Essentiality of calcium supplement in the diets of Heterobranchus bidorsalis fingerlings

Abstract

An 84-day feeding trial was conducted to determine the effect of calcium (Ca) supplemented diets on growth and body mineral composition of Heterobranchus bidorsalis, initial mean weight (5.05 ± 0.31 g). Glass aquaria (70 × 45 × 40 cm) each filled up to 70 L of its volume with Ca -free water were used for the experiment. Eleven practical diets were formulated to contain graded levels of calcium carbonate (CaCO3) at 0 (Control), 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0%, respectively. Each diet was fed twice daily (08:00 and 16:00) to triplicate groups of fish at 15 fish per replicate. Fish fed DVI (2.5% CaCO3) had the best growth response in terms of final mean weight gain (MWG) (16.3 ± 1.30) g; specific growth rate (SGR) (1.15 ± 0.12) and feed conversion ratio (1.43 ± 0.20). Protein efficiency ratio (PER) and net protein utilization (NPU) values were significantly (P > 0.05) highest (3.69 ± 0.10; 3.07 ± 0.15) in fish fed DVII and DVIII, respectively. Highest values of magnesium (Mg) and phosphorus (P) (13.9 ± 0.12; 36.98 ± 0.21) mg/g were recorded in fish fed DVI and DXI, respectively. The feeding trial confirmed that Ca supplementation would be necessary in the diet of H. bidorsalis for maximum growth and body mineralization. Key words: Heterobrachus bidorsalis, calcium supplement, growth performance, body mineral.