Gerard Cuzon

Metabolism and growth of juveniles of Litopenaeus vannamei: effect of salinity and dietary carbohydrate levels.

The present study was designed to understand how carbohydrate (CBH) and protein metabolism are related in the penaeid shrimp Litopenaeus vannamei. With this information, we obtained a comprehensive schedule of the protein-carbohydrate metabolism including enzymatic, energetic, and functional aspects. We used salinity to determine its role as a modulator of the protein-carbohydrate metabolism in shrimp. Two experiments were designed. The first experiment evaluated the effect of CBH-salinity combinations in growth and survival, and hemolymph glucose, protein, and ammonia levels, digestive gland glycogen, osmotic pressure, and glutamate dehydrogenase (GDH) of L. vannamei juveniles acclimated during 18 days at a salinity of 15 per thousand and 40 per thousand. The second experiment was done to evaluate the effect of dietary CBH level on pre- and postprandial oxygen consumption, ammonia excretion, and the oxygen-nitrogen ratio (O/N) of juvenile L. vannamei in shrimps acclimated at 40 per thousand salinity. We also evaluated the ability of shrimp to carbohydrate adaptation. We made phosphoenolpyruvate carboxykinase (PECPK) and hexokinase activity measurements after a change in dietary carbohydrate levels at different times during 10 days. The growth rate depended on the combination salinity-dietary CBH-protein level. The maximum growth rate was obtained in shrimps maintained at 15 per thousand salinity and with a diet containing low CBH and high protein. The protein in hemolymph is related to the dietary protein levels; high dietary protein levels produced a high protein concentration in hemolymph. This suggests hemolymph is able to store proteins after a salinity acclimation. Depending on the salinity, the hemolymph proteins could be used as a source of osmotic effectors or as metabolic energy. The O/N values obtained show that shrimp used proteins as a source of energy, mainly when shrimps were fed with low CBH. The role played by postprandial nitrogen excretion (PPNE) in apparent heat increase (AHI) (PPNE/AHI ratio) is lower in shrimps fed diets containing high CBH in comparison with shrimps fed diets containing low CBH levels. These results confirm that the metabolism of L. vannamei juveniles is controlled by dietary protein levels, affecting the processes involved in the mechanical and biochemical transformations of ingested food. A growth depression effect was observed in shrimps fed with low-CBH protein diets and maintained in 40 per thousand salinity. In these shrimps, the hemolymph ammonia concentration (HAC) was significantly higher than that observed in shrimps fed with low CBH and maintained in 15 per thousand salinity. That high HAC level coincided with lower growth rate, which suggests that this level might be toxic for juveniles of L. vannamei. Results obtained for GDH activity showed this enzyme regulated both HAC and hemolymph protein levels, with high values in shrimps fed with low CBH levels and maintained in 40 per thousand salinity, and lower in shrimps fed with high CBH and maintained in 15 per thousand salinity. These differences mean that shrimp with a high-gill GDH activity might waste more energy in oxidation of the excess proteins and amino acids, reducing the energy for growth. It was evident that L. vannamei can convert protein to glycogen by a gluconeogenic pathway, which permitted shrimp to maintain a minimum circulating glucose of 0.34 mg/ml in hemolymph. A high PECPK activity was observed in shrimps fed a diet containing low CBH level indicating that the gluconeogenic pathway is activated, as in vertebrates by low dietary CBH levels. After a change in diet, we observed a change in PEPCK; however, it was lower and seems to depend on the way of adaptation, because it occurred after 6 days when adapting to a high-CBH diet and with little change for the low-CBH diet.

Physiological, nutritional, and immunological role of dietary β 1-3 glucan and ascorbic acid 2-monophosphate in Litopenaeus vannamei juveniles

The present study was designed to determine the effect of dietary β 1-3 glucan (BG) and a megadose of vitamin C on the nutrition (growth and survival, blood glucose, lactate, acylglycerides, cholesterol, hemocyanin [Hc], digestive gland glycogen [DGG]) and the immunological system (blood cells, prophenoloxidase [ProPO]) in Litopenaeus vannamei juveniles. Each treatment was replicated five times. Nutritional condition and immunological response of shrimp were recorded after 40 days of feeding with specific diets and during 48 h after a salinity shock (35–0‰). A significantly greater growth rate was observed in shrimp fed with BG or vitamin C diets than in the control group. Higher blood protein, total blood cells, granular cells, and ProPO activity were recorded in shrimp fed with vitamin C as compared to the remaining treatments. That means that BG was degraded in the digestive gland by β-glucanases to produce energy, permitting the use of more proteins for growth, whereas vitamin C was used to improve animal health, enhancing general metabolism in shrimp. The salinity stress induced a rapid use of reserves, triacylglycerols (TAGs), and cholesterol were reduced in blood and probably used as a source of energy or synthesis in the digestive gland. The increase in digestive gland glycogen 24 h after the salinity shock evidenced the use of these reserves by shrimp fed with all diets. In general, after the salinity, shock blood cells increased in shrimp fed with glucans and decreased in shrimp fed with vitamin C, whereas ProPO decreased in all shrimp after the salinity shock. This could mean that after the salinity, shock shrimp fed with glucans could synthesize cells and ProPO, whereas in shrimp fed with vitamin C, blood cells were just used to respond to the stress. After the salinity shock, an increment in the ProPO/granular cell ratio was observed in shrimp fed with vitamin C, indicating that these shrimp could rapidly increase the components of their immune system. In contrast, a continuous reduction in ProPO/granular cell ratio was observed in shrimp fed with glucans, revealing that with this type of immunostimulant, shrimp drive their immunological equipment to respond continuously to the stress. These results could explain why shrimp fed with immunostimulants presents immunological fatigue in contrast to shrimp fed with additives that improve their nutritional status, like vitamin C.

An energetic and conceptual model of the physiological role of dietary carbohydrates and salinity on Litopenaeus vannamei juveniles

We are reporting results directed to explain the relation between carbohydrates (CHO), protein metabolism, and the energetic balance of Litopenaeus vannamei juveniles. The interaction of dietary CHO and salinity was measured to try to understand the relation between osmotic control and metabolism, both from a biochemical and energetic point of view. Two experiments were done. In the first experiment, shrimp were fed with 0%, 5%, 33%, and 61% CHO and maintained at 15‰ and 40‰ salinity. Glucose, lactate protein, hemocyanin, ammonia concentration, and osmotic pressure were measured in blood. Digestive gland glycogen (DGG) was measured also. In the second experiment, shrimp were fed with 0% and 38% dietary CHO and maintained at 15‰ and 40‰ salinity. From that shrimp, absorbed energy (Abs) was calculated as: Abs=respiration (R)+ammonia excretion (U) and production (P); assimilated energy (As) was calculated as the product of R×P. Osmotic pressure, hemocyanin, protein, lactate, and blood ammonia increased with the reduction in dietary CHO. In contrast, an increase in blood glucose was observed with an increase in dietary CHO. Digestive gland glycogen (DGG) increased following a saturation curve with a DGG maximum at 33% dietary CHO. Blood metabolites of fasting and feeding shrimp showed the same behavior. Energy balance results showed that shrimp maintained in low salinity and fed without CHO waste more energy in U production than for shrimp maintained in high salinity and fed with high CHO levels. Notwithstanding, the production efficiency was higher in shrimp fed without CHO than that observed in shrimp fed with high CHO independent of salinity. A scheme trying to integrate the relation between CHO and protein metabolism and the way in which both are modulated by salinity is presented. From published and present results, there are two factors that apparently control the use of high dietary CHO levels; α-amylase enzyme-dietary CHO level capacity and glycogen saturation in DG. Production of glucose is limited in shrimp because of saturation of α-amylase when shrimp are fed with diets above 33% CHO. This is the first control point of starch metabolism. The digestive gland is saturated with glycogen in shrimp fed with dietary CHO levels >33%. This is apparently the second control point of CHO metabolism that limits growth rate in such conditions. The high metabolic cost related to high CHO diets could explain why shrimp are well adapted to use protein as a source of energy.

Influence of dietary carbohydrate on the metabolism of juvenile Litopenaeus stylirostris

The effect of dietary carbohydrates (CBH) on glucose and glycogen, digestive enzymes, ammonia excretion and osmotic pressure and osmotic capacity of Litopenaeus stylirostris juveniles was studied. The increase of CBH, ranging between 1 and 33%, stimulates activities of alpha-amylase and alpha-glucosidase in the hepatopancreas. High levels of glucose in hemolymph and of glycogen in the hepatopancreas were reached at the highest level of dietary CBH; however, the kinetics of accumulation is different. Shrimps fed with low level of CBH needed 3 h to reached glucose peak, whereas only 1 h is necessary for high CBH levels. A saturation curve was observed in glycogen level and alpha-amylase activity with maximum values in shrimp-fed diets containing 21% CBH. This level could be used to be included as a maximum shrimp dietary CBH level. Pre-prandial glycogen levels were observed in shrimp fed a diet containing 1% CBH, indicating an important gluconeogenesis, which affected the protein metabolism. The present results show that a diet containing 10% CBH may not be enough to cover the CBH requirement, which could be satisfied by dietary protein content. The low osmotic capacity observed in shrimp fed on a diet containing 10% CBH coincided with a relatively low post-prandial nitrogen excretion which reflects a low concentration of amino acids circulating in hemolymph, which affected the osmotic pressure and the osmotic capacity. These results reflect the high plasticity of shrimp species to use protein to obtain metabolic energy from food and its limited capacity for processing dietary CBH.

Composition, preparation and utilization of feeds for Crustacea☆

Abstract Feeds for Crustacea, especially those for penaeid shrimp, are used extensively and represent a key factor in the success of any farming activity whether it is run under semiintensive, intensive or super-intensive conditions according to the stocking density of postlarvae or juveniles. Composition of the feeds differ according to the stage of development of the animals. Currently three types of feed are available: (1) microbound or microencapsulated, for post-larvae; (2) starter and grower feeds provided under different granulometries; and (3) broodstock feeds. A major difference from fish feeds is that the pellet must be very water-stable; this has led to a large amount of research on the use of proper binders. Reaction of binders with other ingredients especially during processing is discussed. The manner in which food is distributed in a pond or tank can dramatically influence the performance of a given feed formulation. Various aspects of feed utilization by crustaceans are considered including digestibility of major components, enzyme secretions, nutrient absorption, protein and energy metabolism and excretion.

Time lag effect of feeding on growth of juvenile shrimp, Penaeus japonicus Bate

Abstract Five experiments described below related to growth and survival of Penaeus japonicus fed a 76.1.1.0 pelleted diet. Pellets were given at different hours of the day according to the behaviour of the species. The hour of food distribution played a major role on the loss of soluble nutrients from the pellets into water. Owing to effect of leaching, extended stay in water could decrease the nutritional quality and value of the pellet to shrimp and consequently reduce the level of food consumption by the shrimp. P. japonicus comes out from the sand at night, between 17.00 and 20.00 h, according to season or experimental photoperiod. It lives in burrows during day time. Food was given either at 17.00, 20.00 or 22.00 h by means of an automatic feeder or by hand. Water stability of pellets seems to be between 7 and 20% loss of dry matter after 1 h. Nevertheless the nutritional qualities and freshness of pellets were significantly improved when the time lag between food distribution and start of night time activities of the shrimp was shortened.

Digestibility of starch in Penaeus vannamei: in vivo and in vitro study on eight samples of various origin.

Apparent digestibility coefficients (ADC) of carbohydrate, protein and lipid were investigated in Penaeus vannamei (18–25 g) with diets containing eight starches of various origin. Test ingredients, included at a level of 35% of diet, were native (NC) or gelatinized (GC) corn starch, waxy corn starch, either native (XC) or gelatinized (GX), high amylose corn starch (AC), potato starch, either native (NP) or gelatinized (GP), and native wheat starch (NW). Experimental diets differed only in the type of starch. Chromic oxide was included as a marker. On each starch sample, water solubility index (WSI) was determined and in vitro digestibility assays were carried out with shrimp digestive gland homogenates in order to evaluate correlations between criteria. In vitro digestibility was estimated as the initial rate of hydrolysis (IRH) in micrograms of reducing units per minute per microgram of substrate in glucose equivalents. Starch ADC ranged from 63.1 (AC) to 95.8% (GX), WSI ranged from 0.06 (NP) to 0.69% (XC) for native starch and from 55 (GX) to 85% (GP) for gelatinized starch, while IRH was between 17 (AC) and 89.10−4 μg min−1 μg−1 (GC). Significant differences (P < 0.05) appeared within each of the parameters depending on the source of dietary starch; in vitro tests were significantly (P < 0.05) correlated with each other as was IRH with starch ADC (y = 8.0 In(104x) + 59.0; R2 = 0.81; x representing IRH). IRH appeared to be more suitable than WSI to predict in vivo digestibility for starch. Protein and lipid ADC which ranged from 94.1 to 97.8% and from 76.6 to 84.8%, respectively, were also significantly affected, thus indicating some associative effects.

Effect of a size-based selection program on blood metabolites and immune response of Litopenaeus vannamei juveniles fed different dietary carbohydrate levels

Blood metabolites in wild and seventh-generation cultivated shrimp were measured to determine how size-based selection could alter the nutritional and immunological conditions of Litopenaeus vannamei. Wild L. vannamei juveniles and a sample of seventh-generation cultured shrimp were acclimated under identical conditions. During 55 days, shrimp were fed a high (HCHO: 44%) or a low (LCHO: 3%) carbohydrate diet for 55 days. Wild shrimp showed a direct relation between dietary CHO and lactate, protein and hemocyte levels indicating that dietary CHO was used for protein synthesis via transamination pathways. In seventh-generation cultured shrimp these parameters were inversely proportional to dietary CHO level, indicating the capacity to synthesize protein from dietary CHO was repressed in cultured shrimp. Farmed shrimp showed a limited capacity to respond to LCHO diets demonstrating high protein dependence in their metabolism and immune response. These results demonstrate that during size-based breeding programs other metabolic process than CHO catabolism can be selected. The incapacity of shrimp to use dietary CHO could limit protein reduction of diets and limit the efforts of the shrimp industry to be ecologically and environmentally profitable.

Raw material freshness, a quality criterion for fish meal fed to shrimp

Abstract Raw material freshness is an important criterion of fish-meal quality for salmonids and also for swine and broiler starter feeds, but needs to be assessed for shrimp. Three batches of anchovy meal were produced in a commercial low-temperature processing plant in Chile, from a unique source of raw fish, either fresh (FR, 12 h post capture), moderately fresh (MF, 25 h post capture) or stale (ST, 36 h post capture). Freshness was assessed through the total volatile nitrogen content in fish before process (TVN 14, 30 and 50 mg N/100 g, respectively), and biogenic amines in fish meal (histamine 28, 1850 and 4701 mg/kg, respectively, and also with increasing content of cadaverine, putrescine and tyramine). Samples of the three fish meals were incorporated at levels of 30% or 40% into isoenergetic diets fed ad libitum to shrimp during various feeding trials. Feeding trials were conducted in Monterrey, Mexico, on Penaeus vannamei early juveniles (0.9 and 1.5 g initial weight) held in a synthetic seawater recirculating system, and in Tahiti on P. vannamei (7.6 g), P. monodon (2.5 g) and P. stylirostris (8.4 g) in a natural seawater flow-through system. Small P. vannamei (0.9 g) expressed significantly higher feed consumption (P=0.028) and percent weight gain (P=0.048) when fed the fresh raw material fish meal: growth increased by 25% compared with the moderately fresh and stale raw material treatments, but no significant differences were detected in feed conversion, nor survival. Larger P. vannamei (1.5 and 7.6 g) did not show any significant response. P. monodon had a tendency to better growth with the FR treatment (non significant, P=0.109). Finally, P. stylirostris late juveniles (8.4 g) fed the FR feed showed a highly significant increase in weight gain (P=0.007), but also a poorer feed conversion (P=0.004). A global interpretation of this set of results could be that susceptibility to raw-material spoilage would be higher in species with carnivorous tendencies (like P. stylirostris, known for its higher protein requirement), and also in young stages of less carnivorous species (as in the case of 0.9 g P. vannamei). However, raw material freshness, as indicated by TVN levels in raw material (less than 30 mg N/100 g) or by the sum of amine contents in the final product (less than 2000 mg/kg), is a quality parameter that should be considered when selecting fish meal for shrimp diets, particularly for very young juveniles and carnivorous species.

Biofloc Technology (BFT): A Review for Aquaculture Application and Animal Food Industry

© 2013 Emerenciano et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Biofloc Technology (BFT): A Review for Aquaculture Application and Animal Food Industry