EFFECT OF OESTROGEN HORMONE, 17β-ESTRADIOL ON FEMINIZATION, SURVIVAL RATE AND GROWTH RATE OF TIGER SHRIMP, Penaeus monodon (FABRICIUS, 1798) POSTLARVAE

 

ABSTRACT. This study was conducted to determine the effect of different concentrations of oestrogen hormone, 17β-estradiol (E2) on feminization for the production of all female P. monodon postlarvae, as well as survival rate and growth rate. The treatments consisted of three replicates of each diet containing six concentrations of oestrogen hormone, E2 at 0, 200, 400, 600, 800 and 1,000mg/kg feed. The experiment was carried out continuously for 50 days. At termination of experiment, the specimens in each treatment group were individually weighed and measured for their wet body weight (BW) and total length (TL) to estimate the mean final BW and TL, and the specific growth rate (SGR). The mean sex ratio values of male to female with the concentration of  0, 200, 400, 600, 800 and 1000 mg/kg were 1:1, 1:1, 1:2, 1:2, 1:4 and 1:5 respectively. The mean survival rate for 0, 200, 400, 600, 800 and 1000mg/kg were 42.33% ± 2.52, 37.67% ± 2.52, 38.67% ± 2.08, 47.33% ± 2.52, 41.00% ± 3.00 and 40.67% ± 2.08 respectively. The mean final TL and BW were 24.57 mm ± 2.84 and 0.11 g ± 0.05 for control, 26.97 mm ± 2.99 and 0.16 g ± 0.07 for 200 mg/kg concentration, 28.95 mm ± 2.30 and 0.20 g ± 0.06 for 400 mg/kg concentration, 30.77 mm ± 4.33 and 0.24 g ± 0.09 for 600 mg/kg concentration, 32.97 mm ± 5.59 and 0.27 g ± 0.06 for 800 mg/kg concentration and, 34.54 mm ± 5.32 and 0.32 g ± 0.08 for 1000 mg/kg concentration. The mean SGR for control treatment of P. monodon PL after 50 days was 2.67 g/day ± 0.18 while for E2 hormone concentration treatments of 200, 400, 600, 800 and 1000 mg/kg were 3.31 g/day ± 0.003, 3.86 g/day ± 0.13, 4.15 g/day ± 0.50, 4.41 g/day ± 0.02 and 4.74 g/day ± 0.30 respectively. The study shows that as the concentration of E2 hormone increased, the female sex ratio and the growth rate of P. monodon PL also increased. The number of PL surviving in all hormone treated diets was similar to the control treatment. But, treatment of 600 mg/kg shows the highest survival rate compared to the other treatments. Treatment 600 mg/kg can be considered the most effective concentration for survival in the study.

 

KEYWORDS. 17β-estradiol, feminization, Penaeus monodon, postlarvae, growth performance, survival rate.

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TRIPLOIDY INDUCTION USING COLD SHOCK TREATMENT IN BANANA SHRIMP, PENAEUS MERGUIENSIS (DE MAN, 1888)

ABSTRACT. A study was conducted to determine the optimum parameter to produce triploid in banana shrimp, Penaeus merguiensis using cold shock treatment. Three different temperatures were introduced to the shrimp eggs after 10 minutes of spawning which are 10°C, 15°C and 20°C with 3 different times of exposure (10, 15 and 20 minutes) for each temperature. Three hours after treatment, 20 eggs from each treatment were collected for chromosome analysis. Chromosome numbers were analyzed using Video Karyo Test software version 3.1. It was found that 15°C with duration of 10, 15 and 20 minutes induced 100% triploid (3n). The metaphase chromosome number ranged from 118 -154 with the mode of 132 chromosome. Treatment conducted at 10°C and 20°C for the same duration of time produced diploid, (2n) and the metaphase chromosome number ranged from 86 – 88 with the mode of 88 chromosome. The findings of this study indicate that cold shock treatment at 15°C appears to be the optimum temperature for production of triploid in banana shrimp.

KEYWORDS. Banana shrimp, penaeus merguiensis, cold shock treatment, triploid.

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SUITABILITY OF SEAWEED MEAL INCORPORATED WITH RHODOVULUM SP. BACTERIUM AS FEED SUPPLEMENT FOR FINFISH LARVAE

ABSTRACT. The proximate compositions of three Chlorophyta (Caulerpa sp., Halimeda macroloba, and Halimeda opuntia), three Phaeophyta (Sargassum sp., Padina minor, and Dictyota sp.), and one Rhodophyta (Laurencia sp.) were determined in order to evaluate their suitability for feed supplement. The evaluated seaweed showed variable protein content between 4 to 14% (dry weight). The highest protein level of 14% dry weight (lDW) was determined in Sargassum sp., but this species also recorded the lowest level (0.2-0.5%) of lipid. On the other hand, the highest content of 4% (DW) lipid and 11% (DW) protein level was observed in the species Dictyota. Of the other species, Padina minor from the same group, shows 10% (DW) and 1% (DW) levels of protein and lipid respectively. Seaweed meal of these three species was prepared and mixed separately with 2% of Rhodovulum sp. Thus, three types of supplementary diet were prepared for Tilapia fry feeding trials. Rhodovulum sp. bacterium biomass alone was used as control diet. The preliminary feeding trial showed that the growth and survival of fin fish larvae were improved with the supplemented diet made from Dictyota meal mixed with 2% of Rhodovulum sp. Thus, indigenous self-flocculated phototrophic bacterium Rhodovulum sp. is  improved when used as a feed additive enhanced with this seaweed meal in Tilapia (Oreochromis niloticus) fry rearing period.

KEYWORDS. Growth, Rhodovulum sp., seaweed meal, survival, Tilapia fry.

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TRACKING THE MOVEMENT OF MUD CRABS, GENUS SCYLLA FROM MANGROVE AREA USING TELEMETRY SYSTEM

 

ABSTRACT. The study was conducted to determine the movement of mud crabs, genus Scylla, within three sites in Sematan mangrove forest, Sarawak, Malaysia. 10 crabs were tagged using ultrasonic tags attached to the mid-dorsal carapace surface of each crab. Four tagged crabs were released to the small mangrove channel, another four tagged crabs were released to the main estuary channel and the other two crabs were released to the mouth of the estuary. The hydrophone system and portable Global Positioning System (GPS) on board the tracking boat were used to track the crabs’ locations. Date of release, tracking time, duration of tracking, distance travelled by the tagged crabs, weather conditions and water current direction were among the parameters recorded during the tracking study. Three tagged crabs remained within the small mangrove channel, three tagged crabs remained within the main estuary channel and only one tagged crab remained in the estuary mouth. Tagged crabs remained in the small mangrove channel more than 173 hours but those in the main estuary channel and estuary mouth are a remained for more than 48 hours. Only one crab covered a much greater distance than the other nine tagged crabs, moving a total distance of 2,600 m within 48 hours monitoring. The mean ground speed of the tracked crabs in the small mangrove channel was slower than in the main estuary channel and estuary mouth. The mean ground speed ranged from 0.2 to 3.8 m.h-1 in the small mangrove channel and from 15.2 to 54.2 m.h-1, both in the estuary channel and estuary mouth. 390 crab movements were recorded of which 157 (40.3%) crabs moved with the current and 233 (59.7%) crabs moved against the current with 32.45 m.h-1 mean ground speed. From the half an hour and hourly interval monitoring, the crabs were mainly active at night with the mean distance travelled being 808.3 m and mean ground speed 44.7 m.h-1. During day time, the mean distance travelled was 482.8 m and ground speed 20.7 m.h-1. No continuous movement was recorded even though the crabs were active at night especially from midnight till sunrise. The direction of travel was not straight with the straightness index range from 0.2 to 0.3 except for one crab which moved nearly in a straight line with a straightness index of 0.9.

KEYWORDS. Telemetry system, ultrasonic tag, movement, mud crab, genus Scylla.

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ROCK CUT SLOPE STABILITY EVALUATION OF THE CROCKER FORMATION ALONG JALAN UMS, KOTA KINABALU, SABAH

ABSTRACT. The aim of this paper is to present the result of an evaluation of the cut rock slope stability of the Crocker Formation along Jalan UMS, Kota Kinabalu, Sabah. Geological mapping, discontinuity survey, and kinematic analysis have been conducted on ten (10) selected cut rock slopes in the study area. Result of kinematic analysis shows that wedge, toppling and planar failures are potential in five cut rock slopes. However, no potential modes of failure are identified in cut rock slopes numbers 2, 7, 8, 9 and 10. Flatten slope range from 30o to 55o, wire mesh and drainage ditches are proposed as mitigation measures for the cut rock slopes in the study area.

KEYWORDS. Slope stability, crocker formation, Kota Kinabalu, mode of failure, optimum slope angle.

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A STUDY ON THE PERFORMANCE OF IMPEDANCE MATCHING CIRCUIT IN PARTIAL DISCHARGE MEASURING SYSTEM

ABSTRACT. Partial discharge (PD) phenomena often result in serious faults in insulation. They may lead to electrical breakdown and cause loss of revenue to repair and replace the damaged part of the electrical equipment due to lack of precise and early detection of PD occurrence. PD measurements are important diagnostic tools to monitor the insulation condition of a device. Filtration in a PD measuring system is essential to eliminate or reduce noise pulses from affecting the measurement value. The device that is widely used nowadays is a high pass filter (HPF). In this project, an alternative filter device is established and studied, which is an impedance matching circuit (IMC). The aim of this project is to build an IMC in a PD measuring system for filtration purposes. The IMC is then measured to observe its characteristics and performance as a filter device in a PD measuring system. By measuring the number of PD occurrences and magnitude of PD on an insulation sample, the outcomes of PD obtained in the measurement system of impedance matching circuit are compared with those in high pass filter. From the tests, it was observed that IMC shows a smaller number of false PD occurrences and higher individual PD magnitude of each occurrence compared to HPF. Thus, the PD can be observed clearly even at smaller supply voltages by using IMC and breakdown of insulation can be avoided.
KEYWORDS. Partial discharge (PD), Impedance matching circuit (IMC), High pass filter (HPF).

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EFFECT OF MICRO-FABRICS ON UNIAXIAL STRENGTH OF WEATHERED VOLCANIC ROCKS FROM TAWAU, SABAH

ABSTRACT. This paper discusses the effect of micro-fabrics on uniaxial strength of weathered volcanic rocks from Tawau, Sabah. Volcanic rocks consist of basalt and andesite, aged from Pliocene to Quaternary. Weathered rock samples with grade range from slightly weathered (II) to completely weathered (VI) were collected from the road-cut slopes. Micro-fabric analysis was performed using polarizing microscope and Scanning Electron Microscope (SEM) techniques. Uniaxial strength analysis involved Point Load Test index (PLT) and Unconfined Compression Strength (UCS) test. The petrography analysis of basalt showed the domination of plagioclase with existence of orthoclase and pyroxene in aphanite texture. Meanwhile andesite consists of plagioclase, feldspar and amphibole in porphyritic matrix. Basalt samples with weathering grade from II to V showed the alteration of primary minerals from 12% to 55% and Imp (micro-petrography index) value ranging from 8.8 to < 0.2. Meanwhile andesite showed alteration of primary minerals ranging from 15% to 60% with Imp value of 4.9 to < 0.4. Andesite contains 16.8% stable minerals of quartz and feldspar phenocrysts that remain intact throughout the weathering process. Uniaxial strength results indicated that andesite exhibited a higher strength with value from 181.2 to 87.7 MPa while basalt showed 127.2 to 35 MPa. The porosity of andesite with Grade II to V was 4.1% to 49.5% whereas basalt ranged from2.5% to 47.8%. The uniaxial strength of Grade V showed basalt is slightly higher than andesite with 0.3 MPa and 0.2 MPa respectively. This is due to the presence of more clay minerals in basaltic soil (75.1%) than in andesite soil (65.2%). This study showed that the weathering process is able to alter the micro-fabric characteristics of rocks which contributes to the decrement of the strength of volcanic rocks.

KEYWORDS. Micro-fabrics, uniaxial strength, volcanic rocks, weathering.

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EXTRACTIONS, PHYSICOCHEMICAL CHARACTERIZATIONS AND SENSORY QUALITY OF CHICKEN FEET GELATIN

 

ABSTRACT. This study was carried out to determine the percentage of gelatin yield (w/w) extracted from chicken feet (CFG), and to compare the physicochemical properties and sensory qualities of CFG with bovine commercial gelatins (CBG). CFG extraction was based on gelatin type B method through three alkaline treatments by soaking in 4% HCl, 10% NaOH then 60°C thermal hydrolysis for 5 hours. A higher percentage of CFG powder was obtained at 18% w/w, and texture profile analysis showed correlation (r2=0.98) between bloom strength and the gel hardness. Proximate analysis has shown that the powder of CFG extracted meets the standard as regulated in Food Act 1983 and Food Regulations 1985 with 6.43% humidity, 1.54% ash, 67.40% protein and 0.42% fat. There were no significant differences (p≥0.05) in ash and fat percentage of CFG and CBG as the values are 1.56±0.01 and 1.36±0.14 for ash, also 0.32±0.01 and 0.19±0.03 for fat respectively. Significant differences (p≤0.05) existed in water and protein percentage of the CFG and CBG with values of 6.64±0.20 and 8.03±0.16 for water, also 67.40±0.82 and 88.18±1.90 for protein. Sensory evaluations showed CFG was less acceptable (n=20) compared to CBG for colour, aroma and texture attributes. The score mean value for overall acceptance of CFG compared to CBG is 5.95±0.39 and 6.65±0.49 respectively.

 

KEYWORDS. Chicken feet gelatin, halal gelatin, food hydrocolloids, nutraceuticals, pharmaceuticals.

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