ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00028.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractLarvae of two caridean shrimp species,Macrobrachium rosenbergii(De Man) andPalaemon elegansRathke, were fed live and artificial diets.P. eleganslarvae fed exclusively liveArtemia salina(15 nauplii mL−1) developed into first postlarval stage (PL1) within 12 days at a temperature of 25°C and salinity 32.5 g L−1. Their survival and mean total length at this stage were 88.5% and 6.7 mm respectively.M. rosenbergiilarvae fed on 15ArtemiamL−1started to metamorphose into PLl within 24 days at 29–30°C and 12 g L−1. Attempts to completely replace liveArtemiafor rearingP. elegansduring early stages failed, and only a partial replacement was achieved for the larvae of both species.P. eleganslarvae survived (49%) solely on a microgranulated diet (Frippak PL diet) from stage zoea (Z) 4–5 to PL1. Similarly, a microencapsulated diet (Frippak CD3) also sustainedM. rosenbergiilarvae from Z5–6 to PL1 with a 28% survival. Development of the larvae of both species was retarded by 2–3 days and their survivals were lower than those fed on the live diet.The inability of the early larvae of these caridean species to survive on artificial diets is attributed to their undeveloped guts and limited enzymatic capabilities. Trypsin activity in the larvae was determined for all larval stages. It was found that the highest trypsin activity, at stage Z4–5 inP. elegansand at stage Z5–6 inM. rosenbergii, coincides with a rapid increase in the volume of the hepatopancreas and the formation of the filter apparatus. These morphological changes in the gut structure appear to enable the larvae to utilize artificial diets after stage Z5–6. Low larval trypsin activities may be compensated by the easily digestible content of their live prey during early larval stages (Z1–Z4/5) and by longer gastroevacuation time (GET) and almost fully developed

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00029.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe effects of the density and type of food on oxygen consumption and ingestion rate of larvae of the white shrimpPenaeus setiferusfed diatomsChaetoceros ceratosporum, flagellatesTetraselmis chuiiandArtemia franciscananauplii were analysed. Diatoms, flagellates andArtemianauplii were fed at five densities from 10 to 5 × 103cells mL−1, 0 to 4 × 103cells mL−1, and 0.1, 0.5, 1.0, 1.5 and 2 nauplii mL−1, respectively. In three experiments, two of three types of food were maintained constant at concentrations of 30‐40 × 103cells mL−1(diatoms), 2 × 103cells mL−1(flagellates) and 1Artemianauplii mL−1. The oxygen consumption in three experiments increased with larval stage, reaching maximum values in Mill except at lower feed concentrations. A maximum ingestion peak in MI was recorded in larvae fed diatoms, whereas that peak was observed in Mil in larvae fed flagellates. The maximum ingestion rate ofArtemianauplii was observed in Mill. Feed concentrations that produced an optimum metabolic rate as a consequence of equilibrium between ingested food and larval stages were obtained with 20 and 30 × 103cells mL−1ofC. ceratosporum, 2 and 3 × 103cells mL−1ofT. chuii, and 1.0Artemianauplii mL−1. These concentrations would be the most suitable for produc

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00030.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractYear‐1 channel catfish,Ictalurus punctatus(Rafinesque) (average initial weight, 48 g) were fed diets containing 240 g kg−1, 300 g kg−1, or 360 g kg−1dietary protein with 0 or 20 mg kg−1ractopamine to satiation and diets containing 240 g kg−1and 360 g kg−1protein with 0 or 20 mg kg−1ractopamine at a restricted rate (60% of satiation) in aquaria at 29 ± 2°C for 8 weeks. Fish fed ractopamine at the 360 g kg−1protein level gained significantly more weight than controls when fed to satiation but not when the ration was restricted. Fish fed ractopamine at the 240 g kg−1protein level did not gain more weight than the controls at satiation or restricted feeding. Fish fed ractopamine in the diet containing 300 g kg−1protein gained significantly more weight than controls when fed to satiation. Ractopamine caused no significant differences in feed conversion at the 240 g kg−1or 360 g kg−1protein levels with restricted or satiation feeding. Muscle fat decreased when ractopamine was fed at all dietary protein levels and at both feeding rates. Muscle protein increased with ractopamine feeding in all treatments except the high‐protein, satiation treatment. Weight gain response of year‐1 channel catfish to ractopamine is dependent upon nutrient concentration of the diet and ration size; however, the effect of ractopamine on muscle composition of channel catfish is less dependent on nutrient conc

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00031.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThe individual food intake of each fish in each of four groups of Atlantic halibut,Hippoglossus hippoglossus(L.) (mean weight: 422 g) was monitored by direct observation over a period of 21 days. Gross feed conversion efficiency (= growth·feed intake−1), net feed conversion efficiency and maintenance ration were estimated by regression analysis. Specific growth rates were found to be linearly related to weight‐specific consumption at a temperature of 8–9°C: growth = 1.922· feed intake − 0.242. Maintenance ration was 0.126% of body weight day−1. The gross feed conversion efficiency increased asymptotically with increasing feed intakes and growth rates, and was found to approach 1.9 at high growth rates (0.5 on a dry weight basis). One feeding per day seemed to be sufficient for maximum food intake and

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00032.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractAfter feeding Atlantic salmon,Salmo salarL., five graded amounts of wheat starch from 0 to 310 g kg−1, low but increased levels of glycogen in kidney, heart and gills were determined. No variations were found in proximate or glycogen compositions of muscle, whereas the liver composition reflected the diet composition. Whole‐body homogenates varied in dry matter and lipid levels; the variation was according to g lipid eaten per fish. Plasma glucose levels ranged above average levels only when the starch level in the feed was higher than 220 g kg−1. Although feed intake and thereby lipid intake increased as dietary carbohydrate increased in the present experiment, no differences in plasma concentrations of cholesterol and only small changes in triglycerides were determined. The increase in dietary carbohydrate was balanced with protein, and total plasma protein concentrations followed the decrease in feed protein content. Haematocrit, haemoglobin, mean cell volume and mean cell haemoglobin all showed significantly reduced levels as dietary starch increased, indicating a fibre effect from ‘left‐over’ starch in the intestine followed by reduced absorption of divalent ions, s

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00033.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractThis study was undertaken to assess dorsal aorta cannulation as a method to evaluate alterations in diet composition and feeding protocol on pigment retention in salmonid fish. Temporal changes in blood astaxanthin concentrations of dorsal aortacannulated Atlantic salmon,Salmo salarL., were followed in relation to variations in dietary pigment concentration and fish‐feeding husbandry protocol.The fish were held individually in 200‐L fibreglass tanks supplied with running sea water. Each fish was forced to swim at 0.5 body lengths s−1and was fed daily by hand to satiation. The fish had an average growth rate of 1% day−1. Blood astaxanthin concentrations were noted to be highly correlated (r= 0.995) with dietary levels of astaxanthin, but not as well correlated (r= 0.71) with total gut content of this pigment. Marked variations in blood astaxanthin concentration were noted between individual fish at each dietary pigment concentration, but the ranking of the fish was generally unaffected between each dietary pigment level. After cessation of feeding a diet supplemented with 75 mg of astaxanthin kg−1, salmon fed a diet with no pigment showed more‐rapid blood pigment clearance than those that were starved. Likely, feed remaining in the alimentary tract of the starved fish functioned as a reservoir of pigment for the blood until the intestinal tract was empty. Blood pigment levels were not depressed in salmon fed a diet supplemented with 75 mg of astaxanthin kg−1once daily instead o

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00034.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractPlasma and liver vitamin E concentrations in a population of farmed Atlantic salmon,Salmo salar L., fed commercial diets were measured by high‐performance liquid chromatography. In healthy fish fed diets containing 160‐210 mg kg−1all‐racα‐tocopheryl acetate, vitamin E accumulated in the liver and plasma. Over a 20‐month period, beginning 4 months prior to seawater transfer, mean vitamin E concentrations ranged from 51 to 754 μg g−1wet tissue in liver and from 7 to 68 μg mL−1in plasma. In liver, a sharp increase in vitamin E concentrations was recorded between 6 and 10 weeks after transfer. In plasma a similar increase occurred between 4 and 5 months post transfer.Total lipid and polyunsaturated fatty acid concentrations were also measured in these tissues. Liver total lipid concentrations fell during the period of smoltification, but there was no relationship between vitamin E and either total lipid or total polyunsaturated fatty acid concentrations

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00035.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

AbstractEffects of feed ration levels (RLs) and age on sensory characteristics, fillet lipid content (LC) and fatty acid composition (FA) of rainbow trout,Oncorhynchus mykiss(Walbaum), fillet were investigated in a longitudinal feeding experiment. Daily RLs were administered as a percentage of the ration size necessary for expected maximum growth (RL100). Fish on RL50, RL75, RL100 and RL200 were sampled at 1.4, 2.0 and 2.4 years of age. Analyses of LC and FA were carried out on a fillet cross‐section. Sensory analyses were performed by an expert panel using ranking and conventional profiling. RL had no effect on the intensity of fresh smell or any sensory characteristic of taste or consistency of fish on RLs over 75%, irrespective of age; fish on RL50, however, scored significantly lower for fresh taste and firmness. Age had no effect on the intensity of total taste, whereas fresh taste increased and rancidity decreased with increasing age irrespective of RL. LC related strongly to RL and age, and increased up to 2.0 years of age. An increase in LC resulted in a higher level of monounsaturated FA and a lower level of polyunsaturated FA. A restriction to RL75 had no negative effects on sensory characteristics, LC or FA of the fille

ISSN:1353-5773    

DOI:10.1111/j.1365-2095.1995.tb00036.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY