1. GRASSES
2. LEGUMES
3. MISCELLANEOUS FODDER PLANTS
4. FRUITS AND VEGETABLES
5. ROOT CROPS
6. CEREALS
7. OIL-BEARING SEEDS AND OIL CAKES
8. FEEDS OF ANIMAL ORIGIN
9. MISCELLANEOUS FEEDSTUFFS
This appendix is intended to provide introductory descriptions of the major ingredients used in aquaculture feedstuffs. For more detailed descriptions of these and the many other feedstuffs which are available, you should consult the list given in 'further reading' at the end of section 4 of the manual. The feed categories given below are the same as those used in that section of the manual.
Analytical information on some of the ingredients dealt with in this appendix are given in Appendix IV. Analytical information on the others can be obtained by consulting more elaborate feed compositional tables and other papers, such as Göhl, 1981; Manik et al., 1977, Malik and Chughtai, 1979, Hubbell, 1984, NAS, 1971, Devendra, 1981, NAS, 1969, and Sadiq and Seng, 1982.
DRIED GRASS. If available, this expensive ingredient can be used as a source of protein and vitamins. It contains vitamins of the B group and, more importantly, b -carotene, a precursor of vitamin A. Its high fibre content and its cost would prevent more than a minimal inclusion rate. If added as a source of vitamin A, its potency must be measured because the amount of b -carotene in grass meals depends on standards of drying, the grass species and variety, age at harvest and age of the product. With the limitations noted above, undried grass could, if well chopped, be included in moist rations.
Foliage of several legumes has been utilized in aquaculture feeds. That of other leguminous plants is probably also satisfactory but its successful use has not yet been specifically reported in the literature. Amongst those plants whose foliage has been used are alfalfa (lucerne) and ipil-ipil (wild tamarind).
Ipil-ipil is a deep rooted tree or arborescent shrub cultivated widely as a fodder crop. Its leaves and seeds contain the glucoside mimosine which is reduced in level if they are stored for a week before use or are soaked in water and dried. It has been used successfully in shrimp and fish feeds at low levels (5-10%).
Alfalfa is a deep rooted perennial herb extensively grown for fodder purposes and as a major compound feed ingredient. It is a safe and valuable ingredient for fish feed, contributing protein and fat-soluble vitamins. In compound feed it is included as a dried meal.
Apart from the oil-bearing leguminous seeds (which are included in section 7 of this appendix) many other leguminous seeds or their by-products have potential as aquaculture feed ingredients, though their successful use has not yet been fully documented. These include the following:
|
Leguminous seeds with aquaculture feed potential | |
|
Common name |
Special notes |
|
Horse gram |
low fibre |
|
Cow pea |
low fibre |
|
Mung bean (black gram) |
no glucosides; successfully used in aquaculture feeds |
|
Tamarind |
high fibre |
|
Sesbania |
|
|
Saman (rain tree) |
high protein; high in tannins; used in experimental fish feeds |
|
Red gram (dahl) |
as good as soybean for poultry |
|
Split peas (red dahl) |
high protein bran |
|
Lupin |
high protein; bitter varieties contain alkaloids and must be soaked before use |
|
Algaroba |
ripe pods palatable to other animals |
|
Senegal gum |
high protein |
Most of the leguminous seeds eaten by humans may be too expensive for use in aquaculture feeds but those of other legumes, either alone or together with the foliage of the plant, remain relatively unexploited sources for aquaculture. Care should be taken to check their palatability and to remove toxic substances before their large-scale use, however.
Sisal hemp leaf waste pulp could be used in small quantities in moist feeds but its protein is not very digestible. The leaves of the pawpaw (papaya), which are high in protein yet quite low in fibre could be a useful ingredient. The leaves of coffee are low in protein but high in fibre. Water hyacinths could be a useful ingredient for moist feeds if first boiled to form a paste. Kangkong (swamp cabbage), is another water plant, this time a rooted one, which has similar potential. Small quantities of sago palm starch can be used in feeds - its ease of gelatinization improves feed stability.
In many countries large quantities of citrus wastes are available. Whole fruits are sometimes wasted when they cannot be marketed quickly enough. Dried citrus pulp, a waste from juice production, citrus molasses and citrus seed meal, an oilcake, are available. However, the seed meal is toxic to chicken and pigs and may be so to fish. Most wastes from fruits e.g., coffee are very high in fibre and therefore of limited use in fish feeds. Coffee wastes are also unpalatable to other livestock and depress growth. Banana plants have some potential as ingredients. Banana waste has been used as a binder in crustacean feeds. Banana peels are rich in tannins and cannot be used until they are yellow. Limited quantities of various banana wastes could be utilized as sources of carbohydrate.
Root crops cannot be used at a very high level in aquaculture diets because of their high carbohydrate level and their high value as human food. However, at least four, cassava, sugar beet molasses, and meals made from potatoes and sweet potatoes have been used for their binding qualities in aquaculture feeds. Sometimes potato or cassava starch is used in its raw form, sometimes in a pre-gelatinized form.
Ground whole cereals which can be used in fish feeds include the millets (various species), oats, barley, sorghum milo or dari, wheat, and corn or maize. The quantity of grain used depends on its cost and the limited utility of high carbohydrate ingredients for fish. However, many cereal by-products are available and potentially useful for aquaculture feeds. The major ones are defined as follows:
|
BROKEN RICE |
damaged rice separated out after rough rice has been dehulled and polished. It has the |
|
RICE HULLS |
an extremely high fibre material, not recommended for fish feeds. |
|
RICE BRAN |
a good source of B group vitamins, it is the material scoured off before initial rice polishing, It has a higher protein content than the original grain and, in the unextracted form, has a high lipid level which is prone to rancidity. Rancid rice bran is much reduced in feed value. The oil is often extracted for human use and the resultant rice bran is favoured, because of its keeping quality, by feed millers. The fibre in extracted rice bran absorbs water and leads to a water unstable pellet. |
|
RICE POLISHINGS |
this is the part of the starch endosperm which is removed during polishing, to improve the appearance of the polished rice for human use. It is therefore lower in protein and fibre than rice bran. It has the same keeping problems as rice bran. |
|
RICE POLLARDS |
a mixture of rice bran and rice polishings, usually sold as a grade of rice bran. |
|
RICE MILL FEED |
a mixture of all the rice milling by-products, typically 60% hulls, 35% bran, and 5% polishings. |
|
RICE (GENERAL) |
there are many intermediate products between those identified above. The secret of their origin is in their chemical analysis. From the original rough rice (padi) about 50-60% becomes polished rice, 20% hulls, 10% bran, 3% polishings and 1-17% broken rice. |
|
WHEAT BRAN |
contains most of the vitamins and protein of the wheat grain. It is the fibrous coating of the grain beneath the husk. It does not contain the wheat germ. There is a coarse outer layer and a fine inner layer to the bran area. It is quite high in protein and fibre. Like extracted rice bran, wheat bran can cause water stability problems in fish feeds. |
|
WHEAT MIDDLINGS |
this is a mixture of 'shorts' (itself a mixture of fine bran and feed flour - the outer endosperm layer) and wheat germ. It is sometimes known as WHEAT POLLARDS or MILL RUN. It is less fibrous than wheat bran, has a higher feed value and contains more wheat protein (gluten). It is thus better from a water stability point of view. |
|
MAIZE (CORN) GLUTEN FEED |
a by-product of the wet-milling of maize for the manufacture of corn starch or corn syrup, corn gluten feed is usually 20-30% protein and quite high in fibre. It contains the corn colouring pigment. Like other maize products it is very lysine deficient. |
|
MAIZE (CORN) GLUTEN MEAL |
this corn by-product is much higher in protein and lower in fibre content. |
|
MAIZE-GERM OIL MEAL |
this is a high oil/low protein by-product of the same industry. |
The major oil-bearing seeds contribute large quantities of by-products which are used in animal feeds, all of which have potential as aquaculture feed ingredients. An explanation of the various descriptive terms (expeller, extracted, etc.) used in conjunction with these products, which indicate their analytical characteristics, is to be found in section 4.1.7. of the manual. The following is a list of the major plants contributing products to this category of ingredients:
|
COMMON NAME OF OILCAKE OR MEAL |
SPECIAL CHARACTERISTICS |
|
GROUNDNUT |
methionine deficient; prone to aflatoxin development; extensively used in carp diets. |
|
MUSTARD) |
also used in carp diets but need great care, as non-detoxified meals contain a range of toxins. |
|
COCONUT |
prone to rancidity; absorbs water, thus water unstable feeds; low in protein; high in fibre. |
|
OIL PALM |
kernel high in protein; fats saturated; (African oil palm). |
|
SOYBEAN |
high protein; low lipid; generally good source of EAA's including lysine but methionine deficient; contains a trypsin inhibitor and urease but these are destroyed during processing; with EAA supplementation it is a potential partial replacement for fish meal. |
|
COTTON |
screw-press cake contains high level of free gossypol which is toxic; high in fibre; potentially valuable but knowledge of effect of gossypol on fish not adequately known (see ADCP, 1983). |
|
SUNFLOWER |
richer in methionine and cystine than soybean; lysine deficient; no toxins. |
|
SAFFLOWER |
poorer in the EAA's lysine and methionine than sunflower. |
|
PARA RUBBER |
must be de-toxified to remove prussic acid; suitability probably similar to coconut. |
|
FLAX (LINSEED) |
like para rubber, contains an enzyme and a glucoside that produces prussic acid but normal processing destroys the enzyme; not known whether its additional toxicity to poultry (which can be eliminated by supplementary vitamin B6) affects fish or not. |
|
SESAME (GINGELLY) |
rich in methionine but deficient in lysine; would be good ingredient in conjunction with soybean; value for Indian carps has been demonstrated. |
High protein meals from animal sources are of great value in aquaculture feeds, particularly if they are of marine origin. Lipids from animals, as well as plants, are dealt with in section 9 of this appendix. Animal proteins are generally rich in EAA's especially those (lysine and methionine) which are often limiting in plant proteins. They also are good sources of vitamins, unidentified growth factors and trace minerals. The major ingredients of this type are:
|
MEAT WASTE |
only available where offal is not valued for human food; may be contaminated and spoiled before use; may also contain animals condemned as unfit for human consumption. Meat scraps and trimmings after fat removed are dried into meat meal. This is inferior to fish meal or soybean meal and is prone to damage (evidenced by low available lysine) by poor processing. If refrigeration is available or the waste can be collected daily both it and blood are potential moist feed ingredients. |
|
BLOOD |
blood is often widely available and can be used fresh or as a dried meal. Dried meals are often poorly produced, however, and the protein may be damaged. Blood has an extremely high protein content but does not have such a good amino acid profile as meat waste. The digestibility of its protein is high but its leucine/isoleucine ratio is unbalanced. |
|
BONE MEAL |
bone is sometimes mixed with meat meal to form 'meat and bone meal'. Some bone meals contain quite high levels of 'crude' protein but the nitrogen detected in the analytical test comes mostly from indigestible collagen. Bone meal is not usually needed as a calcium and phosphorus source in aquaculture feeds but may become so as less fish and meat meals are used in them. |
|
LIVER MEAL |
a source of B group vitamins, if available. |
|
POULTRY BY-PRODUCTS |
poultry feet, heads and undeveloped eggs which, like other slaughterhouse wastes are of no value as human food locally, can be used fresh or as a dried meal. Gizzards and intestines can also be used if their contents are removed. Similar in value to meat meal. Very rich in choline. |
|
HYDROLYSED POULTRY FEATHER MEAL |
feathers hydrolysed by cooking are a highly digestible source of nitrogen for ruminants. However as it is severely deficient in most EAA's this product can only be used in aquaculture feeds in small amounts if well balanced by other, good quality, protein. It is believed to be of more value in crustacean than in fish diets. |
|
'TRASH FISH' |
'trash fish' is difficult to define because it differs from location to location in species composition. It consists of fish which are too small, too large, or disliked to an extent to make them unmarketable. What is 'trash' fish in one location may be highly prized elsewhere. What is 'trash' when in super-abundance in one season of the year may be scarce and more valuable at others. Often it is used for fish meal production and may be mixed with crustacean waste. It is much used as an aquaculture feed alone, or mixed with other materials, or as part of an extruded moist feed. It must be used fresh or refrigerated. Unless pasteurized, some species especially contain the enzyme thiaminase which destroys vitamin B1, in the other dietary components 1/. Trash fish is a valuable aquaculture ingredient which is becoming increasingly exploited. Local analysis is necessary before it can be accurately formulated into a compound diet. |
|
FISH MEAL |
this is either made by crude processes locally or forms part of the quite sophisticated manufacturing process of an international feed commodity. Fish meals vary widely in their analysis according to the nature of the raw material and the method and care by which it is processed. White fish meal (e.g., South African, Scottish) is made from whole non-oily fish and fish residues which are oven dried and ground. Dark coloured fish meals involve cooking the raw material, pressing it to remove the oil, drying the residue in a steam jacket and grinding it. Shark and dogfish need to be processed by the latter method as they are of little value unless cooked. Peruvian and That fish meals are of the dark variety but differ greatly. That fish meals are made from the whole by-catch (mixed species); Peruvian fish meal is made from one species, the anchovy, and is much higher in its crude protein content. Fish meals are often overcooked, causing damage to the quality of the protein, or undercooked, causing contamination with Salmonella bacteria. Fish meals are often adulterated with urea (which, with a nitrogen content of 46%, has an apparent (N × 6.25) crude protein level of 288%), to make low grade products seem like high protein fish meals. If of good quality, there is no better high protein ingredient readily available for aquaculture feeds. Fish meals should have less than 2% salt and should contain an antioxidant. They are also a considerable source of poly-unsaturated fatty acids, particularly of the higher members of the n-3 series. The key to the successful use of fish meals is a knowledge of the processes and quality control standards used by the factories producing them and regular analysis by the user for component quantity and quality. Fish meal is a very costly ingredient. |
|
FISH SOLUBLES |
this product, which is the watery material remaining after the oil is removed from the substance pressed out during the manufacture of brown fish meals, can be condensed and sold separately as a liquid (condensed fish solubles) if not mixed back into the press cake, or dried to form dried fish solubles. Much of the protein of this product is in a non-protein form but it is sometimes used in small quantities in aquaculture feeds as an attractant. It is high in the B group vitamins and contains an unidentified growth factor for poultry. |
|
FISH SILAGE |
see Appendix VI. |
|
SHRIMP MEAL |
a dried meal similar to fish meal, made from the waste heads and shells of large prawns or shrimps, or from whole small shrimps or crustacea of no human food value. Its true protein value is only about 50-70% (depending on the proportion of heads to shells in the original material) of the apparent, or 'crude' protein content. This is because much of it derives from an indigestible (nitrogen containing) polysaccharide, chitin. However, it is an important source of this chitin for shrimp feeds, it is high in choline and it is used for pigmentation as it contains important carotenoids. Both shrimp and fish meals, unless finely ground, give poor stability to aquaculture feeds. Again, as with fish meals, it is important to know the source of the material and to analyse it. Some meals are nearly all shells, with little value. Waste shrimp heads and shells can, if available fresh or refrigerated, be used as excellent ingredients in moist aquaculture feeds, especially for shrimp. |
|
SQUID MEAL |
if available, this is an excellent ingredient for shrimp feeds, but expensive. It appears to have growth promoting properties. Fresh squid can also be used in moist diets. |
|
MOLLUSCS |
as for squid meal. Can also be utilized fresh in moist diets. |
|
SNAILS |
can be of value, if cooked and dried. |
|
SILKWORM PUPAE |
where available in quantity, this is a valuable ingredient, especially for shrimp feeds. The lipid is prone to rancidity. Only 75% of the total protein is available because, as in the case of shrimp meal, it is partially chitin. Cocoons have no value. |
|
MILK BY-PRODUCTS |
surplus or damaged milk powder is sometimes available and, if its cost is acceptable, of potential value in aquaculture diets. Whey, a residue for the production of cheese, as well as a high-protein waste from the refining of animal ghee, are utilizable up to a 10% inclusion level, at least for salmonids. Whole milk powder has an EAA profile which is generally regarded as better than fish meal and close to the 'ideal' food, chicken egg protein. Skimmed milk has a similar EAA profile. |
1/Raw tissues from freshwater fish, clams, mussels and shrimp are particularly likely to contain thiaminase
As the grouping implies, these feedstuffs are diverse in origin and only a few are mentioned here:
SEAWEEDS: Seaweed meals are of value in aquaculture diets, particularly in those for shrimp. They are a source of trace minerals and vitamin A and probably increase palatability. Shrimp are able to digest cellulose better than fish. (See Appendix XII).
CANE MOLASSES: This diluted by-product of cane sugar refining can be used as a partial source of energy, as a 'filler', as a binder and as a possible attractant. It is cheap and widely available, except where fermented for alcohol production.
BREWERS SPENT GRAINS: This material, the extracted malt, is a valuable source of protein and energy which is often thrown away or used as a fertilizer. It is very wet. If dried it is an excellent ingredient but often no market has been developed for it. It could be used fresh as an ingredient in moist diets if transport costs for such a moist product (75-80% moisture) to the farm site are not prohibitive. If not boiled before use, its enzymes may ferment carbohydrates in other ingredients to produce alcohol.
BREWERS YEAST: Dried brewers yeast, if available, is an excellent raw material. It is a by-product of beer production. Like brewers spent grains, the fresh material requires boiling to inactivate the enzymes present before use as a wet ingredient. It is a rich but expensive source of B group vitamins and protein. This yeast is usually Saccharomyces spp.
GRAIN DISTILLERS BY-PRODUCTS: These by-products of ethanol or acetone butanol production vary in analysis according to the method of production (see Göhl, 1981) and the type of raw cereal used. They are generally of greater value than brewery wastes and more expensive. They appear to stimulate growth in poultry but it is not known whether they would be as effective in aquaculture feeds. Useful if economically available.
LIPIDS: Many different natural animal tallows (solid above 40° C), lards (melting point between 20-40° C) and oils (liquid below 20° C) are available. Generally tallows come from cattle or sheep, lard from pigs, horses and any type of bones, and oils from marine animals. The vegetable lipids which are available are also mainly oils. Processed animal lipids are not always available but vegetable oils are; however they may be very expensive because they are refined for human food. They may thus be quite an expensive source of energy and EFA's for livestock. Soapstocks, materials which are used in the production of soap, consist of the sodium salts of free fatty acids and traces of protein. Some also contain carotenoid pigments. Soapstocks can be used as sources of energy and fatty acids in feeds.
Fish oils and most vegetable oils are high in PUFA's and need to have antioxidants added to them during processing to delay the onset of rancidity. Hydrogenated (hardened) fats made from fish oils and beef tallow are poorly digested if their melting point is above 40° C. Table 1 shows the levels of PUFA's for a range of lipids. The fatty acid profile varies from sample to sample but Table 1 gives broad indications of quality. It can be seen that although vegetable oils are very rich in TOTAL PUFA's, the quantity of the higher (HUFA) n-3 series fatty acids, which are so important for fish and shrimp feeds (see section 3.1.2), is nil. Amongst the vegetable oils listed in Table 1, only soybean oil has a higher content of linolenic acid (18:3n-3) than the marine oils. Linseed and rapeseed oils are also high in linolenic acid. The main difference is that the marine oils have significant levels of HUFA's (n-3 series) whereas the vegetable oils do not.
MICROBIAL PROTEINS: Bacterial proteins, grown from aqueous solutions of mineral salts with a nitrogen source, using methane as an energy source, and yeasts (mostly 'torula' or fodder yeasts) grown on paraffins and industrial wastes, such as molasses, sulphite waste liquor from the paper industry, fruit wastes, etc., are becoming increasingly available as ingredients for animal feeds. Both types, especially the bacterial type, are rich in protein. The presence of large quantities of nucleic acids limits their use as human food but it is unknown if this is a problem in their use for fish feeds. The amino acid profile varies according to the type and the media on which it is grown. Some yeasts are particularly deficient in methionine while some are very high in lysine level.
Table 1: Major PUFA 1/ Contents of Various Lipids (% of Lipid)
ALGAE: Dried unicellular algae - like microbial protein, sometimes referred to as single cell protein (SCP) (mostly Chlorella, Spirulina and Scenedesmus species) - are high in protein but usually too expensive for use in animal feeds. Those fed alive to larval aquaculture stock are specially cultured. Algae are rich in carotenoids.
MANURE: Animal manures and litter wastes can be used in fish and shrimp feeds in addition to being used as manures. However, over 50% of the crude protein of manures consists of non-protein nitrogen, such as uric acid. It is believed that in most cases where manures have been used as an ingredient in compound aquaculture feeds the true effect has been to fertilize the natural food in the pond. However, there have been reports of the successful use of small quantities of poultry manure in shrimp feeds and of tilapia being fed a trout feed with up to 30% dried poultry waste in it without any depression of growth rate. For further reading on this subject, see Edwards (1982), Müller (1980), and Woynarovitch and Kühnhold (1979).
NON-PROTEIN NITROGEN (NPN): Although there are conflicting reports about the ability of some species of fish and crustacea to utilize sources of NPN, such as urea, biuret and ammonium phosphates, it has not yet been recommended that these materials should be used in fish feeds.
MINERALS AND VITAMINS: These materials have been dealt with in section 3.1 of the manual.
BINDERS: See Appendix XII.
