bluuebunny/crossref_metadata_2025 huggingface dataset:
RESPONSE SURFACE MODEL FOR EFFECTS OF TEMPERATURE, WATER ACTIVITY AND pH ON GERMINATION OF BACILLUS CEREUS SPORES
Authors: SINIGAGLIA MILENA , CORBO MARIA ROSARIA , ALTIERI CLELIA , MASSA SALVATORE
Published: April 2007

A response surface model was developed for effects of temperature (20 to 40C), pH (4.5 to 6.5) and water activity (aw) (0.94 to 0.99) on germination of Bacillus cereus ATCC 11778 spores. Germination depended, to varying extents, on the interactions among the independent variables and complexity of the medium. In particular it was affected (P <0.05) by interactions of aw with temperature and pH and by temperature in its quadratic term. The model was validated against data not used in its development. Mean absolute relative error of predictions (model accuracy) was 22.8% in model systems and 10.17% in real systems. Bias factors were 0.887 and 0.922 for model and real systems, respectively. Results indicated that the model developed was “fail safe” and provided reliable predictions of germination of B. cereus.
GROWTH KINETICS OF CLOSTRIDIUM PERFRINGENS IN COOKED BEEF1
Authors: HUANG LIHAN
Published: April 2007

The objective of this work was to investigate the growth kinetics of a three‐strain cocktail of Clostridium perfringens in cooked beef. The study was conducted by growing the heat‐activated spores in ground beef under isothermal conditions between 17–50C. A four‐parameter Gompertz equation was used as a primary model to fit the growth curves along with a modified Ratkowsky model to analyze the temperature dependence of the bacterial growth. Results indicated that the Gompertz model could accurately describe the growth of C. perfringens in cooked beef. The estimated theoretical minimum, optimum, and maximum growth temperatures of this organism in cooked beef were 9.8, 47.1, and 50.8C, respectively. A linear relationship between the durations of the lag and exponential phases of growth curves was observed in this study. Such a linear relationship can be used to generate a linear isothermal growth curve complete with the lag, exponential, and stationary phases without complex mathematical computation. The kinetic models and growth parameters obtained from this study potentially can be applied to the food industry to design appropriate cooling schedules and estimate the growth of C. perfringens in thermally processed beef products under temperature abuse conditions.
ACID TOLERANCE OF ESCHERICHIA COLI FOLLOWING COLD SHOCK TREATMENT
Authors: BLANK GREG , CHO CHAI‐HUI , ISMOND ANNE
Published: April 2007

The effect of an initial cold shock treatment (2 h at 10C), following an abrupt downshift in temperature from 37 to 10C, on the subsequent growth and survival of Escherichia coli strains O157:H7 and MY20 (Biotype 1) in acidified Trypticase soy broth (TSB) and fruit juices (orange, apple) was investigated. Overall, no difference in growth at 37C was observed between each cold shocked and noncold shocked E. coli strain when cultured in TSB adjusted with either acetic acid (pH 6.0)or malic, citric and tartaric acid (each adjusted to: pH 4.5, 5.0, 5.5, 6.0). However, significant (P ± 0.05) differences in survival were observed between cold shocked and noncold shocked populations in TSB acidified with acetic acid (pH 5.0) or citric, malic and tartaric acid (pH 4.0). For strain MY20, survivor levels for cold shocked cells in TSB acidified with acetic acid citric, malic and tartaric acid at 8C were significantly (P ± 0.05) higher than in noncold shocked populations. Also, at 37C survival levels for cold shocked cells were significantly (P ± 0.05) higher than noncold shocked cells in TSB acidified with either malic or tartaric acid (pH 4.0). For the O157:H7 strain, survivor levels were higher (P ± 0.05) for cold shocked cells when maintained in TSB at 37C regardless of acid type. At 8C, cold shock treatment only increased (P ± 0.05) the survival of the O157:H7 strain in TSB adjusted with acetic acid (pH 6.0). Acid cross protection induced by cold shocking, as evidenced by enhanced survival, was not apparent for either E. coil strain in apple (pH 3.5) or orange juice (pH 3.8) maintained at 8C.
ESCHERICHIA COLI O157 IN IRISH FEEDLOT CATTLE: A LONGITUDINAL STUDY INVOLVING PREHARVEST AND HARVEST PHASES OF THE FOOD CHAIN
Authors: MINIHAN DONAL , WHYTE PAUL , O'MAHONY MICHEÁL , CLEGG TRACY , COLLINS JOHN D.
Published: April 2007

The aim of this study was to investigate fecal shedding and transmission of E. coli O157 in cohorts of cattle within a feedlot, to assess subsequent contamination of carcasses with this pathogen and to identify risk factors associated with fecal shedding of E. coli O157. A cohort of 133 heifers housed infour adjacent pens was examined over a five month period, from entering the feedlot to slaughter. Individual rectal fecal samples and pen environmental samples were taken at monthly intervals. The entire outer and inner surfaces of a carcass side of each animal were swabbed immediately following slaughter.

E. coli O157 was isolated from 136 (23%) of the 600 rectal fecal samples; 96% of which contained virulent markers. One hundred and sixty environmental samples were examined and E. coli O157 was isolated from 46 (29%), all of which contained virulent markers. E. coli O157 was not isolated from any of the dressed carcasses. The prevalence of E. coli O157 fecal shedding may be related to the pen and E. coli O157 contamination of the pen floor feces, water trough and feed.

E. coli O157 should be considered as a pathogen shed in the feces of a substantial proportion of feedlot cattle. However, with good hygienic practice at harvest, a very low level of this pathogen can be achieved on dressed carcasses.
SURVIVAL OF A SALMONELLA TYPHIMURIUM POULTRY MARKER STRAIN ADDED AS A DRY INOCULUM TO ZINC AND SODIUM ORGANIC ACID AMENDED FEEDS
Authors: PARK S.Y. , BIRKHOLD S.G. , KUBENA L.F. , NISBET D.J. , RICKE S.C.
Published: April 2007

The effects of different organic acid compounds on the survival of a dry inoculum of Salmonella typhimurium marker strain added to poultry feed were determined. Organic acids were added as 1% Zn or Na salts (w/w) to poultry feeds and stored at room temperature for 9 days. Reduction of S. typhimurium populations from 0 to day 9 was not substantially different between poultry layer ration nonamended feed (96.76%) and Zn acetate (99.72%) or Zn propionate (99.60%) amended feed. However, over 90% reduction of S. typhimurium populations occurred in Zn acetate and Zn propionate amended feed by day 3 while poultry layer ration populations reached 90% reduction by day 5. S. typhimurium populations after 9 days were nearly 40% more reduced in Na propionate amended feed than Na acetate amended feed. The results of this study indicated 1% Zn compounds may have potential to reduce survival of S. typhimurium in a poultry diet during the early stages of storage.
SLIME PRODUCTION AND DNase ACTIVITY OF STAPHYLOCOCCI ISOLATED FROM RAW MILK
Authors: ÇITAK SUMRU , VARLIK ÖZGÜR , GÜNDOǦAN NESLIHAN
Published: April 2007

In this study, 851 Staphylococci isolates isolated from 38 raw milk samples were investigated for DNase activity and slime production. The 851 Staphylococci isolates were identified as 704 Staphylococcus aureus and 147 coagulase‐negative staphylococci. Coagulase – negative staphylococci isolates were classified as 32.7% S. cohnii, 19.7% S. hominis, 19.1% S. xylosus, 12.9% S. epidermidis, 8.2% S. capitis, 4.8% S. haemolyticus, 1.4% S. simulans and 1.4% S. saprophyticus by using Dichotomous scheme. DNase agar was used to investigate for DNase activity. DNase activity was found in 93.6% of 704 S. aureus and 10.2% of 147 coagulase – negative staphylococci. DNase activity was positive in 42.9% of S. haemolyticus, 20.7% of S. hominis, 17.9% of S. xylosus and 2.1% of S. cohnii isolates. No DNase activity was found in S. epidermidis, S. capitis, S. simulans and S. saprophyticus isolates. Slime production of S. aureus and coagulase – negative staphylococci from raw milk samples was investigated by using Congo Red Agar method. Slime production was positive in 5.1% of S. aureus and 42.2% of 147 coagulase – negative staphylococci. Slime production was positive in 100% of S. simulans, 68.4% of S. epidermidis, 50% of S. cohnii, 50% of S. saprophyticus, 37.9% of S. hominis, 32.1% of S. xylosus and 16.7% of S. capitis isolates. None of the 7 S. haemolyticus isolates had slime production. In conclusion, slime production and DNase activity are important virulence factors to identify pathogenic staphylococci.
CONTROL OF CLOSTRIDIUM PERFRINGENS IN A MODEL ROAST BEEF BY SALTS OF ORGANIC ACIDS DURING CHILLING1
Authors: JUNEJA V.K. , THIPPAREDDI H.
Published: April 2007

Control of Clostridium perfringens germination and outgrowth by the following salts of organic acids, sodium lactate [Purasal™S/SP (Purasal); 1.50, 3.00 and 4.80%], sodium lactate supplemented with sodium diacetate [Purasal™ Opti.form™ (Optiform), 1.50, 3.00 and 4.80%], buffered sodium citrate [Ional™ (Ional), 0.75, 1.00 and 1.30]) and buffered sodium citrate supplemented with sodium diacetate [Ional Plus™ (Ional Plus), 0.75, 1.00 and 1.30%] was evaluated during continuous chilling of a model roast beef product. Beef rounds were ground through an 1/8′’ plate and NaCl, potato starch and potassium tetra pyrophosphate were added to final concentrations of 0.85, 0.25 and 0.20%, respectively, and mixed. Portions (250 g) of the meat were mixed with either Purasal (1.5, 3.0 or 4.8%), Optiform (1.5, 3.0 or 4.8%), Ional (0.75, 1.0 or 1.3%) or Ional Plus (0.75, 1.0 or 1.3%) along with a control that did not have any added antimicrobials. Each product (10 g) inoculated with C. perfringens spores (ca. 2.2 log10 spores/g) was packaged into vacuum bags (2 in. × 3 in.), vacuum sealed, heated to 60C within 1 h, and subsequently chilled from 54.4C to 7.2C in 18 or 21 h following exponential chilling rates. Products were sampled immediately after cooking to enumerate the C. perfringens populations (spores surviving heat treatment) and subsequent to chilling (total C. perfringens populations, including spores and vegetative cells resulting from germination and outgrowth of the spores). Chilling of cooked, model ground roast beef resulted in germination and outgrowth of C. perfringens spores; the population densities increased by 4.13 and 4.40 log10 CFU/g, following 18 and 21 h chill rates, respectively.

Incorporation of Purasal (1.5–4.8%), Optiform (1.5–4.8%), Ional and Ional Plus (0.75–1.3%) substantially (P ± 0.05) inhibited germination and outgrowth of C. perfringens spores. Incorporation of antimicrobial ingredients resulted in ± 1.0 log10 CFU/g increase of the pathogen, except for model roast beef with Ional Plus at 0.75% concentration, following 18 h chilling rate. Similar results were obtained when 21 h chilling rate was followed, with roast beef containing ingredients (at all the concentrations) resulting in either reductions or ± 1.0 log10 CFU/g growth in total C. perfringens populations, except for Purasal and Ional Plus at 1.5 and 0.75% concentrations, respectively. Use of sodium salts of organic acids in formulation of model roast beef can reduce the risk of C. perfringens spore germination and outgrowth during extended chilling rates.
REDUCTION OF FUNGI AND MYCOTOXINS FORMATION IN SEEDS BY GAMMA‐RADIATION
Authors: AZIZ NAGY H. , MOUSSA LOUTFY A.A. , FAR FERIAL M.E.
Published: April 2007

Ninety samples of maize, chick‐peas and groundnut seeds collected from the Egyptian market were found to be heavily contaminated by molds. Alternaria, Aspergillus, Cladosporium, Eurotium, Fusarium, Mucor, Penicillium and Rhizopus were the most common fungal genera isolated from nondisinfected seeds. Aspergillus alutaceus, A. flavus, Fusarium verticillioides and F. oxysporum were isolated from all surface‐disinfected seeds and were reported to produce ochratoxin A, aflatoxin B1 and zearalenone, respectively. Irradiation at a dose 4.0 kGy reduced the mold growth greatly relative to unirradiated controls. There was no growth at dose 5.0 kGy. On the basis of the radiation survival data, the decimal reduction values D10 for A. alutaceus, A. flavus and F. verticilliodies were 0.70. 2.10 and 0.93 kGy in maize. A dose of 5 kGy inhibited the toxigenic molds and mycotoxin formation in seeds. Aflatoxin B1 and ochratoxin A were detected in maize and chick‐peas, whereas zearalenone was detected in maize samples. Application of radiation at a dose of 6.0 kGy detoxified aflatoxin B1 by 74.3–76.7%, ochratoxin A by 51.3–96.2% and zearalenone by about 78%.
INHIBITION OF LISTERIA MONOCYTOGENES BY NATIVE MICROFLORA OF WHOLE CANTALOUPE1
Authors: UKUKU DIKE O. , FETT WILLIAM F. , SAPERS GERALD M.
Published: April 2007

Fresh‐cut cantalcupe has been recalled due to the possible presence of Listeria monocytogenes. Several studies have reported that naturally occurring microflora of vegetable surfaces may be antagonistic to pathogen attachment, growth or survival. To test this possibility for L. monocytogenes and cantaloupes, whole melon were treated with water, ethanol (70%) or chlorine (200 ppm) to reduce the native microflora on the melon surfaces. Treated or untreated melons were immersed in a six strain cocktail of L. monocytogenes (107 CFU/mL) for 10 min and then allowed to dry for 1 h inside a biosafety cabinet followed by storage at 5, 10 and 20C for 15 days. Fresh‐cut pieces prepared from the treated or untreated melons and directly inoculated with L. monocytogenes (3.48 log CFU/g) were stored under the same conditions listed above. Populations of L. monocytogenes and five classes of native microflora were investigated. Growth of L. monocytogenes in sterile or nonsterile rind and fresh‐cut homogenates was also studied. The population of L. monocytogenes recovered from inoculated (103 to 108 CFU/mL) whole melons given no disinfection treatment or washed with water was significantly less (P < 0.05) than that recovered from melons treated with chlorine or EtOH. In general, populations of L. monocytogenes declined on the surface of treated and untreated whole melons and on fresh‐cut pieces over the 15 days storage period at the temperatures tested. However, the decline in pathogen populations was less rapid in the presence of reduced populations of native microflora. Higher populations of L. monocytogenes were attained in sterile tissue homogenates than in nonsterile homogenates. Addition of yeast and mold to sterile rind homogenates was highly inhibitory to growth and survival of the pathogen. The results of this study indicate that native microflora of whole cantaloupe inhibited attachment to rind surfaces as well as survival and growth of L. monocytogenes on cantaloupe surfaces and homogenized fresh‐cut pieces. Thus, L. monocytogenes recontamination of melons having a reduced level of native microflora following application of a disinfection treatment may be a food safety concern.
CONSUMER ATTITUDES AND PERCEPTIONS TOWARDS MICROBIAL FOOD SAFETY IN THE DOMESTIC KITCHEN
Authors: REDMOND ELIZABETH C. , GRIFFITH CHRISTOPHER J.
Published: April 2007

The domestic kitchen is an important point of origin for foodborne disease and food safety communication strategies are required to improve food‐handling behaviors in the home. A key to the design of effective strategies is an understanding of factors that influence food safety behaviors. Attitudes may influence food safety behaviors and therefore, attitude determination towards food safety in the domestic kitchen is important for development of targeted food safety communication strategies.

A questionnaire was administered to consumers (n = 100) representing a cross‐section of the population of Cardiff, South Wales. Results showed that attitudes towards implementation of key food safety behaviors including cross contamination, cooking and storage were positive, however, attitudes towards other practices, for example cooling, were negative. Significant correlations (P < 0.05) between specific attitudinal responses and respondent demographics were identified, indicating that targeted strategies may be required for different groups of consumers. Results of this study will be discussed within the context of previous consumer food safety research, optimistic‐bias and development of communication strategies designed to raise awareness of food safety issues and bring about behavioral improvement.
The Induction of Tetraploidy in Salmonids
Authors: Myers James M. , Hershberger William K. , Iwamoto Robert N.
Published: April 2007

The induction of tetraploidy was attempted in three intraspecies crosses (autotetraploid) of sal‐monid: chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch) and rainbow trout (Salmo gairdneri), and in the interspecies hybrid (allotetraploid) coho × Atlantic salmon (Salmo salar).

Pressure treatments of 6.2 × 104 kPa (9,000 psi) were applied for six minutes at intervals from 50% of the time to cleavage to beyond first cleavage. Analysis of eyed stage embryos via flow cytometry indicated two periods of tetraploid induction existed corresponding to 55–75% and 100–110% of the first cleavage interval (FCI).

The effects of different pressures and the times of application were analyzed in a study with rainbow trout. Treatments of 4.8 × 104 kPa (7,000 psi) for eight minutes, and 5.5 and 6.2 × 104 kPa (8,000 and 9,000 psi) for four minutes, were applied at 65, 78, and 100% FCI. Tetraploids were found in the 5.5 and 6.2 × 104 kPa group treatments only when applied at 65% FCI.

The results indicate that, while tetraploidy is inducible in salmonids, further experimentation is necessary to discern the appropriate time and treatment for optimal tetraploid induction in each species.
Estimation of the Dietary Lipid Requirement Level of the White Crayfish Procambarus acutus acutus
Authors: Davis Donald A. , Robinson Edwin H.
Published: April 2007

Six isonitrogenous and isoenergetic diets containing graded levels of lipid (menhaden fish oil) were fed to juvenile white crayfish (Procambarus acutus acutus) over a 10 week period. A significant depression in weight gain was observed in crayfish fed diets containing 9% or more lipid. There were no significant differences in growth of crayfish fed diets containing 0 to 6% lipid. Whole‐body percentages of lipid and dry matter decreased, and protein increased in crayfish fed high‐lipid diets. Dietary lipid did not appear to influence survival or molting frequency. Whole‐body lipids generally reflected dietary fatty acid composition.
Predation by Dragonfly Naiads Anax junius on Young Crawfish Procambarus clarkii
Authors: Witzig John F. , Huner Jay V. , Avault James W.
Published: April 2007

Anax junius (Odonata: Aeschnidae) predation on young crawfish, Procambarus clarkii, was measured in the laboratory. Predation rates (0.066–1.16 crawfish/day) were estimated at 25, 15, and 5 C and for two sizes of crawfish (11–20 and 21–30 mm total length). Naiad predation increased with increasing temperature and decreasing crawfish size. At 5 C, naiads had no significant effect on survival of large crawfish but did significantly reduce survival of small crawfish. At 15 and 25 C, predation rates were significantly affected by temperature and prey size. Relative naiad abundance in a 0.8 ha crawfish pond was estimated from September through May. Larger naiads (head width, >6.5 mm; total length, >30 mm) capable of preying on young crawfish were not present until after most crawfish had reached invulnerable sizes. Large naiads, as a result, may not affect crawfish production under normal management conditions.
Oocyte Development and Induced Spawning of Smallmouth Bass (Micropterus dolomieui) in Response to Photoperiod and Temperature Manipulation: Preliminary Results
Authors: Cantin Marie‐Claude
Published: April 2007

Smallmouth bass (Micropierus dolomieui) in Quebec spawn between the end of May and mid‐June. Wild broodstock (4 to 8 years old) and laboratory‐reared ones (0+ years old) reared in a water recycling system were submitted to different temperature and photoperiod regimes to extend their natural spawning period. Oocyte maturation followed in vivo showed that oocytes developed to stage III in both cases but final maturation and ovulation was limited to the laboratory‐reared bass and this, a month before the normal spawning period, at 20.5 cm TL. Exogenous factors are examined, specifically duration of long photoperiod and vital space related to non‐spawning of wild broodstock.
Practical Molt Staging of Penaeus setiferus and Penaeus stylirostris
Authors: Robertson Lori , Bray William , Leung‐Trujillo Joanna , Lawrence Addison
Published: April 2007

Molt staging has many applications in penaeid aquaculture as a routine procedure. Using criteria developed for various crustaceans, a method of rapid molt staging was applied to Penaeus stylirostris and Penaeus setiferus adults. The most useful characters were the degree of epidermal retraction from the setal bases and epidermal retraction from the cuticle coupled with the development of new setae. The duration of the molt cycle of P. stylirostris was 11.5 ± 1.0 days (N = 5) at 27–29 C. The early postmolt, late postmolt, intermolt, early premolt and late premolt stages were readily determined. For P. stylirostris, the duration of postmolt was 27% of the cycle; intermolt, 17%; and premolt, 56%. The length of the molt cycle of P. setiferus at 27–29 C was 13.6 ± 1.0 days (N = 21) with postmolt occupying 22% of the cycle; intermolt, 19%; and premolt, 59%. Unilaterally eyestalk enucleated P. setiferus had a significantly shorter molt cycle than intact P. setiferus (11.7 ± 1.21 days vs. 13.6 ± 1.02 days, P < 0.05). There were no differences in molt cycle duration between the sexes, whether enucleated or intact (P > 0.05). A series of illustrations identifies the key characteristics for determining stage of molt in these penaeids.
Experimental Infections with Baculovirus penaei in the White Shrimp Penaeus vannamei (Crustacea: Decapoda) as a Bioassay
Authors: Overstreet Robin M. , Stuck Kenneth C. , Krol Rena A. , Hawkins William E.
Published: April 2007

Infections of the virus Baculovirus penaei (BP) have historically impacted penaeid shrimp production in both hatcheries and ponds. BP causes cytopathological alterations and mortality in at least four species, including Penueus vannamei. This study established experimental infections with BP in laboratory‐reared P. vannamei. The most useful protocol involved BP infection in third substage protozoea (P3) induced by feeding virus‐contaminated material to rotifers and, in turn, feeding those rotifers to the shrimp larva. Infections were also established by delivering virus‐containing brine shrimp to mysis (M) and postlarval (PL) stages. When virus originating from infected adults and juveniles was fed to P3's, the shrimp exhibited patent infections with hypertrophic nuclei, polyhedra, free virions, and occluded virions five or six days after being fed the virus. In contrast, when the source of virus material was from bioassay larvae rather than from adults and juveniles, similar patent infections developed in P3's by one to two days. A significant mortality in the resulting M's and PL's was associated with the infections with short but not long prepatent periods. In experimentally infected shrimp, examination by light microscopy and transmission electron microscopy revealed extensive viral infection in many cells in the anterior midgut and as many as 80–90% of the proximal and medial hepatopancreatic tubular cells. Free and occluded virions capable of producing disease ruptured into the gut lumen soon after infections became patent. Tests conducted in 1 L Imhoff cones, 160 L spat‐cones, and aquaria all produced infections, usually with a prevalence of 100%. The system provides a useful method to detect and assay for infective agents, to amass infective material for research purposes, and to assess the biology of and host response to the virus under different conditions.
Dietary Zinc Requirement of Oreochromis aureus and Effects of Dietary Calcium and Phytate on Zinc Bioavailability
Authors: McClain W. Ray , Gatlin Delbert M.
Published: April 2007

Two experiments were conducted to determine the dietary zinc requirement of fingerling blue tilapia (Oreochromis oureus) and the effects of dietary calcium and phytate on zinc bioavailability. Purified egg white diets containing graded levels of supplemental zinc were fed to fingerling tilapia in triplicate aquaria for 80 days. No overt signs of zinc deficiency were observed; however, scale and bone zinc concentrations of fish fed the various diets were significantly (P < 0.05) affected and increased linearly as dietary zinc increased until plateauing at 20 mg Zn/kg diet and greater. Based on these data, 20 mg Zn/kg of dry diet was determined to be the minimum dietary zinc requirement of blue tilapia. Purified egg white diets containing 20 mg Zn/kg were also supplemented with 0.5 or 2.0% calcium and 0 or 1.5% phytate in a factorial arrangement to determine the effects of these dietary factors on zinc bioavailability. At this level of supplemental zinc, 1.5% phytate significantly (P < 0.05) reduced zinc bioavailability as reflected in scale and bone zinc concentrations; whereas, dietary calcium did not affect zinc bioavailability. Results from this study establish the dietary zinc requirement of blue tilapia and indicate that higher levels of supplemental zinc should be included in practical feeds to compensate for reduced zinc bioavailability caused by dietary phytate.
Comparison of Three Solvent Systems for Extraction of Chlorophyll a from Fish Pond Phytoplankton Communities
Authors: Lloyd Steven W. , Tucker Craig S.
Published: April 2007

Chloroform‐methanol (2:1 v/v), absolute methanol, and 90% acetone were evaluated for their effectiveness as extractants of chlorophyll a from samples of phytoplankton communities collected from catfish ponds. Chloroform‐methanol consistently extracted more chlorophyll a than either 90% acetone or methanol. Precision for the methanol extraction was also unacceptably low, with an average coefficient of variation of 17%. Average coefficients of variation for the chloroform‐methanol and 90% acetone extraction procedures were 6 and 5%, respectively. Filtered samples should be steeped in chloroform‐methanol for at least 4 h to obtain maximum chlorophyll extraction, and the addition of MgCO3 to the extractant as a buffer is not necessary.
An Estimate of the Dietary Lysine Requirement of Juvenile Red Drum Sciaenops ocellatus
Authors: Brown Paul B. , Davis D. Allen , Robinson Ed H.
Published: April 2007

Quadruplicate groups of juvenile red drum (initial mean weight 2.7 g; 20 fish per replicate) were fed experimental diets containing 35% crude protein and graded levels of lysine for eight weeks. Lysine concentration in the basal diet was 1.2% and was supplied by a combination of peanut meal and shrimp‐head meal. The basal diet was supplemented with lysine‐HCl to provide 1.6, 2.0, and 2.4% lysine. Each of these diets contained an essential amino acid (EAA) premix. Two additional diets were formulated to contain 1.2 and 2.4% lysine without the EAA premix. Weight gain and feed efficiency (FE) data indicated between 1.2 and 1.6% dietary lysine was adequate. However, serum lysine concentrations indicated 1.6‐2.0% lysine was required. Fish fed 1.2 or 2.4% lysine, without the EAA premix, exhibited reduced weight gain and feed efficiency. Results indicated that red drum were able to utilize crystalline amino acids when incorporated into diets containing intact protein and, when lysine was adequate, the proteins were deficient in at least one other essential amino acid. It is recommended that a dietary lysine level of 5.7% of the dietary protein be used in formulating red drum diets.
Explanation of Size Diversity Among Artemia Cohorts: A Model of Food Uptake Kinetics
Authors: Brune David E. , Anderson T. H.
Published: April 2007

Models describing the food uptake kinetics of a growing Artemia culture and the hatching rate of Artemia cysts are combined to yield equations capable of predicting the effects of variable algal cell concentration upon the growth rates of brine shrimp cohorts. The model illustrates that the feeding ability of the brine shrimp can be viewed as one becoming increasingly more efficient as the animals mature. This increasing efficiency in a population of variable age animals (from a single hatch) results in accelerated growth of first hatched animals relative to later hatched animals, especially at algal cell concentrations below certain threshold values. Growth rates of variable age groups of brine shrimp are mathematically manipulated to predict variable size brine shrimp at low algal cell concentration and uniformly sized brine shrimp at high algal cell concentration. This predicted result is confirmed with data from Artemia growth trials at high and low algal cell concentrations. It is suggested that similar variations in population attributes of other species may be explained as an animal‐food interaction in which minor initial variations in individual animal maturity (weight, size, etc.) are magnified as a consequence of continuous competition for a common pool of food.
Production of the Freshwater Prawn Macrobrachium rosenbergii Stocked as Juveniles at Different Densities in Temperate Zone Ponds1
Authors: D'Abramo Louis R. , Heinen John M. , Robinette H. Randall , Collins Jeffrey S.
Published: April 2007

Juvenile freshwater prawns Mucrobruchium rosenkrgii (mean wet weight = 0.75, 1986 or 0.17g, 1985) were stocked into 0.06–0.07 ha earthen ponds at densities ranging from 39,536 to 118,608/ha during two separate growing seasons. After growout periods ranging from 135 to 142 days, survival was from 54.3% to 89.9% (x = 77.0%). Mean prawn weight at harvest ranged from 15.0 to 44.3g and decreased with increasing stocking density. The larger stocking weight of prawns was associated with harvest weights that were 16.8 to 39.6% greater than those achieved with the smaller stocking weight at comparable stocking densities.

Stocking of juveniles of the proper size and the effective management of the social structure of M. rosenkrgii appear to be critical to the success of intensive pond culture in temperate climates where the length of the growing season is restricted.
Apparent Digestible Energy Coefficients and Associative Effects in Practical Diets for Red Swamp Crayfish
Authors: Brown Paul B. , Robinson Edwin H. , Clark Ann E. , Lawrence Addison L. , Bordner Clark E.
Published: April 2007

Adult red swamp crayfish (Procambarus clarkii) were held in fecal collection chambers and fed common feedstuffs in two different types of diets, as the sole feedstuff and as a 30% substitution in a reference diet. Feedstuffs tested were soybean meal, peanut meal, wheat shorts, cooked corn, menhaden fish meal, and shrimp‐head meal. Feed consumption, apparent digestible dry matter, and energy coefficients were determined for feedstuffs when fed in both diets. Addition of menhaden fish meal, shrimp‐head meal, and peanut meal in the reference diet resulted in decreased consumption, and menhaden fish meal was poorly digested when incorporated at 30% in the reference diet. Apparent dry matter and energy digestion coefficients Indicated that plant feedstuffs have greater potential as ingredients in crayfish diets than feedstuffs of animal origin. Differences in consumption and digestibility between the two types of diet were observed. Therefore, it appears that the associative effects of additions of feedstuffs in diets should be considered when formulating crayfish feeds.
Toxicity of Ammonia to Red Drum Sciaenops ocellatus Fingerlings with Information on Uptake and Depuration1
Authors: Wise D. J. , Weirichand C. R. , Tomasso J. R.
Published: April 2007

Median lethal concentrations of un‐ionized ammonia‐nitrogen to red drum (Sciuenops ocellarus) were 0.9 ± 0.14 mg/L (mean ± SE) after 24 h and 0.8 ± 0.16 mg/L after 48 h (salinity = 4.0%, temperature = 20 C, pH = 6.8–7.1). Ammonia moved quickly from the environment into the plasma with 90% of steady state concentrations being reached after 33 minutes. When ammonia‐exposed fish were moved to ammonia‐free water, 90% of the ammonia which had accumulated in the plasma was no longer present after 3.3 minutes. The sensitivity of red drum to environmental ammonia appears to be similar to that of most other fishes tested. Based on the median lethal concentrations for red drum observed in this study and the acute‐chronic concentration ratios for other species of fish, it is suggested that red drum fingerlings be chronically exposed to no more than 0.05 mg/L un‐ionized ammonia‐nitrogen.
Acute Toxicity of Nitrite to Red Drum Sciaenops ocellatus: Effect of Salinity1
Authors: Wise D. J. , Tomasso J. R.
Published: April 2007

Acute toxicity of nitrite to red drum fingerlings was investigated under static conditions in environments containing 36.0 to 0.6 g/L salinity. The 48 h median lethal concentrations ranged from 85.7 mg/L nitrite‐N (36.0 g/L salinity) to 2.8 mg/L nitrite‐N (0.6 g/L salinity). Plasma nitrite concentrations increased with exposure time during a 48 h study and exceeded environmental concentrations in fish exposed to 9.1 and 5.1 mg/L nitrite‐N (1.4 g/L salinity). During 24 h of exposure, methemoglobin levels increased with increasing environmental nitrite conditions in fish exposed to 3, 6 and 9 mg/L nitrite‐N for 24 h (1.4 g/L salinity). The chloride component of salinity was not as effective in preventing nitrite toxicity as in other species of fish, indicating a potential problem for the culture of red drum in low‐salinity waters.
Preliminary Evaluation of Baits and Traps for Harvesting Orconectid Crayfish from Earthen Ponds
Authors: Brown Paul B. , Hooe Michael L. , Buck D. Homer
Published: April 2007

Four commercially available crayfish baits and two trap types were evaluated for efficiency in trapping Orconecres virilis and O. immunis from 13 unmanaged, contiguous earthen ponds in southern Illinois from May through October 1988. Specifically, this study compared three long‐life baits and one one‐day bait to gizzard shad, and four‐funnel submerged pillow traps to three‐funnel stand‐up pyramid traps in matched‐pair comparisons. Data from O. immunis harvest was not included in the final evaluation because of the relatively low numbers caught (343). The three long‐life baits attracted significantly more O. virilis than did gizzard shad, but the attractability of the one‐day bait was not significantly different from shad. There were no significant differences between four‐funnel pillow traps and three‐funnel pyramid traps or between catch per unit effort from deep or shallow ends of typical culture ponds. These data indicate that wild populations of O. virilis are susceptible to trapping with typical baits and traps used in the southern United States, and these methods may be more effective than those currently employed.
Replacement of Fishmeal with Soybean Meal in Male Tilapia (Oreochromis niloticusxO. aureus) Fingerling Diets at a Suboptimal Protein Level
Authors: Shiau Shi‐Yen , Kwok Chung‐Ching , Hwang Jean‐Yu , Chen Chin‐Mei , Lee Shue‐Li
Published: April 2007

A feeding trial was conducted to study the feasibility of using soybean meal (SBM) to replace fish meal (FM) as a protein source for tilapia feeds containing 24% dietary protein. Replacement levels were 0%, 33%, 67% and 100%. At each replacement level, methionine was either supplemented up to the amount that the 100% FM protein diet contained or not supplemented. The experiment was carried out for eight weeks in a recirculated water system. Fish fed diets in which 100% of the FM was replaced with SBM either with or without methionine supplementation had significantly (P < 0.05) lower weight gain, feed conversion ratio, protein efficiency ratio and protein digestibility than that of the groups fed the diets containing FM as the sole source of protein. Also, fish fed diets in which 67% and 33% of the FM was replaced with SBM did not differ significantly (P > 0.05) from that of the control group. These data suggest that when dietary protein level was suboptimal (24%), up to 67% of the FM protein in tilapin feeds can be replaced by hexane‐extracted SBM protein without any adverse effect on tilapia growth and feed conversion ratio.
Use of Cottonseed Meal in Channel Catfish Feeds
Authors: Robinson Edwin H. , Brent J. Robert
Published: April 2007

Solvent extracted cottonseed meal was substituted for soybean meal in catfish feeds on a nitrogen basis. The feeds, which contained either 0, 10, or 20% cottonseed meal, were formulated to contain about 32% protein and 2.9 kcal digestible energy/g. The fish were reared in 6 m3 net pens suspended in a 1.6 ha earthen pond. Twelve pens (four per treatment) were stocked with 400 fish with an initial average weight of 95 g/fish. All fish were fed to satiation once daily. A sample of 60 fish from each pen was weighed at 76 days to evaluate feed consumption, feed conversion, and weight gain. At the end of the experiment (132 days), fish from each net pen were weighed collectively and samples were taken to determine tissue free gossypol concentrations, proximate composition of fillets, and dressout percentages. There were no significant differences in weight gain, feed conversion, or survival of fish sampled at 76 days or of fish at the end of the experiment regardless of dietary treatment. At 76 days, feed consumption of fish fed the 20% cottonseed meal feed was significantly higher than that of other fish, but there were no significant differences in feed consumption at the end of the experiment. Free gossypol levels were below detectable limits in fish tissue. There were no significant differences in percentage dressout or in body composition, except for a slightly higher ash content in fish fed the feed containing 10% cottonseed meal. It appears that cottonseed meal can be used to partially substitute for soybean meal in catfish feeds. At the present, it is recommended that cottonseed meal be limited to 15% of the catfish diet.
Production and Nutritional Quality of Two Small‐Sized Strains of the Rotifer Brachionus plicatilis1
Authors: James Charles M. , Abu‐Rezeq Tawfiq S.
Published: April 2007

The rotifer Brachionus glicatilis, strain‐S (from Japan) and strain‐S1 (Pozuelo 1975) were mass cultured using Chlorella and bakers' yeast. Under the same feed regime, a significant increase (P < 0.001) in rotifer strain‐S production (44.19 ± 8.50 individuals/mL/d) was observed compared with strain‐S1 (29.64 ± 9.38 individuals/mL/d). The population growth rate was significantly higher (P> 0.001), and doubling time was significantly lower (P> 0.0001) in rotifer strain‐S than in strain‐S1. There was a significant decline (P> 0.001) in birth rate of strain‐S rotifers in the culture system compared with strain‐S1, suggesting short longevity and deterioration of the culture system while using strain‐S. In general, no significant difference (P< 0.05) in the presence of ω3 polyunsaturated fatty acids (ω3 PUFA) in different strains of rotifers was observed.
Heavy Metal Content of Coho Oncorhynchus kisutch and Chinook Salmon O. tschawytscha Reared in Deep Upwelled Ocean Waters in Hawaii1
Authors: Fast Arlo W. , D'Itri Frank M. , Barclay David K. , Katase Steven A. , Madenjian Charles
Published: April 2007

Coho (Oncorhynchus kisutch) and chinook salmon (O. tschawyrscha) were reared in seawater pumped from the 600 m depth at the Natural Energy Laboratory of Hawaii. Fish were reared in either 100% deep water at 11 C, or a mixture of 55% deep and 45% surface waters at 17 C. Salmon flesh was analyzed for mercury, zinc, cadmium and lead. Mercury concentration in coho salmon reared at 11 C was significantly lower than the concentration in coho reared at 17 C (P < 0.05), but other heavy metal concentrations in tissue did not differ between the two species or between the two rearing temperatures. Compared with wild salmon from the northwest Pacific Ocean, salmon reared in Hawaii had significantly lower concentrations of mercury and lead (P < 0.05), but significantly higher concentrations of zinc and cadmium. These differences in heavy metal concentration between wild and cultured salmon were most readily explained by differences in the heavy metal content of diets and the lack of heavy metal concentrations in rearing water. The concentration of mercury in salmon tissue was at least 20 times less than the 1.0 μ/g U.S. Food and Drug Administration action level for mercury. Action levels have not been established for zinc, cadmium, and lead.
Effectiveness of Commercially Formulated and Fish Baits in Trapping Cambarid Crawfish1
Authors: Huner Jay V. , Pfister Vernon A. , Romaire Robert P. , Baum Tammy J.
Published: April 2007

In the USA, cambarid crawfishes are harvested commercially with traps baited with fishes, formulated baits, or a combination of the two. Commercially formulated baits and fish baits, done and in combination, were evaluated to assess their relative effectiveness M attractants for crawfish. Traps baited with a combination of fish and formulated bait generally captured the most crawfish. Traps baited with common carp, the most effective natural bait, captured more crawfish than traps baited with skipjack herring, gizzard shad or channel catfish heads. Crawfish harvest from traps baited with several types of commercially formulated baits was equal to that obtained with traps baited with either gizzard shad or skipjack herring. Population density of crawfish and the availability of natural forage did not appear to influence relative effectiveness of either formulated baits or fish baits.
Toxicity of Ammonia and Nitrite to Penueus monodon Juveniles
Authors: Chen Jiann‐Chu , Lei Shun‐Chiang
Published: April 2007

Pcnaeus monodon juveniles (35.4 ± 2.2 mm TL) were exposed to seawater (20 ppt) having different concentrations of total ammonia (NH3+ NH,+) and nitrite. Median lethal concentration (LC50) was determined with static‐renewal tests. The LC50, of total ammonia‐N, NH3‐N and niMte‐N on shrimps decreased with increase of exposure time. The 24, 48, 72, % and 120 h LC50 were 94.96, 61.09, 47.47 45.58 and 38.00 mg/L total ammonia‐N (2.68, 1.73, 135, 1.29 and 1.08 mg/L NH3‐N) and 215.85, 185.33, 88.54, 54.76 and 37.97 mg/L nitrite‐N, respectively. The 144h LC50 of total ammonia‐N and NH3‐N was 36.71 mg/L and 1.04 mgL. The “threshold” of ammonia and nitrite was found at 144h and 120h respectively, from the toxicity curve approaching asymptote. A “safe value” was 3.7 mg/L total ammonia‐N, 0.1 mg/L NH3‐N (20 ppt, pH 7.70, 27C) and 3.8 mg/L nitrite‐N for P. monodon juvenile.
A Derived Climatology of Water Temperatures for the Mississippi Catfish Industry
Authors: Wax Charles L. , Pote Jonathan W.
Published: April 2007

A 36 year (1951–1986) record of water temperatures in Mississippi catfish ponds is synthesized from relationships with existing air temperature records. Multiple regression analysis is used to produce the following predictor equations for morning and afternoon pond temperatures: morning pond temperatures = 2.218 + 0.062(max air temp, day before) + 0.285(min air temp, same day) + 0.561 (afternoon pond temp, day before) (1) afternoon pond temperatures

= 2.071 ‐ 0.068(min air temp, same day) + 0.651 (morning pond temp, same day) + 0.373(max air temp, same day) (2)

The derived pond temperature record is analyzed to produce annual average regimes; daily average, maximum, and minimum temperatures with standard deviations; and probabilities at 10 levels of Occurrence through the year and for each individual month. Applications for the aquaculture industry are presented and evaluated.
Reproduction of Eyestalk‐AblatedPenaeus stylirostrisFed Various Levels of Total Dietary Lipid
Authors: Bray William A. , Lawrence Addison L. , Lester L. James
Published: April 2007

Effects of total dietary lipid (TDL) on reproduction ofPenaeus srylirostriswere compared using a series of diets ranging from 7.8% to 13.9% TDL. In addition, a commercial feed was compared to the experimental feeds, and a single fresh diet component (squid as 40% of diet) was compared to a multiple fresh component portion (squid, bloodworms, shrimp, and brine shrimp as 40% of diet). The control diet consisted of the four fresh components in equal proportions.

Significant differences among diet treatments during 87 days of evaluation were observed for mean percent hatch, number of nauplii per spawn, and percent females mating per night. A new parameter, protozoea I length, was evaluated also and appeared to be a sensitive measure of treatment differences. In general, the all‐fresh component diet (control) and diets with multiple fresh components performed better than those with a squid‐only component. Among the three diets varying only in total lipid content, the middle level (11.1% TDL) treatment means were significantly higher (P< 0.05) than the highest lipid treatment (13.9% TDL) based on number of nauplii per spawn, percent females mating per night, and protozoea length. The middle level treatment means were also higher than the low lipid level tested (7.8% TDL) for these parameters, but only protozwa length was significantly higher (P< 0.01).

In the best treatment (100% Fresh), there were 189,000 ± 10,300 eggs per spawn (mean ± SE), 103,000 ± 10,400 nauplii per spawn, 51.3 ± 4.3 percent hatch (N =64), and 7.0 ± 0.7 percent females mating per night (N= 174). The High Lipid treatment, in which the poorest results were obtained, produced 164,000 ± 11,100 eggs per spawn, 39,000 ± 9,400 nauplii per spawn, 23.0 ± 4.8 percent hatch (N =40) and 3.9 ± 0.5 percent females mating per night (N= 174). Results indicate that dietary lipid levels affect reproduction and that 10% to 11% total lipid produced better results than 7.8% and 13.9%.
Acceptance and Consumption of Food by Striped Bass and Hybrid Larvae
Authors: Tuncer Haluk , Harrell Reginal M. , Houde Edward D.
Published: April 2007

Food acceptance, consumption and weaning times were investigated for striped bass (Morone saxatilis) and hybrid striped bass (M. saxatilis×M. chrysops) larvae. Experimental treatments consisted of: control groups of striped bass (SC) and hybrids (HC) fed Artemia nauplii; hybrids fed formula food (HF); and hybrids weaned from Artemia nauplii to formula food at 11–15 days (HF1), and 18–22 days (HF2) posthatch. The formula diet did not support growth and resulted in total mortality of the HF hybrids by the third week posthatch. HF1 fish had significantly slower growth and lower survival than HF2 of HC. The HF2, HC and SC groups had similar growth and survival, which indicated no heterosis in hybrids. There were no differences in Artemia nauplii consumption by the SC and HC groups. Daily consumption increased exponentially for both groups (0.8 to 50–60 cal/day/larva between 7 and 30 days posthatch). Weight specific consumption (WSC) decreased initially and then increased for both groups. A mean WSC of 58% (range of 24–83%) was found for the combined SC and HC groups. Food conversion ratio, growth efficiency, caloric efficiency, and productive protein values were similar for striped bass and hybrid larvae.
Changes in Plasma Concentrations of Sex Steroids in Adult Pacific Halibut, Hippoglossus stenolepis
Authors: Wu Liu Han , Stickney Robert R. , Dickhoff Walton W.
Published: April 2007

Blood samples were collected from captive Pacific halibut, Hippoglossus stenolepis, at intervals of about six weeks from early December 1986 to late November 1987. Concentrations of plasma androgen and estradiol‐17β were determined by radioimmunoassay. The plasma concentrations of steroid were highest during autumn and winter in halibut that matured during late winter. The concentrations of steroids in samples collected in December were above 2 ng/mL (estradiol) or 1 ng/mL (androgen) in maturing females and below 0.5 ng/mL for both steroids in non‐maturing females. The levels of steroids decreased rapidly about one month before spawning. In a mature male, androgen began to rise in August and November, and reached a peak of 7 ng/mL in early December. One month before spawning, the androgen concentration fell to 0.16 ng/mL. Estradiol concentrations were detectable in the male and varied little during the year. In immature fish, neither androgen nor estradiol changed significantly throughout the year. These results suggest that the concentrations of estradiol or androgen measured in blood samples taken during December may be used to determine the sex and state of maturation of Pacific halibut.