bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Phase‐Shifted Photoperiod Regimes on Oocyte Growth and Hormonal Profiles in Female Striped Bass Morone saxatilis
Authors: Vuthiphandchai Verapong , Stubblefield John , Zohar Yonathan
Published: April 2007

Abstract.— The use of 12–mo long, but phase‐shifted advanced and delayed photoperiod cycles in the regulation of the reproductive cycle was investigated in captive‐reared female striped bass Morone saxatilis during the 3‐yr study in an attempt to control the timing of sexual maturation under simulated photoperiod conditions. Phase‐shifted photoperiod cycles did not induce a full shift in oogenesis during the first year cycles, but did in the following years. Spawning time, indicated by maximum oocyte diameters, was advanced up to 4 mo in females maintained under the phase‐shifted advanced photoperiod, and delayed up to 4 mo when they exposed to the phase‐shifted delayed photoperiod, compared to the natural spawning time in Spring (March‐May). Phase‐shifted photoperiod regimes shifted the profiles of plasma testosterone (T) and estradiol (E2), corresponding to the shift of oogenesis in the respective groups. Significant increases in T and E2 levels occurred during the vitellogenic phase, and these levels peaked before the occurrence of maximum oocyte diameters. The studies demonstrate that phase‐shifted photoperiod regimes can be used to control oogenesis, and have implications for ensuring the year‐round supply of mature female striped bass, particularly in domesticated striped bass.
Influence of Dietary Levels of Magnesium on Growth, Tissue Mineral Content, and Resistance of Channel Catfish Ictalurus punctatus Challenged with Edwardsiella ictaluri
Authors: Lim Chhorn , Klesius Phillip H.
Published: April 2007

Juvenile channel catfish were fed purified diets supplemented with magnesium (Mg) from Mg sulfate at levels of 0, 200, 400, 600, 800, and 1,000 mg/kg and 0, 200, 400, 600, and 800 mg/kg in two separate feeding studies. In study I, the effect of dietary levels of Mg on growth response, vertebral mineral content, and macrophage chemotaxis were evaluated. Study II had similar objectives except that whole body mineral content was measured, and resistance of channel catfish to Edwardsiella ictaluri challenge was also determined. Fish with an average weight of 10.89 g were stocked at a rate of 50 fish/110‐L aquarium (study I). In study II, fish with an average weight of 4.14 g were stocked at rates of 40 fish/110‐L aquarium. Prior to stocking, each batch of fish was acclimated to laboratory conditions and fed the basal diet for 2 wk. The concentration of Mg in rearing water was 1.8 mg/L. Each diet was fed to fish in quadruplicate and triplicate aquaria to apparent satiation for 10 wk for studies I and II, respectively. Fish fed the basal diet started to die as early as 3 d after the study began (17 d of feeding the diet without Mg supplementation). In both studies, weight gain, survival, and feed efficiency were lowest for fish fed the basal diet but increased with increasing dietary levels of Mg. However, the differences between the values of each of these parameters for fish fed diets containing supplemental Mg were not always significant. Magnesium‐deficiency signs observed were anorexia, sluggishness, convulsions, deformed snout, vertebral curvature, muscle flaccidity, and high mortality. Vertebral and whole body ash concentrations were high, but Mg content was low for fish fed the basal and the 200‐mg Mg diets. Bone Ca content did not differ among fish fed different diets (study I), but whole body Ca tended to increase for fish fed the basal diet, suggesting the possibility of calcification of soft tissues. Macrophage chemotaxis in the presence of exoantigen was highest for fish fed diets supplemented with Mg at 400 and 200 mgkg for studies I and II, respectively. When expressed in terms of chemotaxis index, however, maximum or near maximum value was observed at a dietary Mg level of 400 mg/kg. Thus, a dietary level of Mg of 400 mg/kg from Mg sulfate was required for optimum growth and survival, maintaining high tissue levels of Mg, prevention of muscle flaccidity and skeletal deformity, and stimulating macrophage chemotaxis. Dietary levels of Mg had no effect on the resistance of juvenile channel catfish to Edwarsiella. ictaluri challenge.
Management Strategies for Seabream Sparus aurata Cultivation in Floating Cages in the Mediterranean Sea and Atlantic Ocean
Authors: Gasca‐Leyva Eucario , León Carmelo J. , Hernández Juan M.
Published: April 2007

For decades, research and development efforts have focused on fish cultivation in floating cages. Despite this focus, and the considerable private and public sector resources invested in these systems, there is a scarcity of economic data derived from the great number of variables present in these systems. A reliable way of generating economic studies is through systems modeling that relates biological, environmental, technical, and economic variables. This study presents results from a computer simulation of seabream production in floating cages under two scenarios: one representing conditions in the Mediterranean Sea, and the other in the Atlantic Ocean. A company operating in the Atlantic (Canary Islands, Spain) provided the majority of data, though some of them were provided by the University of Las Palmas, also in the Canary Islands. Given the assumptions in the simulation case study, the production cost for 1 kg of seabream in floating cages in the described systems is US$2.64 in the Mediterranean and US$2.90 in the Atlantic, and the internal rates of return were 27% and 59%, respectively. The results of model sensitivity analysis for both scenarios show that this cultivation system is more sensitive in the Mediterranean than in the Atlantic. This means that changes in system variables convey lower effects on the production and economic results in the Atlantic scenario than in the Mediterranean. In both scenarios, the feed ration size was one of the variables that improved feed conversion rates. It also improved costs and profitability in greater proportions than the other variables. The reduction of the feed ration below the levels recommended in feed tables lowered the feed conversion rate but increased the number of days in the seabream cultivation cycle, leading to higher production costs and lower internal rates of return. The analysis also showed that greater benefits and profitability could be obtained by raising production capacity through increases in the final stocking density of the system.
Performance of Post‐juvenile Rainbow Trout Oncorhynchus mykiss Fed Diets Manufactured by Different Processing Techniques
Authors: Schwertner Margaret A. , Liu Kenneth K. M. , Barrows Frederic T. , Hardy Ronald W. , Dong Faye M.
Published: April 2007

Four different methods of pelleting—extruded (EXT), steam pelleted (STM), using a Universal Pellet Cooker (UPC), and expanded (EXP)—were performed on subsamples of a single batch of mash to determine the effects on feed pellet characteristics, in vivo feed digestibility, and performance of rainbow trout Oncorhynchus mykiss fed the diets for 16 wk. Results indicated that the STM feed was the most (851 g/L) and UPC feed the least (672 g/L) dense, and that UPC feed had the highest % float (8.3%) and, of the pellets that sank, the fastest sink rate (15.1 cm/sec). While some differences occurred among pelleted diets in loss of dry matter (% dry loss) after incubation in a water bath for up to 10 min, the overall % dry loss was only approximately 1–2%. The method of pelleting did not affect fish weight gain, feed conversion ratio, or specific growth rate. Measurement of the apparent digestibility coefficient of dry matter of the test diets using Cr2O3 as the marker ranged from 71–89%. While it appeared that the method of pelleting can affect feed characteristics and the amount of feed offered to the fish, fish performance was not affected.
Effect of Water Temperature on Growth, Survival, and Biochemical Composition of Largemouth Bass Micropterus salmoides
Authors: Tidwell James H. , Coyle Shawn D. , Bright Leigh Anne , Van Arnum Aaron , Yasharian David
Published: April 2007

The effects of water temperature on growth rate, survival, and biochemical composition of juvenile largemouth bass Micropterus salmoides were evaluated under controlled conditions in tanks for 12 wk. Feed‐trained juvenile largemouth (9.1 ± 1.9 g) were stocked into nine 3,610‐L polyethylene tanks inside a greenhouse structure at 140 fish/m3 (500 fish/tank). Three treatment temperatures were evaluated (20, 26, and 32 C) with three replicates per treatment. Bass were fed to apparent satiation twice daily using a commercially available floating salmonid diet (45% crude protein and 16% lipid). After 97 d bass grown at 26 and 32 C had significantly higher (P < 0.05) average weights, SGR, condition factor (K), and production rates (kg/m3) than those in the 20 C treatment. Bass in the 26 C treatment had significantly lower (P 0.05) FCR and higher percent protein deposit (PPD) than bass raised at 20 and 32 C, which were not significantly different (P >0.05). There were no significant differences (P >0.05) in survival among treatments which averaged 97%, overall. Bass raised at 32 C had higher (P 0.05) lipid levels in the liver than other treatments. Whole body amino acid concentrations were not significantly impacted (P >0.05) by culture temperature. Largemouth bass raised at 26 C had significantly lower (P 0.05) levels of stearic acid (18:0) and significantly higher (P 0.05) levels of arachidonic acid (20:4 n‐6) than bass raised at 20 or 32 C. Bass raised at 32 C had significantly higher (P 0.05) levels of Linoleic acid (18:2 n‐6), total saturates, and dienes than bass raised at 26 or 20 C. These data indicate that growth and feed conversion efficiency are reduced at 20 C. Growth is similar at 26 and 32 C, but feed and dietary protein are more efficiently utilized at 26 C.
Growout of Freshwater Prawn Macrobrachium rosenbergii in Fertilized Ponds with Reduced Levels of Formulated Feed
Authors: Correia Eudes S. , Pereira José A. , Silva André P. , Horowitz Ami , Horowitz Sarah
Published: April 2007

Formulated feed for freshwater prawn farming under semi‐intensive conditions is expensive, presenting a significant portion of the farm's operating costs. Production and availability of natural food in earthen ponds may reduce the needs for formulated feed. This paper evaluates growth of freshwater prawn Macrobrachiurn rosenbergii under three feeding regimes, where supplemental feed was reduced and natural productivity of the ponds was increased by a fertilization program that included the addition of lime, phosphorus and nitrogen. Prawns (4.35 g) were stocked into 12 50‐m2 earthen ponds (6 juveniles/m2) and grown for 84 d feeding on 25% crude protein ration. Chemical and physical water parameters were monitored routinely. Growth and production were similar at 100% formulated feed supplementation with no fertilization and at 50% formulated feed with fertilization, as determined by weight gain, specific growth rate, and net yield (P >0.05). However, further reduction in feed supplementation (0, 25%, and 50% of feeding rate, respectively, for each subsequent 28‐d period) with fertilization, yielded shrimp smaller than market size. Feed conversion ratios were significantly higher (P 0.05) for the 100% versus the 50% feed supplementation. Survival rate averaged 86% with no significant differences among treatments. Reducing up to 50% of the supplemental feed with added fertilization for increased natural productivity does not reduce yield of M. rosenbergii raised under semi‐intensive conditions in northeastern Brazil. Under the local conditions of semi‐arid and warm water temperatures (24.0–33.5 C), increasing natural productivity of ponds significantly improves feed conversion ratio, which is reflected in feed cost savings and potential savings of the farm operating cost.
Use of White Fat as a Replacement for Squid Liver Oil in Practical Diets for Surubim Pseudoplatystoma coruscans
Authors: Martino Ricardo C. , Trugo Lulz C. , Cyrino José Eurico P. , Portz Leandro
Published: April 2007

The effect of dietary lipid on culture performance, fatty acid composition of carcass, and the liver polar lipid of surubim fingerlings Pseudoplatystoma coruscans was investigated. Five isonitrogenous (46.5% crude protein) and isolipidic (19% crude lipid) diets were formulated with squid liver oil (SLO) and white fat (pig lard‐PL) as lipid sources. Diet 1 was supplemented with 12% SLO, diet 2 with 8% SLO and 4% PL, diet 3 with 6% SLO and 6% PL, diet 4 with 4% SLO and 8% PL, and diet 5 with 12% PL. Fish were fed to apparent satiation over a 64‐d feeding trial. No statistically significant difference (P >0.05) was observed in growth performance of fish. In contrast, fatty acid profile of fish carcass and liver polar lipid fraction was affected (P 0.05) by dietary fatty acid composition. Palmitic (16:O) and the oleic (18:1n‐9) acids were the major saturated and monoene fatty acids respectively found in fish carcass, independent of the lipid source in the diets. The total amount of saturated and monoene fatty acids was significantly higher (P 0.05) in the carcass of the fish fed diets 4 and 5, than in the other fish. The concentration (P 0.05) of eicosapentaenoic and docosahexaenoic acids and the n‐3/n‐6 ratio in fish carcass and in polar lipid fraction of liver increased in direct proportion to the level of squid liver oil in diet. Results of this experiment clearly demonstrated that both squid liver oil and pig lard have a positive nutritive value for surubim and that it is possible to increase the n‐3 to n‐6 ratio in favor of n‐3, without loss in the growth performance, feeding fish with a diet containing a lipid source rich in this fatty acid.
Tissue Residues of Diuron in Channel Catfish Ictalurus punctatus Exposed to the Algicide in Consecutive Years
Authors: Tucker Craig S. , Kingsbury Susan K. , Ingram Reba L.
Published: April 2007

In 1999, the United States Environmental Protection Agency granted an emergency exemption under Section 18 of the Federal Insecticide, Fungicide. and Rodenticide Act authorizing the use of the algicide diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] to manage cyanobacterial off‐flavors in channel catfish Ictalurus punctcatus. Catfish may remain in ponds for more than one growing season and may therefore be exposed to more than one set of diuron treatments. This study was conducted to determine whether diuron residues in fish carry over from one year to the next and, if so, whether the cumulative exposure causes residues to exceed the tolerance level of 2.0 mg/kg in fillets. Catfish in earthen ponds were exposed to the label‐specified treatment protocol of nine consecutive weekly applications of diuron at 0.01 mg/L in the fall of one year and again the following spring. Diuron concentrations in fillets were below limits of detection (0.05 mg/kg) in all fish (N = 18) prior to the initial diuron treatment series. Immediately after the ninth weekly diuron application in the fall. tissue diuron levels averaged 0.353 mg/kg (pooled SEM = 0.036; range = 0.078–0.724 mg/kg; N= 18). On the day before the second set of diuron treatments 6 mo later. diuron concentrations were below limits of detection in all fish sampled. Immediately after the second set of nine weekly diuron applications, tissue concentrations averaged 0.127 mg/kg (pooled SEM = 0.015; range = not detected to 0.191 mg/kg; N = 18). This study showed that diuron residues in channel catfish were depleted within 2 to 4 mo after exposure to the chemical and there was no carryover of residues in fish from one year to the next. Maximum residue levels in catfish fillets were less than half the tolerance level of 2.0 mg/ kg.
Dietary Lipid Utilization by Juvenile Summer Flounder Paralichthys dentatus
Authors: Gaylord T. Gibson , Schwarz Michael H. , Davitt Gina M. , Cool Ryan W. , Jahncke Michael L. , Craig Steven R.
Published: April 2007

The ability of juvenile summer flounder Paralichthys dentatus to utilize dietary lipid as energy, and the effect of dietary lipid on weight gain and body composition was investigated in a 12‐week feeding trial. Diets were formulated to provide 55% crude protein from herring meal and casein. Menhaden oil was added to produce diets with 8, 12, 16 or 20% total lipid while providing 16.0 kJ available energy/g dry diet. The diet containing 20% total lipid supplied 16.7 kJ available energy/g dry diet due to the high levels of protein and lipid. An additional diet was included to reproduce currently available commercial diet formulations for flounder, providing 55% crude protein supplied solely from herring meal and 16% total dietary lipid. Juvenile summer flounder (initial weight 23 g) were stocked into triplicate aquaria in a closed, recirculating system maintained at 20 C. Fish were fed 2% of body weight each day divided into two equal feedings. Upon termination of the study, effects of dietary lipid on weight gain, body condition indices, and proximate composition were determined. Weight gain (96–149% of initial weight), feed efficiency ratio values (0.43–0.48). fillet yield, and whole‐body composition all were unaffected by dietary lipid level. High levels of dietary lipid did increase the lipid content in the finray muscle, as fish fed diets containing 16 and 20% dietary lipid had significantly higher lipid levels than fish fed the diet containing 8% lipid. No apparent protein sparing effect of lipid was observed. These data indicate that currently available commercial feeds for summer flounder may be over‐formulated and show a need for further research to determine specific and accurate nutritional information for this species.
Toward the Genetic Improvement of Feed Conversion Efficiency in Fish
Authors: Doupé Robert G. , Lymbery Alan J.
Published: April 2007

Feed conversion efficiency (FCE) is the effectiveness with which feed is converted to saleable fish product. Feed costs are a major input to aquaculture production systems, and genetic improvement in FCE may therefore have an important influence on profitability. FCE is usually expressed by a composite measure that combines feed intake and growth rate. The two most common measures are feed conversion ratio (feed intake/weight gain over a specified time interval) and its inverse, feed efficiency. Feed conversion ratio and feed efficiency are measures of gross FCE, because they do not distinguish between the separate energy requirements of growth and maintenance. There is abundant evidence of substantial genetic variation in FCE and its component traits in terrestrial livestock species and, although data are few, the same is likely for cultured fish species. The major problems with selecting from this variation to genetically improve FCE in fish species are:

It appears impractical to measure feed intake on individual fish, so that family mean data must be used.

We do not know the optimal time period over which to test fish for FCE.

We do not know the genetic correlations between FCE under apparent satiation or restricted intake conditions, or between FCE at different times in the production cycle.

If these problems can be overcome, selection to improve FCE might be best achieved by measuring feed intake of growing animals, and by utilizing genetic correlations that are likely to exist between feed intake and other production traits to develop a weighted selection index.
Volitional Spawning of Black Sea Bass Centropristis striata Induced with Pelleted Luteinizing Hormone Releasing Hormone‐Analogue
Authors: Watanabe Wade O. , Smith Theodore I.J. , Berlinsky David L. , Woolridge Christopher A. , Stuart Kevin R. , Copeland Kimberly A. , Denson Michael R.
Published: April 2007

The black sea bass is a high‐value marine serranid and is a prime candidate for intensive cultivation. Reliable methods for controlled spawning are needed to accelerate the development of hatchery technologies that result in mass production of healthy juveniles. During 1998–2001, spawning studies were conducted at The University of North Carolina at Wilmington (UNCW) and at the South Carolina Department of Natural Resources (SCDNR), Charleston, using pelleted luteinizing hormone releasing hormone analogue (LHRH‐a).

From April through July 2001, 28 vitellogenic‐stage females, with mean oocyte diameters (MOD) ranging from 277–448 μm, were implanted with a 95% cholesterol‐5% cellulose pellet containing LHRH‐a (‐50 μg/kg body wt) at UNCW. In 10 individual spawning trials, females with MOD of 305–448 μm and maximum oocyte diameter × 475 μm spawned volitionally beginning 2–3 d post‐implantation (PI) and continued spawning over an average of 1.9 d (range = 1–4 d). Individual females released a mean total of 149,000 eggs (117,000 eggs/kg) with a mean buoyancy rate of 40.5% (floaters). Fertilization and hatching rates were 98% and 27.2% of floaters, respectively, yielding 14,600 yolksac larvae/female (12,600 yolksac larvae/kg body wt), and overall egg viability averaged 8.9%. In eight group spawning trials (2–3 females/group), average performance of females, including fecundity (103,800 eggs/female; 105,500 eggs/kg body wt), buoyancy rate (42.5%), fertilization and hatching rates (97.7% and 24.3% of floaters), numbers of yolksac larvae produced (10,900 yolksac larvae/female; 10,100 yolksac larvae/kg body wt), and overall egg viability (10.6%) was comparable to what was seen in individual spawning trials.

From 1998–2000, a total of 58 vitellogenic stage (70% of oocytes 500 pm) females were implanted with pelleted LHRH‐a (‐50 μg/kg body wt) in nine group spawning trials (2–19 females/group) at SCDNR. Volitional spawning typically began 18–42 h PI and recurred every 1–3 d for an average duration of 9 d. Female groups released a mean of 560,000 eggs (84,000/female; 132,000/kg body wt) over the spawning period, with mean buoyancy rate of 25.7% floaters. Fertilization and hatching rates were 17.7% and 11.6 % of floaters, respectively, yielding 4,300 yolksac larvae/female (4,600 yolksac larvae/kg body wt). Overall egg viability was 2.9%.

Captive wild‐caught black sea bass were induced to undergo repetitive volitional spawning by implantation of pelleted‐LHRH‐a, consistent with a multiple clutch group synchronous pattern of ovarian development. Group spawning appears to be a practical way to compensate for variable fecundity and egg viability of individual females. Research is needed to identify optimum hormone treatments and eligibility requirements.
Lipid Nutrition and Feeding of Cobia Rachycentron canadum Larvae
Authors: Faulk Cynthia K. , Holt G. Joan
Published: April 2007

This study examined the fatty acid composition of cobia Rachycentron canadum eggs and yolksac larvae, as well as the ovaries of wild caught females as an initial guide to lipid nutritional requirements. A 2‐wk feeding study also was conducted to investigate the effectiveness of four dietary treatments on the growth and survival of cobia larvae. Cobia eggs in the tailbud stage contained 31.4 ± 1.3 μg lipid/egg. After hatching, the amount of lipid decreased significantly (P < 0.05) from 28.3 ± 0.3 to 23.2 ± 0.1 μg lipid/larvae during the yolksac larval stage (days 1 to 3 after hatching). Ovaries from wild caught adults and captive spawned eggs and yolksac larvae contained high levels of PUFAs with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) accounting for approximately 80% of the total suggesting that cobia larvae may have a high dietary requirement for these fatty acids. For the feeding study, larvae were fed: 1) Artemia only; 2) enriched rotifers for 1 d only + microparticulate diet (day 313); 3) enriched rotifers for 3 d (day 3–5) + Artemia (day 3–13); and 4) enriched rotifers for 6 d (day 3–8) + Artemia (day 3–13). Cobia larvae began feeding on rotifers 3 d after hatching and on newly hatched Artemia nauplii by the fifth day following the onset of exogenous feeding (day 7). On day 7, no differences in larval growth were found among larvae fed rotifers for 3 versus 6 d, whereas larvae fed only Artemia or rotifers for I d followed by microparticulate diet were significantly smaller (P < 0.05) and did not survive beyond day 9 and 13, respectively. The results of the feeding study indicate that cobia larvae require rotifers for a minimum of 4 d following the onset of exogenous feeding.
Evaluation of Experimental and Practical Diets for Bluegill Lepomis macrochirus and Hybrid Bluegill L. cyanellus × L. macrochirus
Authors: Twibell Ronald G. , Wilson Keith A. , Sanders Shawn , Brown Paul B.
Published: April 2007

Two experiments were conducted to identify appropriate experimental and practical diets for bluegill Lepomis macrochirus and hybrid bluegill L. cyanellus × L. macrochirus reared in aquaria. In the first study, four experimental diets and five commercial diets were evaluated in juvenile hybrid bluegill initially weighing 4.8 g/fish. The experimental diets contained casein (CAS), casein + gelatin (CAWGEL), casein + L‐arginine‐HCI (CAS/ARG), or casein + gelatin + crystalline amino acids (CAS/AA) as sources of crude protein. The commercial diets included three diets formulated to meet the nutritional requirements of rainbow trout Oncorhynchus mykiss and two diets formulated to meet the nutritional requirements of channel catfish Ictalurus punctatus. Each diet was fed twice daily at a rate of 4% of body weigh/d to triplicate groups of fish. At the end of the 8‐wk feeding trial, weight gain was significantly higher in fish fed the best commercial rainbow trout diets (205–217%) compared to fish fed diets formulated for channel catfish (87–104%). Weight gain and feed efficiency (FE) of fish fed the experimental diets (5346% and 0.19–0.32, respectively) were significantly lower than those of fish fed the commercial rainbow trout diets (143–217% and 0.49–0.64, respectively). In the second experiment, the same dietary treatments were fed for 8 wk to juvenile bluegill initially weighing 3.7 g/fish. Each diet was fed twice daily at a rate of 4% of body weight/d to triplicate groups of fish. Weight gain was significantly higher in fish fed commercial trout diets (291–402%) compared to fish fed diets formulated for channel catfish (164–191%). Weight gain and FE of fish fed CAS/ARG were significantly higher than those of fish fed the commercial catfish diets, but significantly lower than those of fish fed the best commercial trout diets. Results of this study indicate that commercial rainbow trout diets are preferable to commercial channel catfish diets for culture of bluegill and hybrid bluegill. More research is needed to identify appropriate experimental diets for this group of fishes.
Incorporating Date Pits Phoenix dactylifera and their Sprouts in Semi‐purified Diets for Nile Tilapia Oreochromis niloticus (L.)
Authors: Belal Ibrahim E. H. , Al‐ Owafeir M. A.
Published: April 2007

The expansion in date processing has produced a large quantity of date pits Phoenix dactylifera L.: var. ruzeiz that could be used in animal feeds. To evaluate the nutritional value of date pits and their sprouts, two growth trials were conducted using semi‐purified diets and fingerling tilapia Oreochromis niloticus (L.). In the first trial, four isocaloric‐isonitrogenous diets containing different levels (0, 15, 30, and 45%) of date pits as a replacement for corn starch were fed to three replicate groups of fingerlings with a mean initial weight of 3.09 ± 0.10 g/fish. At the conclusion of the 9‐wk growth trial, final weight gain, feed conversion, specific growth rate and PER were significantly reduced in fish fed diets with all levels of date pits as compared to those fed the control diet (without date pits). However, there were no significant differences in these parameters for fish fed diets contained 15%, 30%, or 45% date pits. Body crude fat was gradually reduced as the level of date pits in the test diets was increased. Consequently, body moisture, crude protein and total ash were proportionally increased. In second trial, three isocaloric‐isonitrogenous diets containing 0% date pits (control diet), 15% date pits sprouted for 15 d, and 15% date pits sprouted for 30 d were fed to triplicate groups of tilapia with mean initial weight 2.60 t 0.09 g/ fish) for 9 wk. Growth rates and body composition of fish fed diets containing date pits that were sprouted for 15 or 30 d were similar to that of those fed the control diet. Under the reported conditions the inclusion of sprouted date pits did not affect growth and body composition, whereas nonsprouted date pits negatively influenced fish performance.
Characteristics of Effluents from Central Arkansas Baitfish Ponds
Authors: Bodary Melinda J. , Stone Nathan , Lochmann Steve E. , Frimpong Emmanuel
Published: April 2007

Scientific information on baitfish effluents is important to provide a basis for the development of appropriate and cost‐effective management practices that minimize environmental impacts. Effluents from 10 commercial golden shiner Notemigonus crysoleucas ponds in central Arkansas were sampled December 2000 through June 2001. Grab samples of the first and last 10% of pond volume were collected during intentional draining events. Effluents were sampled as they exited pond drainpipes and at the ends of drainage ditches just prior to stream discharge. Concurrent receiving stream samples were collected upstream and downstream of the discharge point. Total nitrogen (TN), total phosphorus (TP), 5‐d biochemical oxygen demand (BODS), and total suspended solids (TSS) of each sample were measured. Mean whole effluent concentrations for the first 10% were 36 mg TSS/L, 9 mg/L BOD5, 2 mg TN/L, and 0.5 mg TP/L. The water quality of the first and last 10% of pond effluent were not significantly different (P < 0.05). Filtering effluents through a 5‐pm mesh screen did not significantly reduce nutrient concentrations. Serial fractionation of effluents resulted in small but significant decreases in TSS concentrations in samples filtered through the 10, 8, and 5‐μm meshes (P < 0.05). Effluent discharge through farm ditches generally did not improve effluent water quality. Effluents collected at ditch ends were significantly less than drainpipe samples in BOD, concentrations only (P < 0.05). Limited data on receiving stream water quality indicated that only TP concentrations were greater in pond effluents than in receiving streams. Overall, baitfish pond effluents are similar in composition to effluents of other phytoplankton‐based pond production systems.
Replacement of a Natural Diet by a Prepared Dry Feed for Successful Maturation and Spawning of Female Litopenaeus vannamei (Boone) Broodstock
Authors: Du Shaobo , Hu Chaoqun , Shen Qi
Published: April 2007

A prepared dry feed containing bloodworm meal Glycera chirori Izuka and oyster meal Crassostrea rivularis Gould, together with a natural diet consisting of G. chirori and shelled C. rivularis (1:1 ratio) and a mixed diet consisting of the prepared dry feed and the natural diet in equal proportion were evaluated as broodstock diets for female Pacific white shrimp Litopenaeus vannamei‐ (Boone). Results showed that shrimp fed the prepared dry feed gave higher maturation ratio and significantly higher hepatosomatic index (HSI) values (P < 0.05) than those fed the natural diet and the mixed diet. The prepared dry feed and the mixed diet induced higher total spawn numbers and significantly higher average daily spawns per female than the natural diet (P < 0.05), while the gonadosomatic index (GSI) values and fecundity (eggs per spawn) were not significantly affected by these diets. Results of this study showed that both the prepared dry feed and the mixed diet outperformed the natural diet to improve the spawning performance of female L. vannamei, and that using G. chirori meal and C. rivularis meal as the main ingredients of the prepared dry feed would be an effective way to promote the broodstock nutrition.
Effects of Artificial Substrate and Stocking Density on the Nursery Production of Pacific White Shrimp Litopenaeus vannamei
Authors: Moss Komarey R. K. , Moss Shaun M.
Published: April 2007

Nursery production may be enhanced by the addition of artificial substrate to increase the surface area upon which shrimp graze and to serve as refuge. The objective of this study was to assess the effects of the artificial substrate, AquaMatsTM, on the performance of postlarval Pacific white shrimp Litopenaeus vannamei stocked at three densities. Eighteen 230‐L tanks were stocked with 10‐d postlarvae (mean weight < 0.01 g). Six treatments were evaluated and consisted of shrimp stocked at three densities (778 shrimp/m2, 1,167 shrimp/ m2, and 1,556 shrimp/m2) with and without access to artificial substrate. Shrimp in all treatments received a commercial diet ad libitum. After 6 wk, shrimp were harvested from each nursery tank, counted, and batch weighed. Mean final weight, survival, production, feed conversion ratio, and water quality parameters were analyzed by 2‐way ANOVA. There were highly significant (P < 0.001) density and substrate effects on final weight, but there was no significant interaction effect. Final weight was 26.0, 17.4, and 34.5% greater in treatments with substrate than without substrate when stocked at 778, 1,167, and 1,556 shrimp/m2, respectively. There was no significant density, substrate, or interaction effect on survival or water quality. Mean survival was ± 89.1% for all treatments. Increased shrimp growth in the presence of added substrate was likely due to the availability of attached particulate organic matter on the AquaMatsTM that served as an additional food source. Results from this study indicate that artificial substrate can be used to mitigate the potential negative effects of high stocking density on growth of L. vannamei in nursery systems.
Significant Increase in Survival of Captive‐bred Juvenile Banggai Cardinalfish Pterapogon kauderni with an Essential Fatty Acid‐Enriched Diet
Authors: Vagelli Alejandro A.
Published: April 2007

Pterapogon kauderni is an endemic, direct developing, coral reef fish from Indonesia, which has become very popular in the aquarium community. During development of a captive breeding program, high frequency of shock syndrome events and associated mortality was observed in juveniles fed a diet of newly hatched Anemia. After about a week post‐release, juveniles became extremely sensitive to external stimuli, such as feeding and turning the lights on. A series of five tests (mean duration = 116 d) were conducted to investigate a possible dietary essential fatty acid deficiency. A significant increase in survival (P < 0.001) and decrease in frequency of shock syndrome events (P < 0.05) were observed in juveniles fed a highly unsaturated fatty acid‐enriched diet. Juveniles fed the un‐enriched diet suffered a mean of 1.4 events/ individual, whereas those fed the enriched diet had a significantly lower mean of 0.08 (P < 0.001). Mean mortality (all tests) for juveniles fed the un‐enriched diet was 80.7%. whereas it was 5.3% for those fed the enriched diet. No individual fed the enriched diet died after suffering a shock event, whereas in four out of five tests several individuals (mean = 2.26) fed the un‐enriched diet died a few minutes after the event. No event was observed during the first week after juvenile release: the mean days at which the first event occurred (all tests) were 26.8 (un‐enriched) and 26 (enriched). and the mean week at which the highest frequency of shock events occurred was 4.7 (un‐enriched). The results of this study have particular significance for conservation because of the threatened status of P. kauderni.
Optimization of Artemia Metanauplii on Growth and Survival of Gilthead Sea Bream Larvae Sparus aurata
Authors: Mihelakakis Apostolos , Tsolkas Christos , Yoshimatsu Takao
Published: April 2007

–Growth, feed efficiency and survival of gilthead sea bream Sparus aurata larvae fed exclusively various levels of enriched Artemia during the period 25 DPH‐34 DPH were investigated. Larvae had an average initial fresh body weight (BW) of 4.99 mg and were fed on Artemia at rates of 20, 35, 50, 65, and 80% of their body weight per day, in two equal meals. Each ration was administered to duplicate groups of 1,000 larvae, with ration readjusted every second day. Feeding rate had a significant effect on larval survival, which was lower in larvae fed the 20 and 35% BS/d rations. The specific growth rate (SGR) showed a curvilinear significant increase when the feeding rate was increased from 20 to 65% BW/d, but there was no improvement when the feeding rate was increased from 65 to 80% BW/d. Percent feed efficiency (FE) decreased significantly from a maximum value at 20% ration to 80% BW/d but at 65% and 80% rations the values of FE were not significantly different. Optimum ration (minimum quantity of Artemia concomitant with maximum larval growth) was estimated close to 65% BW/d. The significance of the results is discussed in relation to potential economics of Artemia cysts use in commercial hatcheries.
Spawning Characteristics of the South African Mudcrab Scylla serrata (Forskål) in Captivity
Authors: Davis Jerome A. , Churchill Giles J. , Hecht Thomas , Sorgeloos Patrick
Published: April 2007

Scylla serrata is a potential aquaculture species in Southern Africa. Information about its reproductive biology is required as a prerequisite to establishing hatchery technology. Adult female S. serrata were caught in the Umlalazi estuary on the subtropical east coast of South Africa and kept in captivity to observe and record spawning characteristics. Data collected included crab size and mass, time in captivity prior to spawning, fecundity per batch, relative fecundity, individual egg mass and size, size of zoea 1 larvae, incubation time, and hatch success rate. Of the 119 crabs kept in captivity 83% spawned in the maturation system– most within 40 d of capture. The crabs were highly fecund (mean relative fecundity per batch = 10,655 ± 4,069 eggs/g female) and the majority of the batches hatched within 288 h (12 d) at 27 C. Spawning in captivity occurred throughout the year, with a peak in late winter/early spring. This differs slightly from records of ovarian maturity stages of the crabs in the wild. A pattern of synchronous spawning was recorded where the females were observed to extrude their eggs in groups, commonly within 3 d of one another, separated by long periods of inactivity, suggesting an exogenous spawning cue. A total of 1,374,488 zoea larvae were obtained per kg of female per month. This means that if sufficient mature females can be caught from the wild, these could be used for stocking hatchery operations. The crabs were easy to maintain, mature, and spawn in captivity. This will facilitate future domestication which will eventually reduce the need for wild caught broodstock. The spawning characteristics of South African 5. serrata At in well with those observed for the genus throughout its distribution implying that ecological and fisheries management could be similar.
A Biphasic Model for Micro-Indentation of a Hydrogel-Based Contact Lens
Authors: Chen Xiaoming , Dunn Alison C. , Sawyer W. Gregory , Sarntinoranont Malisa
Published: April 2007

The stiffness and hydraulic permeability of soft contact lenses may influence its clinical performance, e.g., on-eye movement, fitting, and wettability, and may be related to the occurrence of complications; e.g., lesions. It is therefore important to determine these properties in the design of comfortable contact lenses. Micro-indentation provides a nondestructive means of measuring mechanical properties of soft, hydrated contact lenses. However, certain geometrical and material considerations must be taken into account when analyzing output force-displacement (F-D) data. Rather than solely having a solid response, mechanical behavior of hydrogel contact lenses can be described as the coupled interaction between fluid transport through pores and solid matrix deformation. In addition, indentation of thin membranes (∼100μm) requires special consideration of boundary conditions at lens surfaces and at the indenter contact region. In this study, a biphasic finite element model was developed to simulate the micro-indentation of a hydrogel contact lens. The model accounts for a curved, thin hydrogel membrane supported on an impermeable mold. A time-varying boundary condition was implemented to model the contact interface between the impermeable spherical indenter and the lens. Parametric studies varying the indentation velocities and hydraulic permeability show F-D curves have a sensitive region outside of which the force response reaches asymptotic limits governed by either the solid matrix (slow indentation velocity, large permeability) or the fluid transport (high indentation velocity, low permeability). Using these results, biphasic properties (Young’s modulus and hydraulic permeability) were estimated by fitting model results to F-D curves obtained at multiple indentation velocities (1.2 and 20μm∕s). Fitting to micro-indentation tests of Etafilcon A resulted in an estimated permeability range of 1.0×10−15 to 5.0×10−15m4∕Ns and Young’s modulus range of 130to170kPa.
One-Dimensional Models of the Human Biliary System
Authors: Li W. G. , Luo X. Y. , Johnson A. G. , Hill N. A. , Bird N. , Chin S. B.
Published: April 2007

This paper studies two one-dimensional models to estimate the pressure drop in the normal human biliary system for Reynolds number up to 20. Excessive pressure drop during bile emptying and refilling may result in incomplete bile emptying, leading to stasis and subsequent formation of gallbladder stones. The models were developed following the group’s previous work on the cystic duct using numerical simulations. Using these models, the effects of the biliary system geometry, elastic property of the cystic duct, and bile viscosity on the pressure drop can be studied more efficiently than with full numerical approaches. It was found that the maximum pressure drop occurs during bile emptying immediately after a meal, and is greatly influenced by the viscosity of the bile and the geometric configuration of the cystic duct, i.e., patients with more viscous bile or with a cystic duct containing more baffles or a longer length, have the greatest pressure drop. It is found that the most significant parameter is the diameter of the cystic duct; a 1% decrease in the diameter increases the pressure drop by up to 4.3%. The effects of the baffle height ratio and number of baffles on the pressure drop are reflected in the fact that these effectively change the equivalent diameter and length of the cystic duct. The effect of the Young’s modulus on the pressure drop is important only if it is lower than 400Pa; above this value, a rigid-walled model gives a good estimate of the pressure drop in the system for the parameters studied.
Hip Actuations Can be Used to Control Bifurcations and Chaos in a Passive Dynamic Walking Model
Authors: Kurz Max J. , Stergiou Nicholas
Published: April 2007

We explored how hip joint actuation can be used to control locomotive bifurcations and chaos in a passive dynamic walking model that negotiated a slightly sloped surface (γ<0.019rad). With no hip actuation, our passive dynamic walking model was capable of producing a chaotic locomotive pattern when the ramp angle was 0.01839rad<γ<0.0190rad. Systematic alterations in hip actuation resulted in rapid transition to any locomotive pattern available in the chaotic attractor and induced stability at ramp angles that were previously considered unstable. Our results detail how chaos can be used as a control scheme for locomotion.
Anisotropy of Fibrous Tissues in Relation to the Distribution of Tensed and Buckled Fibers
Authors: Ateshian Gerard A.
Published: April 2007

Fibrous tissues are characterized by a much higher stiffness in tension than compression. This study uses microstructural modeling to analyze the material symmetry of fibrous tissues undergoing tension and compression, to better understand how material symmetry relates to the distribution of tensed and buckled fibers. The analysis is also used to determine whether the behavior predicted from a microstructural model can be identically described by phenomenological continuum models. The analysis confirms that in the case when all the fibers are in tension in the current configuration, the material symmetry of a fibrous tissue in the corresponding reference configuration is dictated by the symmetry of its fiber angular distribution in that configuration. However, if the strain field exhibits a mix of tensile and compressive principal normal strains, the fibrous tissue is represented by a material body which consists only of those fibers which are in tension; the material symmetry of this body may be deduced from the superposition of the planes of symmetry of the strain and the planes of symmetry of the angular fiber distribution. Thus the material symmetry is dictated by the symmetry of the angular distribution of only those fibers which are in tension. Examples are provided for various fiber angular distribution symmetries. In particular, it is found that a fibrous tissue with isotropic fiber angular distribution exhibits orthotropic symmetry when subjected to a mix of tensile and compressive principal normal strains, with the planes of symmetry normal to the principal directions of the strain. This anisotropy occurs even under infinitesimal strains and is distinct from the anisotropy induced from the finite rotation of fibers. It is also noted that fibrous materials are not stable under all strain states due to the inability of fibers to sustain compression along their axis; this instability can be overcome by the incorporation of a ground matrix. It is concluded that the material response predicted using a microstructural model of the fibers cannot be described exactly by phenomenological continuum models. These results are also applicable to nonbiological fiber–composite materials.
In Vitro Study of Flow Regulation for Pulmonary Insufficiency
Authors: Camp T. A. , Stewart K. C. , Figliola R. S. , McQuinn T.
Published: April 2007

Given the tolerance of the right heart circulation to mild regurgitation and gradient, we study the potential of using motionless devices to regulate the pulmonary circulation. In addition, we document the flow performance of two mechanical valves. A motionless diode, a nozzle, a mechanical bileaflet valve, and a tilting disk valve were tested in a pulmonary mock circulatory system over the normal human range of pulmonary vascular resistance (PVR). For the mechanical valves, regurgitant fractions (RFs) and transvalvular pressure gradients were found to be weak functions of PVR. On the low end of normal PVR, the bileaflet and tilting disk valves fluttered and would not fully close. Despite this anomaly, the regurgitant fraction of either valve did not change significantly. The values for RF and transvalvular gradient measured varied from 4 to 7% and 4to7mmHg, respectively, at 5lpm for all tests. The diode valve was able to regulate flow with mild regurgitant fraction and trivial gradient but with values higher than either mechanical valve tested. Regurgitant fraction ranged from 2 to 17% in tests extending from PVR values of 1to4.5mmHg∕lpm at 5lpm and with concomitant increases in gradient up to 17mmHg. The regurgitant fraction for the nozzle increased from 2 to 23% over the range of PVR with gradients increasing to 18mmHg. The significant findings were: (1) the mechanical valves controlled regurgitation at normal physiological cardiac output and PVR even though they failed to close at some normal values of PVR and showed leaflet flutter; and (2) it may be possible to regulate the pulmonary circulation to tolerable levels using a motionless pulmonary valve device.
Antimicrobial Susceptibilities of
Peptostreptococcus anaerobius
and the Newly Described
Peptostreptococcus stomatis
Isolated from Various Human Sources
Authors: Könönen Eija , Bryk Anne , Niemi Päivi , Kanervo-Nordström Arja
Published: April 2007

Peptostreptococcus anaerobius
sensu lato, currently including two closely related species,
P. anaerobius
and
P. stomatis
, is known to be more resistant than other gram-positive anaerobic cocci. We reidentified potential
Peptostreptococcus
isolates and tested their susceptibilities to eight antimicrobials. Notably,
P. anaerobius
had constantly higher values for the MIC at which 50% of the isolates are inhibited (MIC
50
) and the MIC
90
than
P. stomatis
.