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Feed Ingredients and Physical Characteristics

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1 Feed Ingredients and Physical Characteristics

2 Formulating Feeds Nutritionally complete feeds should be used whenever natural foods are absent or where natural foods only make a small contribution to nutrition when substantial amounts of natural productivity are available, supplemental feeds don’t need to contain all essential nutrients we will focus on nutritionally-complete feeds

3 Nutrient Requirements
Most requirements for nutrients that have been published focus on juvenile fish/shrimp many represent single lab experiments, unchallenged, unsupported by others optimum performance can be affected by management, environmental factors and fish/shrimp size in formulating diets for a species for which nutrient requirements are unknown, those for a related species are used

4 Nutrient Requirements
Most variation among aquatic species can be associated with whether the animals are: 1) coldwater vs. warmwater; 2) freshwater or marine; 3) finfish vs. crustaceans values in nutrient requirement tables only represent minima, don’t allow for processing or storage losses AA’s, minerals stable wrt heat, moisture, oxidation vitamins and lipids are not stable (affected by heat, oxidation, light, moisture, etc.; store in cool area) 50% of ascorbic acid is lost in processing, half-life of 2-3 months in storage

5 Physical Properties various sizes of fish feed particles
Ground meals are not suitable for feeding to aquatic animals due to poor ingestion, feed conversion, and reduced water quality pellets need to be stable in water until consumed by the target animal good pellet stability required for slow-feeding species such as shrimp particle size is important to insure appropriate consumption various sizes of fish feed particles

6 Physical Properties Diet texture is also important for some aquatic species: some prefer moist vs. dry feeds (e.g., eels, salmon) sometimes farmers prefer floating pellets, allowing confirmation of ingestion shrimp prefer sinking pellets (density greater than that of water, 1 g/cm3) floating feed can be detrimental with respect to consumption by competitors

7 Practical Feed Ingredients
Ingredients used in practical fish/shrimp feeds can be classified as: protein sources (including amino acids) energy sources (COH) lipid sources (also essential fatty acids) vitamin supplements/premixes mineral supplements/premixes growth/pigment enhancers ingredients improving palatability ingredients improving preservation/storage

8 Fish Meal (FM) If made from good quality whole fish, properly processed, it is the highest quality protein source commonly available rich source also of energy and minerals highly digestible, highly palatable, also serves as an attractant usually contains about 65% protein, that is around 80% digestible high in LYS, MET (deficient in plant sources)

9 Fish Meal (FM) Fish meal also contains 1-2.5% n-6 fatty acids, essential to many fish and all shrimp if made from byproducts, its quality is not as good as trawler-caught only problem observed: high ash content can sometimes result in mineral imbalance used sparingly because of high cost can be partially replaced by soybean meal and other animal meals

10 Fish Meal (FM) When using FM, one must remember that it cannot be stored forever can rancidify due to high lipid content further, not all FM is created equal some types (menhaden) appear to be superior to others (sardine meal) FM must be very well ground and sieved to help remove indigestible parts big producer countries are USA, Peru, Mexico, Ecuador

11 Soybean Meal (SBM) Soybean meal has one of the best essential amino acid profiles of all protein-rich plant feedstuffs Table 5.3 (Lovell) SBM does not appear to be deficient in any EAA for catfish can be deficient wrt eel, because their MET/CYS requirement is twice that of catfish some fish find SBM unpalatable, for this reason maximum levels are suggested


13 Soybean Meal (SBM) soy protein
Soybean meal is commonly used to spare fish meal, however, only to a point true for chinook, but not for catfish shrimp will consume high SBM feeds, but diet must be supplemented with fish meal at some point another problem involves losses in energy, minerals and lipids in diets where SBM replaces FM or other animal byproduct proteins soy protein

14 Soybean Meal (SBM) Another variety of soybean meal is known as “de-hulled” de-hulled soybean meal contains 25% less ME, 85% less available P and 90% less n-3 FA’s than anchovy meal soybeans also contain trypsin-inhibitors trypsin inhibitor reduces digestibility of soy protein by the enzyme trypsin solution: most soybeans are roasted prior to milling (destroys inhibitor)

15 Full-fat Soybeans Full fat soybean meal is different from regular SBM in that it has a full fat complement fat has not been solvent extracted 18% fat vs 0.5% often used as an energy source or for general balancing of the formula mainly used in salmonid (cold water) fish diets REM: too high fat = reduced nutrient intake

16 Grains and By-products
Grains are primarily used as COH sources when whole, they contribute about 62%-72% of dietary starch starches are fairly well digested by warm-water species (60-70%), but not by cold heating via extrusion improves digestibility by 10=15% can also be used as binding agents

17 Grains and By-products
Corn is commonly used in the U.S., but is high in xanthophyll (a pigment), giving tissue a yellow color (not good for fish sales!) corn gluten meal is high in protein (60%) and contains high levels of MET (excellent for formulation) rice bran often used in developing countries due to local rice production rice bran is a reasonable COH source, but is high in fiber and fat wheat gluten is a good protein source, but too expensive, often used as a binder

18 Animal By-products MM MBM
Meat and bone meal is a byproduct of the slaughter house contains 50-55% crude protein protein quality is low, so only marginally useful and varies dependent upon meat source can be a good source of energy, P, TM’s another problem: high ash content digestibility improved by flash- or spray-drying poultry by-product meal (PBM) is often used by mills also producing chicken feed feather meal high in protein, but indigestible MM MBM

19 Crustacean Meals krill meal
Shrimp waste meal is a reasonably good feed ingredient, if heads are included otherwise, the shell is primarily chitin and of limited digestibility the ammonia in chitin accounts for about 10-15% of the nitrogen in whole meal also a reasonable source of n-3 fatty acids, cholestrerol and astaxanthin (carotenoid) highly palatable and often serves as an attractant in feeds at 1-2% others: krill meal, Artemia meal krill meal

20 Fats and Oils Used as energy sources, provide essential fatty acids, attractant, coating of pellet to reduce abrasion both animal and plant fats can be used, animal fats cheaper, better attractants marine lipids often added as oils if FM level is low (otherwise no source of marine FA’s) sources: menhaden, shark, cod liver must be careful in storage of oil, feeds with oils due to rancidification menhaden oil

21 Fibrous Feedstuffs rice kernel
Most monogastric animals (e.g., fish) do not digest fibrous feedstuffs well it is unlikely that adding fiber to diets already with more than 3-5% will have any beneficial effect high fiber content reduces binding capacity of feeds, inhibits intake (due to reduced palatability), increases rate of passage and waste production sources: brans rice kernel

22 Binding Agents Binding agents are really needed for pelletized feeds, but not necessarily for extruded feeds (we discuss this later) in extruded feeds, all ingredients are gelatinized by high temperature and bind together well as a result of the process show Table 5.4 (Lovell, page 118)


24 Binding Agents most organic binders are good for about 30 min of submergence starch is often used at over 10%, however it will hydrate and swell the pellet chemical binders (e.g., Basfin) have good binding potential, form cross-linkages with COH and PRO, but are toxic

25 Non-nutrient Diet Components

26 Basic Facts In addition to the essential nutrients, feeds may contain organic and inorganic materials that have various effects on aquatic species: beneficial, detrimental or negligible they can affect growth, health or the processed product may be naturally occurring, intentionally or unintentionally added can be produced via microbial growth

27 Toxins and Antimetabolites
The more important toxins affecting animal feeding are those associated with molds these are called “mycotoxins” three important genera are Aspergillus, Penicillium and Fusarium they exist and grow anywhere as long as there is enough COH substrate, no less than 14% moisture, adequate temperature, oxygen usually produced in feedstuffs prior to harvest, but also result from poor storage

28 Aflatoxin Aflatoxin is the mycotoxin of greatest concern in feeding of culture species both outright toxic and carcinogenic liver (hepatoma) and blood clotting problems rainbow trout are highly sensitive at 1 ug/kg exposure traditionally, sources include corn, cottonseed and peanuts aflatoxin contamination varies year to year

29 Ochratoxin These are compounds produced by Aspergillus and Penicillium molds widely found in nature typically associated with kidney toxicity toxic level is 4.7 mg/kg in diet other mold toxins have been found in warm-blooded animals, but not in fish most mold toxins also destroy nutrients in feeds example: Pseudomonas can separate glutamic acid from folic acid, making it ineffective

30 Microbial Toxins in Commercial Fish/shrimp Feeds
Usually not known that the feed is contaminated commercially-processed feeds are less likely to have these toxins screened against international transport and by feed manufacturers by law must contain less than 20 ppb up to manufacturer to require testing not destroyed by steam pelleting or extrusion presence in feeds reduced by proprionic acid

31 Histamine, etc. This is a toxic compound found in fish meal, a typical feed ingredient results from bacterial removal of COOH (carboxylic acid) from the EAA histidine comes from improper storage of raw fish prior to production of fish meal causes a reduction in growth rate usually comes from “dark” meat portion of fish other fish meal toxin is “gizzerosine”

32 Phytic Acid, Gossypol Phytic acid is an organic molecule related to inositol integral component of plant feedstuffs and holds 60-70% of the phosphorus problem is, it’s poorly available to fish reduces availability of zinc “Gossypol” is a component of pigment lands in the cotton plant limits availability of cottonseed meal used in feeds (suppresses growth rate and causes liver damage)

33 Fish Oils, Fiber Marine fish oils contain 20-25% PUFA’s
the “autoxidation” of PUFA’s results in formation of large numbers of free radicals and peroxide compounds these are toxic due to reaction with other nutrients, limiting availability also cause cellular/subcellular damage severity of effect reduced by Vit E fiber can also be mildly “toxic” as it increases rate of gut passage high rate of passage causes reduced availability of nutrients

34 Diet Additives: Hormones
Hormonal control used to produce mono sex cultures of fish reduces reproduction/increases growth ex. Androgenic steroids (ethyltestosterone) fed to tilapia fry = 90% males does not work the same on all fish 17-alpha-methyltestosterone improves growth and survival in salmonids andorgenic better than estrogenic used as implants in cattle

35 Pellet Binders Steam pelleted aquatic feeds, especially those fed to shrimp, contain binders these are used for improving water stability (reduced leaching and nutrient loss) two different types: organic matrix (lignosulfonates or polysaccharides) other type: chemical compounds (sodium hexametaphosphate) no evidence of detrimental effect on aquaculture species


37 Antibiotics Some feeds can be formulated with antibiotics for treatment of Vibriosis, other bacterial infections Three antibiotics approved in U.S. are sulfadimethoxine, sulfamerazine and terrymycin (oxytetracycline, OTC) OTC commerically available as “medicated” fish (shrimp) feed, 1,500 mg/kg Must not feed medicated diets within days from slaughter/harvest (more regulations!)

38 Attractants Attractants are materials added to feeds to serve as intake (feeding) stimulants They are cost effective since they cause shrimp/fish to eat feeds that otherwise would not be attractive (consumed) Facilitates inclusion of by-products Usual inclusion level is around %, largely due to cost Examples: krill meal, Artemia meal, fish oils, fish meal Sometimes used to reduce protein content of feed (but most also feed more frequently)

39 Antioxidants Oxidation of lipids in feeds or feedstuffs can cause reduction of the nutritional value of certain lipids and vitamins It can also result in production of toxic free radicals and peroxides (REM?) Potential for formation of these toxic compounds reduced by synthetic compounds such as BHA (butylated hydroxyanisole, BHT (butylated hydroxytoluene) Also via natural compounds (Vit E)

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