Effect of Diet Size on Feeding Behavior and Growth of Pacific White Shrimp,Litopenaeus vannamei

Abstract

Six diet sizes, manufactured from crumbling large pellets, were investigated for their effect on the feeding behavior and growth of Pacific white shrimp, Litopenaeus vannamei. These diets containing 44.7% protein and 8.2% lipid were fed to 0.9 g shrimp for a period of eight weeks under indoor controlled laboratory conditions. Shrimp were stocked at a density of 12 animals per 52 L aquarium (50/m²) and were evaluated for feeding behavior, final weight, growth rate, feed conversion ratio (FCR), and survival. Feeding behavior was observed weekly starting at the beginning of the 4th week until the end of the trial. Results indicated that the variation in diet sizes did not produce significant differences in shrimp growth, FCR or survival. However, shrimp feeding behavior (in terms of total attacking incidents during feeding) was significantly different among diet sizes. This shrimp behavior was observed more frequently in aquaria fed larger diet size (3.0 mm pellet) as compared with those fed smaller diet sizes (0.7 mm and 1.2 mm crumbles). When shrimp were fed larger pellets, some of the individuals obstruct other individuals and monopolize the diet. Such “selfish” behavior of shrimp could result in considerable size variation and severe mortality of smaller individuals, which could be the case when shrimp are reared to market size. The effect of diet size on shrimp feeding behavior deserves further investigation and the use of a continuous monitoring device such as a video camera is strongly recommended. Future study should also consider various shrimp and pellet sizes more meaningful to aquaculture producers.     

Method for determining the physical stability of shrimp feeds in water

Three methods for measuring the water stability and leaching characteristics of shrimp pelleted feeds were developed and tested: static water method, horizontal shaking method and vertical shaking method. Each method was tested using a commercial and experimental pelleted shrimp feed. Both feeds had a pellet size of 2.4 mm × 5.0 mm with similar proximate composition (35% protein and 9% fat). Each test run consisted of leaching c. 2 g of feed at six intervals of immersion time (0, 30, 60, 120, 240, 360 min), two concentrations of salinity (0, 34 ppt), and three different water temperatures (15, 25, 35 °C). A refrigerated circulating water bath was used to maintain the desired level of water temperature. For the static water and horizontal shaking methods, a Buchner filtration apparatus with Whatman filter paper no. 3 (5 μ) was used to separate the remaining pellets from leached water. The vertical shaking method (VanKel) utilized a perforated stainless‐steel basket (381 μ) for leaching and serving as a filter to separate pellets from leached water. For all three methods, the leached feed and original feed samples were dried in a convection oven at 105 °C for 24 h and then cooled in a desiccator. Dried feed samples were weighed and analysed for dry matter retention. Pellet stability was calculated as the ratio of dry matter retention after leaching and dry matter of original samples expressed as a percentage. Results indicated that any method for pellet stability analysis should take into account water temperature and salinity in addition to actual pellet agitation rate to obtain accurate and consistent measurement of pellet disintegration and nutrient leaching. Dry matter retention was different for each shrimp feed with experimental feed (72.8%) showing lower retention than commercial feed (88%) after 6 h of VanKel leaching under normal shrimp culture conditions. The three methods provided reproducible results with both horizontal and vertical shaking methods recommended for routine laboratory analysis because they could provide different degrees of pellet agitation that simulate actual indoor and outdoor shrimp culture conditions.     

Effects of replacing fish oil with stearine as main lipid source in diet on growth and survival of Pacific White Shrimp,Litopenaeus vannamei (Boone, 1931)

The stearine fraction from raw fish oil refinement has been treated as a waste material. This study was conducted to evaluate effects of replacing prime refined fish oil with stearine as the main lipid source to a control diet on shrimp growth and survival as well as on pellet water stability of diets. Test diets were processed containing three levels (0.7%, 1.3% and 2.7%) of either stearine or refined fish oil in a semi‐purified control diet. These diets were each assigned to five or six replicated tanks and each tank was stocked with seventeen juvenile shrimp (ca. 0.50 g) in an indoor seawater recirculating system. At the end of 6 weeks, the survival of shrimp was 89.4–95.3% with no significant difference (P > 0.05) among dietary treatments. The six test diets obtained significantly higher (P < 0.05) shrimp growth rates (1.46–1.83 g week^?1) than the control diet (1.38 g week^?1). The shrimp that were fed the three stearine‐added diets exhibited high growth rates (1.75–1.83 g week^?1). Increasing the inclusion level of the stearine improved pellet water stability (91.7–93.9%; P < 0.05). These results suggest that stearine can replace fish oil in shrimp feed based on the growth performance.     

Nutritive values of low and high fibre canola meals for shrimp (Penaeus vannamei)

This study was undertaken to determine acceptable dietary concentrations of high-fibre canola meal (CMHF) and low-fibre canola meal (CMLF) for juvenile shrimp, Penaeus vannamei. Four groups of 0.78 g shrimp held in running, 24.0–27.8°C sea water on a 12 h light: 12 h dark cycle were each fed one of seven isonitrogenous (340 g kg^?1 protein) and isoenergetic (18.5 MJ of gross energy kg^?1) diets to satiation four times daily for 56 days. Each of the test canola protein products comprised either 150, 300 or 450 g kg^?1 of the protein in a basal (practical) diet by replacement of one-third, two-thirds or all of the menhaden meal protein. Shrimp that ingested diets in which CMHF and CMLF comprised 450 and 300 g kg^?1 of the protein, respectively, exhibited significant reductions in growth and feed intake relative to those fed the basal diet. Feed and protein utilization were not significantly depressed unless menhaden meal in the basal diet was completely replaced by CMHF or CMLF. In general, percentage survival and final whole-body levels of protein, minerals, and thyroid hormones were not significantly affected by dietary treatment. Terminal whole-body levels of moisture were raised significantly in shrimp fed diets containing the highest levels of CMHF and CMLF. Potassium levels were significantly higher in shrimp fed the diet containing the lowest level of CMLF relative to those fed the basal diet and the diet with the highest level of CMLF. Water stability of the diet pellets was negatively correlated with their levels of CMHF and CMLF. It is concluded that commercial high-fibre canola meal can constitute 300 g kg^?1 of the dietary protein of juvenile shrimp (Penaeus vannamei) without compromising growth, feed intake and feed and protein utilization. However, because of a trend towards reduced shrimp survival at this dietary concentration of canola meal, it is recommended that this protein source not exceed 150 g kg^?1 of the protein in practical juvenile shrimp diets. Fibre-reduced canola meal did not have improved nutritive value for shrimp. However, we postulate that one or more fibre-reduced, and solvent-extracted canola protein products may be cost-effective substitutes for fish meal protein.     

Digestibility, growth and excretion response of rainbow trout (Oncorhynchus mykiss Walbaum) to feeds of different ingredient particle sizes

The effects of feed ingredient particle size on apparent digestibility, growth and excretion responses of rainbow trout were investigated in pilot production systems. Particle size of the feed ingredients (ground using a hammer mill with 0.6 and 3.0 mm screen sizes) had no significant effect (P > 0.05, d.f. = 1/6) on the apparent digestibility of dry matter, phosphorus and crude protein in cold‐extruded diets. Feed ingredient particle size had an impact on the feed conversion ratio over an 85‐day feeding trial when key ingredients (78.65% of diet) were ground using a pulverizer and a hammer mill with 3.0 mm screen size and heat extruded. No significant differences (P > 0.05, d.f. = 1/12) were observed in the excretion ratios of TAN (total ammonia nitrogen), TKN (total Kjeldahl nitrogen), TP (total phosphorus), BOD₅ (5‐day biochemical oxygen demand) and TSS (total suspended solids) among three feed types, which included a wide ingredient particle size distribution.     

An acoustic based approach to evaluate the effect of different diet lengths on feeding behavior of Litopenaeus vannamei

Studying shrimp feeding behavior is challenging and, traditionally, studies have been using direct visual observation or video recordings with image analysis under laboratory conditions. Passive acoustics monitoring (PAM) is a non-invasive approach to study feeding behavior of penaeids, as their mandibles emit clicking sounds during feed ingestion. Considering the wide variation available in shrimp diet lengths, our knowledge is still limited about their effects on feeding behavior. The present study was designed to use acoustics to evaluate the feeding behavior of Litopenaeus vannamei fed different diet lengths. A commercial pelleted diet with similar diameter (2.4 mm) and three different lengths was used as treatments “small” (2.35 mm), “medium” (4.26 mm) and “large” (8.42 mm). Three separate trials were performed with fastened shrimp (20 g), using omnidirectional hydrophones and external audio recorders. Our approach started with the characterization of the click acoustic parameters produced by three shrimps when fed the different diet lengths in anechoic chambers (15 L). We then analyze the number of clicks produced per pellet and duration of the clicking activity when shrimp fed a single pellet in individual tanks (1 L). Finally, the acoustic energy of feeding activity and feed consumption, as well as theirs relationship to predict feed intake was evaluated in aquaria (70 L) with five shrimps. The acoustic parameters of isolated clicks were not affected by the different diet lengths, however, doubling the length of the pellet resulted in doubling the number of clicks emitted during feeding activity. The duration of clicking activity per pellet indicated that small pellets are consumed 2.9 and 4.7 times faster than medium and large pellets, respectively. Furthermore, feeding acoustic energy of small pellets decreased rapidly after feed offer, as their faster consumption probably contributed to shrimps achieved satiety earlier than larger diets. Feed consumption was similar among diets length, but significantly correlated with the feeding acoustic energy emitted by L. vannamei, which is a breakthrough in feeding behavioral research. The results highlight the potential and possibilities of an acoustic approach to estimate feed consumption, as well as an alternative to traditional methods in feeding behavioral studies to improve efficiency of feed management.     

The value of sea urchin,Lytechinus variegatus,egesta consumed by shrimp,Litopenaeus vannamei

Sea urchins produce high‐energy, membrane‐bound fecal pellets that contain residual nutrients and large quantities of microbiota. These egesta are readily consumed by the shrimp, Litopenaeus vannamei. Egesta of the sea urchin, Lytechinus variegatus, were evaluated as a feed supplement or total replacement for a commercial shrimp diet. Shrimp were stocked at 0.49 g ± 0.06 g initial body weight and housed individually in 2.8‐L tanks in a commercial recirculating zebrafish system. Shrimp were assigned to one of six diets: commercial shrimp feed, reference sea urchin feed, collected dried sea urchin egesta, collected wet sea urchin egesta, half ration of shrimp feed and half collected wet sea urchin egesta, and egesta naturally produced by two sea urchins in polyculture. Equivalent dry matter amounts of each diet were proffered to shrimp in each treatment twice daily, except for those that had complete access to natural egesta excreted by sea urchins in polyculture. Sea urchins were proffered a reference sea urchin feed at 2% body weight daily. After 27 days, shrimp proffered collected dried or wet egesta did not differ significantly in percent weight gain and showed the lowest weight gain. The percent weight gain of shrimp fed the commercial shrimp diet did not differ significantly from that of the shrimp fed half commercial shrimp diet and half egesta. The highest weight gain was recorded for those shrimp that consumed the untouched egesta produced by sea urchins in polyculture. These data suggest that consumed egesta have noteworthy nutritional value and therefore would be beneficial to the culture of extractive species in an integrated multitrophic aquaculture system.     

Substitution of fishmeal with soybean meal in practical diets for juvenile white shrimp Litopenaeus schmitti (Pérez‐Farfante & Kensley 1997)

The feasibility of substituting soybean meal for fishmeal diets for juvenile white shrimp Litopenaeus schmitti (0.35±0.01 g) was evaluated, and an adequate substitution level was determined. Five diets were evaluated using 46%, 59%, 75%, 88% and 100% substitution levels. Pellet water stability was significantly affected by dietary soybean content (P<0.05). Increased soybean content produced lower pellet stability, ranging from a dry matter loss of 14–22% after a 2‐h immersion, and 20–33% after an 8‐h immersion. After 52 days, significant differences (P<0.05) were found in shrimp weight, feed conversion ratio and protein efficiency ratio. The values were 0.64–1.06 g, 2.8–7.9 and 0.45–1.21, respectively, for the three measurements. Overall, better results were obtained with diets where soybean meal was substituted for fishmeal up to 75%. The 100% soybean meal diet resulted in poor growth performance of shrimp. Survival rates were acceptable for all treatments (90% or higher) and no significant differences were found in survival between treatments. Regression analysis using the broken‐line methodology indicated that 76.5±2% is an optimum soybean substitution level in diets that contained fishmeal and soybean as the major protein sources for grow‐out of juvenile white shrimp.     

Utilization of Deoxynivalenol‐Contaminated Hard Red Winter Wheat for Shrimp Feeds1

Wheat is used in shrimp feed as protein and energy sources, as well as a nutritive binder that promotes water stability. However, wheat may be contaminated with deoxynivalenol (DON or vomitoxin) when wet weather conditions prevail during the growing season. Deoxynivalenol‐contaminated wheat was added to shrimp diet to obtain DON levels of 0.2, 0.5, and 1.0 ppm. Pelleted diets were fed 3 times daily until satiation to Pacific white shrimp Liropenaeus vanna‐mei. Biological performance (live weight, weekly growth increment, feed conversion ratio, and survival) was determined biweekly for 16 wk. Histological characteristics of shrimp were determined on samples obtained after 8 and 16 wk of growth. The DON levels in ground wheat, feed mash, pellets, and freeze‐dried shrimp were determined using thin layer and high performance liquid chromatography. Deoxynivalenol levels of 0.2, 0.5, and 1.0 ppm in the diet significantly reduced shrimp body weight and/or growth rate. However, the effects of 0.2 and 0.5 ppm DON were manifested at later stages of shrimp growth, and 0.2 ppm DON significantly affected only growth rate and not body weight (P > 0.05). Feed conversion ratio and survival of shrimp fed diets containing 0.2, 0.5, and 1.0 ppm DON were not significantly different from those of shrimp fed the control diet (0.0 ppm DON). After 16 wk of growth, no DON was detected in freeze‐dried shrimp, and no consistent difference was observed in the histological organ profiles of shrimp fed diets containing various levels of DON. Because low levels of DON in the diet can significantly reduce body weight and growth rate of shrimp, feed ingredients should be monitored for DON.     

Determination of physical behaviour of feed pellets in Mediterranean water

Settled uneaten feed causes the most intense impact under sea cages, and settling velocity of the feed pellets represents a key parameter for waste dispersion models. Even if some data about physical properties of feed pellets have been published in the framework of salmonid rearing, there is a complete lack of information related to the Mediterranean Sea, as regards typical values of temperature, salinity and feed composition for Gilthead Sea Bream (Sparus aurata L.) and Sea Bass (Dicentrarchus labrax L.). In this study we try to fill this lack, determining dimensions, water adsorption properties, floating times and settling velocities of a typical growing sequence of pellets for the species mentioned above, under defined laboratory conditions reproducing Mediterranean Sea water. The settling velocity increases with pellet size from 0.087, for the smallest pellet (3 mm), to 0.144 m s^?1, for the 5 mm pellet. The biggest extruded pellet (6 mm) falls slower (0.088 m s^?1). The floating time before pellet's fall is found to be a critical parameter in determining settling velocity. The latter depends on pellet's size, water temperature and salinity. The examined pellets reach a 42% of weight increase after 10 min of immersion, while no appreciable dimension change is observed. Our results are in part different from previous ones and could play a role in evaluating and modelling Mediterranean aquaculture environmental impact.     

Improvement of the stability of commercial feed pellets for the giant shrimp (Macrobrachium rosenbergii)

Different feed pellets for the giant shrimp, Macrobrachium rosenbergii, were compared with respect to water stability, food conversion ratio and growth rate. Pellet stability was observed under tank conditions with and without animals, and leaching rates were measured. Purina Marine Ration M20 was repelletized with Kelco HV algin binder at 0.5% level (designated RM20-0.5%), 1.0% level (RM20-1.0%), and 2.0% level (RM20-2.0%). The base commercial pellet was also tested unaltered and with 0.5% Kelco HV algin encapsulation. Recording of pellets presented and pellets apparently consumed by individual animals was maintained on a daily basis for each treatment.The RM20-2.0% bound pellet gave the best results in both physical stability and efficient biological utilization. The RM20-2.0% was followed in quality by the 0.5% encapsulated and 1.0% bound pellets. The unaltered M20 commercial pellet and 0.5% bound pellet were deemed unsatisfactory by the same criteria.     

Intrinsic settling rate and spatial diffusion properties of extruded fish feed pellets

Spatial and temporal feed distribution in sea cages are important factors for the farmer, fish and environment due to the strong relation to growth, feed loss, pollution and welfare. This study presents a set of experimentally derived diffusion parameters and settling rates obtained in still water from four sizes and three densities of extruded fish feed pellets commonly used in aquaculture. It was found that pellet size is positively correlated with increased diffusion and that pellet density plays a less important role. Both the size and density of pellets had a significant impact on the settling rate. Results are compared to values obtained during feed production as well as other relevant studies. The findings suggest that parameters related to hydrodynamic behaviour of groups of feed pellets may vary across different pellet types. The results may be applied to refine and parameterize pellet motion in sea cage feeding models, improving estimates of fish behaviour, growth and feed loss.     

Effect of microencapsulated diets supplemented with genetically modified bacteria on the growth and survival of Fenneropenaeus indicus postlarvae

Microencapsulated diets were prepared and supplemented with two genetically modified bacteria that produced digestive enzymes. One produced a protease (strain Escherichia coli XL1Bluep635), and the other a lipase and a protease (strain E. coli XL1Bluep7). Fenneropenaeus indicus at the postlarval 1 stage (PL1) were fed these diets for 16 days, and their total length and survival were recorded every 2 days. The results were analyzed by anova and sequential Turkey–Kramer analysis. Shrimp fed on the diet supplemented with strain E. coli XL1Bluep635 (diet 635) exhibited the fastest growth rate of 0.26 mm day⁻¹, followed by shrimp fed on the control commercial unsupplemented diet CD2 – 0.21 mm day⁻¹, and shrimp fed on diet supplemented with strain E. coli XL1Bluep7 (diet 7) – 0.20 mm day⁻¹. The growth rates of shrimp fed on diet supplemented with control strain E. coli XL1BluepUC19 (diet XL1), and those fed on unsupplemented diet prepared in our laboratory (D2), were 0.15 and 0.14 mm day⁻¹, respectively. The survival of shrimp fed on diets CD2 and 635 showed the same level of survival of 83.3%, followed by those fed on diet D2 with 76.6%. Shrimp fed on diet 7, showed 71.6% survival, and those fed on diet XL1, 55%.     

Use of Porcine Meal in Plant‐based Practical Diets for Pacific White Shrimp,Litopenaeus vannamei

Two growth trials were conducted to evaluate and confirm the efficacy of a porcine meal (PM) with high protein content (>90%) as an alternative feed ingredient in commercial‐type feed formulation for Pacific white shrimp, Litopenaeus vannamei. Six experimental diets were formulated for the two growth trials. The first five diets contained increasing levels (0, 1, 2, 4, and 6%) of PM as a replacement for soybean meal in a plant‐based diet with low inclusion level (6%) of fish meal (FM). The last experimental diet was produced utilizing 4.2% PM to completely replace FM. In Trial 1, shrimp (1.5 g initial mean weight, 20 shrimp/tank, n = 4) were offered test diets for 6 wk in a semirecirculation system. At the end of Trial 1, shrimp fed with the diet containing 6% PM exhibited significantly enhanced weight gain (WG), feed conversion ratio (FCR), and survival compared to those fed with the diet devoid of FM. As survival was poor across all treatments and different densities could mask growth results the trial was repeated. In Trial 2, shrimp (0.85 g, 15 shrimp/tank, n = 4) were offered diets for 6 wk. Dietary supplementation of PM at 6% significantly improved WG, FCR, and apparent net protein retention in contrast with the treatment devoid of FM, confirming the same trends in Trial 1. No significant difference was detected in protein, lipid, moisture, and mineral profiles of whole‐body shrimp as well as survival across all the treatments. Results of this study indicate that PM is a good high protein source in shrimp feeds, which can be included up to 6% in the low FM‐based diet without compromising the growth of shrimp.     

Effects of different natural or prepared diets on growth and survival of juvenile spider crabs, <Emphasis Type="Italic">Maja brachydactyla</Emphasis> (Balss, 1922)

The effects of different diets (natural or pellets) on growth, survival, and moulting interval of juvenile spider crabs, weighing between 0.011–1.56 g and up to 17.6 mm in carapace length, were tested over a period of 90 days. During experiment I, five diets were tested: (1) frozen shrimp—Paleomonetes sp., (2) fresh mussels—Mytilus sp., (3) white fish fillets—Merlucius merlucius, (4) blue fish fillets—Sardina pilchardus, and (5) commercial crustacean pellets. Spider crabs fed fresh mussels grew larger (0.98 ± 0.69 g) and had higher growth rates (4.0 ± 0.7 %BWd⁻¹) compared to the other four diets. The crabs fed shrimp pellet and frozen shrimp grew to intermediate sizes and were smaller than the ones fed fresh mussels, but they were larger than spider crabs fed either blue or white fish fillets (0.46 ± 0.63 and 0.26 ± 0.13 g, respectively) compared to the ones fed white fish fillets (0.12 ± 0.04) and blue fish fillets (0.04 ± 0.02 g). The spider crabs fed blue fish fillets only lasted until day 60 of the experiment, after this day none of the 20 fed this diet were left. During experiment II, two diets were tested: (1) white and blue fish fillets and (2) commercial fish pellet. There were no differences in growth both in weight or carapace length (2.9 ± 1.8 and 2.1 ± 1.5 g in weight, and 18.9 ± 5.0 and 17.7 ± 3.3 mm, respectively) at the end of the experiment. Similarly, there were no differences in growth rates in weight between the two diets (1.2 ± 0.4 and 0.9 ± 0.3 %BWd⁻¹, respectively) or in carapace length (0.4 ± 0.1 and 0.4 ± 0.2 %BWd⁻¹, respectively). Fresh mussel appears to be a very good diet to culture the early stages of this species, while shrimp pellets also deliver acceptable results. On the contrary, frozen shrimp, fish fillets either from blue or white species (much higher lipid content in the blue species), and fish pellets were found to be bad diets for the culture of the early stages of M. brachydactyla.     

Effects of temperature and feed processing on protease activity and dietary protease on growths of white shrimp,Litopenaeus vannamei,and tilapia,Oreochromis niloticus × O. aureus

Effects of temperature and processing on the stability of a commercial protease were assessed in an in vitro trial followed by growth trials with white shrimp and tilapia. Results showed that the protease has a high heat stability against pelleting, and it could hydrolyse dietary proteins during feed processing. In Exp. 2, white shrimp (3.3 g) fed low fish meal (FM) diet (LFD) with protease addition had similar growth to that fed high fish meal diet, and both had higher weight gain (WG) and lower feed conversion ratio (FCR) than that fed LFD without protease addition (P < 0.05). In Exp. 3, compressed (CD) or extruded (ED) diets containing 30 g kg^?1 or 90 g kg^?1 FM were supplemented with or without protease and then fed to tilapia (1.7 g) for 8 weeks. WG was improved and FCR decreased (P < 0.05) by the supplementation of protease in 30 g kg^?1 FMCD, but not in 90 g kg^?1 FMCD and ED diets when compared to those diets without protease supplementation. The digestibility trial with CD indicated the improved apparent digestibilities of dry matter and crude protein by dietary protease in 30 g kg^?1 FMCD, but not in 90 g kg^?1 FMCD. Results above showed that the protease has a high heat stability and the supplementation of protease in CD with low FM level can improve the growth of shrimp and tilapia.     

Effects of dietary mannan oligosaccharide on growth, body composition and hepatopancreas histology of Penaeus semisulcatus (de Haan 1844)

The effects of dietary mannan oligosaccharides (MOS) on growth, body composition and hepatopancreas histology of Penaeus semisulcatus (postlarvae stage 20) were investigated for 48 days. Different dosages of MOS (0, 1.5, 3.0 and 4.5 g MOS kg⁻¹) were tested in triplicate groups. Shrimp postlarvae averaging 0.34 ± 0.01 g attained 1.52 ± 0.31, 1.51 ± 0.15, 2.18 ± 0.13, 1.57 ± 0.13-g final weight and 42.7 ± 2.7, 37.3 ± 1.3, 64.0 ± 6.9, 50.7 ± 4.8% survival, respectively. At the end of the study, generally enhanced growth performance and feed conversion ratio were observed in shrimp fed on diet containing 3.0 g kg⁻¹ MOS with the highest final live weight (2.18 ± 0.13 g) and survival rate (64.0 ± 6.9%) after 48 days of feeding. The protein contents in the whole body decreased with increasing rates of dietary MOS (P < 0.05). Different levels of dietary MOS used in this study showed no detrimental effects on hepatopancreas tissue judged by histological screening. In conclusion, 3.0 g kg⁻¹ MOS could be used as a healthy growth promoter in shrimp diets.     

Effects of supplementation of crystalline or coated methionine on growth performance and feed utilization of the pacific white shrimp,Litopenaeus vannamei

This study was conducted to evaluate the effects of supplementation of crystalline methionine or coated methionine supplemented in diets of Pacific white shrimp (Litopenaeus vannamei) on growth performance and feed utilization. Five iso‐nitrogen and iso‐caloric diets were prepared in which diets were supplemented with cellulose‐acetate‐phthalate (CAP), tripalmitin‐polyvinyl alcohol (TPA), acrylic resin (RES) coated l ‐methionine, hydroxyl‐methionine calcium (MHA) and crystalline l ‐methionine diet (MET, control), respectively. After 7 weeks, shrimp (0.81 ± 0.01 g in initial body weight) weight gain fed with MET and RES diets were significantly higher than that of the others (P < 0.05), while feed conversion ratio of shrimp fed with RES was significantly lower than the others (P < 0.05). Crude protein (as wet weight basis) in whole body of shrimp fed the RES diet was markedly higher than the others (P < 0.05). Methionine contents in muscle of CAP and MHA groups were significantly higher than those of MET group (P < 0.05). Apparently digestibility for essential amino acid of MET group was the highest except methionine. In the present study, RES coating methionine appeared to effectively improve feed protein utilization and enhance growth performance of Pacific white shrimp fed with low fishmeal practical diet.     

Effects of replacing fish meal with soybean meal and peanut meal on growth,feed utilization and haemolymph indexes for juvenile white shrimp Litopenaeus vannamei,Boone

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal (FM) with soybean meal (SBM) and peanut meal (PM) on growth, feed utilization, body composition and haemolymph indexes of juvenile white shrimp Litopenaeus vannamei, Boone. Five diets were formulated: a control diet (FM30) containing 30% fish meal and four other diets (FM20, FM15, FM10 and FM5) in which protein from fish meal was substituted by protein from SBM and PM. The dietary amino acids of diets FM20, FM15, FM10 and FM5 were equal to those of the diet FM30 by adding crystalline amino acids (lysine and methionine). Each diet was randomly assigned to triplicate groups of 30 shrimps (initial weight = 0.48 g), each three times daily. The results indicated that shrimp fed the diets FM15, FM10 and FM5 had poor growth performance and feed utilization compared with shrimp fed the control diet. No difference was observed in feed intake, survival and body composition among dietary treatments. The plasma total cholesterol level of shrimp and the digestibility of dry matter, protein and energy contained in the diets decreased significantly with increasing PM and SBM inclusion levels. Results of this study suggested that fish meal can be reduced from 300 to 200 g kg^?1 when replaced by a mixture of SBM and PM.     

An evaluation of pink salmon (Oncorhynchus gorbuscha) testes meal in diets for pacific white shrimp (Litopenaeus vannamei): effect on palatability,digestibility and growth performance

This study compared the nutritional profiles of menhaden fishmeal and pink salmon (Oncorhynchus gorbuscha) testes meal and investigated the nutritional values of the testes meal based on its effect on palatability, digestibility and growth performance of Pacific white shrimp (Litopenaeus vannamei). The testes meal replaced 0–91% of fishmeal protein in a control diet containing 150 g kg⁻¹ fishmeal. Replacement of 69% of the fishmeal protein in the control diet significantly increased feed intake of shrimp from 0.61% to 1.10%. The apparent digestibility coefficient of dietary protein increased significantly when 91% of the fishmeal protein was replaced by the testes meal. Replacement of dietary fishmeal protein with up to 46% testes meal protein did not cause adverse effects on growth rate or nutritional composition of tail muscle. However, growth rate was significantly decreased in shrimp fed diets in which 69% or 91% of fishmeal protein was replaced by the testes meal. Results of this study indicate that the testes meal can be used as a feed additive to enhance the palatability and protein digestibility of low fishmeal diets for shrimp. It can replace up to 46% of fishmeal protein without any adverse effect on the growth performance of shrimp.