Genetics and biotechnology

  • RAPD of P. monodon collected from Kakdwip, Chilka lake, Kakinada, Chennai, Cochin and Goa areas were analysed and the dendogram revealed that the samples from Kakdwip, Chilka lake, Cochin, Goa and Kakinada exhibited  more similarity (>0.60). The Chennai stock appears to be farthest from this cluster (0.39)
  • RAPD of Lates calcarifer collected from Kakdwip, Chilka Lake, Kakinada, Chennai and Goa was carried out. The dendrogram revealed that Kakinada and Goa stocks exhibited a similarity of 0.73. The Chilka stocks had a similarity of 0.66 to this cluster. The cluster of Kakinada, Goa and Chilka had a similarity of 0.62 with the Kakdwip stock. Chennai stocks had a similarity of 0.50 with this cluster. The truss morphometry also exhibited a similar trend.
  • The 12s and 16s rRNA genes were amplified in P. monodon. A 415 bp amplified product was obtained from 12s rRNA gene, whereas a 520 bp amplified product could be obtained from 16s rRNA gene by PCR. The RFLP of 16s PCR product when digested with Mbo I showed restriction fragments of  approx. 300 bp and 200 bp. All the PCR products obtained from different regions showed monomorphism. Cla I was found to be a non-informative restriction enzyme and no restriction fragments could be generated using this enzyme.
  • PCR-RFLP of 12s rRNA and 16s rRNA of Lates calcarifer was carried out. A 415 bp amplified product was obtained from 12s rRNA gene, whereas 700 bp amplified product could be obtained from 16s rRNA gene by PCR. The  RFLP of 16s PCR product when digested with Mbo I showed restriction fragments of  approx. 275 bp and 200 bp. All the PCR products obtained from different regions showed monomorphism. Cla I was found to be a non-informative restriction enzyme and no restriction fragments could be generated using this enzyme. Alu I restriction digestion of 12s PCR product showed restriction fragments of approximately 250 bp and 75 bp. However, Alu I also generated monomorphism on samples collected from different regions
  • Restriction pattern profile was observed to be similar in both species of mud-crabs Scylla serrata and Scylla tranquebaricaon using Cla I and Mbo I restriction enzymes with 12s PCR product. Similarly, no difference in both species was observed with restriction pattern of Mbo I restriction enzyme with 16s PCR product. However, the RFLP of 16s PCR product using Hind III restriction enzyme showed a clear distinction in the restriction pattern between the two mud crab species.
  • PCR-RFLP analysis of mitochondrial control region (CR) gene segment in P. monodon revealed sequence variation indicating its usefulness as marker for population studies in penaeid shrimps.  Sequences pertaining to P. monodon, M. japonicus, F. indicus and M. cephalus have been submitted to the Genbank.
  • A 643 bp PCR product of WSSV was labeled using Digoxigenin (DIG) label with sensitivity of 1pg/ul final concentration. The labeled probe was used for detection of virus in the infected tissues.
  • A molecular epidemiological study to identify the Indian strain of WSSV and sequence comparison study of the amplified PCR products of the structural genes was carried out with three reported complete genome sequences of WSSV isolates of China, Taiwan and Thailand. Sequence variations between the four isolates were found only in VP19 and VP24 genes. The conserved nature of WSSV viral structural proteins in different isolates, indicates the suitability to develop immunodiagnostic assays and vaccines targeted against these structural genes which can be used as a common remedial measure against the shrimp viral disease occurring with different WSSV geographical isolates
  • The presence of MrNV in Macrobrachium rosenbergii in India was confirmed by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) and sequencing of the PCR amplified product. A 850 bp amplified product could be obtained by RT-PCR. The nucleotide sequence analysis of 850 bp segment amplified from nodavirus RNA-1 genome, showed  98% and 95% nucleotide identity with West Indies and Chinese isolates respectively whereas 99% amino acid sequence identity was observed with the reported amino acid sequences of West Indies and Chinese isolates.
  • Comparison of growth in pond in 8 full-sib and 2 inbred families of Kuruma shrimp was carried out. The average wet weight after 153 DOC ranged from 23 to 30 g in the full-sib families whereas it was 25 and 30 in the 2 inbred families. The coefficient of variation for wet weight at 153 DOC ranged from 16 to 22% indicating that this trait would respond to genetic selection. The survival ranged from 18 to 52% and the females were significantly heavier (2g) than males (22g).
  • Comparison of resistance to WSSV in the wild and inbred stocks of Kuruma shrimp revealed that there were no significant differences in the survival curves.
  • As part of challenge trials to determine the LD50 dose for WSSV, an experiment was carried out to determine the viral dose that kills 50% of the shrimp (LD50) in P. monodon.  Five different doses of virus (2 X 102, 2 X 103, 2 X 104, 2 X 105 & 2 X 106 viral copies) were tested on 12 shrimps each in duplicate tanks. It was observed that 2 X 102 copies is the LD50dose that kills 50% shrimp.
  • A genetic selection programme for growth and WSSV resistance was taken up in P. monodon. Under the programme, the methodology and protocols for family (visible implant elastomer tagging) and individual (eye-ring tagging) identification were standardized. The study demonstrated substantial additive genetic variability for growth and pond survival. For survival in challenge test, the estimate of heritability indicated the presence of additive genetic variance. The growth performance of tagged shrimps in ponds was monitored over a period of 4 months and results indicated sexual dimorphism for growth. The performance of families from Andhra Pradesh when analysed, indicated a very high correlation between breeding values in two different geographic locations, thereby pointing to a low Genotype x Environment effect.
  • A commercial product called Furanone extracted from Australian marine macro algae (Delisia pulchera) was challenged against luminescence disease causing bacteria Vibrio harveyi among postlarvae of P. monodon.  A dosage of 1mg/ml of furanone reduced luminescence signal and 80% Vibrio inhibition. A similar dosage of fresh garlic extract also inhibited 80% of V.harveyi and reduced the luminescence signal.

Fish meal & fish oil replacement

  • Shrimp feed incorporated with vegetable oils, palm oil, coconut oil, soyabean oil, groundnut oil, sesame, sunflower and rice bran oil replacing 3% of fish oil fed @ 4% body weight of P. monodon indicated that  fish oil can be effectively replaced by  other vegetable oil without compromising growth and FCR.
  • To assess the suitability of plant protein sources as a component in organic shrimp feed, four oilseed cakes, three leguminous tree species leaves and pods, three mangrove species leaves, duckweed, Azolla and Moringa oleifera leaf were analyzed. Among the oil cakes, soybean cake with 40-42% crude protein (CP) can replace major portion of fish meal in organic shrimp diet. Other alternate organic feed ingredients are duckweed, Sesbania, Azolla and Moringa oleifera leaf containing 20-27% CP and seed pods from leguminous tree species (L.leucocephala and Acacia sp.) containing 14-20% CP.
  • Lysine and methionine were incorporated in low fish meal shrimp feed individually and in combination and fed to juvenileP. monodon. This resulted in higher weight gain (194.3%) compared to the control feed without amino acid supplementation (178.7%).
  • Low fishmeal (15%) based shrimp feed developed was tested with P. monodon stocked @ 6 nos./m2 and in 140 days of culture, the shrimp attained average weight of 32g and resulted in 1289 kg production with FCR.of 1.28. 

Seabass feed

  • Developed a weaning micro-diet as supplement/replacement for Artemia nauplii for rearing seabass larvae.
  • A micro diet with 45% protein and 12% lipid developed for nursery rearing of seabass was tested in hapas and nursery ponds of eight farmers in Tamil Nadu and Andhra Pradesh and the results indicated 70% survival in 30 days.  The average body weight attained range from 2-4g in hapas.  In ponds the fry attained 60-80g with 35-50% recovery in 60 days.
  • Seabass fingerlings (9-10g) fed with diets containing high, medium and low levels of protein in 60- day feeding trial showed that they require high protein and high energy diet for better growth. Feeding @ 10, 15, 20 and 25% body weight daily indicated that 5-20% rate of feeding is optimal for of 2-8g and 6-8% for 50g fingerlings.
  • Grow-out feed containing 38% protein and 8% fat was developed as sinking pellets and fed to seabass reared in FRP tanks at Muttukadu and in farmer’s ponds. The feed acceptability was very good and the fish attained 0.8 to 1.0kg in 6-8 months with an FCR of 1.8:1 in FRP tanks.
  • The CIBA pellet feed was tested in farmer’s ponds at Nellore and Bhimavaram. At Bhimavaram, at the end of 8 months 2255 number of sea bass with average body weight range of 900-1100gram and a total quantity of 2000 kg of fish was harvested with a survival 55% and FCR of 2.1. At Nellore, at the end of 6 months 840 kg of seabass was harvested with an average body weight of 1000 gram. Survival was 70% and FCR was 2.0. 

Shrimp feed

  • The indigenous shrimp feed technology developed by the Central Institute of Brackishwater Aquaculture (CIBA), ICAR, Chennai has been successfully commercialized. The feed technology was transferred to M/s Bismi Feeds Ltd., Perunthottam, Tamil Nadu. The Bismi prawn feed was officially launched on 11-10-2008. Bismi Feeds Pvt. Ltd has set up a shrimp feed mill to produce 1 ton of feed per hour with an annual production of 3000 tons and made total investment of rupees 2.5 crores.
  • The feed technology was also successfully transferred to an entrepreneur Sri Tapan Mandal, Village Madhubati, P.O. Kamarpukur, Hoogly Distrcit, PIN- 712612, West Bengal.
  • L- Carnitine, as growth promoting additive was tested at different levels (0.25 to 1.0%) in tiger shrimp feed (fishmeal based) with 38% protein. The feeding trial indicated positive response of the additive (at 0.25% level) on growth of shrimp and FCR.
  • Tamarind seed powder rich in starch was tested for its binding quality in shrimp feeds from 0.5 to 2% levels.  At 1% inclusion level, it can be used as a good feed binder with a water stability of 80-85% for 3 hrs.
  • The dietary effects of aflatoxin B1 on shrimp was studied by incorporating it at 0, 50, 100, 200, 500 and 1000 ppb levels in the feed.  In 30 days, the growth and feed conversion ratio in shrimps fed with diets containing aflatoxin declined from 273% for control to 183% for the test group, although there was no mortality of the shrimps up to 1000 ppb of aflatoxin in the diet.
  • Feeding trials conducted using standard shrimp feed on P. monodon stocked at different salinities ranging from 3 to 50 ppt revealed that best growth (151.33 ± 3.79), FCR, dry matter and protein digestibility were recorded at 20%. The iso-osmotic point haemolymph osmolality and hepatopancreas trypsin activity were highest at low salinity compared to high salinity. The results indicate that P. monodon tolerates lower salinity better than higher salinities (50%).
  • The carotenoids produced by the fungus Monascus purpureus (MP) were used as an additive in shrimp feed. MP was grown in different medium such as shrimp shell powder, tapioca flour powder, wheat flour, raw rice, fish meal powder, fish cooked fish meat etc.  Better growth was observed after eight days in shrimp shell waste powder when compared to others.
  • Shrimp feeds  formulated with plant protein sources, maize gluten and wheat gluten at 5 to 25% level replacing fish meal were fed to tiger shrimp and the results revealed that maize gluten can be incorporated at 10% level and wheat gluten at 15% level individually in place of fishmeal without compromising the growth and FCR.

Crab feed

  • The dietary requirement of vitamin C for juvenile mud crab S. tranquebarica was determined using test diets.  The diet containing 0.6% vitamin C resulted in better growth, FCR and survival of the crab.
  • Pellet feed containing 38% protein was developed for grow-out culture of crabs which resulted in higher growth and production.
  • At Nagayalanka in AP the pellet feed was successfully tested in a farmer’s farm. Stocked 600 juvenile Scylla tranquebarica crabs (40-170g) in each of the three ponds. In two ponds, CIBA  pellet feed was given and in third pond (control) trash fish was used .After six months of culture the farmer harvested 112kg and 97kg from two test ponds (380-485g) and 110 kg from the control pond.  Expenditure incurred on pellet feed (400 kg)  Rs.6,400/- in each pond and Rs.7,200/- in control pond (720 kg).
  • Pellet feed for mud crab fattening was demonstrated with the involvement of fishermen and women self help groups and the results indicated that CIBA feed performed equally well as trash fish.
  • Experiments were carried out to determine nutrient digestibility of fish meal from sardine, Acetes meal, soy flour, wheat and rice in S. tranquebarica. The results indicated that both animal and plant protein sources are effectively utilized by the mud crab. Evaluation of energy sources revealed that rice is better utilized than wheat.

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