J.Syama Dayal

Central Institute of Brackishwater Aquaculture, Chennai, Tamil Nādu, India

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Publications (10)4.87 Total impact

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    ABSTRACT: Among the emerging diseases in shrimp aquaculture, monodon slow growth syndrome (MSGS) is a major concern in South and Southeast Asia. Shrimp farming in Thailand was severely affected during 2000-2002 due to MSGS, which caused an economic loss, of about US$ 300 million. MSGS is characterized by abnormally slow growth with coefficients of size variation of >35 %, that has impacted P. monodon production in Thailand. A new shrimp virus, Laem-Singh virus (LSNV) was identified to be associated in MSGS affected shrimp. LSNV a RNA virus of about 25 nm diameter is phylogenetically related to the insect-borne viruses in the families Barnaviridae, Tymoviridae and Sobemoviridae an important histopathological observation is exclusively noticed in growth-retarded shrimp. The LSNV infections have been confirmed in various organs of infected shrimp such as lymphoid organ, gills and nervous tissues by various diagnostic techniques such as reverse transcription polymerase chain reaction (RT-PCR), in situ hybridization, quantitative real-time RT-PCR and reverse transcription loop-mediated isothermal amplification combined with a lateral flow dipstick (RT-LAMP-LFD) and these tools are available for the diagnosis of LSNV. Recently, an integrase containing element has been identified in absolute association with LSNV in stunted growth shrimp. The transmission of LSNV through horizontal and vertical routes has been experimentally demonstrated. The known natural host-range of LSNV includes P. monodon and other penaeid shrimp. The putative RdRp gene involved in replication of LSNV was targeted for dsRNA-mediated gene silencing and appeared to be effective in a dose-dependent manner. Since the discovery of LSNV in 2006 in Thailand, it has been added to the list of viruses to be excluded from domesticated specific pathogen-free stocks of P. monodon and it has been recommended that shrimp farmers avoid stocking post larvae positive for LSNV to prevent MSGS in their farms.
    Indian Journal of Virology 09/2012; 23(2):215-25. · 0.36 Impact Factor
  • National Conference on New vistas in Indian Aquaculture; 02/2012
  • National Conference on New vistas in Indian Aquaculture; 02/2012
  • 9th Indian Fisheries forum; 12/2011
  • 11/2011;
  • The 13th Biennial Conference of Animal Nutrition Society of India; 12/2009
  • The 13th Biennial Conference of Animal Nutrition Society of India; 12/2009
  • I S Azad, J Syama Dayal, M Poornima, S A Ali
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    ABSTRACT: Juveniles of milkfish, Chanos chanos (Forsskal), were fed two independent supra dietary levels of vitamins C (500 and 1500 mg kg(-1) feed, T1 and T2) and E (50 and 150 mg kg(-1), T3 and T4). Milkfish fed diets with supra (in addition to the vitamins present in the control diet) and normal levels (T5 containing 90 and 1.2mg of vitamins C and E, respectively, kg(-1) of feed) of vitamins were immunized (ip) with formalin-killed Vibrio vulnificus (FKVV). Priming and booster antibody responses to the injected bacterin were significantly (P<0.05) better in the milkfish juveniles fed supra dietary levels. Survival response of the experimental fish fed supra dietary levels of vitamins (T1, T2 and T3) was significantly (P<0.01) better than that of the control set. Protective response against virulent bacterial challenge of the vaccinated fish fed vitamin-supplemented diets (T2 and T3) was better than the control (T5) and T1 and T4. Memory factor reflecting immunological memory was superior in the fish fed vitamin-supplemented diets. Diets supplemented with either 1500 mg of Vitamin C or 50mg of Vitamin E kg(-1) produced the best antibody responses, final survival and protective response upon challenge. No conclusive inferences could be drawn on the growth responses from the experiment.
    Fish &amp Shellfish Immunology 08/2007; 23(1):154-63. · 2.96 Impact Factor
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    ABSTRACT: Fertilized eggs and developing larvae of hatchery reared Asian seabass, Lates calcarifer (Bloch), were analyzed to determine the changes occurring in their proximate and amino acid (AA) composition. The fertilized dry egg weighed 31 μg and contained 13.71 μg (44%) protein, 8.48 μg (27%) lipid and 0.657 J of gross energy. Dry weight decreased by 39% during hatching. The protein, lipid and carbohydrate nutrients decreased by 4.86, 4.15 and 0.09 μg, respectively from egg to 2-days post hatching (dph) larvae (pre-feeding). The protein content of the spawned eggs and larvae were hydrolysed to AA in the laboratory. The fertilized eggs had a total AA content of 42% of their dry weight. The egg contained 1.287 μg, 1.132 μg, 0.964 μg, 0.942 μg, 0.787 μg and 0.713 μg of leucine, lysine, arginine, valine, threonine and phenylalanine, respectively and these six indispensable amino acids (IAA) constituted approximately 78% of the total IAA. In the early feeding stages of L. calcarifer larvae, the ratio of IAA/DAA increased from 0.797 in the pre-feeding stage to 1.632 after 2 days of feeding. During larval growth of L. calcarifer, the percentage contribution of isoleucine and leucine to total IAA contents increased, while it decreased for lysine, phenyl alanine and arginine. L. calcarifer larvae were found to have proteins, which are rich in glutamic acid, leucine and lysine, and poor in threonine and histidine, suggesting high dietary leucine and lysine IAA requirement.
    Fish Physiology and Biochemistry 01/2003; 29(2):141-147. · 1.55 Impact Factor
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    ABSTRACT: Protein being the most important and expensive nutrient in shrimp feed, determination of its appropriate level in relation to the digestive capacity of shrimp is essential in order to make the feed cost effective as well as to minimize the nitrogenous waste excretions. Six diets having different levels of crude protein (30-41 %) were investigated by in vitro digestibility method using the homogenate of hepatopancreas (digestive proteases) of tiger shrimp Penaeus monodon. Peak digestibility of dietary protein was observed at 3 hours incubation. Maximum digestibility of protein (69.19 %) was recorded with diet having 35.28 % protein. The in vivo results in tiger shrimp (2.0 g) also showed that the weight gain in the shrimp was also highest at this dietary protein level. The average apparent protein digestibility was highest (76.02 %) in animals fed with diet having 35 % crude protein. The results of the study suggested that dietary protein for P.monodon can be lowered to 35 %, considerably reducing the cost of the feed and making it more environmental friendly. [ Key words: Digestibility, enzyme studies, Penaeus monodon, shrimp nutrition ] Compounded feeds play a major role in penaeid shrimp culture, constituting up to 60 % of total costs 1 . Protein is the most critical ingredient in shrimp diets in terms of its cost 2 as well as growth of shrimp 3 .The feeds must be nutritionally adequate and economical. The protein requirement for optimal growth of penaeid species has been reported to be in the range of 35 and 61 % 4-6 . The pronounced differences in re-ported protein requirements may be due to different protein sources, dietary energy levels in diets and rearing conditions used in these studies. One of the factors in the environmental management in aquacul-ture is the feed related nitrogenous wastes. Nitrogen is provided in high concentrations in shrimp feed but most (80 %) of it is added to the ponds and it is not retained as shrimp biomass 7 . The low retention of die-tary N can be caused by several factors : sub optimal feed formulations or quality of ingredients, and poor water stability of feeds 8 . Therefore, determination of protein level vis-à-vis the digestive capability of the shrimp, will help not only in optimizing the protein levels in feed but also reducing the nitrogenous waste generation, and makes the feed more cost effective and environmental friendly. The digestibility of protein in shrimp diets is prin-cipally determined by feeding trials using inert mark-ers, which are often time consuming and expensive. The in vitro digestibility method, though may not re-place the conventional digestibility method, but it can be used to assess the potential digestibility of diets and feed stuffs 9 . Digestive proteases from the test animal rather than those commonly used and com-mercially available (i.e. from mammals or micro-or-ganisms), can better assess the digestibility of pro-tein 10 . The present study was aimed at investigating the effect of dietary protein level on its in vitro and in vivo digestibilities in the tiger shrimp Penaeus monodon Fabricius (Crustacea: Decapoda: Penaeidae), based on which more appropriate level of protein in shrimp diets could be suggested.