INDUSTRIAL MANUFACTURE OF COMPOUND FOOD FOR MARINE SPECIES

Mr. J. J. SABAUT

The aim of industrial manufacture of compound food is to feed animals in rearing, while ensuring their maximum growth at the lowest production cost and preserving optimal hygiene.

The perfectioning of compound food for aquaculture was started in the fifties and became widely used in the seventies with the development of salmonculture in fresh and marine water.

Food is an essential element for all animal production. It can represent 40 to 60% of the production costs, depending on the methods employed and the species reared.

The constraints defining which is to be manufactured and what industrial structures are to be built so as to ensure the coverage of the rearing needs, are as follows :

- knowledge of the species reared and of food needs.

- availability of raw materials: nature, price, stockage, renewals,

- importance and divisions of the rearings,

- variations in the seasonal needs concerning the quality and quantity of food.

1. Knowledge of the species reared and their nutritive requirements

On the contrary to land animals, fish have great requirements of proteins. These are carnivorous species mostly, which require quality proteins, rich in the essential amino-acids.

The species requirements are shown in table 1 and 2.

These species do not make good use of carbohydrate as a source of energy. Important inputs of fatty matter, rich in unsaturated fatty acids, ensures this requirement while at the same time giving the necessary fatty acids.

Depending on the species, the fatty inputs vary from 8to 15% of the ration which comprehends 40 to 50% of proteins.

All compound food manufacturers, depending on their competance and especially on the technological capacities of their facilities, define the food ranges having specified characteristics.

In table, the sea-bass food composition, commercialized by the Aqualim Company as shown, along with the table for the daily distribution of food, expressed in live weight percentages of fish.

2. Availability of raw materials

Essential raw materials, employed in compound food for aquaculture have high proteinic content.

For fish meal, along with the local production available in numerous countries, meal found on the world market is employed. This comes from big exporting countries: Norway, danemark, Island, Peru.

In any case, it is very important to define the type of fish meal, as their characteristics can vary considerably from one product to another. It is also necessary to ensure the non-oxydation of the constituent fatty matters, as when not verified, these products would be inadequate and even toxic for the animals being reared.

Other proteinic mater of animal origin is also employed, such as meat meal, blood meal, hydrolysates, lactoserums, yeast, etc…

Among the vegetable proteins, the most commonly employed, although in smaller amounts, are soya meal and whole cooked soya beans, distillery solubles, wheat or corn granules, lucerns, cereals, and wheat by-products.

The diverse characteristics of these products are shown in table 4, 5, 6 and 7.

For the manufacturer, the between these products depends on the formulation objectives, the analytic characteristics, the price and supply possibilities. The calculations are carried out by means of a computer and optimization programmes which takes all these constraints into account.

All the products and in particular animal meal should be stocked properly, so to ensure perenniality of their nutritive qualities. It should be advisable to ensure a proper rotation of the stocks thus avoiding that they become stable oxydate. This depends on the buying facilities of the local products and on importation. In relation with the food qualities to be manufactured for a given period. Avoiding stocking over many months especially in high temperatures.

3. Technological aspects

At this necessary to cover the food requirements of the species reared, it is alos essential to distribute standard size food particles, suitable to the size of the mouth of the fish during the production cycle. The particle sizes vary from a hundred microns to ten millimeters. This presentation aspect is of prime importance.

The manufacture of compound food is based on the caking of dry meal by compressing it through circular die holes having different diameters (See figure 1).

This technic, commonly employed for the production of compound food for land animals has been adapted, which led to the construction of very specialized units for the manufacture of compound food in aquaculture.

Certain constaints have been remarked. They result principally in the following points :

- As little dust as possible and good caking (pelleter) of the particles is required so as to limit losses and pollution of the rearing waters.

- The proteinic products which are base of the formulation are difficult products to manipulate, mince or cake and require properly adapted technical solutions.

- Specific and costly investments are required to manufacture the food particles of less than 2 mm in diameter.

- Finally, due to the improvement in knowledge on the nutritive requirements of fish, it becomes imperative to incorporate more and more quantities of fatty materials, which lead to the requirement of the appropriate technical solutions.

Indeed, from a standard diagramme, such as given in figure 2, it was necessary to modify and innovate on it, which means a unit for the manufacture of fish food is quite original when compared to that for land animal food.

The animal food industry is a heavy industry which requires high investments for a feeble return. The raw materials make up more than 605 if the cost price of the food manufactured.

To define the production capacity of one unit, the rearing divisions which would buy the food must be well known, along with their capacities and their production cycles. There are indeed important seasonal variations concerning quantity and quality.

Each manufacture has its own particularities which must be studied according to the market requirements and production perpectives over the next 10 years. The raw material supply conditions must be taken into account (in bulk or in sacks) together with the availability of a specialized manual labour and the deswired automatization level of the circuits of the whole unit.

TABLE N^o 1

ESTIMATE OF THE PROTEINIC REQUIREMENTS OF CERTAIN FISH (1)

(1) by C.B.COWEY, 1978

The essential amino acid requirements of six species of fish

^a Data for chinook salmon and rat from Merts (1969)

^b Data for Japanese eel and carp from Mose (1979)

^c Data for Rainbow trout and carp from Ogino (1980)

^d Data for tilmpia from Jackson & Capper (1982)

^e Data for Channel catfish from Wilson et al. (1977, 1978, 1980; Harding et al, (1977); Robinson etal. (1978, 1990a, b, 1981) Values are expressed as grams per 100g of dry diet. In paranthesis the numerators are grams per 100g of protein and the denorinators are the percent total dietary protein.

This chart indicates the quantity of feed in Kg for 100 kg of fish to be distribute daily according to the type of nutriment and the rearing water temperature.

Remarks: The ration bases must be adapted to the particular condition of each rearing control the dissolved oxygen content.

ANALYTIC GUARATEES WHOLE NUTRIMENT FOR SEA BASS

TABLE No 4 - ANIMAL MEAL

Digestible nitrogenous materials D.N.M.

Total digestible food T.D.F

Forage Unit F.U.

Starch Unit S.U.

TABLE 5		Animal by-products
		Dairy products
		fats

TABLE 6

Cereal by-products

Digestible nitrogenous materials D.N.M

Total digestible food T.D.F

Forage Unit F.U.

Starch Unit S.U.

TABLE 7

CEREALS

Digestible nitrogenous materials D.N.M

Total digestible food T.D.F

Forage Unit F.U.

Starch Unit S.U.

Figure N^o 1