Proceedings of the National Seminar-Workshop on Fish Nutrition and Feeds. Tigbauan, Iloilo, Philippines, 1 -2 June 1994

The Seminar-Workshop was conducted to provide a forum for discussion of reviews and original contributions on recent advances in fish nutrition research and on feeds and feeding management. It also identified priority areas for future research on fish feed development, focussing on technologies appropriate for the Philippines and other developing countries. The publication contains papers of invited lecturers and some original papers presented orally and in poster form at the Seminar-Workshop.

Recent Submissions

  • Conference paper

    Screening of inexpensive and indigeneous ingredients for use in practical feed for juvile sea bass (Lates calcarifer Bloch) 

    RM Coloso, JR Hipolito & D Murillo - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    An eight-week feeding experiment with juvenile sea bass (about 15 g) was conducted in 500-1 fiberglass tanks to screen the most cost-effective practical diet for use in ponds and floating cages. Eleven formulations and one control feed were tested. Protein sources used were locally available ingredients such as fish meal, shrimp head meal, scrap squid meal, cow's blood meal, poultry feather meal, leaf meals, soybean meal, and mung bean meal. The diets contained a combination of animal and vegetable protein sources such that the essential amino acid composition was close to the requirement or tissue levels. Crude protein and fat levels were about 42% and 8.3%, respectively. Fish were fed ad libitum twice a day at 0800 and 1600 h. Best weight gain (189%) and feed conversion ratio (FCR, 1.7) were observed in fish given a combination of fish meal, shrimp head meal, scrap squid meal, soybean bean meal, and kangkong leaf meal as protein sources. This was followed by those given a combination of fish meal, shrimp head meal, scrap squid meal, soybean meal, and ipil-ipil leaf meal (139% weight gain, FCR of 2.2). Worst growth (22%) and FCR were observed in fish given a combination of fish meal, cow's blood meal, scrap squid meal, soybean meal, and mulberry leaf meal. Control fish given a combination of fish meal, shrimp meal, and soybean meal showed weight gain of 195% and FCR of 1.8. Survival was high (83-100%) in all treatments. The two diets which gave the best growth rates, survival, and FCR in the screening phase can be tried in ponds and floating net cages.
  • Conference paper

    A preliminary study on the effect of hypoxia on carotenoid metabolism in black tiger shrimp Penaeus monodon Fabricius 

    FI Heralde, M Leaño, A Reyes & R Coloso - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    The pigmentation of black tiger shrimp Penaeus monodon is due to astaxanthin, astaxanthin monoester, and astaxanthin diester. These carotenoids are biosynthesized from beta-carotene or zeaxanthin. Biosynthesis is postulated to be mediated by the enzymes C3 and C4 monooxygenase and caroten-4-ol dehydrogenase. Blue-shrimp syndrome, characterized by low total astaxanthin levels in shrimp epidermis, is associated with nutritional deficiency for carotenoids but other factors such as high organic matter, hypoxia, high density, and high pH may also be involved. In this study, the effect of hypoxia on carotenoid metabolism in P. monodon was investigated with respect to retention and transformation of carotenoids and the activity of the enzymes C3 and C4 monooxygenase and caroten-4-ol dehydrogenase.Two tanks were prepared each containing 25 pieces of shrimp fed a control diet (not containing any carotenoid) for two weeks. Shrimps in one tank (Treatment 1) were given beta-carotene supplemented diet (3.8 ppm) in the next two weeks while those in the other (treatment 2) were fed the control diet. Two days after introduction of the test diets, both treatments were subjected to hypoxia challenge (dissolved oxygen, 2.5-2.7 mg/L) and the carotenoid content and profile of feces monitored for succeeding days. Assay of enzyme activity was performed five days after hypoxia challenge. Results showed a ten-fold increase in fecal total carotenoid content of shrimps in treatment 2 (122.2 ppm) compared with that in treatment 1 (12.4 ppm) on hypoxia challenge and restores to basal level (3.9-4.1 ppm) after three days. The carotenoids found in the feces of shrimps in treatment 2 were astaxanthin, astaxanthin monoester, astaxanthin diesters, and an unidentified carotenoid which was also found in the muscle of stressed shrimp. Using beta-carotene as substrate, conversion to astaxanthin was not observed in the hepatopancreas homogenates of shrimps in both treatments. Instead, a slow conversion of astaxanthin to betacarotene (i.e., a reverse reaction) was noted in treatment 2 exhibiting twice the activity in treatment 1. Radiolabelling studies using 14C-labelled astaxanthin as substrate confirmed the existence of this enzyme-mediated reductive pathway from astaxanthin which occurs at a very slow rate. This study demonstrated the carotenoid-depleting effect of hypoxia on shrimp, both through enhanced fecal release and moderately elevated reductive pathway from astaxanthin. This effect suggests a possible mechanism by which blue-shrimp syndrome may develop.
  • Conference paper

    In vitro digestibility of locally available feedstuffs for white shrimp Penaeus indicus 

    P Eusebio, RM Coloso & B Gumban - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    An in vitro method of determining protein digestibility was modified for application in white shrimps. The protein digestibility of 21 locally available feedstuffs were determined. Vitamin-free casein was used as reference protein. To verify in vitro results, a feeding experiment was conducted using 300 shrimps with average initial weight of 0.075 g. The shrimps were fed isonitrogenous and isocaloric diets containing test ingredients with high (27.6% -33.7%) and low (4.0%-10.5%) digestibility for 61 days. Seawater temperature ranged from 26 to 29°C and salinity from 30 to 33 ppt. Defatted soybean meal (27.2% digestibility) was used as control. Growth and survival were determined. Animal proteins (40.9%-90.9%) were more digestible than plant proteins (0.0%-33.7%), although digestibility of papaya leaf meal (33.7%) was comparable with those of shrimp head meal (40.9%) and Peruvian fish meal (40.7%). Green mungbean meal was most digestible (27.6%) among the legumes. Protein digestibility of defatted soybean meal (27.2%) was significantly higher than that of unprocessed soybean meal (9.4%). Black cowpea meal and ricebean meal were not digestible. Results also showed that white shrimps given a diet containing cassava leaves performed best with weight gain, specific growth rate, and survival (706.4%, 3.44 and 49%) comparable with white cowpea meal (701.3%, 3.35 and 40%) and defatted soybean meal (726.8%,3.50 and 33%), followed by papaya leaf meal (505%, 3.02 and 38%). Shrimps fed a diet containing green mungbean meal showed the poorest response (344.2%, 2.46 and 18%). These results indicate that in vitro protein digestibility is not correlated with growth and survival. The amino acid pattern, anti-nutritional factors, and palatibility of the diets are other important factors that may influence the growth of P. indicus.
  • Conference paper

    Development of artificial diets for milkfish (Chanos chanos) larvae 

    I Borlongan, C Marte & J Nocillado - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    This study aims to develop nutritionally balanced and cost-effective artificial diets for milkfish larvae. Two larval diets (Feed A and Feed B) were formulated and prepared to contain 45% protein and 10% lipid. Several larval diet preparation techniques were tried and diets produced were assessed in terms of feed particle size and bouyancy, water stability, and feed acceptability. The larval diet preparation that gave the best particle size and bouyancy as well as good water stability was the one prepared as microbound diet (using K-carrageenan as a binder) and flaked using a drum drier.A series of feeding experiments were then conducted to determine growth and survival of milkfish larvae reared on various feeding schemes involving the use of these artificial diets. The artificial diets were fed either alone or in combination with live foods. Larvae in control treatments were reared on live foods such as Brachionus and Artemia. Larvae were observed to ingest the diets indicating that the feeds had suitable physical characteristics and were attractive to the larvae. Over-all results of the feeding trials showed that the artificial diets could be fed to milkfish larvae in combination with the rotifer Brachionus starting Day 8 or could be fed alone to milkfish larvae starting Day 15 onward. These promising results would reduce dependence of milkfish larvae on live foods and would have significant economic benefits in the form of simplified milkfish hatchery procedures.
  • Conference paper

    Nutritional requirements of commercially important shrimps in the tropics 

    M Boonyaratpalin - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    The culture of tropical shrimps has gained greater economic importance particularly among Southeast Asian countries. As shrimp fanning moves from low-input, low-technology operation to the intensive and even highly intensive scales of operation, farmers are increasingly seeking ways to achieve more efficient means of production. Feed takes up the major portion of the cost of production. It also has a significant effect on the health of cultured species. Therefore, nutritional adequacy and cost-effectiveness of feeds are critical to the growth of the aquaculture industry. This paper discusses the nutritional requirements for growth as well as for health of some commercially important shrimp species in the tropics with emphasis on P. monodon.
  • Conference paper

    Reproductive performance of captive Penaeus monodon fed various sources of carotenoids 

    ET Quinitio, FD Parado-Estepa, OM Millamena & H Biona - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Three groups of pond-reared Penaeus monodon broodstock were fed formulated diet in combination with carotenoid-containing natural food: mussel + shrimp broodstock pellet (MBP), crab + BP (CBP), and Artemia + BP (ABP). After four months, maturation and spawning rates did not differ significantly among treatments. After eyestalk ablation, MBP-fed shrimps Initially spawned 20 days; 34 days for CBP-fed; 50 days for ABP-fed shrimps. The number of eggs per g body weight of spawner (1616-2359 eggs /g BW) did not differ significantly among all groups. Only nauplii from MBP-fed broodstock reached postlarval stage. Rematuration was observed only in MBP- and CBP fed shrimps. Sperm count was highest in MBP- and lowest in ABP-fed shrimps at the final phase of the test.
  • Conference paper

    Weaning of the Asian catfish, Clarias macrocephalus Gunther, larvae to formulated dry diet 

    AC Fermin & MEC Bolivar - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Two feeding trials lasting 10 days each were conducted to determine the weaning time in the Asian catfish, Clarias macrocephalus, larvae to dry diet feeding. Three-day-old catfish larvae were fed newly-hatched Artemia nauplii for 2,4, and 6 days after which ad libitum feeding with a commercial feed (trial 1) or a formulated diet (trial 2) was started. Fish fed exclusively dry diet (0-day Artemia feeding) or those fed only Artemia for 10 days served as the controls. In trial 1, fish fed Artemia at different durations had significantly higher growth and survival than those reared exclusively on dry diet. In trial 2, percent survival was not significantly different among fish with or without Artemia pre-feeding. However, fish had significantly higher final body weight and SGR when reared initially on Artemia prior to dry diet than those fed exclusively dry diet. Based on the results, catfish larvae can be successfully weaned to dry diet after feeding Artemia for a maximum period of four days (ave. BW=12.25 mg).
  • Conference paper

    Use of the golden apple snail, cassava, and maize as feeds for the tiger shrimp Penaeus monodon in ponds 

    I Bombeo-Tuburan, S Fukumoto & E Rodriguez - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Penaeus monodon stocked in ponds at 8,000/ha were fed four types of farm-made feeds starting on day 16 of a 4-month culture period. The feeds were golden apple snail alone or in combination with cooked cassava or maize, or maize alone. Mixed feeds resulted in significantly higher production and better size-frequency distribution of shrimp. Survival (88-99%) was not significantly different among the treatments. Maize alone and snails alone were inadequate. Presumably, the high amount of carbohydrate in cassava (92%) or maize (87%) provided the needed energy, and the high protein content of golden snail (54%) was available for growth. The fatty acid profile of the golden snail shows that it is a good source of 18:2n-6, 18:3n-3, and 20:5n-3 which are essential fatty acids for P. monodon. Golden snails, with an essential amino acid index (EAAI) of 0.91, are a suitable alternative source of protein for tiger shrimp. Feeding shrimps with golden snails and cassava yielded the highest net income (P 49,332/ha-crop) and return on investment (ROI = 213%) better than feeding with maize alone (net income = P 23,626/ha-crop; ROI = 125%). If shrimp farmers tap golden snails as direct feed or as feed ingredient, the problem of snail infestation in rice fields may be reduced.
  • Conference paper

    Evaluation of local ingredients (fish, shrimps, snail, copra, leaf meals and rice bran) for feeding Nile tilapia (Oreochromis niloticus) fingerlings 

    P Nieves & R Barro - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Seven experimental diets using locally available ingredients (various combinations of fish, shrimp, snail, copra, leaf meals and rice bran) were tested in Nile tilapia kept in 2-1 aquaria measuring 30 cm x 75 cm x 30 cm for 120 days. Treatments were randomly assigned to three aquaria, each stocked with 10 fish. Fish were fed 7 days a week at a rate of 5 percent of the fish body weight and their daily feed allowance was adjusted at bi-weekly interval on the basis of weight gain. Statistically higher growth took place in those fish receiving feed II (23.2g) (15% shrimp meal, 60% rice bran, 14% cassava leaf meal) followed by feed VII (19.3g) (commercial chick starter mash). Lowest growth was found in fish given feed I (9.8 g) (15% fish meal, 60% rice bran, 10% copra meal and 14% cassava leaf meal). Analysis of variance of the mean weight gain in all treatments yielded significant differences (P < 0.05).
  • Conference paper

    Feed formulation and evaluation for semi-intensive culture of fishes and shrimps in the tropics 

    AGJ Tacon - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Semi-intensive farming systems account for about 70% of fish and crustacean aquaculture production in the tropics, employing semi-intensive feeding methods ranging from the use of low-cost pond fertilization techniques to high-cost complete diet feeding strategies. The paper reviews the major feeding methods employed within semi-intensive farming systems, and emphasizes the importance of natural food organisms in the nutritional budget of pond-raised fish and shrimp. It also discusses the need of the aquaculture sector to reduce farm production costs through the use of improved feed formulation and on-farm feeds and new methodological approaches towards fish and crustacean nutrition research within semiintensive pond farming systems.
  • Conference paper

    Kappaphycus and Gracilariopsis meal as binders for diets of tiger shrimp 

    V Peñaflorida & N Golez - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Two locally grown seaweeds, Kappaphycus alvarezii and Gracilaria heteroclada, were tested as binders in diets for shrimp juveniles to minimize the use of wheat flour, a common binder. The seaweeds were washed, dried, ground, and made into paste. Seaweed meals were added to an isonitrogenous diet containing 5% flour at 5, 10 and 15%. The control diet contained 15% flour (no seaweed meal). The diets were fed to juvenile Penaeus monodon for 56 days to assess the acceptability of the seaweed meals in terms of shrimp growth, survival and feed conversion ratio (FCR). Seven dietary treatments, each with three replicates, were arranged in a completely randomized design. Treatment means were compared by analysis of variance and Duncan's multiple range test.Growth of shrimp fed diets with 5% and 10% G. heteroclada, and 10% K. alvarezii did not differ significantly but was higher than the rest of the treatments. Only those fed 10% G. heteroclada had growth similar to those fed the control diet. Diets with 5% and 10% K. alvareziii and 10% G. heteroclada had the best FCR. Shrimp survival decreased as the level of G. heteroclada increased. Survival was not affected by the level of K. alvarezii in the diet.Water stability of the diets was assessed in 4 h. High water stability was observed in the diet with 10% G. heteroclada (91%), 5% G. heteroclada (90%) and the control (90%). The rest of the diets were 87-89% stable. Thus, 10% G. heteroclada or 10% K. alvarezii could be used to supplement 5% flour as binders in shrimp diets with no adverse effect on growth and survival.
  • Conference paper

    Feed quality problems and management strategies 

    PS Cruz - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Feed is the single most important input in increasing aquaculture production and profits. Success or failure in augmenting yield with feeding depends, to a large extent, on the quality of the diet. Feed quality, generally perceived as the responsibility of the feed manufacturer, is affected by factors outside of the plant such as handling, storage, and use. Thus, the maintenance of feed quality becomes partly the responsibility of the farmer. Every fish farmer must be familiar with the nature and occurrence of major feed quality problems and able to prevent and control them. This paper is based on a farmer's viewpoint. Valuable insights are provided for the feed manufacturer.
  • Conference paper

    Growth and production of milkfish (Chanos chanos) in brackishwater ponds: effects of dietary protein and feeding levels 

    N Sumagaysay & I Borlongan - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    The most economical combination of dietary protein and feeding levels for milkfish culture in brackishwater ponds was determined. Milkfish juveniles (average weight, 5 g) were stocked at 7000/ha and fed two diets containing 24% or 31% dietary protein at 2% or 4% of body weight.There was no interaction between feeding level and dietary protein on growth, feed efficiency, and energy assimilation of milkfish. This indicates that the response of milkfish to change in protein levels is not influenced by ration size. Regardless of protein levels, the final weight, weight gain, specific growth rate, and production of milkfish were significantly higher (P < 0.05) when fed at 4% body weight than at 2%. As culture progresses, differences in weights of fish fed varying protein levels were still insignificant. This could be attributed to the balanced amino acid profile of both diets. But, fish weights vary significantly among milkfish fed at different levels. The higher growth at 4% feeding level could be due to the higher amount of amino acids supplied to the fish for protein synthesis. These results suggest that growth will depend on the amount of amino acids supplied when the amino acid profile of the diet is balanced. Higher energy assimilated by milkfish at higher feeding rate demonstrated that energy supply also influences growth. Partial budgeting analysis revealed that bigger profits can be earned by using an amino acid balanced diet with 24% protein at a feeding rate of 4% of body weight. The greater amount of feed given at higher feeding rate can be compensated by faster growth and higher production.
  • Conference paper

    L-ascorbyl-2-phosphate Mg as vitamin C source for juvenile Penaeus monodon 

    M Catacutan & C Lavilla-Pitogo - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Phosphated ascorbic acid (magnesium L-ascorbyl-2-phosphate or MAP) is a stable form of vitamin C. The suitability and growth requirement level of this derivative in practical diet was determined for juvenile Penaeus monodon. The stability and shelf-life of this derivative was compared with that of crystalline ascorbic acid in prepared shrimp diets. Leaching test was conducted at time intervals of 0 to 6 hours while storage test was conducted for 2 weeks to 3 months.In Experiment I, shrimps (183-254 mg) were given MAP at 0 to 1,500 mg/kg diet for 92 days. Shrimps given the diet without MAP supplement had the lowest growth, survival and feed conversion efficiency, but these were not significantly different from those of shrimps fed diets containing different MAP levels. The shrimps were infected with monodon baculovirus at the start of the experiment. At termination, the histological structure of the hepatopancreas showed improvement in those fed diets containing MAP at 100 mg/kg diet or higher.In Experiment II, shrimps (126-135 mg) were fed with diets containing MAP at 0-8,000 mg/kg diet. Seaweed was removed from the diet composition. After 81 days, shrimps given diet without MAP had significantly lower survival rate and feed conversion efficiency than the shrimps fed diets with MAP. Growth was lowest in shrimps without MAP but was not significantly different from that of shrimps given MAP. After feeding for 81 days on diets with different MAP levels, the shrimps were wounded and further maintained with their respective dietary treatments to observe the effects of MAP in wound healing. Complete healing of wounds were observed after two weeks among shrimps given with MAP at 100 and 200 mg/kg diet. In both experiments, shrimps without dietary MAP were weak and showed symptoms of vitamin C deficiency. Higher levels of MAP did not result in very high mortalities in shrimps. This study showed that MAP was utilized by P. monodon as a vitamin C source and the adequate level would be about 100 to 200 mg/kg of diet or 50 to 100 mg as ascorbic acid per kg diet.
  • Conference paper

    The effect of different levels of vitamins premix in the diet of African catfish (Clarias gariepinus) fingerlings 

    P Monje, MP Dizon & CC Divina - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    The present study was conducted to determine the growth and survival of African catfish (Clarias gariepinus) fingerlings fed diets with various levels of vitamin premix. The fingerlings (mean weight, 1.55 to 2.12 g) were stocked in circular concrete tanks measuring 1.5 m x 17 cm at a density of 50 fish/tank. Fish were fed 42% protein diets containing of 0, 1,2 and 3% vitamin premix (commercially blended). The fingerlings were fed at a rate of 10 % of the total body weight. Feeding was done three times daily at 0800, 1200, and 1600h. Feeding rates were adjusted based on the average weight of the fish every after sampling period. The fish were given the experimental diets for a period of 8 weeks. Results showed no significant differences in the weight gain and survival rate of the catfish. Water quality parameters such as dissolved oxygen, pH and temperature were not affected by the addition of vitamin premix at the level of up to 3 percent in the diet of African catfish fingerlings.
  • Conference paper

    Effects of dietary carbohydrate, lipid and energy on the growth, feed efficiency, and tissue composition of bighead carp (Aristichthys nobilis) fry 

    MT Trono-Legiralde - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    The utilization of dietary carbohydrate and lipid as energy sources for bighead carp (Aristichthys nobilis) fry and various protein:energy ratios were investigated in a 2x3x3 factorial feeding experiment. Semi-purified diets containing two protein levels (28.9 and 37%) and three levels of lipid (4.26, 5.93 and 6.95%) and carbohydrate (42,48 and 53%) to give different total energy levels were fed to bighead carp fry (48.5 ± 3.5 mg) for 8 weeks.Growth of fry fed diets with 37% protein was significantly higher (P < 0.01) than that of fry fed diets with 28.9% protein level. An increase in dietary lipid from 4.26 to 6.95% depressed growth (P < 0.05). There were no significant differences in feed conversion efficiency (FCE) at varying levels of protein and lipid, although their increments resulted in a decrease in FCE. Increase in dietary protein significantly decreased (P < 0.01) protein efficiency ratio (PER) while increase in dietary carbohydrate significantly decreased (P < 0.05) FCE and PER. Bighead carp fry fed diets containing 3131 and 3470 kcal metabolizable energy/kg and P:E ratio of 92 and 107 mg protein/kcal had the best overall performance. However, the 37% protein diet with approximately 4470 kcal metabolizable energy produced maximum growth. Growth was better with diets containing dietary lipid level of 4.26% and carbohydrate level of 42%. Tissue lipid increased significantly (P < 0.01) with an increase of dietary lipid and carbohydrate. However, inclusion of the highest level of both components in test diets decreased tissue lipid. Tissue protein was significantly higher (P < 0.01) in fry fed high protein diets and low levels of lipid and carbohydrate. Tissue protein, moisture and ash were inversely related to tissue lipid. Survival (%) increased (P < 0.01) with the increase of dietary protein and carbohydrate. Increase of dietary lipid did not significantly affect survival rates of bighead carp fry.
  • Conference paper

    Future considerations in fish nutrition research 

    C Lim - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Considerable progress has been made In the field of fish nutrition during the past two decades. Nutritional data for some species such as trout, salmon, channel catfish, and common carp are well established and efficient feeds have been developed. However, nutrition of fish species commercially Important In the Southeast Asian region is still in its infancy and much of the existing Information needs further verification. Basic requirements for some of the 5 major nutrient classes and energy have been determined. However, knowledge of larval and broodstock nutrition is limited. The role of nutrition in immune function and disease resistance should be investigated. Nutritional value and nutrient bioavailability of local feedstuffs as well as methods for improving the nutritional quality of inferior feedstuffs should be given priority. The potential benefits of additives, and harmful effects of toxicants and anti-nutritional factors need to be assessed. The effects of the diet on product quality are becoming increasingly important, but work on feed processing technology in relation to the physical and nutritional quality of feeds is lacking. Emphasis must also be given to the improvement of feed performance and feeding strategies for various life stages under different production systems and management practices in order to reduce production costs and minimize the negative impact of feeds on the environment.
  • Conference paper

    Antioxidant properties of tert-butylhydroquinone and propyl gallate in frozen minced sprats 

    EB Panggat, SW Hanson & M Hole - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Relative effects of the combination of tert-butylhydroquinone (TBHQ) and propyl gallate (PG) with or without a sequestering agent (EDTA or citric acid, C A ) on rancidity development in minced sprats stored at -15 C were determined by following the changes in peroxide values, thiobarbituric acid values, sensory scores, and fatty acid composition of lipid extracts. The combination of 0.02% TBHQ and 0.02% PG was most effective in reducing the rate of oxidative rancidity development in frozen sprats. It allowed an extended induction period of at least 250 days. Lowering the concentration of the additives from 0.02% to 0.01% significantly reduced their antioxidant effectiveness giving rise to larger losses of polyunsaturated fatty acids. Addition of either EDTA or CA to the mixture of 0.02% TBHQ and 0.02% PG did not prevent significant losses of 20:5 and 22:6 fatty acids.
  • Conference paper

    Farming of all-male java tilapia (Oreochromis mossambicus) at two stocking densities in cages in a brackishwater pond 

    SM Aban - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    A study was conducted to determine the growth, survival, and yield of allmale Oreochromis mossambicus in cages at two stocking densities: 50 fish/m2 (Treatment I) and 100 fish/m2 (Treatment II) in a brackishwater pond. The artificial diet contained 70% fine rice bran and 30% Peruvian fish meal. The 25% crude protein diet was fed in pellet form at 5% of fish biomass per day for the first two months and in mashed, moist form at 3% of fish biomass per day for the last month of culture. Results showed that fish in Treatment I gave higher mean weight gain (59.75 g) than in Treatment II (45.10 g). Similarly, higher daily growth rate was observed in Treatment I (0.56g/day) than in Treatment II (0.42 g/day). Feed conversion ratios of 2.42 and 2.85 were obtained for Treatment I and Treatment II, respectively. Fish in treatment I had higher percent survival (87.3%) than those in Treatment II(72.0%). Moreover, higher net income per cage was obtained in Treatment I than in Treatment II. Statistical analysis, however, showed no significant differences between the two treatments.
  • Conference paper

    Farm-made feeds: preparation, management, problems, and recommendations 

    F Piedad-Pascual - 1996 - Aquaculture Department, Southeast Asian Fisheries Development Center
    Making feeds exclusively for certain farming activities is quite common in the tropics particularly in the farming of fishes that feed low in the food chain. Feed preparation will depend on several factors such as availability of feed ingredients, capital, labor, type of feed, size of farm, etc. Management procedures will also depend on factors such as frequency of feeding, capital, labor force, farming system, and availability of electricity in the area. Some problems in the use of farm-made feeds are the limited knowledge of pond dynamics, interaction between supplementary feeds and natural food organisms, quantification of the contribution of natural food to the nutrition of the fish, and quality of feed ingredients. Farm-made feed formulations, processing, and feeding management as well as future research and training approaches with reference to the needs of small-scale fish farmers as recommended by FAO are discussed.

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