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Open Access
Effect of eyestalk ablation on androgenic gland and male secondary sexual characters in Macrobrachium Idella (Hilgendorf)
(Department of Aquaculture, College of Fisheries,Panangad, 1998) Sherine Sonia, Cubelio; KAU; Thampy, D M
The present study in the prawn, Macrobrachium idella was taken up to find out morphotypic variation among the males, the endocrine basis for these variations and also to know the role if any, the eyestalk endocrines have, on the control of androgenic gland, which in turn is controlling the development of male primary and secondary sex characters. The study conducted to find the relationship between development of sex characters with that of androgenic gland conducted using 30 male prawns of different sizes has ShO\\-l1 that these sex characters are under the control of androgenic gland and have no relationship with that of the body size. Of the 30, 22 individuals were found to have a bodylength to cheliped length ratio below 1: 1.5, their androgenic gland and appendix masculina, not fully developed indicating that they are reproductively inactive. Remaining 8 individuals have a body length to cheliped length ratio above I: 1.5. They have well developed androgenic gland and appendix masculina showing that there is positive correlation between the biomass of androgenic gland and the cheliped length. An experiment conducted to find out the effect of unilateral eyestalk ablation on growth and development of primary and seconadry sexual characters as well as on the androgenic gland, had shown that destalking brings about a positive change in the development of androgenic gland and sex characters. The increase in the size of the androgenic gland and consequent hypertrophy of primary and secondary sexual characters brought about as a result of unilateral eyestalk ablation do indicate that the GlH, a hormone produced in the eyestalk has got an inhibitory effect on androgenic gland as well as on the growth of the prawn, which when removed by " destalking" , results in the enlargement of the androgenic gland and other sexual characters.
Open Access
Integrated culture of fish with micropropagated plants in a recirculatory system
(Department of Aquaculture, College of Fisheries,Panangad, 2012) Navya, R; KAU; Devika Pillai
An experiment was designed to study an integrated recirculatory sytem with micropropagated aquarium plants, fish and indigenous filter materials like coir, vetiver and bamboo as the filter media. The plants selected for the study were Bacopa caroliniana, Anubias minima, Aponogeton ulvaceus, Rotala rotundifolia and Nymphoides cristata. The first part of the work was to standardise the micropropagation techniques for the above said plants. Murashige and Skoog medium (half and full strength) was used as the basal medium for the establishment of cultures. The explants varied from nodal segments, rhizome buds, leaf petioles and lateral buds. Surface sterilization was carried out with a range of sterilants like mercuric chloride solution, ethyl alcohol, sodium hypochlorite solution etc. for varying durations and concentrations depending on the type of explant. Effect of growth regulators on explants were studied using auxin IAA and cytokinins, BA and Kn. A liquid culture media with 1.5mg l-1 BA and 0.1mg l-1 Kn concentrations was the best medium for Bacopa caroliniana. A combination of auxin cytokinin like 1.5 mg l-1 BA and 1.0 mg l-1 IAA in liquid culture was the best medium for Rotala rotundifolia. In Nymphoides cristata, hormone concentration of 1.0 mg l-1 each of BA and IAA in liquid culture gave the best results. In Anubias minima, a full MS solid medium with 6.0 mg l-1 of BA gave better results compared to lower levels of BA. In vitro trials for Aponogeton ulvaceus was not successful due to the exudation of phenolic extracts in all the treatments which eventually lead to the death of the tissues. Hardening success was 90 percent, 100 percent, 70 percent, 100 percent in the case of Anubias minima, Nymphoides cristata, Rotala rotundifolia and Bacopa caroliniana respectively. The micropropagated plants were incorporated in the recirculatory system along with fish and three different biofilter materials like coir, vetiver and bamboo splits. The study focused mainly on the filtering efficiency of the three filters based on the nitrification curves. The plants were included in the system to be a part of biofilter and their exclusive role in nitrification was not studied since this is a preliminary work. A nitification graph was plotted with the observed values of ammonia, nitrite and nitrate in the three different biofilter systems and compared with a control. It was inferred that coir fibres were the best of filter materials tried in nitrification followed by bamboo and vetiver. The control system took more time (45 days) in stabilizing ammonia levels due to lack of a substratum for growing nitrifying bacteria.
Open Access
Evaluation of growth in Penaeus Monodon Fabricius by incorporation of selected nonhormonal growth promoters in the diet
(Department of Aquaculture, College of Fisheries,Panangad, 1997) Vinodh, M P; KAU; Susheela, Jose
The effect of three growth promoters viz. Chitin, chitosan and glucosamine each at three levels (0.25, 0.5 and 1g per 100g diet) were evaluated in P.monodon early juvenile for a period of 70 days. The three growth promoters at three level were tested with 3 replicates for each treatment. The growth promoters were incorporated into a soyflour clam meal based practical diet containing 40% protein and fed to the shrimps adlibitum. The results showed that the overall growth was not affected by dietary inclusion of chitin though the growth rate at 0.25g chitin per 100g diet was comparatively better than that of the control diet. Chitin does not seem to have any effect on specific growth rate of the juveniles although incorporation at 0.25g/100g diet improved the food conversion of the animal significantly over the control. Percentage survival values were also not significant at any level of incorporation. It does not seem to improve protein efficiency ratio and productive protein value too. Incorporation of chitosan at 0.25 and 0.5g/100g diet significantly improved the weight gain, specific growth rate, food conversion ratio, protein efficiency ratio and productive protein value. However inclusion of chitosan at 1g/100g diet did not have any effect on growth though it significantly improved food conversion ratio, protein efficiency ratio and productive protein value. None of these treatments had any effect on survival of the animal. Incorporation of glucosamine into the diet at 0.25g/100g diet was found to be the most efficient amongst the different treatments as evidenced by various growth parameters. It was significantly different from all other treatments in terms of growth, productive protein value and protein efficiency ratio. However it was not significantly different from glucosamine incorporation at 0.5g/100g diet in terms of specific growth rate and food conversion ratio. Enhancement of glucosamine level to 1g/100g diet was found to give poor result compared to the control. The survival rate of shrimps were not significantly different among the treatments. Hence in the present study, glucosamine was found to be superior to chitin and chitosan as a growth promoter and the optimum level was identified as 0.25g/100g diet for P.monodon juveniles
Open Access
Effect of different diets on growth and survival of angel fish Pterophyllum scalare (Lichtenstein) fry
(Department of Aquaculture, College of Fisheries, Panangad, 1997) Neelakanteswar, A; KAU; Mathew, P M
The effect of different diets on the growth and survival of Angel fish, Pterophyllum sealare (Lichtenstein) larvae was studied. One day old free swimming hatchlings were used in the study for a period of 30 days. The different diets used were Artemia nauplii, Moina micrura, artificial diet, Artemia nauplii + Moina micrura and Artemia nauplii + artificial diet, with four replicates for each treatment. The experiment was repeated twice in order todetermine the consistency of the result. The results showed that the growth of larvae, in terms of gain in length and weight and specific growth rate, was maximum with the mixed diet of live foods. The differences in growth between artificial diet and mixed diet of Artemia nauplii + artificial diet were not consistent. No significant difference was found in the survival rate of larvae fed different diets. O:N ratios showed that the nutritional state of the larvae fed artificial diet was more or less similar to that fed mixed diet of Artemia nauplii + artificial diet, which in turn was comparable with that fed live foods. Thus, the artificial diet has been found to be an effective replacement diet in the larval rearing of Angel fish.
Open Access
Differential growth in the giant freshwater prawn Macrobrachium rosenbergii (De Man) during nursery rearing phase
(Department of Aquaculture, College of Fisheries, Panangad, 1997) Mainuddin, Ahmed; KAU; Thampy, D M
The present study was conducted on freshwater prawn Macrobrachiumrosenbergii (De Man) to find the effect of stocking density and provision of additional substrates in rearing tanks, on differential growth among different size groups of juveniles during early growth phase. The first experiment conducted with various stocking densities ranging from 25 to 800 nos/m2 had revealed that the differential growth and the average size of the post larvae were inversely proportional to the stocking density; however the total biomass production was directly related to the stocking density. The survival rate was not much affected by variation in the stocking density, being almost uniform (87 – 100%) among various treatments. The second experiment has shown that provision of additional substrates could not help to reduce differential growth, rather it enhanced it. However it helped to enhance the average growth, total biomass production and the survival rate. The size grading of juveniles after an initial nursery rearing period of 35 days, into four groups such as small, medium, large and a recombined control group and growing them separately for another 35 days has revealed that the size grading helped in reducing the differential growth and increasing the total biomass production, but could not help to increase the survival rate. It was found that the total biomass production in large size group was about four times higher than that of the small size group and about two times than that of the control group, indicating that growing M. rosenbergii juveniles in grow out systems after size grading and discarding the smaller size group, will be advantageous for increasing production. The male secondary sex character, the appendix masculine was found to appear after 154 days of metamorphosis, when the prawn had reached a size of 6.2 cm and 1.75 g. An allometric pattern of growth was observed in case of appendix masculine wherein a higher ratio of 1:1.34 was recorded in comparison to 1:1.14 of that of the endopod of the second pleopod, in the subsequent moult.
Open Access
Characterization of different stocks of Macrobrachium rosenbergii and development of genetically improved strain through selective breeding
(Department of Aquaculture, College of Fisheries, Panangad, 2010) Shyla, G; KAU; Mohanakumaran Nair
Giant freshwater prawn Macrobrachium rosenbergii (de Man, 1879) is an important species suitable for culture in inland and low saline coastal water bodies. Information on the genetic structure and variation among cultured species are essential for genetic approaches to optimize conservation strategies and breeding programmes for improving stocks. DNA based markers can be used to assess more precisely the genetic variations in the entire genome. Natural populations of M. rosenbergii inhabiting the rivers in different geographical areas of India show wide variation in morphological traits and economic characters. The present work envisages studying the genetic diversity of wild populations of M. rosenbergii collected from different parts of India through phenotypic characters and molecular marker studies. It also aims to develop a superior strain by combining the desirable characters through selective breeding. In this study genetic characterization of Andhra Pradesh (AP), Orissa (OR) and Kerala (KR) stocks of Macrobrachium rosenbergii were done with RAPD and Microstellite markers. Marker analysis showed variation between stocks and AP showed more genetic distance from OR and KR populations.Moreover KR stock from Achankoil River showed slight similarity with AP. Phenotypic trait analysis was done with three stocks. Egg diameter, larval hatch fecundity, larval rearing period, survival rate and larval length were estimated. Highest egg diameter and hatch fecundity were shown by OR and KR populations. AP showed minimum larval rearing period and maximum survival rate. Maximum larval length was for KR. Stress tolerance studies were conducted in V and X stage of M.rosenbergii larvae with temperature, salinity, formaldehyde and ammonia to estimate the relative differences in the ability of different populations to withstand stressed conditions. Among base population KR population showed highest tolerance towards temperature, salinity, formaldehyde and ammonia.Stage wise tolerance variations also found in all populations. X stage showed more tolerance to all stressors except ammonia. Comparison of other economically important parameters such as disease resistance, quality of flesh, percentage survival, growth rate, percentage morphotypes and head tail ratio were also done. Disease resistance was tested with white tail virus and bacteria (Enterococcus aerogenes) by challenge study. In both studies KR population exhibited better tolerance than other populations. Prophenoloxidase activity and total haemocyte count was also estimated in infected prawns to check the immune response. Here again KR showed higher activity and count. Flesh quality of three populations was estimated by carcass proximate analysis. In this study, no variation in body composition was shown by three stocks. Percentage survival rate and weight gain of three populations in cage were estimated. Maximum survival rate was found in AP and highest growth was found in KR stock. Analysis of percentage morphotypes of various populations showed the maximum OC for AP and SM for OR stock, with no significant variations in percentage BC and female prawns, head tail ratio, which was calculated to find out the yield of meat revealed the least ratio for KR. Large healthy prawns of the three stocks were selected from families showing better performance. Breeding experiment was conducted to produce six crosses viz. Andhra Pradesh (male)×Orissa (female) APOR, Orissa (male) × Andhra Pradesh (female) ORAP, Andhra Pradesh (male) × Kerala (female) APKR, Kerala (male) × Andhra Pradesh (female) KRAP, Orissa (male) × Kerala (female) ORKR, Kerala (male) × Orissa (female) KROR. Different phenotypic characters and economically important traits of F1 generations of hybrids were also studied. KROR showed better egg diameter, hatch fecundity, larval survival rate and larval length. But larval rearing period was minimum for APKR. KROR showed resistance to viral and bacterial diseases, which was similar to that of KR and better than other hybrids. In cage culture APOR showed better survival rate, while growth rate was significantly higher for KROR, which was more than that of base populations. Analysis of percentage morphotypes showed a similar pattern as that of base populations. Lower head -tail weight ratio was shown by KROR, which was lower than that of KR. Estimation and comparison of heritability of weight of three better performing hybrids were done. From the data it was found that maximum heritability of weight was for KROR (.75) followed by APKR (.161) and APKR exhibited no heritability.
Open Access
Commercial probiotics in tank reared nursery phase of freshwater prawn,Macrobrachium rosenbergii (De man, 1879)
(Department of Aquaculture, College of Fisheries, Panangad, 2005) Beryl, E B; KAU; Mohanakumaran Nair, C
The efficacy of two commercial probiotics, Waves and Epicin on the growth and survival of M. rosenbergii PL and on the chemical and biological characteristics of water and soil were studied. The experimental set up consisted of fiberglass tanks of 70 l capacity with two treatments and a control, each with 5 replicates. Soil from a fishpond was filled to a height of 5 cm and water filled to a height of 25 cm. The post larvae were stocked @ 500 no/m2 and mild aeration provided. Commercial freshwater prawn feed starter 1 (Higashi) was given @ 100% of body weight. Analysis before the introduction of probiotics showed the presence of microorganisms such as E. coli, Salmonella, Hafnia alvei, Faecal Streptococci, Aeromonas caviae, A. sobria, A. hydrophila and Enterobacter aerogenus in the water and soil. Enterobacteria such as Enterobacter aerogenus, Hafnia alvei, Aeromonas sobria and A. hydrophila were present in the PL. The probiotics Waves and Epicin were added @ 0.5 ppm and 0.25 ppm respectively to the experimental tanks once in ten days and the microbiological observations and water quality parameters were studied once in 15 days. The introduction of the probiotics increased the growth and survival and reduced the F.C.R. of M. rosenbergii in nursery system. The species composition of the bacteria in the soil, water and body of the animal were not affected by treatment with probiotics, other than that the E. coli present originally and continued in the control was not detected in the tanks treated with probiotics. The T.P.C. was also less in the treatments compared to the control. Probiotics considerably reduced the level of NH3-N in culture tanks. Epicin was found to have reduced the NH3-N level effectively than the Waves.
Open Access
Cryopreservation of spermatozoa of critically endangered yellow catfish Horabagrus Nigricollaris (Pethiyagoda & Kottelat 1994)
(Department of Aquaculture, College of Fisheries, Panangad, 2007) Rajani Vadthya; KAU; Dinesh, K
In order to develop gene banking techniques aimed at conserving the critically endangered black collared yellow catfish of the Western Ghats, Horabagrus nigricollaris and popularize this species in the aquaculture scenario a study on cryopreservation of spermatozoa was undertaken. Freshly collected milt was observed for its characteristics. Well water was used to activate the milt in various stages of the experiment. There was no significant difference in motility of spermatozoa or percentage hatching from fresh and milt cryopreserved using 10% dimethyl sulfoxide (DMSO). Screening of four extenders (A, B, C and D) containing NaCl, KCl, CaCl2, NaHCO3, KH2PO4, MgSO4.7H2O, Na2H PO4 and Glucose at various proportions clearly indicated that the extender composition had significant effect on the percentage of motility, fertilization and hatching. Selected milt samples were preserved under cryogenic condition and utilized for experimental spawn production. The quality of milt samples was analyzed for the spermatocrit value, sperm density, pH, motility score and time: values obtained ranged from 57.8 to 59.8%; 16.5 x 109 to 20.9 x 109 spermatozoa/ ml of milt; 7.2 to 7.4; 4+ to 5+ (i.e. 80-100%) and 30 to 70 seconds respectively. The most promising combination was extender - A with 10% DMSO as the cryoprotectant. The ratio of milt and diluent was 1:4. Samples were equilibrated at 0°C ± 4°C on ice and vapourised over liquid nitrogen fumes for 10 minutes and finally stored in liquid nitrogen for three months. Stored milt samples were thawed and utilized to fertilize the eggs. Quick thawing procedure (27°C ± 2°C for 7 seconds) was followed. A French straw containing 0.5ml milt was found to be sufficient to fertilize 200 eggs approximately. Average fertilization % obtained was 30.3 ± 2.8 for extender- A against 35.8± 0.4 for the control. Mean hatching % obtained was 35.0 ± 4.7 for extender - A and 41.6± 4.4 for the control. No significant difference in fertilization success was found between cryopreserved sperm and untreated sperm from the same milt samples. Viable hatchlings were produced from milt that had been cryopreserved for three months indicating the feasibility of establishing a cryopreservation protocol to bank the genes and popularize the aquaculture of this critically endangered species. With the rapid global expansion of aquaculture, there is a need for year-round availability of larvae that could, to some extent, be met through cryopreservation of gametes.
Open Access
Utilization of water spinach Ipomoea aquatica leaf meal as protein source in the feed of Macrobrachium rosenbergii post larvae
(Department of Aquaculture, College of Fisheries, Panangad, 2007) Sijimol, A P; KAU; Thresiamma James
The present study aimed to find out the feasibility of using water spinach leaves as a low cost plant protein source and dietary evaluation of the formulated diet through growth trials employing post larvae of Macrobrachium rosenbergii, thus to determine the optimum level of substitution of spinach leaf meal. The experiment was done for a period of 60 days. A comparison has also been made between the diets having various levels of inclusion of water spinach leaf meal over the control diet without spinach leaf meal. Five isonitrogenous test diets T1 to T5 were prepared with 30% crude protein. The feed ingredients used were clam meat, Ipomoea aquatica leaf meal, wheat bran, ground nut oil cake, tapioca flour, vitamin mineral mixture and sunflower oil. The control diet T1 was prepared by using all ingredients mentioned above, without Ipomoea leaf meal. The test diets T2, T3, T4 and T5 were prepared by using all ingredients mentioned above and replacing clam meat with water spinach leaf meal at inclusion levels of 12 %, 24 % 36 % and 48 % respectively. Results showed better growth rates in prawn post larvae fed with diets (T2) containing 12% Ipomoea leaf meal. Among the test diets, T2 recorded highest growth rate (603.63 mg). Specific growth rate, food conversion ratio and protein efficiency ratio also showed better performance of prawn post larvae fed on test diet with 12% inclusion of spinach leaf meal. The highest SGR (3.67) and PER (2.99) were recorded in prawns fed on diet T2 and lowest SGR (2.68) and PER (1.48) were obtained with diet T5. The survival rate of post larval prawns were not found to be significantly influenced by the various test diets used and the survival ranged from 77.5% to 82.5%.

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