Economic Assessment of Alternative Aquaculture Aeration Strategies     

Carole R. Engle  Upton Hatch 《Journal of the World Aquaculture Society》1988,19(2):85-96

Oxygen depletion is a serious problem for the catfish industry, especially as producers attempt to increase their production intensity. Aeration, either emergency or continuous, is the most common method used to address oxygen depletion.
A risk-programming model using Target MOTAD methodology was developed to study the aquacultural producer's aeration decision-making process. Effects of stocking rate, aeration yield response and availability of labor, capital and electricity on the selection of aeration strategy were analyzed.
Continuous aeration with electric paddlewheels was most often selected as the best aeration strategy. However, as farmers become increasingly concerned with financial risk, they apply continuous aeration with pump sprayers first, then no aeration and lastly emergency aeration with tractor-powered paddlewheels. Emergency aeration was only used when: 1) electricity was not available and the producer desired a highly conservative financial strategy, and 2) the relative efficiency of continuous aeration in the field was dramatically reduced from experimental results.  相似文献   

Gossypol toxicity in preruminant calves     

RZ ZELSKI  JT ROTHWELL†  RE MOORE‡  DJ KENNEDY§ 《Australian veterinary journal》1995,72(10):394-398

SUMMARY Twenty-four of 57 calves fed a diet containing 33% cotton seed meal (CSM) died between 7 and 15 weeks of age. Initial deaths were not accompanied by premonitory signs, but after CSM withdrawal most calves developed rough coats, anorexia, weakness, ascites and subcutaneous oedema. Those that died had large volumes of serous fluid in the body cavities, hard livers of ‘nutmeg’ appearance, and pulmonary congestion. Histopathologically the livers showed periacinar necrosis in acute cases and periacinar fibrosis in chronic cases. Lungs from several calves had oedema, haemosiderosis and fibrosis in some pulmonary vessels. Atrophy of myocardial fibres was present in most cases. The concentration of free gossypol in the diet was 100 to 220 mg/kg. Ante-mortem and post-mortem findings supported a diagnosis of gossypol poisoning. The deaths continued for 4 weeks after withdrawal of CSM from the diet.  相似文献   

Primary tonsillar mast cell tumour in a dog          下载免费PDF全文

CC Shekell  MJ Thomson  RI Miller  JT Mackie 《Australian veterinary journal》2018,96(5):184-187

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The effect of breed,sex, and oral meloxicam administration on pain biomarkers following hot-iron branding in Hereford and Angus calves     

Miriam S Martin  Michael D Kleinhenz  Lily N Edwards-Callaway  Terry E Engle  Octavio Guimaraes  David W Schafer  Shawnee R Montgomery  Andrew K Curtis  Mikaela M Weeder  Devin R Jacobs  Johann F Coetzee 《Journal of animal science》2022,100(3)

Hot-iron branding uses thermal injury to permanently identify cattle causing painful tissue damage. The primary objective was to examine the physiological and behavioral effects of oral meloxicam (MEL), compared to a control, administered at the time of hot-iron branding in Angus and Hereford steers and heifers. The secondary objectives were to investigate breed and sex effects on pain biomarkers. A total of 70 yearlings, consisting of 35 heifers and 35 steers (Angus, Hereford, or Angus × Hereford), were enrolled in the study. Animals were blocked by sex, randomized across weight, and assigned to receive MEL (1 mg/kg) or a placebo (CON). Biomarkers were assessed for 48 h after branding and included infrared thermography (IRT), mechanical nociceptive threshold (MNT), accelerometry and a visual analog scale (VAS), and serum cortisol and prostaglandin E₂ metabolites (PGEM). Wound healing was assessed for 12 wk. Hair samples to quantify cortisol levels were taken prior to and 30 d post-branding. Responses were analyzed using repeated measures with calf nested in treatment as a random effect, and treatment, time, treatment by time interaction, breed, and sex as fixed effects. There was a treatment by time interaction for PGEM (P < 0.01) with MEL having lower values than CON at 6, 24, and 48 h (MEL: 18.34 ± 3.52, 19.61 ± 3.48, and 22.24 ± 3.48 pg/mL, respectively; CON: 32.57 ± 3.58, 37.00 ± 3.52, and 33.07 ± 3.48 pg/mL; P < 0.01). MEL showed less of a difference in maximum IRT values between the branded (2.27 ± 0.29 °C) and control site (3.15 ± 0.29 °C; P < 0.01). MEL took fewer lying bouts at 0–12 h (4.91 bouts ± 0.56) compared with CON (6.87 bouts ± 0.55; P < 0.01). Compared with Hereford calves, Angus calves exhibited greater serum but lower hair cortisol, greater PGEM, more lying bouts, and less healed wound scores at 3, 4, and 5 wk. Compared with heifers, steers exhibited lower PGEM, lower branding site and ocular IRT, higher MNT, and lower plasma meloxicam levels. Steers spent more time lying, took more lying bouts and had greater VAS pain, and more healed wound scores at 5 wk than heifers. Meloxicam administration at branding reduced branding and control site temperature differences and reduced lying bouts for the first 12 h. Breed and sex effects were observed across many biomarkers. Changes from baseline values for IRT, MNT, lying time, step count, VAS pain, and wound scoring all support that branding cattle is painful.  相似文献   

Accelerating invasion rate in a highly invaded estuary   总被引：4，自引：0，他引：4  

AN Cohen  JT Carlton 《Science (New York, N.Y.)》1998,279(5350):555-558

Biological invasions are a major global environmental and economic problem. Analysis of the San Francisco Bay and Delta ecosystem revealed a large number of exotic species that dominate many habitats in terms of number of species, number of individuals and biomass, and a high and accelerating rate of invasion. These factors suggest that this may be the most invaded estuary in the world. Possible causes include a large number and variety of transport vectors, a depauperate native biota, and extensive natural and anthropogenic disturbance.  相似文献   

Beyond Impact Factors: Research that Contributes to the Growth and Development of Aquaculture          下载免费PDF全文

Carole R. Engle 《Journal of the World Aquaculture Society》2016,47(5):603-604

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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

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Growth, Yield, Dressout, and Net Returns of Bighead Carp Hypophthalmichthys nobilis Stocked at Three Densities in Fertilized Earthen Ponds     

Carole R.  Engle David  Brown 《Journal of the World Aquaculture Society》1999,30(3):371-379

Abstract.— Bighead carp Hypophthalmichthys nobilis have been raised in the United States for two decades and sold through the livehaul market, but their profitability in monoculture has not been evaluated. Three studies were conducted in 0.10-ha earthen ponds to evaluate the effect of bighead carp stocking density on growth, yield, dressout yield. and net returns. Initially, bighead carp (average weight of 0.36 kg) were stocked at rates of 500, 320, or 130 fish/ha with three replicates of each treatment. Stocking rates for 2-yr-old fish (average weight of 2.45 kg) were reduced to 320, 220, or 130 fish/ha in the second year. Net yields of bighead carp stocked at 500 fish/ha (963 kg/ha) were significantly higher ( P < 0.05) than net yields at the 320 fishha density (771 kg/ha), and these were significantly greater ( P < 0.05) than net yields at 130 fish/ha (369 kg/ha) in the first growing season. Net yields in the second growing season were not significantly different ( P > 0.05) among densities. There were no significant differences ( P > 0.05) among treatments in yearly growth which ranged from 11–17 g/d in the first and from 6–13 g/d in the second growing season. Dressout percentages for whole-dressed, steak, shank fillet, and shank fillets with white meat only did not differ with stocking density ( P > 0.05). Enterprise and partial budget analysis indicated that monoculture of bighead carp in fertilized ponds is profitable only in the short run at average livehaul market prices, because revenues exceeded variable but not fixed costs. The negative net returns, when all costs were accounted for, indicated that it is not profitable to construct ponds solely for monoculture of bighead carp.  相似文献   

First case of psittacine proventricular dilatation syndrome (macaw wasting disease) in Australia     

ND SULLIVAN  JT MACKIE  RI MILLER  A. GILES 《Australian veterinary journal》1997,75(9):674-674

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Chlamydiosis in workers at a duck farm and processing plant   总被引：4，自引：0，他引：4  

DG HINTON  A. SHIPLEY†  JW GALVIN‡  JT HARKIN‡  RA BRUNTON† 《Australian veterinary journal》1993,70(5):174-176

SUMMARY An outbreak of chlamydiosis was Investigated in workers at a duck farm and processing plant during winter 1989. Chlamydia psittaci was isolated from ducks, but there was little evidence of clinical chlamydiosis in the ducks. Serological tests showed that 76% of workers had been exposed to Infection, 12% recently, 16% had not been exposed and 8% had inconclusive test results. There was a strong association (P < 0.05) between years of employment and exposure to Infection. Infection appeared to be contracted during the first year of employment. Measures were Implemented to reduce shed contamination and control rodents and wild birds. At the same time, ducks were medicated, the processing plant was modified, work practices were altered and workers were advised about chlamydiosis to reduce the risk of human infection.  相似文献