GROWTH, ANTIOXIDANT ACTIVITY AND HISTOPATHOLOGY OF JUVENILE BARRAMUNDI (Lates calcarifer) FED HIGH SOYBEAN MEAL DIETS SIMULTANEOUSLY SUPPLEMENTED WITH ORGANIC SELENIUM

Ilham*, I Nyoman Soeyasa, Ravi Fotedar
 
Department of Aquatic Resources Management
Jakarta Fisheries University Jl. AUP Pasar Minggu Jaksel 12520 Indonesia
alimin212@yahoo.com

The use of fishmeal (FM) as the major protein source for aquaculture production has been plagued by both economic and environmental objections. While FM is disputably sustainable, increased demand for FM from rapidly expanding aquaculture can be expected to remain high in the long term. Soybean meal (SBM) has been commonly utilised as a substitute for FM in the diets of several fish species. However, little is known regarding their effects on trace element availability and thus their importance to fish. The present study employed two feeding trials to evaluate the implications of dietary SBM and selenium (Se) on the growth, accumulation, antioxidant and histopathological responses of juvenile barramundi (Lates calcarifer).

In the first trial, each of three basal diets containing 0%, 15% and 43% SBM as replacements for 0%, 25% and 75% of FM protein on an isoproteic and isocalorific basis were either supplemented or not supplemented with 2 mg kg-1 organic Se (OS). In the second trial, the potential effect of OS supplementation in a high SBM diet was investigated in a feeding trial with five experimental diets: 75% SBM protein as replacement of FM was supplemented with 2, 3, 4, 5 or 7 mg OS kg-1. Growth was independently influenced by the SBM level and the OS supplementation level but not by their interaction. Glutathione peroxidase (GPx) activity, haematocrit, Se accumulation and muscle tissue integrity were significantly enhanced in fish fed on OS-supplemented diets. Furthermore, when high SBM was included in diets, elevated Se tended to lower the barramundi's performance. Histological abnormalities (falsification, disconnection, and longitudinal rupture of muscle fibres) were found in the muscle of fish fed the diets lacking OS supplementation.

These findings suggest that dietary supplementation of OS at 2-3 g kg-1 is necessary when high plant protein ingredients are incorporated in the diet, in order to maintain better growth and to afford protection against oxidative stress.