Production of Fish Feed from Local Feedstuffs
Production of Fish Feed from Local Feedstuffs

Below are terms used in the nutrition of most cultured fish:
Fish feed is that material given singly or in combination to fish which may not be necessarily what it consumes in nature. Fish food, on the other hand, is the edible material that fish choices to consume in their natural environment to furnish nutrients to the animal. At times, however, the term fish food is used to include both prepared diets and natural nutrients. We will stick with the first definition. A diet is any substance prepared as a nutritional substitute for fish food. A nutrient is a dietary constituent of feed or food that aids in the growth and support of life processes. The ration is a 24-hour diet allowance for the animal. A material or mixture of materials to make an allowance for 24 hours.
Some principles to be considered in aquaculture include:
(B) Carbohydrate is more poorly digested in most fish than in land animals. A lot of carbohydrate feed is excreted. Recent research, however, has shown that Clarias spp. efficiently utilize non-protein energy from carbohydrates and can improve protein retention (Luquet and Moreau, 1990).
Feedstuffs or Feed Ingredients
The major local feedstuffs that meet the protein needs of most species without sacrificing amino acid requirements are corn, soybean meal, and fishmeal. Using these ingredients in combination in fish diets ensures that what amino acid that is lacking in one feedstuff is augmented by a relative excess in the other e.g. low methionine in corn is synergistically replaced by that in soybean (Lovell, 1989).

Feed Formulation
Nutrition performance and success of artificial diet for aquaculture depend to a great extent on feed formulation and manufacturer, on-farm feed management, and aquatic environment.
The series of technical and economic considerations in the formulation of feed are:

5 Major factors determining the nutritional performance and success of an artificial diet feeding regime (After Tacon, 1993)
Some other points to note or things to seek out when formulating fish feed:
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Nutrient requirements of the species if known in available – amino acids, lipids, vitamins. If not known those of related species can be used.
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Protein (crude) requirements of the species. This varies from 30 – 55% for many fish species. Invariably fish feeds are balanced from the protein content of the finished diet rather than for the energy in the finished diet. This is so because protein is usually the more expensive input in the feed.
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Based on the type of fish chosen the crude protein range to work with e.g. for larval freshwater fish, 40% may be chosen for catfish; herbivorous and omnivorous species usually require lower crude protein levels e.g. 32% – 35% crude protein compared to ≥ 40% – 45% crude protein input for carnivorous fish like snake fish (Chana obscura) and shrimp.
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It is important to know the percentage of nutrient levels in the available feedstuffs. Nutrient requirements tables from National Research Council (NRC),
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Formulation of the diet should be started using any of the available methods e.g. trial and error method or Pearson’s square method.
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For a high percent crude protein diet, we require a high percentage protein supplement feedstuff in the finished diet, and vice versa for a low percent crude protein diet.
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Through digestibility and resultant availability of nutrients for any feedstuffs to fish may be affected by such factors as temperature, meal size, and possibly body size, it is assumed that any nutrient in any particular feedstuff is just as available as the same nutrient in another feedstuff i.e. low cost determines which feedstuff to use. It is possible to make an infinite number of feed formulations to meet the nutritional requirement of fish. Some of the simple methods used include:
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Pearson’s method,
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Trial and error method,
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Solving simultaneous equations
In this method, the formulation can be done by balancing crude protein level, energy level, or cost. Usually, protein is used.
A. Balancing crude protein level.
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Draw a square and diagonals of the square.
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Place SBM and RB at the left corners of the square with their respective crude protein contents.
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Write down the desired crude protein content of the diet at the intersection (middle) of the diagonals of the square.
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Subtract the protein level of the feed from those of the feedstuff and write answers at the right opposite diagonal corners from the feedstuff. Ignore negative and positive signs. Total up the values at the right-hand corners.
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The proportion of the feedstuffs to mix is:
RB = 14000/358% = 39.1% of rice bran
SBM = 21800/358% = 60.9% of SBM.
To make 100 kg of feed, the different feed ingredients required will be:
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Rice bran = 54.53/2 = 27.265kg
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Corn = 27.265 kg
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Soybean = 45.47/2 = 22.735kg
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Shrimp meal = 22.735kg.
The actual amount of each ingredient should be:
Thus, to make 100 kg of this feed one would mix the following:
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Rice bran 27.265 kg
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Corn 27.265 kg
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Soybean 22.735kg
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Shrimp meal 22.735 kg
Usually it is advisable to start with about three feedstuffs:
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One high in protein and high in ME
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One low or intermediate in protein and high in ME
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One low or intermediate in both protein and energy. It is needful to make allowance or fix the level for feed additives (vitamins, mineral premix, antioxidants (e.g. butyl hydroxyl toluene (BHT), Ethoxyquin, drugs, etc).
Advantages of this method:
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It is easy i.e. simple to apply.
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It can be used to calculate the proportions of feedstuff to meet protein and energy levels.
Disadvantages of this method:
It cannot be used simultaneously to solve for both protein and metabolizable energy (ME) levels.
Other methods
i. Best buy technique
For energy, the best buy technique is also employed when considering which feedstuff to use. For example, if brewer’s waste costs N0.0858/kg; contains 1,2000 kcals ME/kg, i.e. cost/kcal = 0.0875/1,200 = N0.0000715/kcal and wheat middling waste costs N0.1883/kg while containing 1,663 kcal ME/kg i.e. wheat middling costs N0.00001132/kcal. Hence, though brewer’s waste is lower in ME, it is less expensive to use in terms of cost/kcal.
ii. Cost per unit of amino acid
Feed Processing
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Feed processing operation can be summarized to comprise of
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raw material size,
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feed forming and
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feed drying (Wood, 1995)

To effect these, equipment of some form ranging from crude to sophisticated is needed. Some options in fish feed processing are given in Table 1 below:
Table 1: Options for feed Processing Equipment
Process operation
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Equipment
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Raw material/product
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Size reduction
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Mortar and pestle
Mincer
Hammer mill
Plate mill
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Dry of moist grinding or blending
Wet materials e.g.
Trash fish/offals
coarse – fine dry materials
coarse – fine dry materials
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Blending
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Physical
Mechanical mixer
Horizontal
Vertical
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Hand using for small quantities
Items such variable efficiency
As shovel, spatula, etc
Feet Bowl moist day
Dry powders or moist crumbs
Dry powders.
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Forming
Drying
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Hand
Mincer
Pelleter
Cooker extruder
Solar
Mechanical
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Dough ball
Moist noodles
Dry pellets
Semi-moist/dry pellets or noodles
Variable efficiency
Controlled drying
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Larval feeds
For year-round intensive production of fry, there is a need to develop artificial feeds for fry. Some major problems encountered in feeding artificial diets to clariids include
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The larvae do not readily accept artificial diets;
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The material used in compounding most fish feeds competes with conventional human and livestock feeds rendering the finished feed expensive.
Some substances e.g. betaine, glycine, and Spirulina have been reported to have flavour-enhancing effects when included in fish diets (Appelbaum, 1980; Henson, 1990; Hughes, 1991).
Also, Mgbenka and Orji (1994) reported that ripe, raw, fresh palm oil (FPO) used as feed attractants improved growth and acceptance of feeds to clariid larvae and fingerlings but the optimal rate is not yet known. Legendre et al. (1995) made a similar report on the growth of Heterobranchus longifilis larvae fed dietary copra and palm oils.
Food preference in larval fish has been found to depend on a host of factors (Dabrowski, 1984; Verreth and Kleyn, 1987). Ingestion of food particles offered to fish is very strongly influenced by the aroma or palatability of the food (Appelbaum, 1980; Gill, 1989), the availability of nutrients present, and the lipid level of the diet (Machiels and Van Dam, 1987; Verreth et al. 1987). There is a dearth of information on the use of local flavours such as ginger, uda, uziza, etc. as chemoattractants or chemoactivators to improve acceptance, growth, and survival.
Some non-conventional include such feed ingredients as rumen digesta, sprout (sorghum malting by-product), mucuna bean seed, and devil bean (Igbo, “agbara”), to mention a few. Mucuna bean seed and sprout, for example, have been reported to contain 28.59% and 26% crude protein, respectively (Oyenuga, 1968; Okwuosa, 1992). Additionally, the sprout is rich in the essential amino acids Lysine and Methionine (Okwuosa, 1992).
References
Mgbenka, B.O. and Ugwu, L.L.C. (2005). Aspects of mineral composition and growth
rate the hybrid African catfish fry fed inorganic phosphorus–supplemented diets.
Ugwu, L.L.C., Mgbenka, B.O. and Asogwa, M.O. (2005). Nutrient utilization and growth responses of frys of the African hybrid catfish (Clarias gariepinus xHeterobranchus bidorsalis) to inorganic phosphorus supplements. Journal of Agriculture and Social Research, 5(1): 107 – 112.