The establishment of protein and lipid requirements for growth of penaeid species is essential in maximizing productivity but information on the effects of these nutrients on gonad maturation is still lacking. Indian white prawn, Penaeus indicus (H. Milne Edwards) broodstock, were fed formulated maturation diets containing varying levels of dietary protein (35, 45 and 55%) and lipid (6, 12 and 18%) combinations following a 3×3 factorial design. Control group was fed with fresh mussel, squid and polychaete. Results indicate that treatment groups receiving diets of 45/18 and 55/12 protein/lipid combinations and the control exhibited higher maturation rates than the other treatments (p = 1.9 × 10−4). Shrimp broodstocks fed diets containing the lowest protein or lipid levels exhibited poor gonad maturation. Hepatopancreas damage and gonadal atresia were apparent in treatments with high dietary lipid based on histological and biochemical analyses. The diet with 55/12 protein/lipid combination is therefore best recommended for P. indicus gonad maturation. This study demonstrated that a well‐formulated diet that satisfies the protein and lipid requirements can support successful gonadal maturation comparable with feeding the broodstocks fresh maturation diets.
This study assessed the toxicity of water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) of bunker C oil and dispersant (DISP) to a microalga, Tetraselmis tetrathele. The 72-h median effective concentration (72-h EC50) of CEWAF and DISP were determined at 3.30% and 2.40%, respectively. The no observed effect concentration (NOEC) of CEWAF to T. tetrathele was at 2.0% and lowest observed effect concentration (LOEC) was at 3.0% while NOEC and LOEC of DISP to T. tetrathele were determined at 1.0% and 2.0%, respectively. The addition of dispersant to oil increased the amount of total PAH present in the CEWAF test solutions. DISP alone was highly toxic, and the toxicity of CEWAF was primarily caused by the presence of dispersant.
The growth efficiency, productivity and economic viability of Indian white shrimp (Penaeus indicus) fed with diet containing 40% (CP high ) and 34% (CP low ) crude protein (CP) levels were determined in a 90-day grow-out culture trial. Growth parameters including average body weight (ABW), specific growth rate (SGR), survival and feed conversion ratio (FCR) were not statistically different. CP low had lower overall shrimp production (797.53 kg/ha, DOC 90), but was not significantly different from CP high (843.78 kg/ha, DOC 90). The mean values for the water parameters of both treatments, such as DO, pH, salinity, temperature, TAN, NO 2 -N, NO 3 -N and PO 4 -P, also showed no significant differences. However, the TAN values of CP high were consistently higher from day of culture (DOC) 63 and increased significantly (p = .048) at DOC 90. Furthermore, the total bacterial and Vibrio counts in both treatments were not significant throughout the culture period. The economic analysis revealed that CP low obtained higher net profits (6093 USD/ha/year), return on investment (72%) and discounted benefit-cost ratio (1.73). The current study found that feeding a low protein diet to P. indicus is economically viable and profitable and results in improved growth efficiency and productivity while also improving water quality and lowering nitrogen discharge.
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