FISH FEED TECHNOLOGY

UNDP/FAO PROJECT THA/89/003

(1 SEPTEMBER TO 31 OCTOBER 1990)

BY

YASUTOYO NAGAI, Ph.D.

Hyperlinks to non-FAO Internet sites do not imply any official endorsement of or responsibility for the opinions, ideas, data or products presented at these locations, or guarantee the validity of the information provided. The sole purpose of links to non-FAO sites is to indicate further information available on related topics.

This electronic document has been scanned using optical character recognition (OCR) software. FAO declines all responsibility for any discrepancies that may exist between the present document and its original printed version.

CONTENT

Part 1 Scope of the programme

Part 2 Phylosophy and Strategy

1. Phylosophy

2. Strategy

Part 3 An approach to duty matters

Part 4 Advices on duty subjects

Part 5 Farm visit

Acknowledgement

Addendum (Used as texts for discussions)

A. General situation of Japanese fish culture

B. Vitamin Requirement of Yellow Tail fish

C. Penaeus production in Japan

Part 1 Scope of the programme

On arrival to the duty station, a study was commenced to know what is my problem. The first week was spent to visit UNDP, FAO/RAPA, NACA, NIFI to get knowledges on general situation of fish culture in Thailand.

The second week was spent to read documents and governmental statistics, and visited some private companies to discuss on fish feed problems in Thailand.

The problems I found here were:

1. Cheap feed is asked for artificial feeds according to fish culture systems.
2. The effective use of feed additives.
3. The improvement of quality of pellets, using cheap local raw materials.
4. To give water-stability to pellets.
5. Process control to produce good pellets using existing feed mill in NIFI.
6. Introduction of an expander-extruder machine to produce a floating pellets at NIFI.
7. And others.

To fullfil my duty, I have selected a way to start my work. It was to talk on my experience in a Japanese fish feed mill. I asked to Japan to send me commercial fish feed samples of various types and a series of shrimp feeds, related catalogues also.
At the same time, I prepared a small text on which discussions with my counterpartner will begin.

The third week and the fourth week were spent to explain the matters I know to my counterpartners, showing arrived feed samples of various types, pellets, crumbles, granulated small particle feeds and so on. Explications were proceded with my text and catalogues in the morning, then questions and answer as well discussions in the afternoon.

From the fifth week to seventh week, several experiments were done together with my counterpartners using existing equipments in NIFI. Then my report was written.

Because I am interested particularly in a fish feed which should be used for extensive or semi-intensive fish culture but not for intensive fish culture for which the fish feeding theory has developed, a new type of feed mixture was used in our pelleting experiments. Ingredients formulation and the nutrient composition calculated using an analyticle table prepared by Department of Fisheries of Thai government were shown in Table 1.

Table 1. Formulation and nutrient composition of the feed.

Part 2 Phylosophy and Strategy

1. Phylosophy

Many studies on fish feed and fish culture have been carried out on the countries where climate is temperate or is rather cold and seasonal water temperature change is common, aiming to apply the results of research for intensive fish culture. In such a countries, price of fish is comparatively high.
However, in Thailand, social, economical and natural conditions are different from these countries. The climate is tropical, water temperature 3is fairly stable all the year around between 25° – 30° C. Water is very rich in planktons which serve as a natural feed supply source for fish, especially in micronutrient such as vitamins and minerals.
Space and water are very aboundant in Thailand where native fish grow and fresh water fish culture to expand but a feature of land here is very flatt and water runs rather slowly. Then price of fresh water fish is generally cheap.
The artificial fish culture requires three technical elements, i.e. 1) supply of enough seedlings, 2) source of needed amount of artificial feed and 3) feeding technology for a good management.
Another than the application of theory and practice which were borne in different countries where intensive culture is common, a special study is needed to establish Thai system of fresh water fish culture on fish species, on artificial feeds and on feeding technology. An intensive fish culture requires a lot of investments, equipments to prevent water and pond from pollutions, high quality feeds, medicines and energies to keep dense population of fish.

2. Strategy - extensive and semi-intensive fish culture -

2-1 Feed

For an intensive fish culture, generally we select a combination of protein and fat content in feed according to culture conditions, i.e., fish species, a targeted quality of fish, water temperature, period of rearing, density and so on. Basic combination of protein and fat were shown in Table 2.

Table 2. Basic combination of protein and fat in artificial fish feed.

The nutrient requirement of a fish for growth and reproduction does not differ under intensive culture and extensive culture. In intensive fish culture, we can not expect natural feed supply at all but for extensive and semi-intensive culture in Thailand, we can expect natural feed supply in some extent or in a lot. Therefore we may use an artificial feed which is not complete in its nutrient composition compared with fish nutrition theory, for extensive and semi-intensive fish culture. This artificial feed is cheap in price and practical for fish growth, having low protein in the form of a pellet.

For intensive culture we can expect 50 tons fish yield for 1 rai and for extensive and semi-intensive cultures, 2 and 6–8 tons respectively. In Table 3, one model of a clarias catfish culture under different densities and feed is demonstrated.

Table 3. One model for a Clarias catfish culture under different densities depends on natural conditions.

Under the momental social and economical conditions, research and study of extensive and semi-intensive fresh water fish culture in scientific method is seems to be a choice worth to try.

2-2 Raw materials - tapioca and rice bran -

Tapioca (2BT/Kg) and rice bran (4BT/Kg) are the cheapest raw materials available in Thailand. But tapioca is not in use for commercial fish feed in Thailand. For extensive and semi-intensive culture feed, the maximum use of these two raw materials may help to reduce feed cost. A preliminary experiment tried by us here showed a pellet obtained which contained 45% of rice bran and 25% of tapioca meal as formulated as in Table 1 had a possibility to possess a satisfiable physical properties and acceptability by a Clarias catfish.
A further research on the use of tapioca for artificial fish feed is expected.
These feed may applicable only for extensive and semi-intensive fresh water fish culture in tropical areas.

The use of fat as an energy source of fish feed will be discussed later.

Part 3. An approach to duty matters.

NIFI mill has three equipment to prepare experimental feed pellet. They are ;

1. Kneeder-chopper type moter-driven extruder “HOBART”
2. A small pelleter without cutter (the name is unknown)
3. CPM pellet machine.

A pellet obtained by conventional process here with CPM pellet mill is soft and fragile, rough surfaced and collapes very easily in water. Milling of raw materials are not fine enough to prepare a small pellet which diameter is 2.3 mm.

Experiment 1

A feed mixture obtained by conventional mixing of raw materials was tried to make a pellet adding 3% addition of binder (2:1 mixture of guar-gum and CMC) and 40% of moisture. The mixture passed through very easily HOBART chopper and the material was not compressed to obtain pellets. A mixture was pre-steamed before to pass the chopper but physical properties of the product was not improved at all. “HOBART” is not a proper equipment to prepare pellets by the lack of pressure, though this is usable to prepare an experimental feed.

Experiment 2

Each raw material was fractionated according to size of particles by rough shieving. The next distribution pattern of particles are obtained for each raw material (Table 4).

Table 4. Particle size distribution pattern of raw materials

Experiment 3

An attempt was made to prepare a pellet using a mixture of finely powdered fraction of each raw material by a small pelleter, adding 50% of water to this mixture. A pressure was not strong enough to compress the materials, the pellet obtained after drying was stable in some extent in still water. Pellet remained in water without dissolving more than 30 min.
This experiment shows that well-milling of raw materials is required to obtain good pellet. A desirable particle size of raw material is 1 mm-pass.

Experiment 4

A feed mixture prepared by conventional way was milled by an existing crusher of NIFI and the particle distribution pattern was compared before and after remilling. The result of remilling was not satisfactory enough, coarse and middling fractions were decreased and fine fraction was increased from 71% to 88% (Table 5).

Table 5. Particle size distribution after remilling of a raw material mixture.

Experiment 5

Using remilled feed mixture, 100 Kg of 2.3 mm. pellet was produced by CPM pellet machine. A smooth-surfaced good-looking pellet was obtained. After 150 times collision test, powder rate was less than 1% but water stability of this pellet was quite low. It dissolved quickly in water. A boiler took a trouble during pellet production and enough vapour was not available for pelleting. That may be a main reason why the pellet was not strong. The supply of moisture and heat seemed not enough to let work tapioca starch as a binding material.

Experiment 6

Using finely powdered rice bran as a carrier, A vitamin premix was prepared and how to use micronutrient premix was demonstrated.

Experiment 7 Measurement of mixing accuracy

To 2,000 g of a finely powdered feed mixture, 500 sesame seeds were added and mixed by HOBART mixer for 4.5 min, then numbers of sesame seeds in certain amount of samples were counted after shieving. When we sampled 20 g of mixture, the average mixing accuracy was 110% and when we taken out 40 g as a sample size, the average mixing accuracy was 80%. Theoretically 4 g of this feed mixture contained 1 sesame seed and mixing accuracy is expressed as a rate of actual sesame seed numbers to theoretical numbers.
It was demonstrated that mixing time should be determined according to mixing accuracy test and how important is to select sample size to get good mixing.

Experiment 8 Check of fish quality

To establish a standard of fish quality is a basis of fish culture management. Here today, people's interest is in more production in quantities but without having a quality standard, we can not improve fish feed quality and feeding technology scientifically. In experiment A, 5 Clarias catfish were selected and in experiment B, 3 snake-head fish were offered to check fish quality. The average results were shown in Table 6.

Table 6. Fish quality checked.

* Fattening index was calculated as follows
Body weight × 1,000 / (Folk length)³

Generally speaking, fat content of meat is an important index of fish quality. It is noticiable that fat content of catfish in this case is quite low. I don't know how to appreciate this value but fat content in meat is related how to use fat in feed.
How to use fat for fish feed in warm water species of fish is an important problem, I think.

Part 4 Advices on duty subjects

4-1 Description of duties :

1. Advise on the upgrading of the existing fish feed mill of NIFI.
2. Advise on the economic and engineering aspects of feed mill construction with special reference to small-scale and research operations.
3. Advise on the micro-ingredient distribution in feed materials and the related effects on the quality of mixtures.
4. Advise on the improvement of nutritional value and reduction of toxic materials in the feed preparation process.
5. Advise on and review of the feeding regimes as well as the research program related to fish feed technology.
6. Advise on and review of sinking pellet and floating pellet manufacturing by using locally available feed ingredients.
7. Submit a technical report at the end of his assignment.

4-2 Advices

1–2 The chopper-type extruder “HOBART” is good enough to prepare experimental feed but not appropriate to use as a pilot machine of pellet production because this equipment cannot have necessary pressure to compress the material. The another reason is a temperature control is impossible.
A small pelleter also has the same defficit to use for a study of pelleting. A CPM pellet machine is operatable but temperature and vapour are not under control. Repair of the boiler is hoped.

A direct use of purchased raw materials to manufacture of pellet is not desirable because their particle size distribution is too rough to produce a small pellet of good physical properties. To improve physical properties of pellets, shieving or remilling of raw materials are recommended. Remilling after all the raw materials were mixed may be practical. Minor nutrient should be added to remilled mixture. A care should be taken for shieving because a change of nutritional constituent in shieved fraction may occur.

3. A method is presented to check the uniformity of mixtures. The use of premix to add micronutrient into the feed is better than direct mixing. The selection of carrier is to be minded.

An existing mixer “HOBART” has no cover. A cover is necessary to prevent a loss of light component during a mixing.

4. A simplest way to produce good feed is to use good raw materials if the production procedure is the same.

To keep good quality of raw materials, to have a specification of raw material is indispensable. Also a specification of the product is invitable.

An example of specification of fish feed is at minimum,

1. Guarantee of feed quality (nutrient composition)
   1. Moisture (less than)
   2. Crude protein (more than)
   3. Fat (more than)
   4. Ash (less than)
2. Size of pellet
3. Date of production and a term of guarantee (preservable period under certain conditions).

For raw materials

1. Fish meal or other protein source material
   1. Moisture
   2. Crude protein content
   3. Ash content
   4. Allowance for foreign matters (salt et al < 3%)
2. Specification for toxic contaminants. Heavy metals, agrochemical residues, biological toxic materials.
3. For vitamins, potency
4. For minerals, purity
5. For oils, colour, smell, AV (<20), POV (<20), addition of antioxidant.

To remove off toxic contaminants from raw materials is practically hard. The best way is not to use such a raw materials which contaminants exceeds the specification. In the case of inevitable use, contaminants should be diluted by clean raw materials.

5. In Thailand, tapioca is not in wide use as a raw material of fish feeds. Tapioca meal contains more than 70% of starch and hervivorous fresh water fish which has long digestive tract may digest starch well. When tapioca starch is converted to α-starch by the action of water and heat, the digestibility of tapioca meal by fish will be enhanced further. Moreover, α-typed tapioca starch has a binding power which is indispensable to make feed pellet. A price of tapioca is charmingly cheap in Thailand. Rice bran is also a cheap and important raw material for fish feed here. Physical properties of rice bran purchasable in a market is rough to use directly but we can improve the physical properties to mill it into very fine particles less than 0.1 mm in its particle size. With a combination of α-typed tapioca starch, desirably by a use of extruder-expander machine, we can expect to prepare a stable pellet which contains 50% of finely powdered rice bran.
For cold water fish, both of these raw materials, starch and rice bran are not well digestive but our knowledge of nutrition on tropical fish species is poor. To study on the maximum use of tapioca and rice bran on tropical fresh water species has an important meaning from a view point of industry.

A Clarias catfish disected showed a very little fat in muscle.
In commercial fresh water fish feed in Thailand, fat content is generally low and is less than 5%. Does tropical fish species not assimilate well fat? Generally speaking, fat is a good energy source for many species of fish. We can reduce protein content of fish feed by the use of fat and the application of high energy diet is common for fish culture in many not tropical countries.
Researches on high energy feed corelated with fish production and fish quality will be also helpful to design artificial fish feed here.

6. A physical property of pellet to sink or to float is determined by its specific gravity. Using an ordinary pellet machine we cannot produce floating pellet because the machine compresses materials expelling all air included in a feed mixture. We can adjust specific gravity of pellet in some extent by the addition of fat or oil to pellet, but it is difficult to add much fat or oil to pellet because a pellet is compressed well already. The most practical way to produce floating pellet is inject many small air bubbles into pellet and an extruder-expander machine was invented for this purpose.

Inside of the expander a feed mixture is cooked with vapour under high temperature and high pressure and when the mixture is extruded suddenly out of the machine, the material expands enfolding air bubbles inside. This is a principle to produce floating pellet by the expander machine.

NIFI is on the way to introduce an expander. I was told that the expander would come soon and I would work on this machine but machine is not arrive in time.

To keep vapour pressure and temperature constant during the operation of an expander is not so easy. An experience and skill of operater are required to produce expanded pellets which has the same floating property all the time, expansion of feed mixture is affected by a small change of conditions even keeping the same formulation of raw materials.
I expect the expander is a usefull tool to utilize tapioca and rice bran for fish feeds.

Part 5 Farm visit

During my stay at NIFI, I had two study visits to fish farm conducted by Mr. Prasert Sitasit. The one was a visit to a prawn farm in Rayong and the other visit was to snake-head fish farms in Suphan buri.
The prawn farm had a feed mill which produced 1.2 t of 2.3 mm pellet per day and self-made crumbles prepared by a crumbler and shifter were used for young prawns. Partly, commercial feed was used also after fortification of vitamins culture here producing 10t/ha/person/year by 2 crops. The feed cost told was 40% of the total production cost. Actually feeding management is good in this farm though cheaper feed is required. This farm was the only one which has own feed mill among many farms in Rayong province.

In Suphan buri province, self-made moist feed was in use for snake-head and also for catfish culture. Each farm has a chopper-mixer to prepare moist feed. At each time just before of feeding, trash fish and mash feed are mixed adding some another materials such as several byproducts of meat and food processing, to make moist feed.
The productivity of snake-head fish culture in this province is very high using this feeding method.
Water is not seems to be clean at all and several dead fish were floated on a bank side.
Snake-head fish is sayed to be a quite strong fish, can survive under very low oxygen and requires very few oxygen for active metabolism, eating anything for the growth.
To check water temperature, pH, ammonium, oxygen and so on is not required. Only one technical management necessary is to watch colour change of water. When water is observed to be loosing its green colour, immediately, fresh water should be inleted to the pond from a canal to exchange pond water.

This empirical technique to keep water colour constant is very simple but difficult to realize all the time. The use of moist feed may have an advantage here and the accumulation of many experience has helped to give rise present management method under particular natural conditions in Suphan buri. Peoples are very proud of this culture method invented by themselves and successful result. A fish offered us to eat was very good.
It seems that scientific examination will be needed to keep environment clean and healthy and to develop further this fish production.

Acknowledgement

As finishing my duty in Bangkok, I wish to express my heartfull thanks to all the peoples of NIFI where I stayed for two months, especially to Mr. Prasert Sitasit (Government Project Manager and Head of Fish Nutrition Research Group) who gave me usefull informations to understand the situation, to Mr. Pairat Kosutarak and to Dr. Wimol Jantrarotai (Fish Nutritionist of NIFI) who have worked with myself helping me very much and to Ms. Benjaluck Lertbhuddhikul (Administrative Assistant) who was very able to arrange conditions for my work. Another thanks are dedicated to :

Mr. Kitjar Jaiyen (Director of NIFI),
Mr. H. Tsuchiya (Deputy Regional Representative of RAPA),
Mr. Imre Csavas (Regional Aquaculture Officer),
Mr. Ratana Tanchavalit (UNDP Officer)
and many other peoples who concerned on this project.

Addendum A.
A. GENERAL SITUATION OF JAPANESE FISH CULTURE

Total catch 11 million tons including imports
Number of fisherman < 400,000 persons
Annual fish consumption per capita 28 Kg

(1) Inland fisheries

YEN 6 = 1 BT

• Problem; no more water, no more consumption

(2) Marine fisheries (under culture)

Prawn consumption is 2 prawns per week per head.

• Problem

1. diseases, parasites.
2. low profitability by low survival rate.
3. lack of workers.

What to do:

1. introduction of new species.
2. to supply live fish.
3. mechanization of the culture.

(3) Fish culture management

Production cost:

Feed cost should not be exceed 40% of production costs.

(4) Japanese fish feed industry

Japanese formula feed production for fish started at 1960 imitating american trout feed.

In succession, carp feed, eel feed and other feeds production were commenced.

For marine fish culture, the use of Oregone type moist feed is popular but in this few years a replacement by dry pellet started. In winter the use of dry pellet for marine fish has still many problems.

B. Study of the artificial feed

1. Formulation
2. Production
3. Feeding technology
4. Quality control (establishment of specifications)

(1) Topics in the formulation

1. Estimation of nutriment requirement of fish.
   Determination of minimum requirement and desirable amount in the feed.

2. Estimation of nutritive value of the feed.
   Digestibility.
   Feed conversion rate.
   Growth velocity of fish.

The formulation of artificial fish feed by Japanese Governmental Institute is aimed for healthy fish under standard condition.

The formulation by feed manufacturer is more practical aiming fish growth under stressed conditions.

The nutrient requirement is determined by using very purified reagent class substances as feed component. Practical feed is composed of many natural raw materials.

Generally, a Japanese commercial fish diet contains more vitamins than minimum requirement except for Myo-inositol.

1. Fish meal

   Animal protein is very susceptible to heat denaturation. Heat denatured fish meal shows lower Biological value compared with intact one.
   In the course of fish meal production, the higher the temperature, the worse the quality.
   In Norway, LT meal is in wide use to manufacture Atlantic salmon feed. (LT means low temperature which is below 70°C).
   By our experience, heat-dried egg protein and milk protein were good for young fish but useless at all for larvae.

2. Soybean meal

   To use soybean meal for fresh water fish, there is less trouble but to use this for marine fish, a doubt remains.

   Theory        Soybean meal + methionine = fish meal
   Soybean meal + methionine + lysine = fish meal
   Soybean meal + methionine + lysine + tryptphan = fish meal

   but still fish meal is better than adjusted soybean meal.

3. Amino acids mixture feed

   It is very difficult to grow fish by amino acid mixture feed. In many fish, free amino acid is absorbed very quickly and is excreted immediately.
   Fish needs amino acid in the form of a protein.

   How amino acid requirement of fish was determined ?

   The quality of a protein is estimated measuring its Biological value with live fish, not by amino acid analysis.

4. Minerals, Iron

   1. ferrons ammonium sulphate
   2. ferrons citrate, ferrons fumalate, ferrons succinate
   3. ferrons glycine, ferrons threonine etc.
   4. ferrons peptide.

   In my experiments, testing many sorts of ferrons complex as iron sorces in the diets, our tuna showed a low hematochlit value, lower than 50. But feeding fresh fish to tuna, this value was improved easily above 50. Generally speaking, in Japan cultured fish by artificial feed shows a slite anemia, may be the reason is iron defficiency.

5. Vitamins

   Quick growing fish requires more vitamins. Some vitamins are unstable against processing. Examples are vitamin C and folic acid.
   For usual pellet, calcium ascorbate is used commonly and sometimes free ascorbic acid coated by fat also is in use.
   A new trial is to use ascorbic acid derivatives. Ascorbic acid salt
   Ascorbic acid stearate, Ascorbic acid palmitate
   Ascorbic acid sulphate
   Ascorbic acid monophosphate
   Ascorbic acid polyphosphate and its salt

   We repeated to use ascorbic acid 2-sulphate as a vitamin C source but wecould not detect ascorbic acid in fish blood. Someone says that if water temperature is higher, this sulfate increase ascorbic acid concentration in fish blood.

   The phosphate is under investigation but the price of phosphate is too much expensive (8,000 BT/Kg).

   One method to add ascorbic acid to the feed is to mix finly powdered ascorbic acid itself with liquid oil. We pour this suspension into expanded pellet.

   The minimum requirement of vitamins to fish differs depending on the diet composition. When oil concentration is increased (when unsaturated fatty acids are increased), we have to add more vitamin E to the feed.

   Some scientist says that myo-inositol requirement of yellow-tail is 200 mg/Kg feeds. Another scientist says it is 400 mg at minimum. There is a report that yellow-tail requires more than 800 mg myoinositol / Kg feed.
   When the theory is so different we have to choose one level of addition to the practical feed.
   In Japan we don't use myo-inositol in such a high level but fish grows healthy.

6. Fat

   Usually we use oils as an energy source for fish. Generally, melting point of fats is higher than body temperature of fish, but at water temperature above 25°C we can use animal fat such as tallow or lard in a mixture with fish oil which supply necessary HUFA. The addition of anti-oxidant is indispensable.

   Young fish requires lecithin. Inositol + Choline can not replace for lecithin.

7. Water

   We can feed many species of fish by dry pellet after training. But some marine fish does not eat dry pellet. When fish has eaten dry pellet, the pellet in fish stomach absorps water quickly untill the water content reachs 70–80 %, then wet mixture is sent to intestine gradually. Generally 10 to 12 hours are necessary for stomach to get empty.
   When fish does not eat dry feed, if we add water to the feed, fish starts to eat moistend pellet. Sometimes, water is very important palatizer especially when water temperature is low at see.

   Wet feeding
   Presently, wet feeding is very common to culture marine fish. It is as follows. We mix chopped trash fish (mainly frozen sardine) with an artificial feed which contain binder. A mix rate is 50:50 in summer and 70:30 in winter. The mixture is pelleted in a culture site just before of the use by a hand of fish-culture man. This technique has several advantages.

   1. Cost is cheaper than to buy dry pellet.
   2. To help to keep water clean than to use chopped trash fish.
   3. One can choose freely what medicine to use.
   4. fish eat this type of moist feed well.

   But the situation is changing to use dry pellet even in marine culture because this technique needs human hand and moist feed is not suit for mechanical feeding.

8. Governmental regulations in Japan

   There is a strong regulation by central government to produce a commercial feed for sale in Japan. We have to describe clearly what feed we sell. The aim of this regulation is to protect consumers.
   We have to use only permitted raw materials for commercial production. There is another restriction by local government, for example, to feed fish in a big lake (cage culture) to prevent water pollution. The feed should be less than 40 % in protein and phosphate is less than 1.2 % as P.
   A “Law of quality and safety” is a very important law for Japanese feed makers.

B. PRODUCTION OF USUAL PELLETS AND CRUMBLES

1. Grinding of raw materials

   Hammer mill (continuous type)
   Grinder mill

   Separate milling for small-sized feed (0.1 mm)
   Whole milling for large-sized feed (1.0 mm)
   distribution pattern of particles (Fig. 1)

2. Mixing

   Horizontal type (libbon mixer)
   Vertical type (Nauta mixer, V-blender)

   Generally butch-wise

   is mash obtained uniformally mixed?
   no reseparation ?

3. Pelleting

   CPM type pelleter	steam 6–7 %
   Extruder	steam 20–25 % for cooking

   To produce small size pellet (¢= 1 mm, 2 mm), vertical type die is used. (Fig. 2)

4. Crumbling

5. Shieving

6. Drying, cooling and packaging

C PREPARATION OF STARTER FEED (FOR LARVAE)

1. The case of marine fish

1. Egg Æ< 1 mm.
2. When hatched, body length of larvae is 2 mm.
3. Mouth width is less than 20 u.
4. Feed size is less than 10 u.

Digestive truct (digestive organs) is not completed and not active. There is no digestive enzymes in the truct. The way of nutrition is pynocytosis (intra cellular digestion). Fat is absorbed as fine particles and protein also. So only water-soluble protein which has a molecular weight between 200,000 –4,000,000 is available for new born marine fish larvae. Artificial diet for this stage of fish is not yet completed.

A natural feed series we use for fish larvae is diatoms, arotifers and artemia according to fish growth.

To keep fish larvae in / ton of sea water, we needs 3 tons of rotifer tank and 5 tons chlorella tank which is used to feed rotifers.

Artificial feeds to replace rotifers and artemia are in the market.

2. Preparation of larvae feed

1. Built up method

   > Dry process

2. Break down method

   • Microencapsulation by spray-dryer
     Æ= 50 –120 u
     wall materials, carageehan, casein, gelatin etc.

   • Enlargement of particles by floating layer dryer
          (Fig. 3)
     Æ= 1 mm
     binder is usually CMC

   • Micropowderization at low temperature
     Dissolved materials are mixed with binders, freeze-dried then powdered.

     Wet process preparation
     Æ surface - polymerization

     Æ gel formation by the use of alginate
     (Fig. 4)

D. FEEDING TECHNOLOGY

Case of Yellow tail (seriola quinqueradiata ?)

1. People choice is very different at east and west of Japan to meat quality, so at first concern a fish farmer has to decide what fish he grows.

   (Fig. 5)

2. Culture conditions
   Sea water temp: 14°C in Winter, 30°C in Summer

   Cage;    iron cage or plastic net (to be sweep or exchange to remove biological attachers.

   Cage size;   10×10×10 m
   8×8×8 m (a plastic net cage - 50,000 BT)

   Density;   5,000–10,000 young fish in a cage

   Production scale; one family (2.5 persons) can take care of 6 cages and annual production is 50 – 60 tons.
   Small farms as a family business have 3 – 6 cages. A big fish farming company posseses 120 – 170 cages. About 9,000 families are engaging on the culture of yellow tail and sea bream. Number of big farming company is 70 – 80.

3. Growth rate
   Natural fingerlings are caught in 70 – 80 millions in 3 g size between May and June. In a nursery one should use artificial feed to grow fish 50 – 100 g, otherwise, fish does not eat dry pellets in future.

   May	July	October	December ------------------- the next December
   5 g	100 g	800 g	1.2 Kg	4.5 Kg

4. Set up of feeding table. Feeding scheme varies by feed quality and the aim of fish farmers, until when they want to produce what quality fish.

   Satiety feeding is dangerous for fish health when sea temperature changes. To avoid over feeding, 80% feeding is generally adopted. In summer, we reduce feeding rate more.

   Feeding rate is selected by water temperature, fish size and feed quality.

5. Some feeding experiments

   1. Effect of water contents in feeds to the growth giving the same amount of dried material, fish given moist feed grew 10% more in body weight at the end of December compared fish given dry feed. Moist feed contained 60% of water. When feed is moistened by sea water, no effect was observed.

   2. Interval feeding
      1. Given 1/7 feed every day in a week
      2. Given 1/5 feed from Monday to Friday
      3. Given 1/3 feed 3 days a week (Mon. Wed. Fri.)

   After 2 weeks feeding, the fish growth was 1>2>3

6. Artificial moist feed feeding

   Price of materials,	frozen sardine	7 BT/Kg
   	mash	34
   	pelleting cost ad situ	3
   		43 BT/2 Kg feed

   composition of feed

   	CP	Fat	Moisture	Ash
   frozen sardine	17 %	5–25 (20)%	70%	12
   mash	55	6	10	18

   Average composition of mixture (mixed 50:50)

   36 %

   13

   40

   15

   In sardine, fat + moisture = 73 %, so measuring water content we can determining fat content of sardine in 15 min. (Automatic moisture analyzer).

   If sardine is not fat enough (when fat content is below 75%, we have to add fish oil to moist pellet).

   Price of moist pellet is 22 BT/Kg
   Feed conversion rate 3.6
   Feed cost to produce1 Kg fish 22 × 3.6 = 80 BT

   A desirable moist feed composition for yellow tail growth

   CP	35 %	Calorie/protein = 100
   Fat	20
   Moisture	40

   for fattening C/P 120–140

   In winter, we change a mix rate as frozen fish 70% to mash 30%.

   Summer	Growth season
   Winter	Fattening seasen

   Fattening index 19

   

7. Dry feeding

   Composition	CP	Fat	Moisture
   	50%	24%	10%	C/P = 83

   When more energy is needed, we add fish oil (20 BT/Kg).

   Price 46 BT/Kg
   Feed conversion rate 1.8–2.0
   Feed cost to obtain 1 Kg fish 83–92 BT

   Dry feed is very costly but is suitable for mechanical feeding.

   • Mechanical feeding
     Pipeline feeding with water stream from a station.

     To feed breams, a feeder is set on buoy.

E. QUALITY CONTROL

1. To keep specification of raw materials.
2. To maintain the appearance of feeds.
3. Product analysis (nutritional components and residues).
4. Field test in a production scale when the formulation was changed.
5. Biological infections (fungis, insects).

• Sort of claims
  1. feed appearance change
  2. contamination by extra-sized pellets or the powdered.
  3. palatability
  4. deterioration (rancidity of fats)

Addendum B.
Vitamin Requirement of Yellow Tail mg/Kg feed

1. Generally, vitamin requirement of fish has been determined as a requirement for the growth. This requirement is so under the condition where liver content of the mentioned vitamin is saturated or nearly saturated. Recommendation means the amount of vitamins in the feed necessary to saturate the liver. To saturate blood concentration, we need less.
2. When growth retardation is observed even giving a feed which satisfy minimum requirement of vitamins, the vitamin level in liver is lower than normal.
3. Yellow tail does not require para-aminobenzoic acid nor vitamin K.
4. 4. When protein content of the feed is increased 50% to 70%, also vitamin B₆ requirement increases to 1.5 times.
5. When fat content is increased from 8% to 15% and 25%, vitamin E requirement increases as 35, 93 and 160 mg/Kg feed. However in this case, vitamin B₂ requirement changes as 3.0, 3.4 and 3.5 mg/Kg feed.
6. When carbohydrate is increased, B₁ requirement also increases. We have no experience on high carbohydrate diet.
7. In the case of vitamin defficiency, blood vitamin decreases very quickly, generally decreases to 50% in 3 days.
8. Abnormal behaviour of fish by vitamin defficiency is observable generally in 2–3 weeks as retardation of growth, loss of appetite, death, convulsions, hemorrhage, anemia etc.

Composition of a Vitamin Supplement

Emulsifier (monoglyceride or sugar ester)

Addendum C.
Penaeus Production in Japan

B. Artificial culture
Limitted in south western part of Japan

Cultured prawns don't compete for natural one on the price. Price of live prawn moves in a market independently from fresh or frozen one. When cultured prawn is dead, price is as same as imported one. (300– 350 BT/Kg).

1. size of culture prawn in December

   Standard size	20 g/each
   Max	35 g

   Seedling production starts in April and finish in July using tank (100 ton) with aerater and sea water inlet, outlet pipes.
   Minimum size of PL production is about 20,000,000 tails. 2 persons are necessary for this production.
   Diatom culture has many problems. Some times diatoms mutate or change their size and shape. Population control of diatoms is difficult under such a condition.
   Artificial diet which replace diatoms completely does not exist yet. When we use artificial feed, we have to add 1/10 natural feed to artificial feed, may be as a vitamin source.

2. Culture density and farming method

   		density
   (a)	Æ30 m round tank culture	4 Kg/m2 (now not in use)
   (b)	pond culture (Large scale)	1.0–1.2 Kg/m2
   (c)	Dike	1.0–1.4 Kg/m2

   A combination of (b) and (c) are common in new farms. sands are necessary at 20 cm thickness on bottom.

   Each method has different water exchange systems. Temperature and Do should be watched all the time especially in night time.

3. Feed and Feeding

   3 essentials in feed

   1. Polatability
   2. Quick growth
   3. Stability in water (temperature, pH, salinity)

   Best raw materials for P. japonica are 1. squid meal 2. Kril 3. Yeast 4. Fish meal

   Binders are carrageenan, guar gum, wheat gluten (activated) etc.

   Feed is given in the evening every day. By moulding, prawns don't eat feed, so feeding is stopped for this 3 days. In summer, artificial feed is in use almost exclusively but in late autumn when temperature belows frozen trash shrimp is given to mix with artificial diet. A feeding place to the same pond is changed frequently to keep clean bottom of the pond. Prawns move around very actively during night time looking for feeds but they don't get in dirty area.

   Average feed conversion rate (FCR) is 1.4 for artificial feed.

   After the harvest, pond is washed, bottoms are overturned by a cultivator, sterilized by calcium hydroxide or chlorine, sun dryed and new sand is added for the next culture.

4. Transport of live prawns.

   1. To cool live prawns in cool sea water (10–12°C) overnight.
   2. Pack them among cooled thaw dust.
   3. Sea water is not necessary for transport of prawns.
   4. Under such a condition prawn lives for 3 days.
   5. Aeroplanes and trucks equipped refrigerator are used for live prawn transportation.