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Topics to be covered


Feed is one of the major costs of aquaculture operations (30-60 ... larval fish culture (e.g., for barramundi where pond culture of larvae has been successful) ... – PowerPoint PPT presentation

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Title: Topics to be covered

Feeds and Feed production (Chapter 9)
  • Topics to be covered
  • Introduction/types of feed
  • Microalgae
  • Zooplankton
  • Feeding strategy
  • Artificial diets (for larvae)
  • Pond fertilization
  • Compound feeds (for grow out)

Feeds and Feed production
  • Feeds
  • Feed is one of the major costs of aquaculture
    operations (30-60)
  • Two types
  • Hatchery feeds (typically live organisms)
  • Nursery and grow out feeds (artificial

Feeds and Feed production
  • Hatchery feeds
  • Microalgae
  • Zooplankton
  • Rotifers
  • Brine shrimp

Feeds and Feed production
  • Microalgae
  • Used as food source for,
  • Larval, juvenile and adult bivalves
  • Early larval stages for crustaceans
  • Early larval stages for some fishes
  • Zooplankton (food source for crustacean and fish
  • Most often used microalgae include,
  • Golden brown flagellates
  • Green flagellates
  • Diatoms (lack flagellum, non-motile)
  • Culture methods
  • Wells-Glancy method blooming of local species of
    phytoplankton in ponds or tanks containing
    filtered local water (to remove zooplankton while
    retaining phytoplankton)
  • Inexpensive, but
  • A bit unreliable (little control over which algae
    are grown uncertain nutritional value)
  • Monospecific cultures with known starter material
    and controlled environmental conditions
  • Better results than blooming methods, but
  • Much more expensive require careful sterile
    procedures to avoid bacterial contamination and
    greater control over environmental conditions to
    enhance growth (Fig. 9.2-9.3)
  • 4-phase growth (Fig. 9.4) harvest during log
    phase is best (optimal nutritional value)
  • Batch, semi continuous, continuous culture systems

Feeds and Feed production
  • Zooplankton Rotifers
  • Culture of crustacean and fish larvae also relies
    on zooplankton feeds
  • Rotifers are widely used (Small-type and
  • Whether the S-type or the L-type are used depends
    on the size of prey that the cultured organism
    can take in
  • Females are larger than males and more common
  • Under favorable conditions, reproduction occurs
    asexually and females predominate
  • Under unfavorable conditions, reproduction occurs
    sexually and males are more numerous therefore,
    presence of males in rotifer cultures is bad news
  • Rotifers are hardy and are easily mass produced
  • Culture methods
  • By inoculating a culture of microalgae with
  • Population rapidly increases
  • As microalgae are depleted, more is added to the
  • A portion of the culture is usually removed on a
    daily basis and replaced with microalgae culture
  • Bakers yeast can also be used with the algae as
    feed for rotifers
  • Constant conditions are required for optimal
    rotifer cultures tank culture is best

Feeds and Feed production
  • Zooplankton Brine shrimp
  • Brine shrimp (Artemia spp.) are found worldwide
  • Under favorable conditions, females produce
    free-swimming larvae (nauplii)
  • Under unfavorable conditions, females produce
    embryos within a cyst, which are dormant
  • Inactive (dry) cysts can be harvested and stored
    for many years
  • When cysts are immersed in saline solution, cysts
    rehydrate, become spherical and embryogenesis
  • Cyst ruptures within 24 h and free swimming
    nauplius emerges
  • Instar I 400-500 microns lacks digestive system
    and does not feed
  • Instar II 12 h later begins to feed (e.g.,
    microalgae) and to grow in size
  • Additional molting events occur (about 15 molts
    in total)
  • Hatching of nauplii
  • Best at 5 ppt salinity, constant light, 25-30 C,
    strong aeration, pH 8-9
  • Harvest of nauplii
  • Aeration is stopped and container illuminated on
    one side
  • Empty cyst shells float to top
  • Hatched nauplii swim toward light source
  • Separation is easy and necessary to avoid
    problems (bacteria, disease, digestive problems
    caused by cysts)
  • Alternatively, cysts can be decapsulated prior to
    incubation (by treatment of hydrated shells with
    hypochlorite solution)

Feeds and Feed production
  • Zooplankton Brine shrimp
  • If larger brine shrimp are desired, nauplii are
    reared in tanks for additional time
  • Feed for brine shrimp growth is microalgae
  • Growth conditions
  • Good aeration
  • Low light conditions
  • 25-30 C
  • 30-35 ppt salinity
  • Good water quality and food supply

Feeds and Feed production
  • Zooplankton Rotifers and brine shrimp
  • Rotifers and brine shrimp are generally
    considered to be deficient in EFAs necessary for
    the growth of fish larvae, especially for marine
  • To overcome this problem, the EFA content of
    zooplankton needs to be manipulated using fatty
    acid enrichment techniques
  • Zooplankton are fed certain microalgae, oil
    suspensions, microencapsulated diets and yeasts,
    and other preparations
  • Similar enrichment techniques can be used to
    improve the zooplanktons content of vitamins

Feeds and Feed production
  • Zooplankton Copepods
  • Copepods exist in all aquatic systems and are
    natural prey for fish larvae
  • Over 20,000 known species
  • Planktonic forms range in size between 0.5 and
    2.5 mm
  • There has been an effort to develop copepods as
    feed for fish larvae
  • Results available suggest very good potential
  • Nutritional value of copepods is better than
    rotifers and brine shrimp (higher levels of
    omega-3 HUFAs) but rotifers and brine shrimpe
    are used more often because at present they are
    easier to mass-culture.

Feeds and Feed production
  • Zooplankton General feeding considerations
  • As they grow in size larval fishes can be fed, in
    order rotifers, brine shrimp nauplii, larger
    brine shrimp
  • Volume of live feed is determined according to
    the formula
  • A (B x C)/D
  • A required volume (L) of live feed culture to
    be fed to the larval fish
  • B required density of live food in larval fish
    tank (number/mL)
  • C volume of the larval fish tank (L)
  • D density of the live feed culture (number/mL)
  • It is important to monitor the presence of food
    in larval fish tank to prevent over or under
  • Disadvantages of live feeds
  • Nutritional deficiency
  • Nutritional inconsistency
  • Reliability of supply
  • Weaning from live organisms is accomplished by
    introducing formulated diets
  • Efforts are underway to develop artificial feeds
    for fish larvae

Feeds and Feed production
  • Artificial diets
  • Advantages of artificial diets
  • The size of food particle and its nutritional
    value can be adjusted to suit the target
    aquaculture species
  • Nutritional consistency and off-the-shelf
  • But there are a number of criteria that must be
    satisfied (Table 9.7)
  • Two types of microdiets are generally available
  • Microbound diets
  • Nutrients are bound within matrix (agar, gelatin,
  • Prepared in form of slurry and then dried, ground
    and sieved to collect particles of defined size
  • Potential problem is nutrient leaching into
  • Some success with fish larvae
  • Microencapsulated diets
  • Nutrients are enclosed within microcapsule wall
    or membrane
  • Reduces problem of nutrient leaching
  • Used to date primarily with bivalves and shrimp
    as co-feed with microalgae
  • Success with fish larvae has been limited
  • Total replacement of live feeds with artificial
    diet still not fully feasible for fishes

Feeds and Feed production
  • Pond fertilization as food source for aquaculture
  • Extensive and semi-intensive pond culture of
    herbivorous and omnivorous species is usually
    based on some degree of pond fertilization
  • Pond fertilization is usually for the purpose of
    grow out, but it has also been used successfully
    for larval fish culture (e.g., for barramundi
    where pond culture of larvae has been successful)
  • Fertilizers used may be inorganic or organic, or
    a combination

Feeds and Feed production
  • Pond fertilization fertilizers used
  • Inorganic
  • Nitrogen ammonium sulfate
  • Nitrogen and phosphate ammonium superphosphate
  • Organic
  • Animal manure
  • Decomposed plant material

Feeds and Feed production
  • Pond fertilization production in fertilized
  • Fertilization is to encourage primary
    (phytoplankton) productivity. Succession of
    organisms in the ponds include
  • Bacteria and protozoan
  • Plants phytoplankton, periphyton, macrophytes
  • Animals invertebrates including zooplankton,
    zoobenthos, small nekton
  • Not all ponds will yield the same composition or
    amount of plants and animals following
  • Critical standing crop (critical fish biomass)
    maximum density (biomass) of a cultured fish
    population that can be maintained in the pond
    without a decline in growth rates (i.e., without
    a decline in natural feed availability in
    extensive/semi-intensive pond culture)
  • Carrying capacity of a pond maximum density
    (biomass) of a cultured fish population that can
    be simply maintained, without further growth
  • Fertilization increases the levels of both
  • Additional growth can only be achieved with
    supplementary feeds

Feeds and Feed production
  • Compound feeds (grow out)
  • Semi-intensive and intensive aquaculture require
    the use of artificial feeds, usually obtained
  • These feeds are primarily used to raise
    carnivorous and omnivorous fishes and
    crustaceans high-cost products in developed
  • Artificial feeds started as larvae are weaned
    from live feeds
  • Critical aspects of artificial feeds include
  • Meet nutritional requirements of cultured species
  • Lowest possible cost - least-cost formulation
  • Feed composition tables include information such
    as (Table 9.9)
  • Moisture (water content)
  • Crude protein (total nitrogen content)
  • Ether extract (lipid and lipid-soluble vitamin
  • Crude fiber (cellulose)
  • Nitrogen-free extract (carbohydrate content)
  • Ash (inorganic content)
  • Protein usually is the largest and most costly
    component of artificial feeds
  • Square method is used to balance crude protein
    level (Fig. 9.9)

Feeds and Feed production
  • Compound feeds - pellets
  • Compressed pellets
  • Grinding and mixing of coarse ingredients
  • Compression of mixture under steam (85 C) and
    forcing mixture through holes in a metal die
    plate pellets of desired length are cut off as
    they emerge from die. Final moisture content
    after cooling off 10
  • Pellet quality affected by lipid content usually
    should be 2-10
  • Extruded pellets
  • Dietary mixture exposed to high pressure and
    temperatures (125-150 C). Process causes water
    in mixture to evaporate leaving air spaces in the
    resulting pellets. Enables production of either
    floating or sinking pellets.
  • Superior in nutritional value.
  • Some drawbacks as well (Table 9.12)

Feeds and Feed production
  • Compound feeds pellet storage
  • Factors that affect pellet quality
  • Age of feed
  • Environmental factors such as
  • Moisture of feed and humidity of storage area
  • Temperature
  • Light
  • Oxygen
  • Fungal contamination/insect infestation

Feeds and Feed production
  • Compound feeds pellet storage
  • Pellets will gradually equilibrate with
    atmospheric humidity. Cannot be stored in
    tropical climates for very long because of high
    humidity. Ideal moisture content for storage
    should be 10-12
  • Oxygen causes rancidity of dietary fats and
    promotes growth of fungi and insects. Fungal
    damage is major concern in the tropics.
  • Chemical changes that may occur during storage
  • Oxidation of lipids and fermentation of
  • Oxidation and fermentation may yield toxic
    chemicals and reduces the nutritional value and
    palatability of feed
  • Use of antioxidants may help
  • Loss of vitamins (especially vitamin C and B1)
  • Can be compensated by coating or dipping pellets
    in vitamin rich material prior to use
  • Loss of pigment color
  • General rules
  • Minimize storage time
  • Protect from elements
  • Keep storage area clean
  • Refrigeration or air conditioning of storage area

Feeds and Feed production
  • Compound feeds dispensing feeds
  • Ration size species-specific feeding tables have
    been developed (Table 9.14)
  • Feeding tables should be used as guide only
    amount adjusted by observation
  • Methods of feeding
  • Manual (hands, shovels, air-blowers)
  • Feeders
  • On-demand feeders
  • Automatic (on timer, computer-controlled)