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Preliminary studies on the effect of methyltestosterone on Macrobrachium rosenbergii juveniles (Crustaceana: Palaemonidae)

Establishment of a Network of Aquaculture Centres in Asia








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    Optimum dietary protein requirement for Macrobrachium rosenbergii juveniles
    Establishment of a Network of Aquaculture Centres in Asia
    1986
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    The dietary protein requirement of M. rosenbergii juveniles was determined in growth trials performed in indoor aquaria using rations based on fish meal and shrimp meal as the main sources of protein. Five protein levels from 20 – 40% at 5% interval were tested to assess the best growth. Mean body weights and lengths of 4 replicate treatments were subjected to analyses of variance in determining differences between protein levels. Results showed no significant differences in all variables consid ered. Under this laboratory feeding experiment, the prawns attained weights of 0.95 g (994% gain), 0.94 g (921% gain), 1.3 g (1417% gain), 0.95 g (996% gain) and 1.17 g (1263% gain) for 20%, 25%, 30%, 35% and 49% crude protein levels, respectively in 89 day-culture period. 1 Research sponsored by FAO/NACA under the Secondment for Young Scientists Program Bangkok, Thailand October 1985 - September 1986. 2 Research Associate - Southeast Asian Fisheries Development Center (SEAFDEC - AQD), Binan gonan Research Station, Binangonan, Rizal Philippines 3106.
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    A preliminary study of hydrogen sulphide toxicity on juveniles of Macrobrachium rosenbergii (de Man)
    Establishment of a Network of Aquaculture Centres in Asia
    1986
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    Static bio-assays were performed for 96-hour period to determine the mean lethal concentrations (LC50) of hydrogen sulphide toxicity on juveniles of Macrobrachium rosenbergii. Two broods were tested and LC50 values were determined for 24, 48, 72 and 96 hours The LC50 values were 6.36, 4.25, 3.09 and 2.57 mg/l H2S for brood l and 5.57, 4.79, 4.25 and 4.20 for brood 2 respectively, for 24, 48, 72 and 96 hours. The safe concentration of hydrogen sulphide determined for juveniles of M. rosenbergii w as 0.26 mg/l.
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    Studies on the culture of the freshwater prawn Macrobrachium rosenbergii at various stocking size and density in ricefields
    Network of Aquaculture Centres in Asia
    1988
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    Experiments were conducted to investigate the possibility of prawn culture in ricefields. The work was undertaken in cooperation with the Farming System Research Institute in Bangkok and the Sakolnakorn Fisheries Station in Sakolnakorn in the North-east Thailand. The experiments were conducted on farmers' fields. Eight farmers participated in the research. They carried out day to day management of the 16 plots. The plots were prepared for the experiments by digging a trench around the ricefiel d. Paddy was planted and tillered before the prawn were stocked. Prawn were of two sizes, just metamorphosed postlarvae (PL 1) measuring 1–1.5 cm in length, others as PL 60 measuring 4.5 – 4.8 cm in length. The latter ones were first nursed for 60 days in ponds before stocking in the ricefield. The PL 1 were stocked at the rate of 1.25/m2 meter and PL 60 at 0.31, 0.63 and 1.25/m2. Thus the rate of stocking varied from 3100 to 12500/hectare. The size of each of the ricefields in this experiment w as about 1600 square meter. After a culture period of 90 to 100 days the prawn were handpicked after draining or pumping the water out of the field. Six plots belonging to three farmers were infested with large predatory fish following heavy rain that flooded the fields and damaged the screening material of 50 cm height put on the dikes surrounding the plots. Flooding and infestation with fish were perhaps the main reasons for very low survival rates of 1 to 9% in these plots. Other fields gav e survival rates of 10 to 89 %. The PL 1 in ricefields grew to 5.4 grammes after a rearing period of 90 days. However 34 % of the population had an average weight of 17.1 grammes indicating clearly that the stocked PL grew extremely well in a ricefield ecosystem.

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