplementation of combined black cumin (BC) and grape seed (GS) powder at different rates (0%, 1%, 2%, and 4%, respectively) on growth performance and hepatopancreas histology of third instar Turkish narrow-clawed crayfish (Pontastacus leptodactylus). A total of 180 third instar of crayfish with an initial mean weight of (0.06 g ±0.01 g) and mean length (11.0 mm ±0.01) were randomly assigned to four treatment groups with three replications in each group and at a density of 15 crayfish per replicate. Crayfish were fed an experimental diet rate of at 10% of total body weight for 84 days. Growth performance parameters were improved significantly with BC and GS powder supplementation (P<0.05), while survival rates did not differ among all groups (P>0.05). Weight gain, specific growth rate and feed conversion rate of the 1% group tended to be better than the other groups, with significant differences among groups (P<0.05). The number and volume of B cells increased significantly with the increase in the amount of (BC and GS) added to the feed (1, 2, and 4%) in the hepatopancreas. In addition, it was determined that the R cells, which absorb nutrients, are dense in the hepatopancreas tissue of the crayfish fed with 1% (BC and GS) added feed compared to the other groups. The results showed that dietary supplementation of 1% BC and GS could benefit third-instar crayfish's growth and histological data. Therefore, combining BS and GS can be recommended as a promising new feed additive for narrow-clawed crayfish culture.