Now showing items 1-2 of 2

    • Conference paper

      Development of artificial diets for milkfish (Chanos chanos) larvae 

      I Borlongan, C Marte & J Nocillado - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
      This study aims to develop nutritionally balanced and cost-effective artificial diets for milkfish larvae. Two larval diets (Feed A and Feed B) were formulated and prepared to contain 45% protein and 10% lipid. Several larval diet preparation techniques were tried and diets produced were assessed in terms of feed particle size and bouyancy, water stability, and feed acceptability. The larval diet preparation that gave the best particle size and bouyancy as well as good water stability was the one prepared as microbound diet (using K-carrageenan as a binder) and flaked using a drum drier.A series of feeding experiments were then conducted to determine growth and survival of milkfish larvae reared on various feeding schemes involving the use of these artificial diets. The artificial diets were fed either alone or in combination with live foods. Larvae in control treatments were reared on live foods such as Brachionus and Artemia. Larvae were observed to ingest the diets indicating that the feeds had suitable physical characteristics and were attractive to the larvae. Over-all results of the feeding trials showed that the artificial diets could be fed to milkfish larvae in combination with the rotifer Brachionus starting Day 8 or could be fed alone to milkfish larvae starting Day 15 onward. These promising results would reduce dependence of milkfish larvae on live foods and would have significant economic benefits in the form of simplified milkfish hatchery procedures.
    • Article

      Gonadal response of juvenile protogynous grouper (Epinephelus fuscoguttatus) to long term recombinant follicle-stimulating hormone administration 

      P Palma, J Nocillado, J Superio, EGdJ Ayson, F Ayson, I Bar & A Elizur - Biology of Reproduction, 2018 - Oxford University Press
      The role of follicle stimulating hormone (FSH) in the gonadal development of protogynous hermaphroditic grouper (E. fuscoguttatus) was investigated. Recombinant giant grouper (E. lanceolatus) FSH (rggFSH) was produced in yeast. Its receptor binding capacity and steroidogenic potency were confirmed in vitro. Weekly injections of rggFSH to juvenile tiger grouper for 8 weeks (100 μg/kg body weight, BW) resulted in significantly larger and more advanced oocytes (cortical alveolar stage vs. primary growth stage in control). Sustained treatment with rggFSH (20 to 38 weeks at 200 μg/kg BW) resulted in significant reduction in gonad size, degeneration of oocytes and proliferation of spermatogonial cells, indicative of female to male sex change. Gene expression analysis showed that, while initiating female to male sex change, the rggFSH significantly suppressed the steroidogenic genes cyp11b, cyp19a1a and foxl2 which restrained the endogenous production of sex steroid hormones thus prevented the differentiation of spermatogonial cells. Expression profile of sex markers dmrt1, amh, figla and bmp15 suggests that the observed sex change was restricted at the initiation stage. Based on these results, we propose that the process of female to male sex change in the protogynous grouper is initiated by FSH, rather than sex steroids and likely involves steroid-independent pathway. The cortical alveolar stage in oocyte development is the critical point after which FSH-induced sex change is possible in grouper.