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EXTRUDED GRANULES OF MIXED FODDERS IN FISH-BREEDING
J.A.Zheltov, the candidate of agricaltural sciences,
Institute of fish farming UAAS, Kiev, Ukraine
My report concerns production of extruded (floating) granules of mixed fodders and their properties. Now mixed fodders made according to extrusion technology are more widely used in fish-feeding. Made granules become easier than water and float on its surface, therefore named floating.
For forages extrusion special extruders are used and the principles of their work are based on the following technological processes: grain fodder mixtures or their separate components are conveyed to extruder wholly or crushed, humidified or of natural humidity 12-17 %.
Extrusion process passes under pressure of 3-5 МПа and temperature +120-2000° С . The bellied porous product in the form of braid or easier than water granules of different diameter comes then from the opening of extruder head or matrix
It is established, that there are three processes underlying forages extrusion: temperature processing under pressure, mechanochemical deformation and product "explosion" in the front of impact rarefaction. And deep destructive changes occur in nutrients at the same time. For example, starch is split up to dextrines and sugar, proteins are exposed to denaturation. So, natural wheat contains (in % on dry substance): starch - 46,5 dextrines - 4,9 and sugar 5,3, and in extruded accordingly - 18,2; 21,9 and 10,9; in natural barley: starch - 50,5; dexrines - 6,4 and sugar - 5,6, extruded - accordingly - 11,8; 39,9 and 9,6; in natural peas: starch - 25,8; dextrines - 5,5 and sugar - 3,0, and in extruded accordingly - 18,8; 8,1 and 3,5. As we see, after extrusion the quantity of starch decreases and the quantity of dextrines and sugar increases. Nutrients thus become more available to their digestion by fish, especially by predators. Also it is marked that after extrusion flavouring qualities of forages are improved, enzyme inhibitors are inactivated, some toxins are neutralized and their producers are destructed, all this being important at fish-feeding.
The piscicultural estimation of extruded granules of mixed fodders а t fish-farms has shown that due to them it is possible to achieve high fish-breeding parameters at the cultivation of carps for sale - up to 150 kg / m3 of fish products using 1,8-2,3 kg of forage for growth of weight and at cultivation channel silurus in chests and pools it is possible to receive - 125 kg / m3 using 2,0 kg / kg of forage.
Hence, fish-feeding by the granules of mixed fodders increases fish productivity and reduces the forage expences for fish-growth. Feeding fish by floating granules of mixed fodders 2 mm and more in diameter (depending on fish weight), in comparison with the sinking ones of the same diameter which are developed with the help of cubing and pelleting mashine by a dry pressing, it is necessary to take into account the following features: granules of extruded mixed fodders by their physical properties considerably differ from sinking mixed fodders inspite of the identical structure of granules and their unit weight which is 1,5 times less than of sinking granules, therefore these granules remain on water surface longer. The bulk weight of volume unit of sinking granules makes 0,6 and floating - 0,4 mass units in volume unit.
Among the important parameters of granules of mixed fodders their water resistance is nearly the most important one. It is characterized, basically, by swelling, destruction and nutrients extraction. Carried out researches on granules water resistance have shown its being much less in floating granules than in sinking. It is also determined that destruction of floating granules of mixed fodders which is characterized by the isolation of a small amount of fining from the surface of granules begins in two hours after their getting in water, and sinking - in 5-15 minutes at water temperature on average 200° C.
Have being in water during180 minutes floating granules of mixed fodders are destroyed only up to 10 % and preserve the form while sinking ones are destroyed completely and turn to rare mass badly eaten by fish.
Besides it is established that floating granules of mixed fodders can preserve their form more than 24 hours and float long.
From the moment of getting the granules of mixed fodders in water, alongside with their swelling and disintegration into finings, washing away of nutrients takes place.
Have being in water for 15 and 30 minutes for the amount of dry substances in the granules of floating mixed fodders has decreased (with growing result) accordingly in 3,9 and 4,2 % whereas as for sinking granules this parameter was 6,3 and 9,8 %. In due course losses increase and in three hours they have made 8,9 for floating forages and 14,4 % - for sinking ones. This law concerns washing away protein, fat, carbohydrates and ashes from forages as well. Parameters of washing away were more in sinking granules - 10,2 %, and at extruded - 5,9 %.
Hence, nutrients loss in floating granules of mixed fodders was 1,6-2,3 times less than in sinking ones.
Researches have shown that nutrients digestion was better with floating mixed fodders.
Therefore, on the basis of the given data, floating mixed fodders can be used in feeding carps for sale and channel catfish by sinking granules during all period in different conditions. However it is necessary to take into account various physical properties of granules, and in this connection the technical equipment and their rational feeding to a fish.
Institute of fish farming UAAS, Kiev, Ukraine
My report concerns production of extruded (floating) granules of mixed fodders and their properties. Now mixed fodders made according to extrusion technology are more widely used in fish-feeding. Made granules become easier than water and float on its surface, therefore named floating.
For forages extrusion special extruders are used and the principles of their work are based on the following technological processes: grain fodder mixtures or their separate components are conveyed to extruder wholly or crushed, humidified or of natural humidity 12-17 %.
Extrusion process passes under pressure of 3-5 МПа and temperature +120-2000° С . The bellied porous product in the form of braid or easier than water granules of different diameter comes then from the opening of extruder head or matrix
It is established, that there are three processes underlying forages extrusion: temperature processing under pressure, mechanochemical deformation and product "explosion" in the front of impact rarefaction. And deep destructive changes occur in nutrients at the same time. For example, starch is split up to dextrines and sugar, proteins are exposed to denaturation. So, natural wheat contains (in % on dry substance): starch - 46,5 dextrines - 4,9 and sugar 5,3, and in extruded accordingly - 18,2; 21,9 and 10,9; in natural barley: starch - 50,5; dexrines - 6,4 and sugar - 5,6, extruded - accordingly - 11,8; 39,9 and 9,6; in natural peas: starch - 25,8; dextrines - 5,5 and sugar - 3,0, and in extruded accordingly - 18,8; 8,1 and 3,5. As we see, after extrusion the quantity of starch decreases and the quantity of dextrines and sugar increases. Nutrients thus become more available to their digestion by fish, especially by predators. Also it is marked that after extrusion flavouring qualities of forages are improved, enzyme inhibitors are inactivated, some toxins are neutralized and their producers are destructed, all this being important at fish-feeding.
The piscicultural estimation of extruded granules of mixed fodders а t fish-farms has shown that due to them it is possible to achieve high fish-breeding parameters at the cultivation of carps for sale - up to 150 kg / m3 of fish products using 1,8-2,3 kg of forage for growth of weight and at cultivation channel silurus in chests and pools it is possible to receive - 125 kg / m3 using 2,0 kg / kg of forage.
Hence, fish-feeding by the granules of mixed fodders increases fish productivity and reduces the forage expences for fish-growth. Feeding fish by floating granules of mixed fodders 2 mm and more in diameter (depending on fish weight), in comparison with the sinking ones of the same diameter which are developed with the help of cubing and pelleting mashine by a dry pressing, it is necessary to take into account the following features: granules of extruded mixed fodders by their physical properties considerably differ from sinking mixed fodders inspite of the identical structure of granules and their unit weight which is 1,5 times less than of sinking granules, therefore these granules remain on water surface longer. The bulk weight of volume unit of sinking granules makes 0,6 and floating - 0,4 mass units in volume unit.
Among the important parameters of granules of mixed fodders their water resistance is nearly the most important one. It is characterized, basically, by swelling, destruction and nutrients extraction. Carried out researches on granules water resistance have shown its being much less in floating granules than in sinking. It is also determined that destruction of floating granules of mixed fodders which is characterized by the isolation of a small amount of fining from the surface of granules begins in two hours after their getting in water, and sinking - in 5-15 minutes at water temperature on average 200° C.
Have being in water during180 minutes floating granules of mixed fodders are destroyed only up to 10 % and preserve the form while sinking ones are destroyed completely and turn to rare mass badly eaten by fish.
Besides it is established that floating granules of mixed fodders can preserve their form more than 24 hours and float long.
From the moment of getting the granules of mixed fodders in water, alongside with their swelling and disintegration into finings, washing away of nutrients takes place.
Have being in water for 15 and 30 minutes for the amount of dry substances in the granules of floating mixed fodders has decreased (with growing result) accordingly in 3,9 and 4,2 % whereas as for sinking granules this parameter was 6,3 and 9,8 %. In due course losses increase and in three hours they have made 8,9 for floating forages and 14,4 % - for sinking ones. This law concerns washing away protein, fat, carbohydrates and ashes from forages as well. Parameters of washing away were more in sinking granules - 10,2 %, and at extruded - 5,9 %.
Hence, nutrients loss in floating granules of mixed fodders was 1,6-2,3 times less than in sinking ones.
Researches have shown that nutrients digestion was better with floating mixed fodders.
Therefore, on the basis of the given data, floating mixed fodders can be used in feeding carps for sale and channel catfish by sinking granules during all period in different conditions. However it is necessary to take into account various physical properties of granules, and in this connection the technical equipment and their rational feeding to a fish.
