Field Document 1
A report prepared for the Aquaculture Demonstration and Training Project
Kai W. Chow Consultant (Fish Feed Technology)
This informal report is one of a series of reports prepared during the course of the project identified on the title page. The conclusions and recommendations given in the report are those considered appropriate at the time of its preparation. They may be modified in the light of further knowledge gained at subsequent stages of the project.
The designations employed and the presentation of the material in this document do not imply the expression of any opinion whatsoever on the part of the United Nations or the Food and Agriculture Organization of the United Nations concerning the legal or constitutional status of any country, territory or sea area, or concerning the delimitation of frontiers.
FOOD AND AGRICULTURE ORGANIZATION OF THE UNITED NATIONS
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1.1 Terms of Reference
1.2 Background Information
2. SUMMARY OF OBSERVATIONS AND WORK COMPLETED
2.1 Feed Survey
2.2 Formulation, Preparation and Testing of Practical Diets
2.3 Economic Evaluation of Feeding Fish in Egypt
3. COMMENTS AND RECOMMENDATIONS
1. COMMONLY AVAILABLE FISH FEED INGREDIENTS IN EGYPT
2. COMPOSITION OF TEST DIETS FOR TILAPIA AND CARP FINGERLINGS
3. RESULTS OF COMPARATIVE FEEDING TRIALS INVOLVING TILAPIA AND CARP FINGERLINGS
4. EQUIPMENT LIST FOR A 1 t/h PELLET MILL
5. RECOMMENDED TEST DIETS FOR CARP FRY
The Government of Egypt, assisted by the United Nations Development Programme and the Food and Agriculture Organization of the United Nations, have been engaged in the Aquaculture Demonstration and Training Project (EGY/80/002) whose main purpose is to establish and test improved methods of fish farming with a view to formulating and developing semi-intensive/ intensive aquaculture techniques adaptable and appropriate to the Nile Delta Area.
As part of the project operation, FAO assigned Dr Kai W. Chow as Consultant (Fish Feed Technology) from 16 March to 15 April 1981, with the following terms of reference:
to evaluate locally-available ingredients for fish feed;
to provide advice and assistance in the formulation and preparation of fish diets; and
to undertake the evaluation of the economics of feeding fish in farms under local conditions.
Mr Wagdi Hafez, chief of technical services, Under-Secretariat of Aquatic Resources, Ministry of Agriculture, was designated as counterpart to the consultant. Mr Hafez was one of the two Egyptian fisheries officers who attended the UNDP/FAO Training Course in Fish Feed Technology held in the College of Fisheries, University of Washington, Seattle, USA, in the winter of 1978.
The Zaweya Fish Farm is situated in a newly reclaimed area within the Governorate of Kafr El Sheik. The farm comprises a total of 1 000 feddans1 of brackishwater fish ponds fed by a main irrigational canal. One quarter of the farm, constituting the northern sector of the pond complex, is being filled with water for stocking with fish. These 250 feddans comprise the Project Unit of the UNDP-assisted pilot scheme aimed at testing and demonstrating production and management plans proposed earlier under Project TCP/EGY/6702 which established the Zaweya Fish Farm. Included in these plans are the formulation, production and testing of suitable artificial feeds for large-scale fish production.
The Zaweya Fish Farm is intended to be production-oriented involving a polyculture of mullet (principally Mugil capito and M. cephalus ), tilapia (Sarotherodon niloticus), and mirror carp (Cyprinus carpio). The planned stocking composition of the three main species was: 30, 65 and 5 percent respectively.
As started earlier, the farm is situated in a newly reclaimed area. There is no established vegetation in and around the farm site, and the organic matter content in the soil is very low (less than 2 percent). This may, in part, be due to the high salinity of the soil. In preparing new ponds, the present programme calls for 2 t of dried cowdung per feddan, evenly distributed in small piles on the dried pond bottom. This quantity represents approximately 250 kg of organic carbon per feddan. As water is let into the pond, 10 kg of urea per feddan are added after dissolving in water to stimulate bacterial activity. After a period of 3 weeks, the water level of the pond is raised to 40 cm at which time 10 kg of superphosphate per feddan are added to increase the phytoplankton population. Fingerlings are introduced soon after and the pond water level raised to a final depth of 1.25 metres. Thereafter, ponds are periodically fertilized with quantities of urea, superphosphate and poultry manure. Rice bran or wheat bran is given as supplementary feed to the fish every two or three days at the rate of 10 kg per feddan per feeding.
1 One feddan = 1.038 acres
= 0.42 ha
The species selected for culture in Zaweya have varied feeding habits. Sarotherodon niloticus is omnivorous although it feeds primarily on phytoplankton. Its food also includes benthic fauna, decayed organic matter and blue-green algae. Larger size fish accept pelleted food quite readily. The mirror carp is an omnivore which has, in recent years, been shown to thrive on artificial pelleted feed. Studies have also shown that it has a preference for zooplankton and aquatic insects, and that its acceptance of artificial feed increases with diminishing natural food supply. Mullet fingerlings have been observed to feed on finely ground cereal grains and mill by-products such as rice bran and groundnut oil cake, but seem to shun the coarser wheat bran.
Practice of artificial feeding in pond culture is generally to increase stocking density with the aim of higher fish production per unit area. Artificial feeds used in this manner constitute a supplementary source of food supply to augment that arising from natural productivity of the pond. Although supplementary in nature, these feeds must be balanced with respect to protein and energy content, and adequately fortified with vitamins. They should also be sufficiently stable in water to be efficiently utilized by the fish.
Knowledge of the nutritional requirements of the common carp, and to a lesser degree those of tilapia, has increased rapidly in recent years as a result of research employing purified and semi-purified diets. Application of this knowledge in large-scale culture of the species involving compound diets made from relatively inexpensive conventional feed ingredients has been very limited. Nevertheless, such knowledge is indispensable if only to serve as guidelines for commercial feed formulations. The successful application of supplementary feeding techniques for the polyculture system in the Zaweya Fish Farm hinges on the development of an appropriate artificial diet which is efficient as well as economical. Such a diet has to be based on current knowledge on the nutritional requirements of tilapia and carp.
A survey of feed ingredients suitable for fish feed manufacture was carried out in the Cairo area. Time constraints limited this survey to a few commercial establishments. These included two commercial feedmills, and two vendors of feed commodities and veterinary products.
The livestock industry in Egypt is undergoing a period of rapid expansion. Locally-produced feedstuffs are absorbed as rapidly as they are produced by the fledgling feed milling industry. Trade in many, if not most, of the principal feed commodities, such as rice bran and cottonseed meal, is very limited and comes under direct Government control. A subsidy system, instituted by the Government to lower food prices to consumers while at the same time stimulate primary production by the agriculture sector, enables the purchase of certain feedstuffs at very low prices. Preference in allocation of such subsidized feed commodities is accorded to the commercial feedmills which carry large inventories of most of the common items. Feedmills, however, are barred from trading in feed ingredients and may only sell them in the form of compound feeds. Government-regulated feedstuffs, if available elsewhere, are sold at highly inflated prices.
Due to shortages of locally-produced feedstuffs of high protein content, fish meal, meat meal and soybean meal have to be imported. These are not subsidized and are available in small quantities at feed stores.
Local ingredients inspected during the survey appeared of reasonable quality. Imports, mainly from the USA (soybean meal) and Scandinavia (fish meal), are of higher quality.
Table 1 lists the feedstuffs generally available in Cairo.
Two simple but nutritionally balanced diets were formulated for testing at the Zaweya Fish Farm. One diet was based on imported soybean meal as the main source for protein, and the other on domestically-produced decorticated cottonseed meal (Table 2). Both diets were comparable with respect to protein and digestible energy content. Levels of two important and often deficient essential amino acids, lysine and sulphur amino acids, were also identical in both diets.
The diets were prepared in pelleted form as described in footnote 1 of Table 2.
Comparative feeding trials were begun with tilapia and mirror carp fingerlings in hapalike cages set up in one of the smaller ponds (5 feddans) available at the time. The cages were made of 7-mesh woven plastic netting and measured 200 × 180 × 90 cm, and set in 75 cm water. A cover made of the same netting material was hemmed over the upper edges of each cage to prevent fish from escaping.
Fish were fed at up to 4 percent body weight daily and growth data were to be collected fortnightly. Water temperatures during the second half of March ranged between 14°C in the early morning hours to 24°C shortly after noon. The salinity of pond water before renewal in early April was 4.5 ppt. Subsurface dissolved oxygen appeared to be rather low: 4.5 ppm in the early morning and 6.2 ppm at noon time.
Stocking of fish in the cages and feeding schedules are described in Table 3.
The experiment was originally planned for a period of three months. Unfortunately, during tapping operations three days before the scheduled first weighing of fish, the water level had inadvertently been raised above the covers of the cages. As a result, a large number of fish in each cage escaped through openings along the loosely attached covers. Fish that were recovered appeared well fed and had grown over the two-week period.
The experiment will be repeated under closer supervision. Walls of the cages will be raised by 20 cm and covers will be better secured to prevent similar escape of fish.
With plans for a standing crop of 1 000 kg of fish per feddan, the present programme of controlled fertilizer inputs appears inadequate to produce enough natural food for a target yield of 1 400 kg fish per feddan per year1. Therefore, supplementary feeding is desirable.
As indicated in Table 2, a diet made of locally-available feed ingredients (Diet A) would cost about 7.7 piastres2 per kg. Assuming a modest feed conversion ratio of 2.5, the lowest feed cost for producing 1 kg of fish harvested under the polyculture system will be 13.09 piastres3.
1 See next section for further discussion
2 Exchange: One Egyptian Pound (L.E.) = 100 piastres = US$ 1.42 (March 1981)
3 Calculations are based on a harvest of 450 kg mullet and 950 kg tilapia plus carp. Assuming that tilapia and carp are the only species in the culture system benefiting directly from artificial feed, and that the feed conversion ratio is 2.5 for the two species, the quantity of feed needed to produce 1 kg of tilapia plus carp will be 2.5 kg. However, the quantity of feed to produce 1 kg of fish harvested (including mullet)
= 950/1 400 × 2.5
= 1.70 kg
At 7.7 piastres per kg, feed cost per kg fish harvested
= 1.7 × 7.7 = 13.09 piastres
It is generally held that feeds for intensive aquaculture represent 50 to 70 percent total operational cost, depending on cost of feeds relative to other input costs such as seed cost and general overheads. The cost of the proposed diet is based on ingredient prices heavily subsidized by the Government, and set against relatively low overheads but including fairly expensive seed cost (0.5 piastre for each carp fry and the same price for each tilapia or mullet fingerling), would probably account for 50 percent of total operational cost1.
From computations in footnote 3, the cost of producing 1 kg fish under the present system will then be 26.18 piastres. At current farm-gate prices of 40 piastres per kg for tilapia or carp and 120 piastres per kg for mullet, a profit of 39.5 per kg fish harvested can be realized from revenues of 65.71 piastres.
The reported “assisted” prices for cottonseed meal and rice bran - especially the latter, which at L.E. 6.7/ton, is almost as cheap as cowdung - are obviously too low. It is very doubtful that fish farmers will be able to obtain supplies at those prices.
On the other hand, if one uses “unsubsidized” prices for the same ingredients, the same diet would cost 12.9 piastres/kg. Employing the same computational procedure as before, the cost of artificial feed per kg harvested fish will be 21.88 piastres. Adding the previously assumed 13.09 piastres/kg fish for other costs, the total production cost per kg harvested fish under the polyculture system will be 34.97 piastres 2.
From revenues of 65.71 piastres, the profit is reduced to 30.74 piastres per kg of the mixed crop.
From the preceding, it would appear that intensive fish culture employing artificial feeds is a sound economic proposition in Egypt. This is especially so if fish farmers can obtain feed ingredients at the subsidized prices enjoyed by other sectors in the agro-industry. Therefore, clarification by the Government concerning the eligibility of fish farmers to supplies of controlled feed commodities such as rice bran and cottonseed meal at subsidized prices will be necessary.
Even if such relief is forthcoming, the fish farmer will have to adopt a mixed culture system such as the polyculture of tilapia, carp and mullet proposed for the Zaweya Fish Farm. The bonus harvest of high-priced mullet presumed to grow primarily on natural foods derived partly from wastes excreted by the other two species will reduce the cost of artificial feeds for those species.
Under the present programme of pond fertilization, 92 kg of nitrogen from the application of organic and inorganic fertilizers are introduced into the pond with each crop of fish 1. This quantity of nitrogen, if utilized at an efficiency of 70 percent by aquatic micro-organisms, represents an equivalent of 402.5 kg protein (N × 6.25). Translated into biomass containing 30 percent protein on a dry matter basis, this would provide a food source equivalent to 1 342 kg of artificial diet proposed.
1 Seed and fertilizer costs have been estimated at L.E. 58.05 and 42.00/feddan, respectively (or, 3.87 and 2.80 piastres, respectively, per kg fish expected to be harvested)
2 The higher feed cost representing 62.6 percent of total operational cost as compared to 50 percent in the earlier computation using “assisted” prices for ingredients
3 Estimated nitrogen input from fertilizers under the present programme:
|kg/feddan||% N||kg N|
If a production of 1 400 kg fish per feddan is targeted, 3 500 kg diet of that quality is required and the shortfall of 2 178 kg feed must be met by supplementary sources. This shortfall roughly equals the food requirement of carp plus tilapia if fed on artificial food alone 1.
Plans at Zaweya call for the stocking of 840 feddans of production ponds. Should an intensive feeding programme be instituted, 1 821 t/year of compounded feed or 5 t/day would be required. In order to produce this quantity of feed, the installation of a feedmill, capable of producing 1 t/h of pelleted feed, will be necessary.
Table 4 lists th machinery components for a pellet mill that will produce 1–1.5 t of pelleted feed.
The present programme at Zaweya calls for the stocking of fingerling-size tilapia and mullet for production of table fish, but carp fry will first be stocked in nursery ponds for growth to fingerling size, deriving all their food requirements from an appropriately fertilized nursery pond.
Artificial diets have been successfully used for rearing of carp fry in recent years. Table 5 shows five diets of varying costs suitable for common carp fry. These formulations should be evaluated for their relative efficacy either at the Fowa Hatchery or at Zaweya.
The aborted feeding experiment reported herein should be repeated following the procedures outlined earlier in this report. More uniform size fingerlings should be used. Stocking in cages involving mixed tilapia and carp culture should be in the ratio intended for the polyculture system, i.e., 93 percent tilapia and 7 percent carp.
1 Since 950 kg of tilapia and carp are harvested per feddan, their total estimated feed requirement, assuming a conversion ratio of 2.5, is 950 × 2.5 = 2 375 kg
|Moisture||Protein||Fat||Fibre||Ash||NFE1||Lys||Met + Cyst||Subsidized||Unsubsidized|
Maize gluten meal
Poultry by- product
1 Nitrogen-free extract
2 These are Government controlled prices. Subsidized prices apply to qualified users such as commercial feedmills. Practically all imports are unsubsidized. Commodities purchased outside Government price structures are considerably more expensive. Certain ingredients can only be purchased in the open market, viz: dl-methionine, l-lysine and vitamin mixtures cost 600, 725 and 1 200 piastres/kg, respectively
NA: Data not available
Calculated chemical composition
Methionine + cystine
Digestible energy, kcal/g
1 Preparation of diets: rice
bran and bone meal were mixed and boiled with water constituting 100 percent
total weight of the diet. The purpose of boiling was to bring out the natural
binding properties of starch to produce water-stable pellets. The slurry
was then allowed to cool slightly before the remaining ingredients, previously
mixed, were blended in. The resulting dough was then passed through a kitchen
meat grinder fitted with a 2 mm die. The moist pellets produced were dried
in the sun over a fine mesh screen. Pellets were crumbled to smaller particle
size before feeding.
2 The vitamin mixture used was a commercial product for poultry and, as applied, provided the following (per kg diet): vitamin A, 5 000 IU; vitamin D2, 600 IU; thiamine, 10 mg; riboflavin, 20 mg; pantothenic acid, 30 mg; niacin, 50 mg; pyridoxine, 2 mg; and ascorbic acid, 200 mg.
3 Based on lowest ingredient costs from Table 1.
|Cage Number||Diet A||Diet B|
|Species1||T||T + C||C||T||T + C||C|
|No. fingerlings||20||6 + 8||15||20||6 + 8||15|
|Initiate group weight (g)||200||85 + 95||250||220||75 + 105||250|
|No. fish recovered 9/4||2||1 + 4||3||0||2 + 3||12|
|Weight of fish recovered (g)||21||15 + 50||55||-||26 + 45||200|
|Initiate daily feed % body weight3||3||3||3||3||3||3|
1 T - Sarotherodon niloticus; C - Cyprinus carpio
2 It was not possible to provide enough time for fingerlings to recover from stress arising from transport and handling prior to the experiment. To minimize further stress during stocking in the cages, it was decided to record only the group weights in each case. Ideally, fish should be weighed individually. This procedure will be followed in future.
3 The actual daily feed given was based on projected daily growth of 1.25% body weight per day
When fish were weighed for the first time on 9 April, it was discovered that many had escaped through openings along edges of the cage covers loosely hemmed to the walls. This happened when the water level in the pond was allowed to rise excessively. Consequently, the experiment had to be terminated on that date. Plans have since been drawn up for repearing the study with improvements in cage construction and proper conditioning of fish before the experiment.
|Item||Motor Horsepower||Approximate Cost (US$)1|
|- 503 ft capacity||5||9 900|
|- 1.5 and 2 mm screens||30||9 300|
|- pellet mill|
|- steam conditioner|
|- surge bins||45 (total)||41 200|
|- 2 mm dies|
|- 10 m discharge height||1||7 300|
|- 4 m long||3||3 200|
|- 15 HP at 150 psi||0.5||No price|
1 Estimated dockside prices
quoted in mid-1980 by one US manufacturer
2 Excluding boiler cost
|Meat meal (local)||20||15||45||10||-|
|Maize gluten meal||-||-||20||20||20|
|Calculated approximate analysis|
|Methionine + cystine, %||1.4||1.3||1.4||1.5||1.6|
1 See Table 2 for details
2 Based on lowest prices indicated in Table 1