IJA Volume 56, Issue 3, 2004

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    Digestibility Of Nutrients And Energy In Diets For The African Catfish Clarias Gariepinus (Burchell 1822)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Pantazis, Panagiotis A. ; Neofitou, Christis N.
    A purified diet, the raw material zein, and two diets composed of complex foodstuffs (fishmeal, soy, wheat) were tested for eight months in the African catfish Clarias gariepinus (Burchell 1822) to determine the in vivo Apparent Digestibility Coefficients (ADC) for dry matter, crude protein, lipid, carbohydrates, ash, energy, and amino acids. Feces were collected by sedimentation and digestibility coefficients were calculated using chromium oxide as an external indicator. Average ADCs ranged 54-96%. The ADC of crude protein (80-90%) was similar to previously recorded ADCs. Ash digestibility (54-89%) varied significantly between diets, probably as the result of the reduced bioavailability of minerals and trace elements in the constituent raw materials. ADC for individual amino acids ranged 82-99%. Zein, as an experimental feed ingredient, had an accept- able ADC for both gross nutrients and amino acids. When the nutrient level in the test ingredi- ent differed greatly from that in the reference diet, calculation of ADC was based on relative nutri- ent contributions. Results are discussed in relation to the nature of the dietary ingredients and their suitability for related experimental nutritional work.
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    Effects Of Fish Density On Spread Of Infectious Hematopoietic Necrosis Virus (IHNV) In Rainbow Trout, Oncorhynchus Mykiss
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Ogut, H. ; Reno, P.W.
    Rainbow trout (Oncorhynchus mykiss) were held at one of seven densities (8, 4, 0.63, 0.31, 0.16, 0.08 or 0.012 fish per liter) and challenged to the infectious hematopoietic necrosis virus (IHNV) by cohabitation with a single presumably infected donor fish. The trout were exposed to the IHNV-infected fish for 11 days to determine the effect of density on occurrence, spread and prevalence of the disease. The host density and IHNV prevalence were positively associated (r2 = 0.89, regression analysis) with no occurrence of the virus at the two lowest densities (0.08 and 0.012 fish/l). Host density, therefore, is a key factor in determining the incidence and magnitude of IHNV infection.
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    Successful Replacement Of Fishmeal By Plant Proteins In Diets For The Gilthead Seabream, Sparus Aurata L.
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Kissil, George Wm. ; Lupatsch, Ingrid
    Soy protein concentrate, wheat gluten, and corn gluten meal were evaluated in combination and as sole dietary protein sources in diets for gilthead seabream. A growth trial and digestibility determinations demonstrated the effectiveness of these plant proteins as alternatives to fish- meal. Digestibility trials indicated superior protein digestibility for soy protein (92%), wheat gluten (96%), and corn gluten (90%) in comparison with fishmeal (86%), while energy digestibility was higher than fishmeal (84%) only in wheat gluten (91%; it was 75% for soy protein and 72% for corn gluten). For the growth trial, eight isonitrogenous and isoenergetic (as-fed basis) diets were formulated with differences in the protein sources. Growth in the range of 40-130 g was superi- or to the fishmeal control with the diet containing wheat gluten but inferior in the diets containing soy protein concentrate or corn gluten meal. Diets that replaced 25-100% of the fishmeal with a mixture containing equal portions of all three plant proteins outperformed the control with a 9- 16% greater weight gain and 4-10% lower feed conversion ratio. The use of soy protein or corn gluten as the sole protein source in diets for seabream is not recommended but their use in com- bination with wheat gluten can provide a partial or complete alternative to fishmeal. However, the cost of supplemental arginine made replacement economic at only the lowest replacement level (25%). An in-depth evaluation of the need for this amino acid in the protein mixture could signif- icantly affect the feasibility of using higher replacement levels.
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    Enteric Red Mouth Disease In Cultured Rainbow Trout (Oncorhynchus Mykiss) On The Black Sea Coast Of Turkey
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Karatas, Süheyla ; Candan, Akin ; Demircan, Didem
    Although Yersinia ruckeri, the etiological agent of the enteric red mouth disease (ERM), has been isolated from freshwater fish in several countries, there are few reports of its presence in cultured sea and brackish water fish. The aim of this study was to isolate and identify the etio- logical agent of disease outbreaks that occurred in rainbow trout cage farms on the Black Sea coast of Turkey in 2002. Clinical observation, biochemical, API 20 NE, and agglutination tests allowed the diagnosis of ERM caused by Y. ruckeri, which was successfully treated with med- icated feed (oxytetracycline at 75 mg per kg body weight per day for 10 days).
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    Dietary Histidine Requirement Of Fingerling Indian Major Carp, Labeo Rohita (Hamilton)
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Abidi, Shabihul Fatma ; Khan, Mukhtar A.
    A 6-week growth trial was conducted to assess the dietary histidine requirement of fingerling Indian major carp, Labeo rohita (3.50±0.04 cm; 0.40±0.02 g) by using amino acid test diets (40% crude protein; 4.28 kcal/g) containing casein, gelatin, and L-crystalline amino acids. Diets with graded levels of histidine (0.25, 0.50, 0.75, 1.00, 1.25, and 1.50% of the diet) were fed to tripli- cate groups of fingerlings at 5% of their body weight divided into two feedings (07:00 and 17:30). Live weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio were sig- nificantly (p<0.05) affected by dietary histidine concentration. Weight gain and conversion effi- ciencies were best at 0.75% dietary histidine. Whole body protein content was highest and mois- ture and fat were lowest in the 0.75% dietary histidine treatment while whole body ash was the same at all treatment levels. Second-degree polynomial regression analysis of the live weight gain and feed conversion ratio resulted in more accurate histidine requirement estimates of 0.90 and 0.82% of the dry diet, respectively, corresponding to 2.25 and 2.05% of the dietary protein. It is recommended that dietary histidine be included at a level of 0.82% of the feed, correspond- ing to 2.05% of the dietary protein, for optimal growth in L. rohita fingerlings.
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    Spawning And Larvae Production Of Common Pandora, Pagellus Erythrinus L.
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Güner, Yusuf ; Özden, Osman ; Altunok, Muhammet ; Koru, Ediz ; Kızak, Volkan
    Spawning of the common pandora (Pagellus erythrinus L.) in captivity was studied at ambient temperature (21.2±1.2°C) during the breeding season in 1998. Broodstock were cultivated in net fishpens and spawned in large fiberglass tanks (10 m diameter) between June and July. Approximately 33.2 million eggs were collected from 30 mature 4-7 year old females, 97% of which were buoyant healthy eggs with diameters ranging 753-801 μm. The eggs were incubat- ed at 19, 21, or 23°C and development and morphological changes were observed until day 50. The best hatching rate (88.9%) was obtained at 19°C. Swim bladder inflation occurred 8-20 days after hatching. The average survival at day 50, at an initial density of 40 larvae/l, was 3.2%. Exogenous feeding began on day 3. Larvae were first fed rotifers, Brachionus plicatilis, and later Artemia nauplii. Larvae completed yolk absorption 78 hours after hatching. A green water envi- ronment was maintained by introducing cultured microalgae (Nannochloropsis oculata and Tetraselmis suecica). Larvae (13.3 mm) transformed into juveniles (18.71 mm) 29-37 days after hatching.
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    Effects Of Alum On The Quality Of Aquaculture Effluents In Settling Ponds
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Rowan, Martha ; Gross, Amit ; Boyd, Claude E.
    The effectiveness of alum (aluminum sulfate) in reducing the concentrations of potential pollu- tants in pond effluents was investigated in catfish production ponds. Application of alum at 50 mg/l to water remaining in ponds immediately after seining for harvest did not generally result in significantly greater removal of nutrients and solids than did settling alone, although removal rates of some variables were initially higher in the alum treated ponds. Within four hours of sein- ing in both alum treated and untreated ponds, there was removal of more than 85% of total sus- pended solids, 75% of total phosphorus, 72% of turbidity, and more than 40% of biochemical oxygen demand and chemical oxygen demand. Concentrations of soluble reactive phosphorus decreased after 48 h, but total ammonia nitrogen was not removed. Alum may be more effective in improving water quality in settling ponds if it is applied after the initial sedimentation has occurred.
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    Fertility Problems In The Second Generation Of A Four-Species Tilapia Cross
    (Israeli Journal of Aquaculture - BAMIGDEH, 2004) Hulata, Gideon ; Cnaani, Avner ; Slossman, Tatiana ; Gall, Graham A.E.
    Reproductive problems were encountered in attempting to produce the second generation of a four-way cross of tilapia from interspecific F1 hybrids. The cross (Oreochromis mossambicus x O. aureus) x (Sarotherodon galilaeus x O. niloticus) successfully bred for one generation, how- ever, not even a single batch of progeny was obtained in the subsequent generation. It was con- cluded that the complex genetic structure of this cross caused the fertility problem. Any similar breeding programs that are based on multi-species crosses should take into consideration that reproductive problems may occur.