摘要:

AbstractThis paper describes reproducing pancreas disease in Atlantic salmon,Salmo salarL., parr with intraperitoneal inoculation of homogenized kidney and spleen taken From affected fish. Pancreatic necrosis and cardiomyopathy changes were induced consistently in all experimental groups. A time‐course study demonstrated that pancreatic changes occurred as early as 4 days post inoculation and a repair process was evident in some fish on day 7 post inoculation. Heart lesions were first observed on day 5 post inoculation and increased in prevalence and severity as the experiment continued. Both types of lesion were serially passaged. and passively transmitted to fish cohabited with inoculated parr. The incidence of these changes was unaffected by passage of the infective homogenate through a 0.2μfilter. The homogenate was inactivated after treatment with chloroform. Passive immunization with serum from recovered farmed salmon protected parr against challenge. It is suggested that pancreas disease is caused by a virus with a lipid envelo

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00881.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractData on two year classes of Atlantic salmon,Salmo salarL., reared for 2 years in sea water, were analysed. Records were obtained on 1271 offspring of 58 sires and 171 dams mated hierarchically. Medium‐high sire heritabilities (0.30‐0.38) were found for ungutted and gutted body weights, body length, body circumference and condition factor (whole‐body traits). Corresponding estimates for height and width of cutlet and average thickness of the abdominal wall ranged from 0.23 to 0.27. The latter measurements were made on a transversal section anterior to the dorsal fin. Heritability estimates derived from the dam component of variance corresponded in general to the sire estimates, indicating the absence of non‐additive genetic and environmental effects common to full sibs. Estimated phenotypic and genetic correlations among the traits were all positive. With regard to the likely breeding goal of a commercial selection programme, the genetic correlations of ungutted and gutted body weights with condition factor (rG=0.36‐0.37) were judged unfavourable. The results revealed substantial impact of sex and sexual maturation status on growth. The need is stressed for proper adjustment for these effects when assessing growth or growth‐r

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00882.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study was carried out to find out the effects of anaesthetics, 2‐phenoxyethanol. quinaldine sulphate. MS‐222 and metomidate. at various dosages, on the oxygen consumption rates of two size groups of platyfish.Xiphophorus maculatus(Günther) at three temperatures. The results show that the oxygen consumption by the platyfish of both size groups was temperature dependent, being higher at higher temperature, but not size dependent. The effects of anaesthetics on the oxygen consumption rates of platyfish were dosage dependent and temperature dependent, especially for 2‐phenoxyethanol, the effect always being significantly greater at lower temperature. Small and large fish did not show much difference in their responses to anaesthetic treatments. However, with 2‐phenoxyethanol, the effect on the large platyfish was always better than on the small ones at 20‐25°C. At 220‐440 ppm and at 20°C, 2‐phenoxyethanol was more effective than the other anaesthetics in suppressing oxygen consumption

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00883.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTotal ammonia efflux rates of the African catfish,Clarias gariepinus(Burchell), were measured under different combinations of photoperiod (LD 24:0. LD 0:24, LD 12:12) and feeding regime (50% protein diet, 41% protein diet and zero food). A time‐dependent variation of ammonia efflux following feeding was observed, with postprandial excretion rates in the first 12 h being greater than those in the following 12 h. Ammonia efflux rates were directly related to the level of protein in the diet under all photoperiod conditions. Photoperiod had no effect on ammonia efflux rate, except in the LD 24:0‐high protein diet group, which may indicate a stress respo

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00884.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThree size groups ofColossoma macropomumwere submitted to a 4‐week growth trial. Five nearly isocaloric (18.8‐21.0 kJ g−1) diets with protein concentrations ranging between 17 and 64% were administrated at a fixed, near satiation level. Maximum growth was 6.6, 3.6 and 1.9 g protein kg−0.8day−1for 5, 50 and 125 g fish, respectively. The protein requirement to achieve maximum growth decreased from 28.9 g protein kg−0.8day−1for 5 g fish to 11.7 g kg−0.8day−1for 125 g fish. Possibly because of its high growth rate.C. macropomumneeds a slightly higher dietary P/E ration (25.4‐27.9 mg protein kJ−1) to obtain maximal growth than most other fishes. The relation between protein ration and protein gain was studied by a quadratic regression model. In fish receiving protein rations equal or below rations resulting in maximal growth, protein ration and protein gain were almost linearly related. The model showed that the portion of the dietary protein which is digested decreases with increasing protein ration. Body protein content increased and body lipid content decreased with feed protein level. Fish fed a 17% protein diet deposited

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00885.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAlfalfa meal as a source of organic fertilizer was used in a series of pond, enclosure and laboratory experiments to determine its effect on bacteria, algae and water quality. Bacteria and flagellate algae were increased, whereas nonflagellate algae were not significantly affected by organic loadings. Bacterial and algal turnover rates we re 1.9‐2.7 times daily and 0.18‐0.22 times daily at 20‐25oC, respectively. Oxygen consumption rates were enhanced by increasing organic input or temperature. Dissolved oxygen in ponds with organic fertilizer was significantly lower than that in ponds without organic input. Because of low N and P content and high oxygen consumption, organic fertilizer alone is unlikely to provide adequate nutrients for algae and sufficient oxygen for fish. To stimulate the growth of food organisms for fish in aquaculture ponds, a combined use of inorganic and organic fertilizer is recommended, but the amount of organic fertilizer should be determined with care to avoid water quality deterioration. The amount of 10mg alfalfa 1−1wk−1is considered the upper safety limit for organic fertilization. The nitrogen and phosphorus ratio should be kept weekly at 20:1 by weight to promote the development of food organisms

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00886.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY