Natural Food Organisms Research Articles

Fatty acid and amino acid composition of eggs, muscle and midgut glands of freshwater prawns, Macrobrachium rosenbergii (de Man), raised in fertilized ponds, unfertilized ponds or fed prepared diets

Fatty acid and amino acid profiles were determined in three tissues (eggs, muscle and midgut glands) from freshwater prawns, Macrobrachium rosenbergii (De Man), raised unfed in ponds with no organic fertilization, unfed in ponds with organic fertilization or fed a formulated, pelleted diet. Amino acid profiles of tail muscle and eggs were not treatment-dependent. Comparison of amino acid profiles of the diet with those of tissues of animals fed that diet suggest that dietary levels of arginine, histidine, methionine, and especially lysine may be suboptimal. Fatty acid profiles of the midgut gland, tail muscle, and to a lesser extent, eggs reflected the fatty acid composition of the diet in the fed treatment, the organic fertilizer material in the fertilized treatment and natural food organisms in the unfed treatment. Direct consumption of organic fertilizer particles by the prawns is supported by these data. Selective retention of essential fatty acids appears likely in all three treatments. Comparison of the fatty acid composition of prawn eggs and muscle tissue with that of the pelleted diet indicates that 18: 3(n-3), 20: 5(n-3), and especially 20: 4(n-6) are probably below optimal levels. However, under practical culture conditions, prawn growth may not be significantly reduced because of relatively low dietary requirements and contributions from natural foods in the ponds.

Growth, Survival, and Biochemical Composition of Freshwater Prawns Macrobrachium rosenbergii Fed Natural Food Organisms Under Controlled Conditions

AbstractUnder production conditions freshwater prawns Macrobrachium rosenbergii are supplied nutrients by a combination of prepared diets and natural pond organisms. For maximum production efficiency and profitability it is important that the nutritional contributions of natural foods be identified and quantified. In this study the relative importance of forage organisms previously identified as important natural foods for prawns in ponds were evaluated under controlled conditions. Juvenile prawns (average weight 1.80 ± 0.06 g) were stocked into 18 37.5‐L aquaria at a density of 10 prawns per tank. The six dietary treatments tested were: 1) unfed (negative control); 2) commercially prepared diet (positive control); 3) oligo‐chaetes; 4) chironomids; 5) zooplankton; and 6) a combination of the latter three. Each treatment was evaluated in triplicate aquaria for 7 wk. The growth rate of prawns in the unfed treatment was statistically lower than in fed treatments (P < 0.05). There were no significant differences (P > 0.05) between growth rates and survivals among prawns in the five fed treatments. Selective retention of arachidonic acid (20:4n‐6), eicosapentanoic acid (22: 5n‐3), and docosahexanenoic acid (22:6n‐3) in unfed prawns likely indicates the relative nutritional importance of these fatty acids. Comparisons of whole‐body fatty acid and amino acid concentrations of prawns and food organisms indicate that zooplankton and oligochaetes may have the most appropriate biochemical compositions as prawn food sources.

Feed preparation and feed management strategies within semi-intensive fish farming systems in the tropics

Semi-intensive aquaculture, particularly in the tropics, accounts for nearly 70% of the finfish production of the world. The bulk of this production is based on a handful of species, the most important being the cyprinid species, such as Chinese and Indian major carps, feeding low in the food chain. In the culture practices the endogenous food supply is known to play a major role, and equally the exogenous food supply is very diverse; the latter often ranging from simple mixes of ingredients to pelleted feeds of various forms. The paper reviews the different feeding strategies currently employed within semi-intensive farming systems for warm-water fish species, including on-farm preparation techniques and management practices. Particular emphasis is placed on the important role played by natural food organisms in the overall nutritional budget of pond-raised fish and the need to reduce food and feeding costs through the use of improved pond fertilization, feed formulation, food preparation, and on-farm feed and water management techniques.

The effect of varying dietary protein level on the growth, food conversion, protein utilization and body composition of tropical catfish Mystus nemurus (C. & V.) cultured in static pond water system

Tropical catfish, Mystus nemurus (C. & V.) (25.89 ± 0.7 g) were stocked semi-intensively in 0.03-ha earthen ponds at the rate of 10 000 ha”-1 and fed six iso-energetic practical diets ranging from 27% to 50% protein for 8 weeks. Each diet was fed in three replicate ponds twice daily to satiation. Experimental fish were also reared extensively, in control ponds, without supplementary feed. Fish fed the 42% protein diet had the highest standing crop, weight gain and protein utilization values and the differences from other diets were statistically significant (P > 0.05). Protein efficiency ratio (PER) decreased as dietary protein increased. The experiment indicated that natural food organisms contributed to some degree if not significantly to the catfish production. Weight gain, food conversion ratio (FCR). PER and SGR (specific growth rate) indicated that a 42% protein diet with digestible protein-to-energy ratio (D/E) of 27.57 mg kj_1 produced maximum growth in the static pond system.

Nutritional studies in crustaceans and the problems of applying research findings to practical farming systems

Methodological approaches for undertaking research on the dietary nutrient requirements of farmed crustaceans should ensure that the studies are designed and conducted in such a manner that the ensuing results can be applied under practical farming conditions. Sadly, the majority of studies to date have had little practical applicability, the bulk of nutrient-requirement studies having been conducted under controlled, artificial, laboratory conditions. Despite the fact that the giant tiger prawn (Penaeus monodon Fabricius), the whiteleg shrimp (Penaeus vannamei Boone) and the fleshy prawn (Penaeus chinensis Osbeck) are the three most-cultivated crustacean species in the world (total aqua-culture production of these crustacean species in 1993 totalled 625487 metric tonnes or 66.9% of the total world farmed crustacean production), little or no information exists concerning their dietary nutrient requirements under practical semi-intensive pond-farming conditions (where the bulk of the production is currently realized). To a large extent this has been due to the apparent reluctance of the conventional laboratory-based crustacean nutritionist to also work under field conditions and the difficulty of quantifying the contribution of natural food organ-isms in the overall nutritional budget of pond-raised crustaceans. If meaningful conclusions are to be drawn from nutrient requirement studies and dietary feeding trials, it is essential that the experimental animals be reared under conditions mimicking as far as possible those of the intended farm production unit and environment, including holding facility (indoor or outdoor tank, cage or pond), feed preparation technique (grinding, pelleting, drying; diet texture, form, shape, size, buoyancy and water stability), feeding method (hand, demand or automatic feeding; feeding frequency and feeding rate–fixed or satiation feeding; day or night-time feeding), water quality (temperature, turbidity, salinity, oxygen and mineral concentration; water exchange rate, water circulation pattern and artificial aeration), photoperiod (artificial or natural) and crustacean stocking density. Finally, but not least, it is essential that the growth performance of the experimental animals be at least equal to or greater than that of the target crustacean species under practical farming conditions if realistic conclusions are to be drawn, and it is necessary that dietary nutrient requirements can be ascertained under conditions of maximum attainable growth.

Application of nutrient requirement data under practical conditions: special problems of intensive and semi-intensive fish farming systems

Methodological approaches for undertaking research on the dietary nutrient requirements of farmed fish should ensure that the studies are designed and conducted in such a manner that the ensuing results can be applied under practical farming conditions. Sadly, the majority of studies to date, and in particular those for omnivorous warm water fish species, have had little or no practical applicability; the bulk of nutrient requirement studies having been conducted under controlled artificial laboratory conditions. Despite the fact that silver carp (Hypophthalmichthys molitrix), common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), bighead carp (Hypophthalmichthys nobilis) and milkfish (Chanos chanos) are the top five most cultivated fish species in the world (total aquaculture production of these fish species in 1990 totalled 4.8 million metric tonnes or 57% of the total world farmed finfish production), little or no information exists concerning their dietary nutrient requirements under practical semi-intensive pond farming conditions. To a large extent this has been due to the reluctance of the conventional laboratory-based fish nutritionist to work under applied field conditions and the difficulty of quantifying the contribution of natural food organisms in the overall nutritional budget of pond raised fish. If meaningful conclusions are to be drawn from nutrient requirement studies it is essential that the experimental fish be reared under conditions mimicking as far as possible those of the intended farm production unit and environment, including holding facility (indoor or outdoor tank, cage or pond), feed preparation technique (grinding, pelleting, drying; diet texture, form, shape, size, buoyancy and water stability), feeding method (hand, demand or automatic feeding; feeding frequency and feeding rate - fixed or satiation feeding), water quality (temperature, turbidity, salinity, oxygen and mineral concentration; water exchange rate, water circulation pattern and artificial aeration), photoperiod (artificial or natural) and fish stocking density. Finally, but not least, it is essential that the growth performance of the experimental fish be at least equal to or greater than that of the target fish species under practical farming conditions so that dietary nutrient requirements can be ascertained under conditions of maximum attainable growth.

Effect of a diet lacking in vitamin and mineral supplements on growth and survival of Penaeus monodon juveniles in a modified extensive culture system

Penaeus monodon postlarvae (mean weight 6 mg) were reared in 330 m 2 earthen ponds for 120 days at a stocking density of 7.5 m −2, following a modified extensive culture system where natural food organisms are available. Two diets were tested, one with vitamin and mineral supplements and the other without. The results showed that growth, survival, apparent food conversion ratio (FCR), net production, and net cost of production were not significantly different between the two diets. The difference in cost of production between the diets appeared to be lower in shrimp fed a diet without vitamin and mineral supplements. The favorable cost difference of P8.00 kg −1 shrimp produced would make it more profitable to use a diet that contained no vitamin and mineral supplements in a modified extensive culture system.

Aquaculture feeds and the environment: the asian experience

Asia, the birth place of aquaculture, supplies 85% of global aquaculture production and has had a long tradition in the development and use of different dietary feeding strategies, ranging from the use of fertilizers and simple supplementary feed mixtures to the manufacture of ‘water-stable’ pelleted shrimp feeds. The present paper reviews the different aquaculture feeding strategies used within semi-intensive and intensive farming systems in selected Asian countries, and in particular examines their relative impacts upon the aquatic environment. Emphasis is placed on the environmental compatibility and central role played by small scale polyculture-based integrated farming systems in Asian aquaculture, and the need to carefully balance exogenous supplementary feed inputs with the endogenous supply of natural food organisms within semi-intensive pond farming systems. In the case of intensive pond/cage-based farming systems attention is focused on the need to further improve feed formulation, feed manufacture, and on-farm feed and water management so as to maximize feed intake and feed efficiency, and minimize feed wastage and water pollution. Furthermore, in view of the negative experiences of some countries in the region with deteriorating water quality and disease outbreaks within intensive pond/cage-based farming systems, there is an urgent need to improve farm husbandry methods and reduce the current reliance of the aquaculture sector on chemotherapeutants; including limiting the use of the antibiotics only to qualified personnel by developing appropriate Codes of Practice. In this respect there is also a need to recognize the important role played by nutrition in disease resistance. In addition, the paper reviews the legislative controls concerning aquafeed manufacture in selected Asian countries, and highlights the implications of applying government feed legislative controls (i.e. relating to feed composition, feed manufacture, feed efficiency or water pollution) directly from one environmental setting or country to another, and urges countries to develop their own solutions depending upon the farming system employed (i.e. intensive or semi-intensive; tank, cage or pond; coldwater or warmwater; freshwater or seawater), national government policies and priorities, and the resources available to them. In conclusion the paper stresses the key role which can be played by the resident aquafeed manufacturing sector in helping farmers, not only in the provision of feed inputs, but more importantly concerning the management of the feed on the farm and in the use of appropriate environmentally sound husbandry practices; feed manufacturers usually having the closest contact with farmers and in many countries being the only link in the chain between the farmer and the government legislature.

Semi-intensive reservoir fisheries and their supplemental feed in china

中国水库放养鱼的种类、食性以及可利用的天然饵料生物决定了半精养渔业是水库渔业的主要模式。水库半精养有中、小型水库、水库库汊、网拦、网围、网箱养鱼等多种形式。其产量与肥料、饲料的投入有直接关系。最大限度地利用天然饵料,并辅以补充性人工饲料,可实现高产高效。本文以水库鱼类的营养和饲料利用为基础,论述半精养水库渔业的理论和实用技术,并提出尚须研究的问题,以推进半精养水库渔业的发展。;Reservoir fisheries in China have been subjected to a shift from the natural recruitment fisheries depending totall on natural resources to the artificiaJ farming with varying extent of intensification. However, the species and feeding habits of farm fish for reservoir fisheries, as well as the availability of natural food organisms suggest that semi-intensive fisheries are the backbone of reservoir fisheries in China. Middle- and small-sized reservoir, cove, and net enclosure are the main forms of semiintensive reservoir fisheries in China. Fish yield of these culture systems is directly related to manure and feed input. The high yield and high profitability are realized by the maximal utilization of natural food organisms and supplemental feed. The nutritional basis and practical technology of semi-intensive fisheries have been discussed, and the future research efforts on supplemental feed development in semi-intensive system also mentioned.

Aquaculture feeds and the environment: The asian experience

Asia, the birth place of aquaculture, supplies 85% of global aquaculture production and has had along tradition in the development and use of different dietary feeding strategies, ranging from & use of fertilizers and simple supplementary feed mixtures to the manufacture of ‘water-stable’ pelleted shrimp feeds. The present paper reviews the different aquaculture feeding strategies used within semi-intensive and intensive farming systems in selected Asian countries, and in particular examines their relative impacts upon the aquatic environment. Emphasis is placed on the environmental compatibility and central rote played by small scale polyculture-based integrated farming systems in Asian aquaculture, and the need to carefully balance exogenous supplementary feed inputs with the endogenous supply of natural food organisms within semiintensive pond farming systems. In the case of intensive pond/cage-based farming systems attention is focused on the need to further improve feed formulation, feed manufacture, and on-farm feed and water management so as to maximize feed intake and feed efficiency, and minimize feed wastage and water pollution. Furthermore, in view of the negative experiences of some countries in the region with deteriorating water quality and disease outbreaks within intensive pond/cage-based farming systems, there is an urgent need to improve farm husbandry methods and reduce the current reliance of the aquaculture sector on chemotherapeutants; including limiting the use of the antibiotics only to qualified personnel by developing appropriate Codes of Practice. In this respect there is also a need to recognize the important rote played by nutrition in disease resistance. In addition, the paper reviews the legislative controls concerning aquafeed manufacture in selected Asian countries, and highlights the implications of applying government feed legislative controls (i.e. relating to feed composition, feed manufacture, feed efficiency or water pollution) directly from one environmental setting or country to another, and urges countries to develop their own solutions depending upon the farming system employed (i.e. intensive or semi-intensive; tank, cage or pond; coldwater or warmwater; freshwater or seawater), national government policies and priorities, and the resources available to them. In conclusion the paper stresses the key role which can be played by the resident aquafeed manufacturing sector in helping farmers, not only in the provision of feed inputs, but more importantly concerning the management of the feed on the farm and in the use of appropriate environmentally sound husbandry practices; feed manufacturers usually having the closest contact with farmers and in many countries being the only fink in the chain between the farmer and the government legislature.

Fatty acid compositions of 10 freshwater invertebrates which are natural food organisms of Atlantic salmon parr ( Salmo salar): a comparison with commercial diets

Ten species of freshwater invertebrates that are natural food organisms available to Atlantic salmon parr were collected and their lipid composition determined: stonefly nymphs (Plecoptera), beetle larvae (Coleoptera), Chironomidae (Diptera), water boatmen (Corixidae and Notonecta; Heteroptera), mayfly nymphs ( Ecdyonurus venosus, Caenis, Ephemerella; Ephemeroptera), gammerids (crustaceans), Oligochaeta (anelids). Neutral lipids represented 40–70% and polar lipids 26–55% of total lipids. Triacylglycerol was always more than 35% of total lipids. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were the major components of phospholipids. Monoenoic fatty acids and polyunsaturated acids (PUFA) were the most abundant fatty acids in total lipids. Saturated fatty acids comprised only 20–30% of the total fatty acids. PUFAs were principally present as the n−3 series, especially 18:3 n−3 and 20:5 n−3, 22:6 n−3 was present only in small amounts. Fatty acids of the n−6 series were mostly represented by 18:2 n−6 and 20:4 n−6. The invertebrate organisms analysed contained higher levels of 18:2 n−6, 18:3 n−3, 20:4 n−6 and 20:5 n−3 but considerably less 22:6 n−3 than commercial diets used in smolt production. These results suggest that a dietary fatty acid composition more closely resembling the freshwater invertebrates might be beneficial for growth, development and the prevention of pathologies in salmon parr.

Use of Plant Proteins in Catfish Feeds: Replacement of Soybean Meal with Cottonseed Meal and Replacement of Fish Meal with Soybean Meal and Cottonseed Meal

AbstractPlant protein sources were evaluated in 32% protein grow‐out feeds for channel catfish (initial weight: 180 g/fish) stocked at high densities (24,700 fish/ha) in 0.04 ha earthen ponds. Each of the eight practical‐type feeds was assigned for five replicate ponds. The fish were fed to satiation once daily for 170 d. Specifically, cottonseed meal and cottonseed meal plus supplemental lysine were evaluated as replacements for soybean meal. Soybean meal, a combination of soybean meal and cottonseed meal, or a combination of soybean meal and cottonseed meal plus supplemental lysine were evaluated as a substitute for animal protein sources. Based on weight pin, feed conversion ratio, body composition, percentage visceral fat, and dressed yield, the data indicated that cottonseed meal plus lysine can be used as a total substitute for soybean meal in catfish feeds. However, it is not recommended that more than 30% cottonseed meal be used in catfish feeds until additional data are available on the effects of gossypol on reproduction in catfish. Also, data indicated that plant proteins can be used as a total replacement for animal protein without detrimental effects. Reduced weight gain was observed in fish fed a feed that contained 68% of the established available lysine requirement. However, fish fed feeds estimated to contain only 76 or 82% of the available lysine requirement did not show reduced weight gain. This suggests that lysine may be more highly available from cottonseed meal than previously estimated, or that natural food organisms in the pond contributed nutrients including lysine, or that fish were able to consume enough of the marginally deficient feeds to meet their requirement for lysine. This study was conducted with large catfish fed a 32% protein feed to satiation once daily. If smaller fish, a lower protein fed, or a restricted feeding regimen had been used, the results may have been different.

Production of sunfish ( Lepomis spp.) and channel catfish ( Ictalurus punctatus) in acidified ponds

Sulfuric acid was used to acidify ponds and obtain four different average levels of total alkalinity (1.6, 4.2, 9.6, and 32.8 mg/l as CaCO 3) in fertilized ponds stocked with sunfish ( Lepomis macrochirus and L. microlophus). Each treatment was replicated three times. Concentrations of available carbon dioxide, pH values, phytoplankton abundance, gross primary productivity, and net sunfish production were greater in the highest alkalinity treatment than in the three lower ones ( P<0.05). Sulfuric acid applications also were made at three rates to channel catfish ( Ictalurus punctatus) ponds to provide average alkalinity levels of 2.1, 5.8, and 46.2 mg/l as CaCO 3. Each treatment was used in three ponds, and fish were provided a pelleted ration. Net production of channel catfish did not differ among acid treatments. The different response between the two aquaculture systems resulted because sunfish relied on natural food organisms while channel catfish derived their nutriment primarily from pelleted feed. Therefore, lower natural productivity in acidic waters affected sunfish production but not channel catfish production.

The propagation of juvenile mullet ( Chelon labrosus) in earthen ponds

Survival of 23% (length 31.2 mm) was achieved for fry of Chelon labrosus reared in earthen ponds from Day 20 to Day 58, compared with 31.2% (24.6 mm) for the indoor controls. Pond conditions were: temperature range 20.6–27.5° C, dissolved oxygen range 6.2–8.0 ppm, and water exchange rate 1 l/s. Natural food organisms available in the pond were supplemented with nauplii of Artemia salina and copepods. Comparisons are made with traditional culture practices for Mugilidae, and the significance for developing countries is discussed.

Gastrointestinal overload — A problem with formulated feeds?

Mechanisms regulating gastric emptying are briefly discussed and predictions are made about how differences between the emptying of natural and formulated feeds could affect intestinal digestive and absorptive efficiency. The digestibility coefficients of processed, formulated feeds are 5–10% lower than those of natural food organisms. The results support the hypothesis that high energy, small particles are emptied overrapidly from the stomach, leading to an overloading of the intestinal digestive capacity and a reduction in absorption efficiency.

Evaluation and preparation of an optimal dry feed for the primary nursing of Clarias gariepinus larvae (Pisces: Clariidae)

An optimal dry feed, developed over a 2-year period, for primary nursing of Clarias gariepinus larvae was tested against natural live food organisms in an 11-day feeding trial. Those larvae fed on artificial dry feed elicited a significantly superior ( P < 0.005) growth response compared with those fed on live food. Mortalities throughout the trial were negligible. A ration size (on a dry weight basis) of 25% of the total fish mass per day is recommended; a proportionate amount of the ration should be fed once every 4 h. The physical requirements of larval feeds are discussed. Based on these requirements, a simple process for the manufacture of the feed is described. The feed is suitable for use in commercial hatcheries and is recommended as a standard food source for C. gariepinus larvae during the primary nursing phase.

Some Observations on the Winter Feeding Habits of Brook Trout Fingerlings in Relation to Natural Food Organisms Present

Abstract At the Hunt Creek Experiment Station near Lewiston, Michigan, water was first admitted to a newly-excavated stream channel on October 16, 1940, after adult aquatic insects had apparently disappeared. The first bottom organisms to invade the new habitat, blackfly larvae, were observed 1 week later. It is concluded that these and subsequent invaders were drift-borne from natural areas upstream. On December 20, a square-foot bottom sample contained 187 organisms representing 8 species, with a volume of 0.20 cubic centimeters. On February 4, 1941, a sample contained 21 species and 1,535 organisms, with a volume of 1.575 cubic centimeters. The section was first screened and drained down on January 18, 1941. At that time, 34 eastern brook trout (Salvelinus fontinalis) were removed, of which 22 were retained for stomach analysis. These fish had an average total length of 80.3 millimeters and an average weight of 5.0 grams. A comparison of stomach contents with bottom samples revealed that the percentage...

Observations on the Winter Feeding Habits of Eastern Brook Trout in Relation to Natural Food Organisms Present

Observations on the Winter Feeding Habits of Eastern Brook Trout in Relation to Natural Food Organisms Present