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Thedegreeofhydrolysis(DH)oftheingredientswasevaluatedforCentropomusundecimalisjuveniles. The in vitro experiment included wheat gluten (WG), corn gluten (CG), soybean meal (SBM) and pretreatedphytase(SBM+phytase),soyproteinconcentrate(SPC),canolameal(CAN)andpretreated phytase (CAN+phytase), poultry byproduct meal (PBPM), chicken meal (CHKM), dried whey (DW), Pota meal (PM: mix of giant squid, fish soluble protein concentrate, crustacean meal, and fish oil), and Protiblend (PTB: aquatic and render mix). The highest acidic DH occurred with PTB (0.38±0.06), CHKM (0.33±0.3), and PBPM (0.25±0.03). In the alkaline condition, PTB (1.6±0.17 and 0.98±0.05 for pyloric caeca and intestine, respectively) and CG (1.04±0.4 and 0.75±0.2 for caeca and intestine, respectively) provided the highest DH values. In vitro digestibility demonstrated that PTB was the highest(85.3%)followedbyPBPM(51.4%),CAN+phytase(47.6%),CG(45.1%),andCHKM(46.5%). The in vivo experiment concerned the WG, CHKM, PBPM, PM, and PTB diets plus a reference diet with fishmeal (Ref diet). The total %DH was different (P<0.05) with the lowest values for the WG diet (0.34±0.09%) and Ref diet (0.34±0.15). Free amino acid released during digestion was displayed for these diets and a bifactorial analysis produced no difference (P>0.05). The apparent digestive coefficients ranged from 89.8 to 92.9% for protein and from 68 to 71.4% for energy. KEYWORDS amino acids, in vitro and in vivo digestibility, pH-stat, protein, snook

Thedegreeofhydrolysis(DH)oftheingredientswasevaluatedforCentropomusundecimalisjuveniles. The in vitro experiment included wheat gluten (WG), corn gluten (CG), soybean meal (SBM) and pretreatedphytase(SBM+phytase),soyproteinconcentrate(SPC),canolameal(CAN)andpretreated phytase (CAN+phytase), poultry byproduct meal (PBPM), chicken meal (CHKM), dried whey (DW), Pota meal (PM: mix of giant squid, fish soluble protein concentrate, crustacean meal, and fish oil), and Protiblend (PTB: aquatic and render mix). The highest acidic DH occurred with PTB (0.38±0.06), CHKM (0.33±0.3), and PBPM (0.25±0.03). In the alkaline condition, PTB (1.6±0.17 and 0.98±0.05 for pyloric caeca and intestine, respectively) and CG (1.04±0.4 and 0.75±0.2 for caeca and intestine, respectively) provided the highest DH values. In vitro digestibility demonstrated that PTB was the highest(85.3%)followedbyPBPM(51.4%),CAN+phytase(47.6%),CG(45.1%),andCHKM(46.5%). The in vivo experiment concerned the WG, CHKM, PBPM, PM, and PTB diets plus a reference diet with fishmeal (Ref diet). The total %DH was different (P<0.05) with the lowest values for the WG diet (0.34±0.09%) and Ref diet (0.34±0.15). Free amino acid released during digestion was displayed for these diets and a bifactorial analysis produced no difference (P>0.05). The apparent digestive coefficients ranged from 89.8 to 92.9% for protein and from 68 to 71.4% for energy. KEYWORDS amino acids, in vitro and in vivo digestibility, pH-stat, protein, snook

The digestibility of pre-selected ingredients was evaluated for Epinephelus morio using pH-stat and multi-enzyme extract (stomach, intestine, and ceca). The degree of hydrolysis (DH) was tested with acid and alkaline proteases using crustacean meals, squid meal, fish protein concentrate (FPC), fish meal, dried whey, as well as canola paste (w/or w/o phytase), soybean meal (w/or w/o phytase), soyprotein concentrate (SPC), and wheat gluten. SPC produced DH values between 3.6-4.1%, obtained from the three different parts of the digestive tract. Canola paste produced high DH in the stomach by adding phytase to 0.8 and 2% feed. This process was repeated under alkaline conditions for DH, with 0.6-2.6% in the pyloric ceca, and 1-2.2% in the intestine. The DH from stomach with crustacean meals (shrimp meal and crab meal) ranged from 32-87%, while values for dried whey from the ceca and intestine ranged from 6-7.4%. It did not differ from crab meal with values of 4.5 and 8.7% from pyloric ceca and intestine respectively. Based on the above results, 4 diets were developed using shrimp meal, dried whey, soy protein concentrate, and canola+ phytase. The DH, FAA (fish amino acid) and SDS-PAGE (analysis of protein gels) for each diet were analysed. After an in vivo test, results on juveniles fed whey protein diet (WPd) and CPd+ ranked high (95% and 92% respectively) compared with other treatments. pH-Stat provided consistent results regarding digestibility of selected protein sources. Therefore, dried whey, shrimp meal, and canola+ phytase ranked first to be included in E. morio feed formulation with a pool of 55% of these components, complemented with a minimum of fish meal, FPC, grains and wheat gluten.

The advantages of FLOC over clear water (CW) in rearing juvenile L. vannamei and its effects on Vibrio communities were evaluated. Survival rate in FLOC and clear water were recorded and a probiotic was tested under both conditions. Daily growth rate (DGR) was higher in FLOC (p < 0.05) than in CW. Survival in each system increased significantly when a probiotic was included in the diet (p < 0.05). The Vibrionaceae community from the hepatopancreas (HP) and the culture medium did not differ between the two culture media. Nevertheless, a novel group of Vibrio strains was found to be unique to FLOC. No high level of lesions was observed in shrimp tissues from the FLOC + probiotic treatment; it suggests that the probiotic contributed to homeostasis and prevented outbreak of opportunistic pathogenic species.

The digestibility of pre-selected ingredients was evaluated for Epinephelus morio using pH-stat and multi-enzyme extract (stomach, intestine, and ceca). The degree of hydrolysis (DH) was tested with acid and alkaline proteases using crustacean meals, squid meal, fish protein concentrate (FPC), fish meal, dried whey, as well as canola paste (w/or w/o phytase), soybean meal (w/or w/o phytase), soyprotein concentrate (SPC), and wheat gluten. SPC produced DH values between 3.6-4.1%, obtained from the three different parts of the digestive tract. Canola paste produced high DH in the stomach by adding phytase to 0.8 and 2% feed. This process was repeated under alkaline conditions for DH, with 0.6-2.6% in the pyloric ceca, and 1-2.2% in the intestine. The DH from stomach with crustacean meals (shrimp meal and crab meal) ranged from 32-87%, while values for dried whey from the ceca and intestine ranged from 6-7.4%. It did not differ from crab meal with values of 4.5 and 8.7% from pyloric ceca and intestine respectively. Based on the above results, 4 diets were developed using shrimp meal, dried whey, soy protein concentrate, and canola+ phytase. The DH, FAA (fish amino acid) and SDS-PAGE (analysis of protein gels) for each diet were analysed. After an in vivo test, results on juveniles fed whey protein diet (WPd) and CPd+ ranked high (95% and 92% respectively) compared with other treatments. pH-Stat provided consistent results regarding digestibility of selected protein sources. Therefore, dried whey, shrimp meal, and canola+ phytase ranked first to be included in E. morio feed formulation with a pool of 55% of these components, complemented with a minimum of fish meal, FPC, grains and wheat gluten.

The advantages of FLOC over clear water (CW) in rearing juvenile L. vannamei and its effects on Vibrio communities were evaluated. Survival rate in FLOC and clear water were recorded and a probiotic was tested under both conditions. Daily growth rate (DGR) was higher in FLOC (p < 0.05) than in CW. Survival in each system increased significantly when a probiotic was included in the diet (p < 0.05). The Vibrionaceae community from the hepatopancreas (HP) and the culture medium did not differ between the two culture media. Nevertheless, a novel group of Vibrio strains was found to be unique to FLOC. No high level of lesions was observed in shrimp tissues from the FLOC + probiotic treatment; it suggests that the probiotic contributed to homeostasis and prevented outbreak of opportunistic pathogenic species.

The digestibility of pre-selected ingredients was evaluated for Epinephelus morio using pH-stat and multi-enzyme extract (stomach, intestine, and ceca). The degree of hydrolysis (DH) was tested with acid and alkaline proteases using crustacean meals, squid meal, fish protein concentrate (FPC), fish meal, dried whey, as well as canola paste (w/or w/o phytase), soybean meal (w/or w/o phytase), soyprotein concentrate (SPC), and wheat gluten. SPC produced DH values between 3.6-4.1%, obtained from the three different parts of the digestive tract. Canola paste produced high DH in the stomach by adding phytase to 0.8 and 2% feed. This process was repeated under alkaline conditions for DH, with 0.6-2.6% in the pyloric ceca, and 1-2.2% in the intestine. The DH from stomach with crustacean meals (shrimp meal and crab meal) ranged from 32-87%, while values for dried whey from the ceca and intestine ranged from 6-7.4%. It did not differ from crab meal with values of 4.5 and 8.7% from pyloric ceca and intestine respectively. Based on the above results, 4 diets were developed using shrimp meal, dried whey, soy protein concentrate, and canola+ phytase. The DH, FAA (fish amino acid) and SDS-PAGE (analysis of protein gels) for each diet were analysed. After an in vivo test, results on juveniles fed whey protein diet (WPd) and CPd+ ranked high (95% and 92% respectively) compared with other treatments. pH-Stat provided consistent results regarding digestibility of selected protein sources. Therefore, dried whey, shrimp meal, and canola+ phytase ranked first to be included in E. morio feed formulation with a pool of 55% of these components, complemented with a minimum of fish meal, FPC, grains and wheat gluten.

The advantages of FLOC over clear water (CW) in rearing juvenile L. vannamei and its effects on Vibrio communities were evaluated. Survival rate in FLOC and clear water were recorded and a probiotic was tested under both conditions. Daily growth rate (DGR) was higher in FLOC (p < 0.05) than in CW. Survival in each system increased significantly when a probiotic was included in the diet (p < 0.05). The Vibrionaceae community from the hepatopancreas (HP) and the culture medium did not differ between the two culture media. Nevertheless, a novel group of Vibrio strains was found to be unique to FLOC. No high level of lesions was observed in shrimp tissues from the FLOC + probiotic treatment; it suggests that the probiotic contributed to homeostasis and prevented outbreak of opportunistic pathogenic species.

The effects of two microencapsulated feeds were evaluated on development, growth, survival, proteolytic activity, and biochemical composition of white shrimp, Litopenaeus vannamei, larvae. The treatments were: (1) basal microcapsules (BM), (2) microcapsules containing krill hydrolysate (BMK), and (3) live food control (LFC: Artemia franciscana nauplii) with all treatments receiving algae (Chaetoceros ceratosporum and Tetraselmis chuii). No significant differences were found in development index and survival among larvae. Growth rate was significantly higher in larvae fed LFC (15 +/- 0.06%/d) as compared with those offered the BM diet (7.5 +/- 0.5%/d) with the BMK (11 +/- 0.04%/d) treatment producing intermediate results. The activity of total proteases and chymotrypsin decreased significantly after Mysis I (MI) in larvae fed LFC or BMK. Protein content of larvae increased significantly toward PL1. The acylglycerides content in MIII fed on LFC (2.3 +/- 0.2%/dw) was higher than that MI fed BM (1 +/- 0.01%/dw). No difference was observed in the cholesterol (CH) content of the larvae. The acylglycerides/protein and cholesterol/protein ratios showed a decreasing pattern between MI and PL1, indicating that these two ratios were related to ontogenetic shifts. These results demonstrate improvements in microparticulate diets when krill hydrolysates are included in the formulation.

The effects of two microencapsulated feeds were evaluated on development, growth, survival, proteolytic activity, and biochemical composition of white shrimp, Litopenaeus vannamei, larvae. The treatments were: (1) basal microcapsules (BM), (2) microcapsules containing krill hydrolysate (BMK), and (3) live food control (LFC: Artemia franciscana nauplii) with all treatments receiving algae (Chaetoceros ceratosporum and Tetraselmis chuii). No significant differences were found in development index and survival among larvae. Growth rate was significantly higher in larvae fed LFC (15 +/- 0.06%/d) as compared with those offered the BM diet (7.5 +/- 0.5%/d) with the BMK (11 +/- 0.04%/d) treatment producing intermediate results. The activity of total proteases and chymotrypsin decreased significantly after Mysis I (MI) in larvae fed LFC or BMK. Protein content of larvae increased significantly toward PL1. The acylglycerides content in MIII fed on LFC (2.3 +/- 0.2%/dw) was higher than that MI fed BM (1 +/- 0.01%/dw). No difference was observed in the cholesterol (CH) content of the larvae. The acylglycerides/protein and cholesterol/protein ratios showed a decreasing pattern between MI and PL1, indicating that these two ratios were related to ontogenetic shifts. These results demonstrate improvements in microparticulate diets when krill hydrolysates are included in the formulation.

The effects of two microencapsulated feeds were evaluated on development, growth, survival, proteolytic activity, and biochemical composition of white shrimp, Litopenaeus vannamei, larvae. The treatments were: (1) basal microcapsules (BM), (2) microcapsules containing krill hydrolysate (BMK), and (3) live food control (LFC: Artemia franciscana nauplii) with all treatments receiving algae (Chaetoceros ceratosporum and Tetraselmis chuii). No significant differences were found in development index and survival among larvae. Growth rate was significantly higher in larvae fed LFC (15 +/- 0.06%/d) as compared with those offered the BM diet (7.5 +/- 0.5%/d) with the BMK (11 +/- 0.04%/d) treatment producing intermediate results. The activity of total proteases and chymotrypsin decreased significantly after Mysis I (MI) in larvae fed LFC or BMK. Protein content of larvae increased significantly toward PL1. The acylglycerides content in MIII fed on LFC (2.3 +/- 0.2%/dw) was higher than that MI fed BM (1 +/- 0.01%/dw). No difference was observed in the cholesterol (CH) content of the larvae. The acylglycerides/protein and cholesterol/protein ratios showed a decreasing pattern between MI and PL1, indicating that these two ratios were related to ontogenetic shifts. These results demonstrate improvements in microparticulate diets when krill hydrolysates are included in the formulation.

The floc system has been successfully applied for shrimp grow-out, but little is known about floc contribution on reproductive performance. In a 30-day trial, spawning performance of broodstock was evaluated in floc and earthen ponds. Floc spawners achieved better results (P < 0.05) compared with pond spawners in terms of number of spawns per ablated female (2.9 vs. 1.3), spawns per spawning female (3.6 vs. 2.4) and number of consecutive maturation (average of 3.6 times compared with 2.5 times in ponds females). Latency period was lower for floc spawners (7.4 days) than pond spawners (10.7 days) (P < 0.05). The percentage of females that spawned at least once were higher in floc (77.1%) when compared with pond spawners (53.8%) (P < 0.05). Number of eggs per spawn per g of spawner's body weight and female mortality presented no significant differences between treatments (P > 0.05). Biochemical analysis as a nutritional status indicator showed no difference between treatments in hepatopancreas (P > 0.05), with the exception of lowest values of acylglycerides and acylglycerides/total soluble protein ratio in floc females ovary (P < 0.05). Results evidenced better overall spawning performance for L. stylirostris broodstock produced under floc condition than in earthen ponds.

Changes in metabolite levels in hemolymph and hepatopancreas were used as indicators of physiological status of juvenile wild and cultivated Farfantepenaeas. duorarum (Burkenroad, 1939), during hyper-osmoregulatory conditions (salinity 22 ppt, 726 mOsm/kg). We analyzed the relationship between biochemical changes of wild and cultivated shrimp at different molt stages by measurement of osmotic capacity, hemocyanin, acylglycerides, cholesterol, glucose, glycogen and total protein. Biochemical analyses of hemolymph (blood) and hepatopancreas showed a decreasing trend in stages closer to molt and an increasing trend before intermolt. Osmotic capacity and blood proteins indicated a significant effect of the molt stage. Stages A. D1' and D''' showed the greatest effect on the biochemical variables. Higher hemocyanin, cholesterol and glycogen concentrations were observed in wild shrimp than in cultivated shrimp. The effect of the molt cycle was associated with changes in cyclic ions and water balance that produced chemical changes in the hemolymph in both wild and cultivated.

In view of the relationship between shifts in diet composition and the activity of digestive enzymes in penaeid shrimp, the present study focused on the analysis of digestive trypsin and a-amylase activities of wild Farfantepenaeus. duorarum (Burkenroad, 1939) juveniles and their changes in phenotypic expression, during the molt cycle as endogenous factor and their changes due to different feeding regimes (exogenous factor) in relation with delta C-13 and delta N-15 isotopic signature as an index of food assimilation induced by the seasonal availability of food items in the nursery area. Wild juveniles of F. duorarum were captured from April 2007 to February 2008, in the Celestun coastal lagoon, Yucatan, Mexico. Samplings were carried out considering all quarters of the lunar cycle and in each of the recognized seasons for this region: dry, rainy, and the Nortes (North Wind). Copepods and amphipods were the main source of food for juveniles of E duorarum. Values of delta C-13 in the muscular tissue were near -20 parts per thousand hence the feeding regime of F. duorarum in the lagoon was composed by material of marine origin. Isotopic signature differences were found between the three annual seasons. It is an opportunist generalist organism that is located in the 4(th) trophic level. The digestive enzymatic activities of both trypsin and alpha-amylase in fresh hepatopancreas tissue showed an interaction between season and molt stages (p < 0.05). Activity of the trypsin was highest during the Nortes at molt stage C (140 mU mg(-1) HP) and activity of a-amylase was higher in the Nortes at stage B-2 (674 mU mg(-1) HP). The amylase/trypsin ratio also showed significant interaction between season and molt stages (p < 0.05), with higher values in premolt stages during the rainy and Nortes seasons. Isoforms of these digestive enzymes differed in expression according to the molt stage and also to the season with expression generally being greater at stage C.

A 30-day trial was performed to evaluate the reproductive performance of wild and 2nd generation domesticated Farfantepenaeus duorarum broodstock. Changes in biochemical composition and fatty acids (FA) profile in the 1st and 4th spawn order females were used as indicators of nutritional condition. Wild population of F. duorarum presented significantly better reproductive outcomes as compared to domesticated ones. Wild spawners achieved significantly higher number of eggs per spawn, number of egg per spawn per g of spawner's body weight and number of nauplii per spawn (P<0.05). Latency period was significantly shorter (P<0.05) for wild than for domesticated females (11 vs 17 days). Wild spawners also presented less mortality (6 vs 12%), higher number of total spawns (51 vs 33), spawns per ablated and per spawning females as well as higher total eggs and nauplii production. On the other hand, domesticated females presented higher number of females that spawned at least once (89 vs 76%). The higher spawning activity was reflected in lower levels of acylglycerides (AG) and cholesterol content in wild hepatopancreas (HP) and ovary (OV) (P<0.05). FA profile, mainly represented by ARA, EPA and sum of n-3 were higher in hepatopancreas and ovary of wild females, however lower levels were detected in eggs as a result of a high spawning activity. Multivariate analysis performed to detected simultaneous variation in biochemical variables indicated AG as variation pattern's responsive. (c) 2012 Elsevier B.V. All rights reserved.

The floc system has been successfully applied for shrimp grow-out, but little is known about floc contribution on reproductive performance. In a 30-day trial, spawning performance of broodstock was evaluated in floc and earthen ponds. Floc spawners achieved better results (P < 0.05) compared with pond spawners in terms of number of spawns per ablated female (2.9 vs. 1.3), spawns per spawning female (3.6 vs. 2.4) and number of consecutive maturation (average of 3.6 times compared with 2.5 times in ponds females). Latency period was lower for floc spawners (7.4 days) than pond spawners (10.7 days) (P < 0.05). The percentage of females that spawned at least once were higher in floc (77.1%) when compared with pond spawners (53.8%) (P < 0.05). Number of eggs per spawn per g of spawner's body weight and female mortality presented no significant differences between treatments (P > 0.05). Biochemical analysis as a nutritional status indicator showed no difference between treatments in hepatopancreas (P > 0.05), with the exception of lowest values of acylglycerides and acylglycerides/total soluble protein ratio in floc females ovary (P < 0.05). Results evidenced better overall spawning performance for L. stylirostris broodstock produced under floc condition than in earthen ponds.

Changes in metabolite levels in hemolymph and hepatopancreas were used as indicators of physiological status of juvenile wild and cultivated Farfantepenaeas. duorarum (Burkenroad, 1939), during hyper-osmoregulatory conditions (salinity 22 ppt, 726 mOsm/kg). We analyzed the relationship between biochemical changes of wild and cultivated shrimp at different molt stages by measurement of osmotic capacity, hemocyanin, acylglycerides, cholesterol, glucose, glycogen and total protein. Biochemical analyses of hemolymph (blood) and hepatopancreas showed a decreasing trend in stages closer to molt and an increasing trend before intermolt. Osmotic capacity and blood proteins indicated a significant effect of the molt stage. Stages A. D1' and D''' showed the greatest effect on the biochemical variables. Higher hemocyanin, cholesterol and glycogen concentrations were observed in wild shrimp than in cultivated shrimp. The effect of the molt cycle was associated with changes in cyclic ions and water balance that produced chemical changes in the hemolymph in both wild and cultivated.

A 30-day trial was performed to evaluate the reproductive performance of wild and 2nd generation domesticated Farfantepenaeus duorarum broodstock. Changes in biochemical composition and fatty acids (FA) profile in the 1st and 4th spawn order females were used as indicators of nutritional condition. Wild population of F. duorarum presented significantly better reproductive outcomes as compared to domesticated ones. Wild spawners achieved significantly higher number of eggs per spawn, number of egg per spawn per g of spawner's body weight and number of nauplii per spawn (P<0.05). Latency period was significantly shorter (P<0.05) for wild than for domesticated females (11 vs 17 days). Wild spawners also presented less mortality (6 vs 12%), higher number of total spawns (51 vs 33), spawns per ablated and per spawning females as well as higher total eggs and nauplii production. On the other hand, domesticated females presented higher number of females that spawned at least once (89 vs 76%). The higher spawning activity was reflected in lower levels of acylglycerides (AG) and cholesterol content in wild hepatopancreas (HP) and ovary (OV) (P<0.05). FA profile, mainly represented by ARA, EPA and sum of n-3 were higher in hepatopancreas and ovary of wild females, however lower levels were detected in eggs as a result of a high spawning activity. Multivariate analysis performed to detected simultaneous variation in biochemical variables indicated AG as variation pattern's responsive. (c) 2012 Elsevier B.V. All rights reserved.

In view of the relationship between shifts in diet composition and the activity of digestive enzymes in penaeid shrimp, the present study focused on the analysis of digestive trypsin and a-amylase activities of wild Farfantepenaeus. duorarum (Burkenroad, 1939) juveniles and their changes in phenotypic expression, during the molt cycle as endogenous factor and their changes due to different feeding regimes (exogenous factor) in relation with delta C-13 and delta N-15 isotopic signature as an index of food assimilation induced by the seasonal availability of food items in the nursery area. Wild juveniles of F. duorarum were captured from April 2007 to February 2008, in the Celestun coastal lagoon, Yucatan, Mexico. Samplings were carried out considering all quarters of the lunar cycle and in each of the recognized seasons for this region: dry, rainy, and the Nortes (North Wind). Copepods and amphipods were the main source of food for juveniles of E duorarum. Values of delta C-13 in the muscular tissue were near -20 parts per thousand hence the feeding regime of F. duorarum in the lagoon was composed by material of marine origin. Isotopic signature differences were found between the three annual seasons. It is an opportunist generalist organism that is located in the 4(th) trophic level. The digestive enzymatic activities of both trypsin and alpha-amylase in fresh hepatopancreas tissue showed an interaction between season and molt stages (p < 0.05). Activity of the trypsin was highest during the Nortes at molt stage C (140 mU mg(-1) HP) and activity of a-amylase was higher in the Nortes at stage B-2 (674 mU mg(-1) HP). The amylase/trypsin ratio also showed significant interaction between season and molt stages (p < 0.05), with higher values in premolt stages during the rainy and Nortes seasons. Isoforms of these digestive enzymes differed in expression according to the molt stage and also to the season with expression generally being greater at stage C.

The floc system has been successfully applied for shrimp grow-out, but little is known about floc contribution on reproductive performance. In a 30-day trial, spawning performance of broodstock was evaluated in floc and earthen ponds. Floc spawners achieved better results (P < 0.05) compared with pond spawners in terms of number of spawns per ablated female (2.9 vs. 1.3), spawns per spawning female (3.6 vs. 2.4) and number of consecutive maturation (average of 3.6 times compared with 2.5 times in ponds females). Latency period was lower for floc spawners (7.4 days) than pond spawners (10.7 days) (P < 0.05). The percentage of females that spawned at least once were higher in floc (77.1%) when compared with pond spawners (53.8%) (P < 0.05). Number of eggs per spawn per g of spawner's body weight and female mortality presented no significant differences between treatments (P > 0.05). Biochemical analysis as a nutritional status indicator showed no difference between treatments in hepatopancreas (P > 0.05), with the exception of lowest values of acylglycerides and acylglycerides/total soluble protein ratio in floc females ovary (P < 0.05). Results evidenced better overall spawning performance for L. stylirostris broodstock produced under floc condition than in earthen ponds.

Changes in metabolite levels in hemolymph and hepatopancreas were used as indicators of physiological status of juvenile wild and cultivated Farfantepenaeas. duorarum (Burkenroad, 1939), during hyper-osmoregulatory conditions (salinity 22 ppt, 726 mOsm/kg). We analyzed the relationship between biochemical changes of wild and cultivated shrimp at different molt stages by measurement of osmotic capacity, hemocyanin, acylglycerides, cholesterol, glucose, glycogen and total protein. Biochemical analyses of hemolymph (blood) and hepatopancreas showed a decreasing trend in stages closer to molt and an increasing trend before intermolt. Osmotic capacity and blood proteins indicated a significant effect of the molt stage. Stages A. D1' and D''' showed the greatest effect on the biochemical variables. Higher hemocyanin, cholesterol and glycogen concentrations were observed in wild shrimp than in cultivated shrimp. The effect of the molt cycle was associated with changes in cyclic ions and water balance that produced chemical changes in the hemolymph in both wild and cultivated.

A 30-day trial was performed to evaluate the reproductive performance of wild and 2nd generation domesticated Farfantepenaeus duorarum broodstock. Changes in biochemical composition and fatty acids (FA) profile in the 1st and 4th spawn order females were used as indicators of nutritional condition. Wild population of F. duorarum presented significantly better reproductive outcomes as compared to domesticated ones. Wild spawners achieved significantly higher number of eggs per spawn, number of egg per spawn per g of spawner's body weight and number of nauplii per spawn (P<0.05). Latency period was significantly shorter (P<0.05) for wild than for domesticated females (11 vs 17 days). Wild spawners also presented less mortality (6 vs 12%), higher number of total spawns (51 vs 33), spawns per ablated and per spawning females as well as higher total eggs and nauplii production. On the other hand, domesticated females presented higher number of females that spawned at least once (89 vs 76%). The higher spawning activity was reflected in lower levels of acylglycerides (AG) and cholesterol content in wild hepatopancreas (HP) and ovary (OV) (P<0.05). FA profile, mainly represented by ARA, EPA and sum of n-3 were higher in hepatopancreas and ovary of wild females, however lower levels were detected in eggs as a result of a high spawning activity. Multivariate analysis performed to detected simultaneous variation in biochemical variables indicated AG as variation pattern's responsive. (c) 2012 Elsevier B.V. All rights reserved.

In view of the relationship between shifts in diet composition and the activity of digestive enzymes in penaeid shrimp, the present study focused on the analysis of digestive trypsin and a-amylase activities of wild Farfantepenaeus. duorarum (Burkenroad, 1939) juveniles and their changes in phenotypic expression, during the molt cycle as endogenous factor and their changes due to different feeding regimes (exogenous factor) in relation with delta C-13 and delta N-15 isotopic signature as an index of food assimilation induced by the seasonal availability of food items in the nursery area. Wild juveniles of F. duorarum were captured from April 2007 to February 2008, in the Celestun coastal lagoon, Yucatan, Mexico. Samplings were carried out considering all quarters of the lunar cycle and in each of the recognized seasons for this region: dry, rainy, and the Nortes (North Wind). Copepods and amphipods were the main source of food for juveniles of E duorarum. Values of delta C-13 in the muscular tissue were near -20 parts per thousand hence the feeding regime of F. duorarum in the lagoon was composed by material of marine origin. Isotopic signature differences were found between the three annual seasons. It is an opportunist generalist organism that is located in the 4(th) trophic level. The digestive enzymatic activities of both trypsin and alpha-amylase in fresh hepatopancreas tissue showed an interaction between season and molt stages (p < 0.05). Activity of the trypsin was highest during the Nortes at molt stage C (140 mU mg(-1) HP) and activity of a-amylase was higher in the Nortes at stage B-2 (674 mU mg(-1) HP). The amylase/trypsin ratio also showed significant interaction between season and molt stages (p < 0.05), with higher values in premolt stages during the rainy and Nortes seasons. Isoforms of these digestive enzymes differed in expression according to the molt stage and also to the season with expression generally being greater at stage C.

Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture. The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp (L. vannamei) were investigated. This involved an examination of growth performance, glutamate dehydrogenase (GDH) and Na+-K+ ATPase mRNA expression,, and GDH activity in muscles and gills. Three experimental diets were formulated, containing 25%, 40%, and 50% dietary protein, and fed to the shrimp at a salinity of 25. After 20 days, no significant difference was observed in weight gain, though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels. Subsequently, shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5, respectively, and sampled at weeks 1 and 2. Shrimp fed with 40% protein at 25 in salinity (optimal conditions) were used as a control. Regardless of the salinities, shrimp fed with 50% dietary protein had significantly higher growth performance than other diets; no significant differences were found in comparison with the control. Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks. Ambient salinity change also stimulated the hepatosomatic index, which increased in the first week and then recovered to a relatively normal level, as in the control, after 2 weeks. These findings indicate that in white shrimp, the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism. Increased dietary protein level could improve the osmoreaulation capacity of L. vannamei with more energy resources allocated to GDH activity and expression.

Proteinases from hepatopancreas (HP) and gastric juice (GJ) from wild and cultured red octopus (Octopus maya) were characterized. Hepatopancreas assays revealed optimal activity at pH 4, 9-10 and 10 for wild and pH 3, 8, and 9, for cultured octopuses, for total proteinases, trypsin and chymotrypsin, respectively. In the gastric juice, maximum activity was recorded at pH 6, 8, and 7 for total proteinases, trypsin, and chymotrypsin, respectively for both wild and cultured octopus. A reduction on enzyme activity of 70 and 20% was observed in HP and GJ extracts, respectively when protease inhibitor Pepstatin A was used. That result suggests that the main proteases in the HP were aspartic acid proteinases type (possibly Cathepsin D) and some of them were present in the GJ. Dissociating discontinuous polyacrylamide gel electrophoresis showed activity bands between 20 and 28, 30 and 34, 35 and 45, 60 and 70 kDa, and a last one between 75 and 100 kDa. We concluded that extracellular digestion of O. maya takes place in an acid environment, around pH 6. In contrast, intracellular digestion in the HP is developed at pHs between 3 and 4, where cathepsin D could be the most important enzyme for O. maya.

Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture. The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp (L. vannamei) were investigated. This involved an examination of growth performance, glutamate dehydrogenase (GDH) and Na+-K+ ATPase mRNA expression,, and GDH activity in muscles and gills. Three experimental diets were formulated, containing 25%, 40%, and 50% dietary protein, and fed to the shrimp at a salinity of 25. After 20 days, no significant difference was observed in weight gain, though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels. Subsequently, shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5, respectively, and sampled at weeks 1 and 2. Shrimp fed with 40% protein at 25 in salinity (optimal conditions) were used as a control. Regardless of the salinities, shrimp fed with 50% dietary protein had significantly higher growth performance than other diets; no significant differences were found in comparison with the control. Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks. Ambient salinity change also stimulated the hepatosomatic index, which increased in the first week and then recovered to a relatively normal level, as in the control, after 2 weeks. These findings indicate that in white shrimp, the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism. Increased dietary protein level could improve the osmoreaulation capacity of L. vannamei with more energy resources allocated to GDH activity and expression.

Proteinases from hepatopancreas (HP) and gastric juice (GJ) from wild and cultured red octopus (Octopus maya) were characterized. Hepatopancreas assays revealed optimal activity at pH 4, 9-10 and 10 for wild and pH 3, 8, and 9, for cultured octopuses, for total proteinases, trypsin and chymotrypsin, respectively. In the gastric juice, maximum activity was recorded at pH 6, 8, and 7 for total proteinases, trypsin, and chymotrypsin, respectively for both wild and cultured octopus. A reduction on enzyme activity of 70 and 20% was observed in HP and GJ extracts, respectively when protease inhibitor Pepstatin A was used. That result suggests that the main proteases in the HP were aspartic acid proteinases type (possibly Cathepsin D) and some of them were present in the GJ. Dissociating discontinuous polyacrylamide gel electrophoresis showed activity bands between 20 and 28, 30 and 34, 35 and 45, 60 and 70 kDa, and a last one between 75 and 100 kDa. We concluded that extracellular digestion of O. maya takes place in an acid environment, around pH 6. In contrast, intracellular digestion in the HP is developed at pHs between 3 and 4, where cathepsin D could be the most important enzyme for O. maya.

Proteinases from hepatopancreas (HP) and gastric juice (GJ) from wild and cultured red octopus (Octopus maya) were characterized. Hepatopancreas assays revealed optimal activity at pH 4, 9-10 and 10 for wild and pH 3, 8, and 9, for cultured octopuses, for total proteinases, trypsin and chymotrypsin, respectively. In the gastric juice, maximum activity was recorded at pH 6, 8, and 7 for total proteinases, trypsin, and chymotrypsin, respectively for both wild and cultured octopus. A reduction on enzyme activity of 70 and 20% was observed in HP and GJ extracts, respectively when protease inhibitor Pepstatin A was used. That result suggests that the main proteases in the HP were aspartic acid proteinases type (possibly Cathepsin D) and some of them were present in the GJ. Dissociating discontinuous polyacrylamide gel electrophoresis showed activity bands between 20 and 28, 30 and 34, 35 and 45, 60 and 70 kDa, and a last one between 75 and 100 kDa. We concluded that extracellular digestion of O. maya takes place in an acid environment, around pH 6. In contrast, intracellular digestion in the HP is developed at pHs between 3 and 4, where cathepsin D could be the most important enzyme for O. maya.

Improvement in the osmoregulation capacity via nutritional supplies is vitally important in shrimp aquaculture. The effects of dietary protein levels on the osmoregulation capacity of the Pacific white shrimp (L. vannamei) were investigated. This involved an examination of growth performance, glutamate dehydrogenase (GDH) and Na+-K+ ATPase mRNA expression,, and GDH activity in muscles and gills. Three experimental diets were formulated, containing 25%, 40%, and 50% dietary protein, and fed to the shrimp at a salinity of 25. After 20 days, no significant difference was observed in weight gain, though GDH and Na+-K+ ATPase gene expression and GDH activity increased with higher dietary protein levels. Subsequently, shrimp fed diets with 25% and 50% dietary protein were transferred into tanks with salinities of 38 and 5, respectively, and sampled at weeks 1 and 2. Shrimp fed with 40% protein at 25 in salinity (optimal conditions) were used as a control. Regardless of the salinities, shrimp fed with 50% dietary protein had significantly higher growth performance than other diets; no significant differences were found in comparison with the control. Shrimp fed with 25% dietary protein and maintained at salinities of 38 and 5 had significantly lower weight gain values after 2 weeks. Ambient salinity change also stimulated the hepatosomatic index, which increased in the first week and then recovered to a relatively normal level, as in the control, after 2 weeks. These findings indicate that in white shrimp, the specific protein nutrient and energy demands related to ambient salinity change are associated with protein metabolism. Increased dietary protein level could improve the osmoreaulation capacity of L. vannamei with more energy resources allocated to GDH activity and expression.

The aim of this study was to evaluate the performance of Patagonian octopus fed with moist diets formulated with several local feed ingredients. All formulated diets were based on crab paste (70%) and the experimental feed ingredient (30%). Experiment I assayed salmon meal, prime sardine meal, and wheat gluten, using fresh fish as a control; experiment 2 assayed prime fish meal and macroalgal meal against crab paste alone as a control. The ingestion rate was lower than expected for all diets except those of fresh fish, crab paste alone, and crab paste plus prime sardine meal. No significant differences were found in the observed digestibility of the diets, indicating, in general, low digestibility, even for fresh fish. The highest protease values were observed for crab paste plus prime sardine meal in both experiments. The better growth of Enteroctopus. megalocyathus was obtained when these were fed fresh fish, which was associated with the greater consumption observed in this diet, as neither the digestibility nor the enzymatic activities of the hepatopancreas were related to this greater growth.

The aim of this study was to evaluate the performance of Patagonian octopus fed with moist diets formulated with several local feed ingredients. All formulated diets were based on crab paste (70%) and the experimental feed ingredient (30%). Experiment I assayed salmon meal, prime sardine meal, and wheat gluten, using fresh fish as a control; experiment 2 assayed prime fish meal and macroalgal meal against crab paste alone as a control. The ingestion rate was lower than expected for all diets except those of fresh fish, crab paste alone, and crab paste plus prime sardine meal. No significant differences were found in the observed digestibility of the diets, indicating, in general, low digestibility, even for fresh fish. The highest protease values were observed for crab paste plus prime sardine meal in both experiments. The better growth of Enteroctopus. megalocyathus was obtained when these were fed fresh fish, which was associated with the greater consumption observed in this diet, as neither the digestibility nor the enzymatic activities of the hepatopancreas were related to this greater growth.

Red shrimp, Farfantepenaeus brasiliensis, larvae's response to different concentrations of live foods (diatoms Chaetoceros gracilis: 20-100 x 103 cells/mL; flagellate Tetraselmis chuii: 2-10 x 103 cells/mL and Artemia nauplii [NA]: 1-5 NA/mL) was investigated in three experiments. Experimental assessments were based on four variables: survival rate, weight gain, development index (DI), and resistance to salinity stress. A combination of C. gracilis 80 x 103 cells/mL, T. chuii 2 x 103 cells/mL, and Artemia 4 NA/mL provided the best experimental response. Specifically, F. brasiliensis larvae fed with the above-mentioned optimal concentrations of microalgae and Artemia grew faster and reached the postlarval stage in less time (168 h) than larvae in other feeding regimes evaluated. The effect of C. gracilis concentration on larval growth, survival, and the DI demonstrated that microalgae-based foods could be a highly productive alternative to more traditional aquaculture feeding regimes.

We evaluated changes in gene expression of Litopenaeus vannamei shrimp in response to a change in diet by comparing specimens which were fed with an animal protein diet against those which underwent a change from an animal protein diet to a plant protein diet. In addition, we also compared specimens which were fed with a plant protein diet with another group which underwent a change from plant to animal protein diet. Results showed that, in the case of hepatopancreas tissue, a total of six genes were differentially expressed and exhibited a high degree of homology with sequences which codify for proteins related to metabolism, transcription regulation, and rRNA subunits. In the case of muscle tissue, four differentially expressed sequences were recorded which codified for proteins associated to the immune system response, as well as cell structure and signaling. By means of RT-PCR, we also detected differentially expressed chitinase transcripts (Delta Ct). We observed Delta Ct expression values of 0.49 when comparing specimens fed a plant diet to those which underwent a change from plant to an animal diet, while a Delta Ct value of 0.52 was observed when comparing animals fed with an animal diet to specimens which underwent a change from an animal to a plant protein diet Differential gene expression was not observed in specimens which did not undergo a change in diet during the experiment.

Red shrimp, Farfantepenaeus brasiliensis, larvae's response to different concentrations of live foods (diatoms Chaetoceros gracilis: 20-100 x 103 cells/mL; flagellate Tetraselmis chuii: 2-10 x 103 cells/mL and Artemia nauplii [NA]: 1-5 NA/mL) was investigated in three experiments. Experimental assessments were based on four variables: survival rate, weight gain, development index (DI), and resistance to salinity stress. A combination of C. gracilis 80 x 103 cells/mL, T. chuii 2 x 103 cells/mL, and Artemia 4 NA/mL provided the best experimental response. Specifically, F. brasiliensis larvae fed with the above-mentioned optimal concentrations of microalgae and Artemia grew faster and reached the postlarval stage in less time (168 h) than larvae in other feeding regimes evaluated. The effect of C. gracilis concentration on larval growth, survival, and the DI demonstrated that microalgae-based foods could be a highly productive alternative to more traditional aquaculture feeding regimes.

The aim of this study was to evaluate the performance of Patagonian octopus fed with moist diets formulated with several local feed ingredients. All formulated diets were based on crab paste (70%) and the experimental feed ingredient (30%). Experiment I assayed salmon meal, prime sardine meal, and wheat gluten, using fresh fish as a control; experiment 2 assayed prime fish meal and macroalgal meal against crab paste alone as a control. The ingestion rate was lower than expected for all diets except those of fresh fish, crab paste alone, and crab paste plus prime sardine meal. No significant differences were found in the observed digestibility of the diets, indicating, in general, low digestibility, even for fresh fish. The highest protease values were observed for crab paste plus prime sardine meal in both experiments. The better growth of Enteroctopus. megalocyathus was obtained when these were fed fresh fish, which was associated with the greater consumption observed in this diet, as neither the digestibility nor the enzymatic activities of the hepatopancreas were related to this greater growth.

We evaluated changes in gene expression of Litopenaeus vannamei shrimp in response to a change in diet by comparing specimens which were fed with an animal protein diet against those which underwent a change from an animal protein diet to a plant protein diet. In addition, we also compared specimens which were fed with a plant protein diet with another group which underwent a change from plant to animal protein diet. Results showed that, in the case of hepatopancreas tissue, a total of six genes were differentially expressed and exhibited a high degree of homology with sequences which codify for proteins related to metabolism, transcription regulation, and rRNA subunits. In the case of muscle tissue, four differentially expressed sequences were recorded which codified for proteins associated to the immune system response, as well as cell structure and signaling. By means of RT-PCR, we also detected differentially expressed chitinase transcripts (Delta Ct). We observed Delta Ct expression values of 0.49 when comparing specimens fed a plant diet to those which underwent a change from plant to an animal diet, while a Delta Ct value of 0.52 was observed when comparing animals fed with an animal diet to specimens which underwent a change from an animal to a plant protein diet Differential gene expression was not observed in specimens which did not undergo a change in diet during the experiment.

Red shrimp, Farfantepenaeus brasiliensis, larvae's response to different concentrations of live foods (diatoms Chaetoceros gracilis: 20-100 x 103 cells/mL; flagellate Tetraselmis chuii: 2-10 x 103 cells/mL and Artemia nauplii [NA]: 1-5 NA/mL) was investigated in three experiments. Experimental assessments were based on four variables: survival rate, weight gain, development index (DI), and resistance to salinity stress. A combination of C. gracilis 80 x 103 cells/mL, T. chuii 2 x 103 cells/mL, and Artemia 4 NA/mL provided the best experimental response. Specifically, F. brasiliensis larvae fed with the above-mentioned optimal concentrations of microalgae and Artemia grew faster and reached the postlarval stage in less time (168 h) than larvae in other feeding regimes evaluated. The effect of C. gracilis concentration on larval growth, survival, and the DI demonstrated that microalgae-based foods could be a highly productive alternative to more traditional aquaculture feeding regimes.

The aim of this study was to evaluate the performance of Patagonian octopus fed with moist diets formulated with several local feed ingredients. All formulated diets were based on crab paste (70%) and the experimental feed ingredient (30%). Experiment I assayed salmon meal, prime sardine meal, and wheat gluten, using fresh fish as a control; experiment 2 assayed prime fish meal and macroalgal meal against crab paste alone as a control. The ingestion rate was lower than expected for all diets except those of fresh fish, crab paste alone, and crab paste plus prime sardine meal. No significant differences were found in the observed digestibility of the diets, indicating, in general, low digestibility, even for fresh fish. The highest protease values were observed for crab paste plus prime sardine meal in both experiments. The better growth of Enteroctopus. megalocyathus was obtained when these were fed fresh fish, which was associated with the greater consumption observed in this diet, as neither the digestibility nor the enzymatic activities of the hepatopancreas were related to this greater growth.

We evaluated changes in gene expression of Litopenaeus vannamei shrimp in response to a change in diet by comparing specimens which were fed with an animal protein diet against those which underwent a change from an animal protein diet to a plant protein diet. In addition, we also compared specimens which were fed with a plant protein diet with another group which underwent a change from plant to animal protein diet. Results showed that, in the case of hepatopancreas tissue, a total of six genes were differentially expressed and exhibited a high degree of homology with sequences which codify for proteins related to metabolism, transcription regulation, and rRNA subunits. In the case of muscle tissue, four differentially expressed sequences were recorded which codified for proteins associated to the immune system response, as well as cell structure and signaling. By means of RT-PCR, we also detected differentially expressed chitinase transcripts (Delta Ct). We observed Delta Ct expression values of 0.49 when comparing specimens fed a plant diet to those which underwent a change from plant to an animal diet, while a Delta Ct value of 0.52 was observed when comparing animals fed with an animal diet to specimens which underwent a change from an animal to a plant protein diet Differential gene expression was not observed in specimens which did not undergo a change in diet during the experiment.

Herbivorous (20% vegetable protein, 40% carbohydrate) and carnivorous diets (40% marine animal protein, 20% carbohydrate) were experimentally tested to assess their effect on the energy balance and energetic substrates utilized by postlarvae (PL's /15 days) and juvenile shrimp (3-6 g) of Litopenaeus vannamei. Postlarval stage 60 (PL60, early juveniles) shrimps fed HeD and CaD diets, then late juveniles (3-6 g) acclimated to the same diets were tested for their respective energy partitioning potential. No significant differences (p>0.05) on growth were obtained in early juveniles (mean final wet weight of 0.19 g). However in late juvenile stages a significant difference (p<0.05) in growth rate was observed. In terms of energy partitioning, both early and late juveniles seem to spend more energy in respiratory metabolism than in the elimination of excretion products. A change in feed composition based on quality protein sources induced some modifications on shrimp's activity measured by heat increment. Shrimps fed with an herbivorous diet showed a higher heat increment. Interestingly, the early stages of L vannamei display a remarkable capacity to assimilate a plant protein-based and a high carbohydrate level diet. Such capacity with a stimulation of genes would lead to a good adaptation of juveniles receiving all-plant diets to sustain growth performances up to a marketable size. The implications of these findings for the shrimp farming feeding costs are briefly discussed. (C) 2009 Elsevier B.V. All rights reserved.

Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland. were studied throughout the molt cycle in juveniles of Litopenaeus vannamei in a high salinity condition (36), and related to variations in the osmotic capacity of organisms. Increasing hemolymph volume before molting modifies circulating glucose and hemocyanin concentrations acting on the osmotic capacity. Variations in glucose concentrations are indicators of differential energy requirements throughout the molt cycle. Hemocyanin was used as an indirect indicator of the energy consumed by shrimp in various molt processes that affect the osmotic capacity. The co-variability of these metabolites is the result of the biochemical adaptations displayed by shrimp to maintain homeostasis. Their relation to changes in the osmotic capacity is given as a model to understand and predict events associated with molting under hypo-osmotic conditions.

Fish meal (FM) has long been considered an essential ingredient for the formulation of shrimp feeds. Until recently, 12%FM was considered a minimum amount, below which weight gain would become reduced due to a reduction in feed intake. In order to test this perceived minimum value, an experiment was conducted on a long-term basis with 4 replicates. Four practical isonitrogenous and isoenergetic diets were formulated for Litopenaeus vannamei juveniles. Survival, weight gain, feed conversion ratio (FCR) and protein efficiency ratio were determined for 0, 6, 10 and 15% FM diets and a reference diet. Shrimp survival ranged from 84 to 86.5%. Shrimp fed a diet with 0% FM showed lower average weight and SGR compared to the other treatments (P<0.05). FCR of shrimp fed the reference diet was significantly lower compared to the other treatments. Shortterm energy budget did not differ in recovered energy (RE). Variations in RE according to FM level were expected, however, it remained low (0.12 kJ prawn(-1) day(-1)) and it was not possible to discriminate among dietary treatments. Data indicate that RE was similar as evidenced by an absence of difference in weight gain among 6. 10 and 15% FM diets and the reference diet (0.98 g/wk). Growth results obtained over a long-term period and in clear water indicated the possibility for FM replacement with soybean plus canola meals. (C) 2009 Elsevier B.V. All rights reserved.

Herbivorous (20% vegetable protein, 40% carbohydrate) and carnivorous diets (40% marine animal protein, 20% carbohydrate) were experimentally tested to assess their effect on the energy balance and energetic substrates utilized by postlarvae (PL's /15 days) and juvenile shrimp (3-6 g) of Litopenaeus vannamei. Postlarval stage 60 (PL60, early juveniles) shrimps fed HeD and CaD diets, then late juveniles (3-6 g) acclimated to the same diets were tested for their respective energy partitioning potential. No significant differences (p>0.05) on growth were obtained in early juveniles (mean final wet weight of 0.19 g). However in late juvenile stages a significant difference (p<0.05) in growth rate was observed. In terms of energy partitioning, both early and late juveniles seem to spend more energy in respiratory metabolism than in the elimination of excretion products. A change in feed composition based on quality protein sources induced some modifications on shrimp's activity measured by heat increment. Shrimps fed with an herbivorous diet showed a higher heat increment. Interestingly, the early stages of L vannamei display a remarkable capacity to assimilate a plant protein-based and a high carbohydrate level diet. Such capacity with a stimulation of genes would lead to a good adaptation of juveniles receiving all-plant diets to sustain growth performances up to a marketable size. The implications of these findings for the shrimp farming feeding costs are briefly discussed. (C) 2009 Elsevier B.V. All rights reserved.

Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland. were studied throughout the molt cycle in juveniles of Litopenaeus vannamei in a high salinity condition (36), and related to variations in the osmotic capacity of organisms. Increasing hemolymph volume before molting modifies circulating glucose and hemocyanin concentrations acting on the osmotic capacity. Variations in glucose concentrations are indicators of differential energy requirements throughout the molt cycle. Hemocyanin was used as an indirect indicator of the energy consumed by shrimp in various molt processes that affect the osmotic capacity. The co-variability of these metabolites is the result of the biochemical adaptations displayed by shrimp to maintain homeostasis. Their relation to changes in the osmotic capacity is given as a model to understand and predict events associated with molting under hypo-osmotic conditions.

Fish meal (FM) has long been considered an essential ingredient for the formulation of shrimp feeds. Until recently, 12%FM was considered a minimum amount, below which weight gain would become reduced due to a reduction in feed intake. In order to test this perceived minimum value, an experiment was conducted on a long-term basis with 4 replicates. Four practical isonitrogenous and isoenergetic diets were formulated for Litopenaeus vannamei juveniles. Survival, weight gain, feed conversion ratio (FCR) and protein efficiency ratio were determined for 0, 6, 10 and 15% FM diets and a reference diet. Shrimp survival ranged from 84 to 86.5%. Shrimp fed a diet with 0% FM showed lower average weight and SGR compared to the other treatments (P<0.05). FCR of shrimp fed the reference diet was significantly lower compared to the other treatments. Shortterm energy budget did not differ in recovered energy (RE). Variations in RE according to FM level were expected, however, it remained low (0.12 kJ prawn(-1) day(-1)) and it was not possible to discriminate among dietary treatments. Data indicate that RE was similar as evidenced by an absence of difference in weight gain among 6. 10 and 15% FM diets and the reference diet (0.98 g/wk). Growth results obtained over a long-term period and in clear water indicated the possibility for FM replacement with soybean plus canola meals. (C) 2009 Elsevier B.V. All rights reserved.

Herbivorous (20% vegetable protein, 40% carbohydrate) and carnivorous diets (40% marine animal protein, 20% carbohydrate) were experimentally tested to assess their effect on the energy balance and energetic substrates utilized by postlarvae (PL's /15 days) and juvenile shrimp (3-6 g) of Litopenaeus vannamei. Postlarval stage 60 (PL60, early juveniles) shrimps fed HeD and CaD diets, then late juveniles (3-6 g) acclimated to the same diets were tested for their respective energy partitioning potential. No significant differences (p>0.05) on growth were obtained in early juveniles (mean final wet weight of 0.19 g). However in late juvenile stages a significant difference (p<0.05) in growth rate was observed. In terms of energy partitioning, both early and late juveniles seem to spend more energy in respiratory metabolism than in the elimination of excretion products. A change in feed composition based on quality protein sources induced some modifications on shrimp's activity measured by heat increment. Shrimps fed with an herbivorous diet showed a higher heat increment. Interestingly, the early stages of L vannamei display a remarkable capacity to assimilate a plant protein-based and a high carbohydrate level diet. Such capacity with a stimulation of genes would lead to a good adaptation of juveniles receiving all-plant diets to sustain growth performances up to a marketable size. The implications of these findings for the shrimp farming feeding costs are briefly discussed. (C) 2009 Elsevier B.V. All rights reserved.

Biochemical changes, specifically in hemocyanin and glucose concentrations in hemolymph, glycogen in the digestive gland. were studied throughout the molt cycle in juveniles of Litopenaeus vannamei in a high salinity condition (36), and related to variations in the osmotic capacity of organisms. Increasing hemolymph volume before molting modifies circulating glucose and hemocyanin concentrations acting on the osmotic capacity. Variations in glucose concentrations are indicators of differential energy requirements throughout the molt cycle. Hemocyanin was used as an indirect indicator of the energy consumed by shrimp in various molt processes that affect the osmotic capacity. The co-variability of these metabolites is the result of the biochemical adaptations displayed by shrimp to maintain homeostasis. Their relation to changes in the osmotic capacity is given as a model to understand and predict events associated with molting under hypo-osmotic conditions.

Fish meal (FM) has long been considered an essential ingredient for the formulation of shrimp feeds. Until recently, 12%FM was considered a minimum amount, below which weight gain would become reduced due to a reduction in feed intake. In order to test this perceived minimum value, an experiment was conducted on a long-term basis with 4 replicates. Four practical isonitrogenous and isoenergetic diets were formulated for Litopenaeus vannamei juveniles. Survival, weight gain, feed conversion ratio (FCR) and protein efficiency ratio were determined for 0, 6, 10 and 15% FM diets and a reference diet. Shrimp survival ranged from 84 to 86.5%. Shrimp fed a diet with 0% FM showed lower average weight and SGR compared to the other treatments (P<0.05). FCR of shrimp fed the reference diet was significantly lower compared to the other treatments. Shortterm energy budget did not differ in recovered energy (RE). Variations in RE according to FM level were expected, however, it remained low (0.12 kJ prawn(-1) day(-1)) and it was not possible to discriminate among dietary treatments. Data indicate that RE was similar as evidenced by an absence of difference in weight gain among 6. 10 and 15% FM diets and the reference diet (0.98 g/wk). Growth results obtained over a long-term period and in clear water indicated the possibility for FM replacement with soybean plus canola meals. (C) 2009 Elsevier B.V. All rights reserved.

The present study was designed to test the effects of type of binder on growth, nutritional physiology, total apparent digestibility, and some elements of the energetic balance of early O. maya juveniles. Two experiments were performed. One was aimed at evaluating the effect of type of binder on growth, nutritional physiology, and energetic balance and the other at knowing the effect of the binder on total apparent digestibility of O. maya. Binder type affected growth and survival of early O. maya juveniles. Octopuses fed alginate-bound crab meat lost weight and died, revealing that this type of binder limits nutrient absorption from the diet. In contrast, when gelatin was used as binder, energetic balance was similar to that obtained in animals fed natural crab, indicating that octopuses can digest gelatin. Apparently, gelatin promotes absorption of nutrients similar to that observed when octopuses were fed pieces of fresh crab. Salivary glands produce enzymes that are used to predigest the food. Results of the present study indicate that octopuses require higher enzyme activity to digest fresh crab than when animals are fed gelatin-bound crab paste, and that intracellular digestion in the digestive gland is similar in animals fed either type of diet. The present study reports, for the first time, differences among binders used for cephalopods' diet. Although no compounded feed formulations are available for cephalopods, it is a necessary step in the search for an adequate compounded feed for this novel species in aquaculture. (c) 2008 Elsevier B.V. All rights reserved.

The present study was designed to test the effects of type of binder on growth, nutritional physiology, total apparent digestibility, and some elements of the energetic balance of early O. maya juveniles. Two experiments were performed. One was aimed at evaluating the effect of type of binder on growth, nutritional physiology, and energetic balance and the other at knowing the effect of the binder on total apparent digestibility of O. maya. Binder type affected growth and survival of early O. maya juveniles. Octopuses fed alginate-bound crab meat lost weight and died, revealing that this type of binder limits nutrient absorption from the diet. In contrast, when gelatin was used as binder, energetic balance was similar to that obtained in animals fed natural crab, indicating that octopuses can digest gelatin. Apparently, gelatin promotes absorption of nutrients similar to that observed when octopuses were fed pieces of fresh crab. Salivary glands produce enzymes that are used to predigest the food. Results of the present study indicate that octopuses require higher enzyme activity to digest fresh crab than when animals are fed gelatin-bound crab paste, and that intracellular digestion in the digestive gland is similar in animals fed either type of diet. The present study reports, for the first time, differences among binders used for cephalopods' diet. Although no compounded feed formulations are available for cephalopods, it is a necessary step in the search for an adequate compounded feed for this novel species in aquaculture. (c) 2008 Elsevier B.V. All rights reserved.