摘要:

AbstractA 12‐week feeding trial was conducted in aquaria with juvenile (8.9 g) blue catfish,Ictalurus furcatus(Lesueur), to examine effects of totally replacing fish meal with a high (65%) percentage of soy bean meal (SBM) in prepared diets. Five isonitrogenous (35% protein) and isocaloric (10.5 kJ digestible energy g−1of diet) diets were formulated. Diet 1 was similar to a high‐quality commercial channel catfish diet, containing 15% fish meal and 42% SBM. Diets 2‐5 contained 0% fish meal and 70% SBM with various amounts (0.0%. 0.3%, 0.6% and 0.9%) of L‐methionine added. After 12 weeks, individual weight, weight gain, survival, specific growth rate, feed conversion ratio, protein efficiency ratio and food intake were not significantly different (P>0.05) among treatments and averaged 36 g, 302%, 100%, 1.6% day−1. 2.4,1.3, and 3.4% body weight, respectively. Whole‐body compositions of fish were not significantly different (P>0.05) among treatments and averaged 75%, 61% and 27% for percentage moisture, protein and fat, respectively. These data suggest that a diet with an all‐plant protein source (SBM) can totally replace fish meal in a diet for blue catfish, without adverse affects on weight gain or body composition, when the dietary protein level is 35% and fish are f

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00917.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe study was conducted to determine the optimum stocking density for rearing tilapia.Oreochromis spilurus(Günther), fingerlings in tanks during winter using warm (21‐26°C) underground sea water (37%o). Seawater‐acclimated fingerlings with mean weight of 2 g were stocked in eighteen 400‐1 fibreglass tanks at 750 and 1000 fish m−3. Fish were fed at the rates of 2.5, 3.0 and 3.5% day−1of the fish biomass.After 83 days, the mean individual daily weight gain was significantly higher (P<0.028) at stocking of 750 fish m−3than at 1000 fish m−3. Feed conversion ratio was significantly higher at stocking of 1000 fish m−3than at 750 fish m−3and at feeding rate of 3.5% day1than at 2.5% day−1. However, because no significant differences were observed on survival rates between the two stocking densities and among feeding rates, it is recommended that the stocking density of 1000 fish m−3and a feeding rate of 2.5% day−1be used for optimum production of tilapia fingerlings in tanks during winter using w

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00918.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe degree of pigmentation in muscle of Atlantic salmon,Salmo salarL., fillets of fish that were fed eight diets fortified with 10, 20, 40, 60, 80.100, 150 and 200 mg astaxanthin kg−1and a non‐supplemented control diet from 3 to 21 months was assessed using different methods. A tristimulus colorimeter (Minolta Chroma Meter) was used to measure the colour composition of the fillets instrumentally. The colour was also determined using the Roche Colour Card for Salmonids. The concentration of astaxanthin in the muscle was measured by chemical analyses. All measurements for colour were done directly on the epaxial muscle anterior to the dorsal fin. The lightness factor (L *). the red/green chromaticity(a*),the yellow/blue chromaticity (b*) and the saturation C* of the colorimetric readings and the Colour Card scores were compared with the chemical analyses.The astaxanthin concentration in the flesh varied from 1 to 10 mg kg−1and the visual appearance of the fillets varied from yellowish‐white to red. The relationship between thea*,b* and C* values and the astaxanthin concentration in the muscle was non‐linear. Non‐linear regression lines were found between thea*value and the astaxanthin concentration in the flesh (r2= 0.974) and theb*value and the astaxanthin concentration in the flesh (r2= 0.984). The instrument was not able to detect differences in astaxanthin concentration at astaxanthin levels above 3‐4 mg kg−1using the presented method directly on the fillet. The instrument might be useful for rejecting groups of salmon with poor pigmentation. A good linear regression was found between the Colour Card score and the mean astaxanthin concentration in the flesh (r2‐ 0.992). The Colour Card provided a better prediction of the astaxanthin concentration at higher astaxanthin levels than the Chroma Meter. None of the methods provided a satisfactory prediction of the astaxanthin concentration in the muscle of individual fish using the

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00919.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractGrowth and feeding of white steenbras,Lithognathus lithognathus(Cuvier). under culture conditions was determined to assess its suitability for mariculture. Ration size ranged from 4.50% to 11.52% and from 1.67% 4.00% dry body weight for small (28 ± 2 g) and large (250 ± 23 g) fish, respectively. Condition factor (K) ranged from 1.19 to 1.35 and from 2.00 to 2.19 for small and large fish, respectively. Specific growth rate (SGR) at 16°C was 0.60% day−1for 28‐g fish, 0.29% day−1for a 74‐g fish, and 0.19% day−1for a 250‐g fish. Gross conversion efficiency (GCE) was inefficient at high feeding levels (21.3%) compared with low feeding levels (32.6%). Proximate body composition in terms of moisture, protein. lipid, ash and energy were not significantly affected by feeding regime or temperature (P>0.05).The experiments indicate that feeding regimes should be maintained at relatively low levels to obtain optimumK, GCEandSGR, and to avoid over‐feeding and food wastage. It was concluded thatL. lithognathuscould be a suitable candidate

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00920.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAtlantic salmon,Salmo salarL., (14 g) were fed a practical fish‐meal‐based diet supplemented with 0. 10, 20. 40, 80 and 160 mg pyridoxine (PN) per kg feed for 20 weeks. Tissue vitamin B6contents were significantly reduced in fish fed the non‐supplemented diet compared with fish fed PN‐supplemented diets. Serum haemolytic complement activity and head kidney lysozyme activity, and the specific antibody response following immunization withVibrio salmonicida.were not influenced by the dietary regimes. Challenge withAeromonas salmonicidashowed that increasing the dietary levels of vitamin B6did not improve the resistance to furunculosis. Growth, mortality and haematology were not affected by supplementing a practical diet with vitamin B6In conclusion, feed levels of vitamin B6higher than the minimum dietary requirement did not enhance immune functions and disease resistance in Atlantic

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00921.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of the time of delivery of a single daily meal was studied in immature rainbow trout,Oncorhynchus mykiss(Walbaum). In a first experiment, fish were fed 1.5 % of their body weight once a day at dawn. 1200 h, dusk or 2400 h and no attempt was made to monitor uneaten food. The best growth performance was observed for fish fed at dawn, while lowest performance was achieved by fish fed at 2400 h. During a second experiment, fish were fed at dawn or 2400 h at 0.9%, 1.2 % or 1.5% of their body weight, and the proportion of uneaten pellets was measured. Fish fed at 2400h showed lower growth performance, and feed intake was 10% lower than that of fish fed at dawn. Protein, lipid and energy retention (nutrient gain/ nutrient intake) was also the lowest in fish fed at 2400 h. These results lead to the conclusion that, in rainbow trout, feeding time has an effect on both feed intake and feed utilization.

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00922.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effect of the dietary incorporation of cassava leaves (Manihot esculentaCranfcz) and peanut vines (Arachys kypogaeaL.) on biomass production, final weight, mortality and feed conversion ratio ofClarias gariepinus(Burchell) was studied in a 10‐week experiment. Two groups of diets were used: one group used cassava chips as the main energetic ingredient and cassava leaves (CL) as the crop residue, the other used corn as the energetic ingredient and peanut vines (PV) as the crop residue. Each group had diets with 0% (control). 10% or 20% crop residue incorporation. Comparison of the two controls (cassava or corn‐based) showed that the cassava‐based diet resulted in a significantly lower biomass and final weight (P<0.01) and higher Teed conversion ratio.FCR(P<0.05). There was no significant difference of biomass yield and final weight for the fish fed diets with 0%, 10%. and 20% CL diets. Fish fed 20% CL appeared to be more sensitive to diseases. Their mortality andFCRwere significantly higher (P<0.01) than those of the control. Incorporation of 10% or 20% PV did not affect any parameter when compared with the control. The results obtained in this experiment show that, forClarias gariepinusunder these conditions, a maximum of 10% cassava leaves can be incorporated in a cassava‐chip diet. For a corn‐based diet, incorporation of 20% peanut vines is

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00923.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractTwo levels (40 or 80 mg kg−1) of avoparcin were tested as a growth promoter in rainbow trout,Oncorhynchus mykiss(Walbaum), fed for 14 weeks. At 80 mg kg‐1the weight gain was higher (P<0.05) than in the unsupplemented control or at the 40 mg kg‐1dose. At either dose, the feed conversion rate and the protein efficiency ratio were more favourable (P<0.05) than in the control. Inclusion of the antibiotic significantly improved (P<0.05) the apparent digestibility of lipids. The lipid content of flesh was significantly increased by inclusion of avoparcin in the diet; moreover, at the high level of inclusion the content of some unsaturated fatty acids (18:3ω3 and 20:5ω3) appeared to be significantly increased. No avoparcin residues were detected in th

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00924.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractHeat shock was applied to fertilized eggs of European catfish,Silurus glanisL., for the induction of triploidy. A heat shock of 40. 5°C lasting 1 min and starting 9 min after gamete activation gave the best results with 88.93% of hatched viable fry (92.41% in control group). Yields of hatched viable triploid fry reached 63.14% or 50.60%, when expressed as percentage of the absolute number of viable fry or number of living eggs in eye‐bud stage, respectively (P<0.0

ISSN:1355-557X    

DOI:10.1111/j.1365-2109.1995.tb00925.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY