No abstract

Juvenile red claw, Cherax quadricarinatus, were obtained from a commercial supplier and stocked into twelve 0.04‐ha ponds with an average water depth of approximately 1.1 m at a rate of 1100 red claw per pond (27,170 red claw/ha). Mean stocking weight (±SD) was 6.25 ± 3.0 g. Three replicate ponds were randomly assigned to each of the four treatments. In Treatment 1 (TRT1), red claw were stocked into ponds to which dried alfalfa hay (forage) was added at a rate of 500 kg/ha/mo; Treatment 2 (TRT2) consisted of red claw being fed a prepared diet containing 13% protein; in Treatment 3 (TRT3), red claw were fed a diet containing 13% protein at which had dried alfalfa hay been added at a rate of 500 kg/ha/mo; and in Treatment 4 (TRT4; control), red claw were fed a complete diet containing 28% protein. Water quality measurements were made three times weekly for dissolved oxygen and temperature (am, pm), pH, total ammonia nitrogen, nitrite, and alkalinity averaging 7.17 mg/L, 8.96 mg/L, 25.5 C, 27.3 C, 8.68, 0.39 mg/L, 0.012 mg/L, and 106.5 mg/L, respectively. After 113 d, the final mean weight of red claw fed TRT3 was significantly (P < 0.05) higher (68.10 g) compared to that of red claw fed hay only (49.40 g) but not different from red claw fed TRT2 (56.03 g) and TRT4 (62.10 g). Likewise, red claw fed TRT3 had significantly higher percent weight gain (990%) compared to that of red claw fed hay only (690%) but not different from TRT2 (796%) and TRT4 (893%). Feed conversion ratio of TRT2, TRT3, and TRT4 and percent survival among all treatments did not differ significantly (P > 0.05), averaging 2.85 and 66.8%, respectively. Total yield of red claw fed TRT3 and TRT4 (968 and 952 kg/ha) was significantly (P < 0.05) higher compared to that of red claw fed hay only (617 kg/ha) but did not differ from red claw fed TRT2 (882 kg/ha). Tail meat yield of male red claw in TRT3 was significantly (P < 0.05) higher (17.3 g) compared to that of male red claw in TRT1 (12.7 g) and TRT2 (14.9 g) but not significantly different (P > 0.05) from male red claw in TRT4 (16.9 g). Tail meat yield of female red claw in TRT3 and TRT4 was significantly (P < 0.05) higher (14.2 and 13.9 g, respectively) compared to that of female red claw in TRT1 (10.5 g) and TRT2 (10.4 g). Tail muscle proximate compositions showed no significant differences (P > 0.05) in protein (wet weight basis) between males and females among treatments (diet) which averaged 16.2 and 14.6%; however, there were little to no significant differences in fat and ash between males and females among treatments. Results from this study indicate that pond‐cultured red claw stocked at 27,170 red claw/ha can be fed a practical diet containing 13% protein, with or without forage (alfalfa hay), compared to red claw fed a complete diet containing 28% protein; however, if alfalfa hay is added to the pond at 500 kg/ha/mo as the sole source of added nutrients, growth is reduced. Therefore, the use of alfalfa hay, in combination with a low‐protein pelleted diet may be a production metho...

Background: EST sequencing is one of the most efficient means for gene discovery and molecular marker development, and can be additionally utilized in both comparative genome analysis and evaluation of gene duplications. While much progress has been made in catfish genomics, large-scale EST resources have been lacking. The objectives of this project were to construct primary cDNA libraries, to conduct initial EST sequencing to generate catfish EST resources, and to obtain baseline information about highly expressed genes in various catfish organs to provide a guide for the production of normalized and subtracted cDNA libraries for large-scale transcriptome analysis in catfish.

Chemokines are a family of structurally related chemotactic cytokines that regulate the migration of leukocytes, under both physiological and inflammatory conditions. CC chemokines represent the largest subfamily of chemokines with 28 genes in mammals. Sequence conservation of chemokines between teleost fish and higher vertebrates is low and duplication and divergence may have occurred at a significantly faster rate than in other genes. One feature of CC chemokine genes known to be conserved is genomic clustering. CC chemokines are highly clustered within the genomes of human, mouse, and chicken. To exploit knowledge from comparative genome analysis between catfish and higher vertebrates, here we mapped to bacterial artificial chromosome (BAC) clones 26 previously identified catfish (Ictalurus sp.) chemokine cDNAs. Through a combination of hybridization and fluorescent fingerprinting, 18 fingerprinted contigs were assembled from BACs containing catfish CC chemokine genes. The catfish CC chemokine genes were found to be not only highly clustered in the catfish genome, but also extensively duplicated at various levels. Comparisons of the syntenic relationships of CC chemokines may help to explain the modes of duplication and divergence that resulted in the present repertoire of vertebrate CC chemokines. Here we have also analyzed the expression of the transcripts of the 26 catfish CC chemokines in head kidney and spleen in response to bacterial infection of Edwardsiella ictaluri, an economically devastating catfish pathogen. Such information should pinpoint research efforts on the CC chemokines most likely involved in inflammatory responses.

Two feeding trials were conducted in a closed system with Nile tilapia Oreochromis niloticus fry (mean weight, 0.10 g; experiment 1) and juveniles (mean weight, 2.84 g; experiment 2) to examine the effects of total replacement of fish meal (FM), with and without supplementation of DL-methionine (Met) and L-lysine (Lys), by plant protein sources. In experiment 1, fry were fed nine isoenergetic (available energy [AE] = 4.0 kcal/g of diet) and isoproteic (40% protein as fed basis) practical diets containing protein primarily from soybean meal (SBM), with and without essential Met and Lys. After 5 weeks, final individual weight (FW; g/fish) and percent weight gain (PWG) of fry fed diet 1 (control with 20% FM) was significantly higher (P < 0.05) compared with fry fed all other diets, while fry fed diet 9 containing 46% SBM and 22% feed-grade poultry by-product meal PBM) was significantly higher than all other diets (diets 2-8). Quantity of diet fed and percent survival did not differ significantly (P > 0.05) among all diets. In experiment 2, juveniles were fed six isoenergetic (AE = 4.0 kcal/g of diet) and isoproteic (35% protein as fed basis) practical diets containing protein primarily from SBM, soybean protein concentrate (SPC), feed-grade PBM, or combinations of those. After 7 weeks, mean FW, PWG, and amount of diet fed for fish fed diets 1 (control with 20% FM) and 6 (with 20% SPC and 20% PBM) were significantly higher (P < 0.05) compared with juveniles fed all other diets. Feed conversion ratio (FCR) was similar among treatments, but fish fed diet 5 (with 36% SPC and 0% FM) recorded the highest FCR value. Likewise, protein efficiency ratio (PER) was similar among treatments; however, PER in juveniles fed diets 3 (with 52% SBM and 0% FM) and 5 were significantly lower than in fish fed all other diets. Overall, no significant (P > 0.05) difference was found in percent survival, which averaged 92.6% among all diets fed. These data suggest that Nile tilapia fry cannot utilize diets containing high levels (>75%) of SBM when no animal protein ingredient is added, even with supplemental Met and Lys. However, a diet containing 20% SPC and 20% feed-grade PBM appears to be suitable for juvenile Nile tilapia, which may help reduce diet costs and allow for sustainable production.