Feed Additives in Fish Feed Presentation by

Binders Fish feeds must be formed in to particles or pellets that are strong enough to withstand normal handling and shipping without disintegrating. More-over, fish feeds must be somewhat water-stable.
These requirements make it necessary for feeds to contain binders. There are numerous materials that act as binders in fish feed, including regular feed ingredients and ingredients added solely for their binding properties.<br>

Some binders are by-products of cereal grains or plants and provide nutrients to the diet. For example, 20% pregelatinized potato starch is added to eel diets to increase the water stability of the dough and to provide energy.
Other commonly used binders include bentonite, lignin sulfonate, and hemi cellulose extract, none of which provides nutrients to the diet.<br>

Bentonite is a naturally occurring clay consisting mainly of trilayered Aluminium silicate. It is available as either sodium bentonite or calcium bentonite.
Sodium bentonite has, by definition, more than 1% and less than 2% available ion content, or sodium exchang.<br>

It swells when added to water, while calcium bentonite does not.
Both sodium and calcium bentonite may be added to dry, compressed fish feeds at no more than 2% to act as a binding agent and also as a lubricant, increasing pellet mill production rates and pellet mill die life (Reinitz 1983).
Some bentonites also bind aflatoxin, carrying it through the gut without harming the fish. Lignin sulfonate is a product of the wood pulping industry.<br>

It aids in pellet binding, reduces fines, and permits the addition of more steam during the manufacture of compressed pellets. Lignin sulfonate is added at up to 4% as a pelleting aid in dry, compressed (steam-pelleted) feeds.
Hemi-cellulose extract is a product made by spray-drying the concentrated, soluble byproduct of pressed wood manufacture.
It is less commonly used than lignin sulfonate. Moist and semi moist fish food production requires the use of both nutritive and non nutritive binder materials.<br>

Nutritive binders include oat groats, vital wheat gluten, finely milled wheat bran, cottonseed meal, gelatin, fish hydrolyzates, and pre gelatinized starches.
Nonnutritive binders include tapioca, carboxymethylcellose, alginates, agar, and various gums.
Chitosan, carageenan, and collagen have been evaluated as binders but are not commonly used.
Semi moist feeds, containing 25—35% moisture, can often be made into satisfactory pellets by careful selection of feed ingredients that possess binding properties.<br>

However, when feed formulations contain ingredients that do not possess suitable binding properties, it is necessary to add ingredients specifically to bind the diet.
Moist feeds, having moisture contents of 35 to 70%, always require the addition of a binder.<br>

For example, semi purified test diets, such as H440, the Oregon Test Diet, and the Guelph semipurified diet, include gelatin and carboxymethyl cellulose as binders.
Moist diets, which are combinations of wet fish ingredients and dry meal, may contain 0.5—2.0% alginates as binders.
Heinen found that alginates were better binders than gum, carageenan, chitosan, collagen, carboxymethyl cellulose, and corn starch in a 41% moisture diet. Agar was an effective binder, but expensive.
Calcium ions and a sequestrant, such as sodium hexametaphosphate, must be present in diets containing alginatesas binders to control alginate activation.<br>

Hormones The use of anabolic steroids in domestic animal feeds is no longer permitted in many parts of the world due to concern about hormone residues in food products.
The same concerns exist for fish products, and the addition of steroids and other hormones to the diets of fish raised for market will almost certainly never be approved.
However, there are some aquaculture situations in which the addition of hormones to fish diets for a short period may pose no human health risk and may prove useful to fish culturists.<br>

Hormones fall into three categories:
1) those that affect growth and feed conversion,
2) those that affect sexual development,
3) those that affect osmoregulation.<br>

In public salmon culture in the Pacific Northwest, salmon fingerlings are reared in freshwater hatcheries until the optimum time of release.
After release, the fingerlings migrate to the ocean, spend 2—4 years growing, and return as adults to the near-shore are as where they enter the fishery
For some species and stocks, the size at hatchery release is positively correlated with the percentage of returning adults.<br>

However, many hatcheries cannot rear fish to the optimum size for high ocean survival by the required time of release.
Fish growth rates can be accelerated by supplementing diets with anabolic steroids and thyroid hormones, thereby increasing feed intake and metabolic efficiency.
An alternative is to add compounds or feed components that stimulate hormone production or that overcome it<br>

Food Colourants: An important factor governing the Consumer acceptance and market value of many Cultivated fish and Shrimp Species is the pink or red Colouration of their flesh or boiled exoskeleton.
In the wild this Colouration is derived through the ingestion of Carotenoid pigments Contained within invert invertebrate food Organisms.
The Characteristics pink Colouration of Salmonids and red sea bream, and the red Colour of the boiled Crustacean exoskeleton. Being mainly due to Carotenoid pigments. Estaxanthin.<br>

The Carotenoid pigments represent a wide Spread group of Plant – Synthesized Polyene pigments, which vary in Colour from yellow and Orange to red.
Although animals, including fish and Shrim, are believed to be unable to Synthesize Carotenoids de novo, Certat, Aquaculture Species ( i. e,Crustaceans Omnivorous/herbivorous fish) are Capable of transforming ingested Carotenoids such as B- carotene and Deposing the resulting end Products, usually astaxanthin, in their tissues.
By Contrast, Carnivorous fish species such as Salmonids and red sea bream are believed to be ingested Carotenoid being deposited in its unaltered state within the body tissues.<br>

Natural Carotenoid pigmentation is usually locking intensively farmed fish and shrimp with no access to live food Organisms. It is necessary to fortify practical rations with Carotenoid rich ingredient Sources. (i.e, marine animal by Products such as Shrimp waste, fish and Crustacean iols marine yeast and algae).
With Purified Carotenoid Preparations ( canthaxanthin powders) if the farmer is to achieve a marketable product with the desired Carcass Pigmentation.
For example, in Scandinavian countries ( i.e. Norway), Shrimp off all meals AR Commonly used as natural Carotenoid Sources within Commercial salmonid rations.<br>

Commercially available Canthaxanthin being Predominant pigment source for Salmonid fish in the United Kingdom.
Although these industrially Produced microbial Pigments are Costly, they usually impart same visual Colourants of muscle as natural astaxanthin Sources, and as ordery powder Can be included Within rations at Controllable levels.<br>

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