Multienzymatic extracts from fishery waste alter digestive metabolism and intestinal microbiota in red claw crayfish across ontogeny

Abstract

Dietary additives, like multienzyme extracts (ME) from fisheries wastes, have emerged as functional ingredients capable of improving nutrient absorption and feed efficiency, contributing to more sustainable aquaculture practices. Considering the developmental stage is essential for optimizing the effectiveness of such additives, as their nutritional requirements and digestive capacities vary. This study evaluated the effects of a diet supplemented with ME from Pleoticus muelleri fishery waste on the physiological responses of Cherax quadricarinatus at two development stages: early juvenile and prepubertal. Trials involved feeding 48 juveniles (~4 g) and 48 prepubertal crayfish (~15 g; 24 females and 24 males) with a control or ME supplemented diet (24 individuals per group). Assessed parameters included growth, digestive enzyme activity, biochemical reserves (proteins, lipids, glycogen) in hepatopancreas and pleon muscle, intestinal microbiota composition, and morphohistological parameters. After 90 days, juveniles fed the ME diet showed higher protein content in the hepatopancreas but decreased specific enzymatic activity of peptidases and lipases, with no significant impact on somatic growth. For prepubertal crayfish, ME diet increased specific activity of peptidases and reduced lipid accumulation in the hepatopancreas, while mass gain was significantly lower than the control group, with a pronounced effect in males. ME supplementation modified intestinal microbiota in both stages, increasing the Firmicutes phylum, which may suggest enhanced digestion and nutrient absorption. This study demonstrates that ME supplementation modulates digestive metabolism in crayfish, with effects depending on developmental stage and sex, providing insights into the potential use of exogenous enzymes as functional feed additives in aquaculture.