Effects on growth and quality of reduced protein intake in red swamp crayfish (Procambarus clarkii, Girard 1852) fed diets containing graded levels of purslane weed (Portulaca oleracea L.)

Abstract In this study, 144 juveniles of red swamp crayfish (Procambarus clarkii, initial mean weight 3.9 ± 0.3 g) were fed for ten weeks diets containing graded levels of purslane weed (Portulaca oleracea) resulting in a decreasing percentage of crude protein (from 17.3–1.0%). Six diets were administered: four fishmeal-based diets containing 5, 15, 25, and 50% of purslane, one diet composed of 100% purslane, and one commercial diet as control. Growth performance, fatty acid, and pigments levels of crayfish were measured. Crayfish groups fed 25% and 50% P. oleracea diets showed optimal contents in fatty acids and astaxanthin, with no negative effects on growth. Fatty acid contents in the crayfish groups revealed significant differences for SFAs, MUFAs, and PUFAs. As for PUFAs, the highest levels of n-3 α-linolenic (ALA) and n-6 linoleic (LA) acids were found in the groups fed 25%, 50%, and 100% purslane diets. This study shows that the most appropriate P. oleracea inclusion in the crayfish diet should range between 25% and 50%. Although the overall nutritional value of purslane is relatively low, its high inclusion in the crayfish diet seems to improve the pigment content and fatty acids quality as well as reducing daily animal protein intake, without affecting growth performance, thus contributing to achieve the goal of a more sustainable crustacean aquaculture.