Gopa Mitra

Modulation of digestive enzyme activities during ontogeny of Labeo rohita larvae fed ascorbic acid enriched zooplankton

The effect of supplementation of ascorbic acid through enriched zooplankton [10%, 20% and 30% ascorbyl palmitate (AP) inclusion in diet of zooplankton] on different digestive enzyme activities during ontogeny of Labeo rohita larvae was studied from 4 day to 15 day post hatch. Ascorbic acid (AA) content in different groups of unenriched (8.6+/-0.71) and enriched zooplankton were, 750+/-29.3, 1409.1+/-45.5, 2009.21+/-199.2 mug/g respectively on dry matter basis with differences (P<0.05) between the treatments. A difference (P<0.05) was found in tissue AA level in different dietary groups. Low amylase, protease, lipase and alkaline phosphatase activities were present in rohu larvae from the mouth opening stage which showed increasing trend with the age of larvae and increasing dietary AA content. A clear dose-dependent modulation of digestive enzyme activities in response to 10%, 20% and 30% AP enriched zooplankton feeding was evidenced from positive correlations between dietary AA content with magnitude of elevation of enzyme activity in different groups. There were 57, 55, 29.2 and 2 fold increases in amylase activity; 7.35, 7.02, 4.43 and 2.73 fold increases in protease activity; 45.636, 41.50, 19.83 and 13.69 fold increases in lipase activity and 6, 5, 3, and 2 fold increases in alkaline phosphatase activity observed in the 15th day post hatch larvae fed 20%, 30%, 10%AP enriched and normal zooplankton respectively, than 4-day post hatch larvae of the respective groups. Enzyme activities were also positively correlated with specific growth rates of wet weight of rohu larvae at the 15th day post hatch. Increased AA might have played an important role in advancing morphological transformation of the digestive tract, protecting gastric mucosa and accelerating growth by the process of tissue formation, which necessitated the requirement of more nutrient thereby, increasing digestive enzyme activity. The regulatory role of AA in the modulation of different digestive enzymes activity and its physiological consequences of nutrient digestibility and utilization during ontogenesis could be extrapolated for better nutrient management of the larvae.

Applied nutrition in freshwater prawn, Macrobrachium rosenbergii, culture.

ABSTRACT The freshwater prawn, Macrobrachium rosenbergii, commonly called ‘scampi,’ is the most important culturable freshwater species of prawn with a fairly high growth rate, wide range of temperature (15-35°C) and salinity tolerance. The nutrients required by this species for growth and associated physiological functions are similar to those required by other crustaceans. Current data suggest that a digestible protein level of above 30 is required for maximum growth and protein efficiency. Ingredients such as mussel meat meal, squid meal, and shrimp meal serve as potential sources of protein in formulated diets. The complete quantitative requirements for all the essential amino acids for this prawn species have not yet been worked out. With respect to non-protein energy supply in the form of carbohydrate, studies indicated that scampi is capable of utilizing various carbohydrate sources efficiently. Dietary carbohydrate in the form of complex polysaccharides appears to be more effective as an energy source. Like other crustaceans, scampi also has limited ability to synthesize sterol from acetate and mevalonic acid. Quantitative estimates of the essential fatty acid requirements have been made in post-larval scampi. Data on vitamin and mineral requirements are scarce. Recent developments in diet formulation, practical feeding practices and the aquaculture potential in India have been indicated with emphasis on sustainable production.

Dietary essentiality of ascorbic acid in rohu larvae: Quantification with ascorbic acid enriched zooplankton

Carp larvae, like any other fish larvae dependon natural food during first few days of theirlife. In nursery conditions, high mortality andslow larval growth are of common occurrence;sub-optimal nutrition might be a possiblereason for such consequences. To improve thesituation the effect of feeding ascorbicacid-enriched live food on survival, growth,tissue biochemical composition includingascorbate level was evaluated in first feeding(3 days old) larvae (av. wt. 2.2 mg) of therohu carp, Labeo rohita (Ham.) for aperiod of 15 days (temp. 28.6 ± 1 °C)under natural photoperiod. The larvae (stockingdensity 10 l−1) were offered enriched andnon-enriched zooplankton ad libitumfollowing a rigid schedule with four feedingregimes, each having 3 replicates. In treatmentT1, non-enriched zooplankton (Moina,Daphnia, Cyclops, Diaptomus) and in T2,T3, T4 ascorbic acid enriched (12 henrichment) zooplankton [@10%, 20% and 30%ascorbyl palmitate (AP) inclusion in diet ofzooplankton] were offered. Highest survival(90%) and growth (9563% live weight gain)could be seen in T3 group and the lowestin T1 (62% survival and 805% live weightgain), thus confirming the dietary essentialityof ascorbic acid for rohu larvae. Therequirement has been shown to be 1409 µg/gdry diet. Whole body tissue analyses for crudeprotein, total lipid and RNA: DNA ratiofollowed the same trend as that of growthresponse and percent survival. Significantpositive correlation (r = 0.949 and 0.861) couldbe found with muscle RNA/DNA ratio and muscleRNA content with specific growth rate indifferent treatments. Significant differencewas found in tissue ascorbate levels betweenenriched plankton fed groups, being highest in T3. Such live foodmediated vitamin transfer might be an effectivemeans to provide higher plane of nutrition forhigh survival and rapid growth for rohu larva.

Growth, Nutrient Utilization, and Tissue Biochemical Changes in Rohu, Labeo rohita, Fed with Natural and Prepared Diets

Abstract A feeding trial was conducted in the laboratory (20-26°C) to evaluate the growth response, nutrient utilization and certain tissue biochemical changes in rohu, Labeo rohita, fingerling (average weight 3.0±0.47 g) fed with a natural and a prepared diet in ×feeding regimens (T1, T2, and T3) for a period of 90 days. The main objective was to investigate live and prepared diet effects on growth rate and associated biochemical parameters. Three tanks per treatment were used as replicates. The T1 group was fed exclusively with mixed plankton as natural diet; the T2 group was fed a combination of prepared diet and mixed plankton in a ratio of 1:3; the T3 group was fed the prepared diet only. The three groups were provided with the same feeding rate. The best performance in terms of fish growth, nutrient utilization, protein and lipid deposition in muscle was observed in the T2 group. RNA/DNA ratio in liver and muscle was the highest in T2, followed by T3 and T1. A positive correlation (r = 0.71) was obtained in muscle RNA concentration with respective specific growth rate of fish in different dietary treatments, and the same was indicated in the case of muscle and liver RNA:DNA ratio and total RNA and DNA content, indicating growth changes were due to the different rates of protein retention. Perusal of the amino acid composition of whole body tissue of T2 and T3 groups of fish indicated comparatively high content of individual amino acids. Total ammonia excretion after feeding was comparatively less in the T2 group, indicating less amino acid catabolism. The present study revealed that supplementation of natural diet with prepared diet led to effective nutrient utilization, thereby ensuring improved performance and minimizing discharge of aquaculture wastes through reduced nitrogen excretion.

Notonectids as Live Food for Olive Barb, Puntius Sarana

A feeding experiment was conducted in 40-L tanks each stocked with four fry of olive barb (2.05 ± 0.22 g). Dead notonectids (T1), live notonectids (T2), co-feeding of live notonectids and prepared diet (T3), prepared diet (T4), and plankton concentrate (T5) were fed ad libitum as the five treatments, each maintained with four replications. Proximate composition revealed higher protein and crude lipid contents in both notonectids and plankton concentrate compared to the prepared diet. The insect consumption rate was significantly higher with provision of dead insects (T1), followed by co-feeding of live insect and prepared diet (T3), and the live form (T2) (P < 0.05). Fry showed significantly higher final body weight and net weight gain, as well as specific growth rate, in co-fed group compared to those provided with live or dead insects. Growth performances decreased significantly when fed with prepared diet or plankton concentrate alone. While olive barb fry exhibited a preference for notonectids over the other diets, co-feeding appeared to offer a better nutritional profile for achieving higher growth. The study also indicated possibility of using olive barb as a good candidate for in situ biological control of notonectids during fingerling rearing of barbs and carps.