Effect of Density at Harvest on the Growth Performance and Profitability of Hatchery‐reared Spotted Rose Snapper,Lutjanus guttatus,Cultured in Floating Net Cages          下载免费PDF全文

Carlos Humberto Hernández  Crisantema Hernández  Francisco Javier Martínez‐Cordero  Nicolás Castañeda‐Lomas  Guillermo Rodríguez‐Domínguez  Albert G. J. Tacon  Eugenio Alberto Aragón‐Noriega 《Journal of the World Aquaculture Society》2016,47(1):51-60

This study evaluated the effect of the density at harvest on the performance and profitability of hatchery‐reared spotted rose snapper cultured in cages. The fish were stocked at harvest densities of 15, 20, and 22 kg/m³ in cages of 222 and 286 m³. More than 39,000 snapper fingerlings with an initial weight of 14 g were stocked. The fish were fed an extruded diet and cultured over a 360 d period. The thermal growth coefficient ranged from 0.04 to 0.05 and survival was 95% for all treatments, with the highest final weight (436.8 g) observed for fish reared at a density of 20 kg/m³. The allometric value b indicated that hatchery‐raised, cage‐cultured snapper were heavier than their wild counterparts. The major costs were feed (ranging from 44.7–45.9%), labor (22.4–32.6%), and seed costs (20.2–26.1%). The total production cost ranged from US$ 6.5 to US$ 7.5/kg. The baseline scenario was not economically feasible. However, a 10% increase in the sales price resulted in increases in the internal rate of return (183%) and net present value (US$ 97,628.9). These results suggest that L. guttatus has the potential for commercial production in cages.  相似文献   

Wirkung einer langjährig differenzierten mineralischorganischen düngung auf ertragsleistung,humusgehalt, netto‐n‐mineralisierung und N‐bilanz     

Erhard Albert 《Archives of Agronomy and Soil Science》2013,59(3-4):187-213

Zur Untersuchung der Wechselwirkung zwischen mineralischer und organischer Düngung auf Pflanze und Boden werden seit 1966 Dauerversuche auf zwei Standorten (Spröda: anlehmiger Sand; Methau: Lehm) mit der Fruchtfolge Zuckerrüben –Sommergerste—Kartoffeln und Winterweizen durchgeführt.

Bei unterlassener und geringer mineralischer N‐Düngung bewirkte Stallmist erhebliche und Stroh keine bzw. geringe Mehrerträge. Bei optimaler N‐Düngung hingegen erreichten die Mehrerträge durch Stallmist 5% und die durch Stroh 3%. Die auf verbesserte Bodeneigenschaften beruhende Sonderwirkung von Stallmist und Stroh kann durch mineralische N‐Düngung nicht substituiert werden. Auf beiden Standorten wurden die Humusgehalte bei unterlassener organischer Düngung nahezu halbiert. Der Einfluß der Strohdüngung auf die Humusgehalte war gering, der von Stallmist deutlicher ausgeprägt.

Die Netto‐N‐Mineralisierung korrelierte negativ zur mineralischen N‐Düngung, wobei Stallmist zu 25 bis 50 kg/ha höheren Werten führte.

Optimale Erträge wurden mit leicht negativen bis leicht positiven N‐Bilanzsalden realisiert. Dabei gelten die niedrigen Werte stets für die alleinige mineralische N‐Düngung und die höheren für die Stallmist‐ bzw. Strohdüngung.

Da mit dem Anstieg der Humus‐ und Gesamt‐N‐Vorräte vor allem das Risiko der Nitratauswaschung wächst, ist eine maßvolle organische Düngung, die jedoch langfristig den Erhalt der Bodenfruchtbarkeit sichert, anzustreben. In der Regel reichen hierzu jährlich 10 t/ha Stallmist aus.  相似文献   

Molecular cloning of two chitinase genes from Serratia marcescens and their expression in Pseudomonas species     

Leif Sundheim  Alan R. Poplawsky  Albert H. Ellingboe 《Physiological and Molecular Plant Pathology》1988,33(3)

Two chitinase encoding EcoRI fragments from the enteric soil bacterium Serratia marcescens were cloned. From a genomic library of 5686 transductants, 21 expressed chitinase activity as indicated by clearing of a chitin-containing medium. The chitinase encoding clones could be divided into two groups. Four had an 18kb EcoRI fragment and 17 had a 9·4 kb EcoRI fragment. In Southern hybridization experiments the 18kb fragment showed no homology to the 9·4 kb fragment and restriction enzyme maps indicated no similarity. Triparental mating with fluorescent Pseudomonas spp. yielded transconjugants that expressed chitinase activity, inhibited growth of Fusarium oxysporum f. sp. redolens germ tubes and reduced disease of radish caused by the same fungus.  相似文献   

New heterocyclic herbicidal sulphonamides     

Albert Percival 《Pest management science》1991,31(4):569-580

The sulphonylurea structures and their relationships with the 1,2,4-triazolo[1,5-a]pyrimidinesulphonamides are first discussed. Three novel examples of heterocyclic sulphonamides, pyrazolo[1,5-a]pyrimidine-2-sulphonamides, thiazolo[3,2-b][1,2,4]triazole-2-sulphonamides and 1,2,4-triazole-3-sulphonamides are highlighted and their synthesis, biological activity and soil behaviour are described.  相似文献   

Inhibition of pheromone action in Sesamia nonagrioides by Haloacetate analogues     

Magi Riba  Matilde Eizaguirre  Albert Sans  Carmen Quero  Angel Guerrero 《Pest management science》1994,41(2):97-103

The electrophysiological activity of some halogenated analogues of the major component of the sex pheromone of the corn stalk borer Sesamia nonagrioides Lef. (1) is presented. The analogues comprise a series of fluoro-, chloro- and bromoacetate analogues 4 – 10 as well as trifluoromethyl ketone 11. The fluoro derivatives 4 – 6 displayed remarkable electro-antennogram (EAG) intrinsic activities in comparison with the parent acetate 1, while the remaining analogues elicited significantly lower response. The compounds have also been tested as inhibitors of the sex pheromone perception in EAG and in the field. In the laboratory. fluoro analogues 4 – 6 were better inhibitors than chloro derivatives 7 – 9 , which in turn behaved similarly to the bromoacetate 10 . Trifluoromethyl ketone 11, however, was a poor inhibitor of the pheromone action. In the field, baits of mixtures of compounds 5 – 11 with the corn stalk borer pheromone in 10 :1 ratio inhibited the concomitant attraction of the clover cutworm moth Scotogramma irifolii Rott., while the difluoro analogue 5, trichloroacetate 9 and trifluoromethyl ketone 11 also diminished the number of catches of the armyworm Mythimna unipuncta Haw. The monofluoroacetate 4. trifluoro analogue 6 and bromo derivative 10 significantly disrupted the pheromone action of the corn borer, whereas trifluoromethyl ketone 11 synergistically increased the number of males attracted to the pheromone trap alone. Addition of 11 to baits containing the corn borer pheromone caught S. nonagrioides selectively with regard to the other habitat-sharing species M. unipuncta and S. trifolii.  相似文献   

Pheochromocytoma in an aged female African elephant (Loxodonta africana).     

Christopher J Bonar  Albert H Lewandowski  Baha Arafah  Charles C Capen 《Journal of zoo and wildlife medicine》2005,36(4):719-723

A 43 yr-old female African elephant (Loxodonta africana) collapsed acutely and died. Necropsy revealed an enlarged right adrenal medulla. Histologic appearance was typical of pheochromocytoma. Special stains and electron microscopy demonstrated chromaffin granules, suggesting that the tumor was derived from catecholamine secreting cells of the adrenal medulla, and may have been functionally secretory. Serum levels of both norepinephrine and epinephrine were elevated at time of death, supporting the functional nature of the tumor. Histologic findings of arteriolar sclerosis and smooth muscle hyperplasia suggested that the animal may have suffered from chronic systemic hypertension. Pheochromocytoma should be considered as a differential diagnosis in cases of suspected hypertension and acute death in elephants.  相似文献   

The role of Eskimo hunters, veterinarians, and other biologists in improving the humane aspects of the subsistence harvest of bowhead whales     

O'Hara TM  Albert TF  Oen EO  Philo LM  George JC  Ingling AL 《Journal of the American Veterinary Medical Association》1999,214(8):1193-1198

  相似文献   

Herbicide resistance in Aster squamatus conferred by a less sensitive form of acetolactate synthase     

Osuna MD  Fischer AJ  De Prado R 《Pest management science》2003,59(11):1210-1216

A biotype of Aster squamatus (Sprengel) Hieronymus with suspected resistance to the ALS-inhibiting herbicide imazapyr was detected in a chicken farm in the province of Seville, Spain, which had been treated once a year with imazapyr for 10 years. Resistance to imazapyr in this biotype was studied using dose-response experiments, absorption and translocation assays, metabolism studies and ALS activity assays. The rate of imazapyr required to inhibit A squamatus growth by 50% (ED50) was 15 times higher for the R (resistant) than for the S (susceptible) biotype. Cross-resistance existed for the ALS-inhibitors imazamox, imazethapyr, amidosulfuron, nicosulfuron, rimsulfuron, triasulfuron and tribenuron, but not for bensulfuron. Control of A squamatus using alternative herbicides was poor with clopyralid, intermediate with quinclorac, amitrole and MCPA, and excellent with 2,4-D, glufosinate and glyphosate. Absorption of [14C]imazapyr increased over time for both the R and S biotypes, and translocation from the treated leaf to shoots and roots was similar in both biotypes, with most of the radioactivity remaining in the treated leaf. No metabolites of imazapyr were detected in either biotype. Sensitivity of the ALS enzyme (target site) to imazapyr was lower for the R biotype (I50(R) = 4.28 x I50(S)). The mechanism of imazapyr resistance in this R biotype appears to be an altered ALS conferring decreased sensitivity to imazapyr at the whole-plant level.  相似文献   

DNA sequences coding for the F18 fimbriae and AIDA adhesin are localised on the same plasmid in Escherichia coli isolates from piglets   总被引：3，自引：0，他引：3  

Mainil JG  Jacquemin E  Pohl P  Kaeckenbeeck A  Benz I 《Veterinary microbiology》2002,86(4):303-311

The adhesin-involved-in-diffuse-adherence (AIDA) afimbrial adhesin is produced by human, but not by animal, Escherichia coli, with the exception of German porcine verotoxigenic Escherichia coli (VTEC) [Clin. Diagn. Lab. Immunol. 8 (2001) 143]. Presence and localisation of DNA sequences (aidA) coding for and production of an AIDA adhesin were investigated in a collection of Belgian VTEC and non-VTEC E. coli isolated from piglets at weaning time. The 174 isolates were also studied by colony hybridisation for the presence of DNA sequences coding for the Stx2e verocytotoxin and the F18 fimbrial adhesin (fed): 71 were Stx2+F18+AIDA+, 26 were F18+AIDA+, 12 were AIDA+, two were Stx2+AIDA+, and one was Stx2+ only. Fifty-four of the 58 (F18+)AIDA+ isolates tested positive in a western blotting assay with an immune serum raised against the AIDA protein. Hybridisation with the AIDA gene probe on plasmid DNA profiles identified a probe-positive plasmid band in the 10 AIDA+ and in 24 of the 25 F18+AIDA+ isolates studied. Moreover in F18+AIDA+ isolates, only one plasmid band hybridised with both F18 and AIDA probes. These results confirm the presence of aidA-related genes in not only VTEC, but also non-VTEC, isolates from piglets and the production of an antigenically AIDA-related protein by the majority of probe-positive E. coli. Moreover the plasmid DNA hybridisation results suggest a localisation on the same plasmid of the aidA- and fed-related DNA sequences.  相似文献   

Evaluation of the sensitivity of reverse-transcription polymerase chain reaction to detect porcine reproductive and respiratory syndrome virus on individual and pooled samples from boars.     

Albert Rovira  Travis Clement  Jane Christopher-Hennings  Bob Thompson  Mark Engle  Darwin Reicks  Claudia Mu?oz-Zanzi 《Journal of veterinary diagnostic investigation》2007,19(5):502-509

  相似文献