Dietary inclusion of Cnidoscolus chayamansa leaf meal improves growth, feed utilization, and coloration in goldfish (Carassius auratus)

Abstract

A 10-week experiment was conducted to determine the effect of fish meal (FM) replacement with chaya leaf meal (CLM) on the growth performance, coloration, total carotenoids content, hematology, and histology of goldfish (Carassius auratus). Five isonitrogenous (426.64 g/kg of crude protein) and isolipidic (90.68 g/kg of crude lipid) diets were formulated. A control diet was formulated to replace 0 %, 8 %, 15 %, 25 %, and 35 % FM with CLM (corresponding to 74, 138, 225, and 315 g/kg CLM). A feeding trial was conducted using a total of 300 goldfish (10.03 ± 0.01 g/fish). Fifteen 120-liter glass tanks were each stocked with 20 fish. Dietary inclusion of CLM resulted in linear and quadratic increase in protein productive value (P < 0.05), while no significant impact was observed on other growth and feed utilization parameters. A notably elevated whole-body protein content was observed with CLM138. Lipid and ash contents exhibited no significant variations. The redness (a* value) and yellowness (b* value) of the head, abdomen, and tail regions increased linearly and quadratically in all CLM replacement groups. The highest redness was observed in head, abdominal, and tail regions of the CLM315 group. Moreover, fish fed CLM315 exhibited linear and quadratic increase of total carotenoid in fin, liver, and serum, while only a linear effect was observed in muscle carotenoid content. Similarly, CLM replacement linearly increased red blood cell, white blood cell, and hematocrit, as well as total cholesterol and HDL-c contents (P < 0.05). In accordance with growth performance, histological observation revealed that goldfish receiving dietary CLM did not show any alternations in liver hepatocytes. These results clearly demonstrate that CLM can replace FM up to 315 g/kg without any adverse effects on growth and feed utilization in goldfish. Moreover, this dietary CLM level enhances goldfish coloration, increases carotenoid content, and supports sustainable ornamental fish diets.