FISH FEED PELLETS LOADED WITH A MICROBIAL OIL

Abstract

The present invention relates to a quick-sinking fish feed in the form of pellets. It has been found that pellets, the diameter of which is <4 mm, have difficulty in sinking, especially in the cold time of the year when the density of water is at its maximum. The reason why the feed does not sink is its low intrinsic weight and the too high surface tension. If the fish does not have time to catch the feed, the pellets will be moved by the waves of the sea through the meshes out into the free water. This problem can be solved by loading or coating the fish feed pellets with an oil comprising at least 10% microbial oil.

Claims

1. A fish feed in the form of pellets, wherein the feed pellet is coated with a coating oil, characterized in that the coating oil comprises at least 10% w/w microbial oil.

2. The fish feed pellet according to claim 1, wherein the feed pellet is an extruded feed pellet or a pressed feed pellet.

3. The fish feed pellet according to claim 1, wherein the coating oil comprises 50% w/w microbial oil.

4. The fish feed pellet according to claim 1, wherein the microbial oil is an algal oil.

5. The fish feed pellet according to claim 4, wherein said algal oil comprises oleic acid (18:1n−9) in the range 0.28-229.15 g/kg feed, linoleic acid in the range 0.22-233.24 g/kg feed, alfa-linolenic acid in the range 0.28-225.06 g/kg, arachidonic acid (ARA, 20:4 n−6) in the range 0.03-24.55 g/kg, eicosapentaenoic acid (EPA, 20:5 n−3) in the range 0.03-73.66 g/kg and docosahexaenoic acid (DHA, 22:6 n−3) in the range 0.03-73.66 g/kg.

6. The fish feed pellet according to claim 1, wherein said coating oil further comprises fish oil and/or one or more vegetable oil(s).

7. The fish feed pellet according to claim 6, wherein the vegetable oil is selected from the group consisting of rape seed oil, soy oil and camelina oil.

8. A method of modulating the sedimentation or sinking speed of dry fish feed pellets characterized by admixing the coating oil with a variable ratio of at least two different oil-sources selected from microbial oil vegetable oil, and fish oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0039] The present invention provides a new and simple process of pronouncedly increasing the sinking speed of fish feed in the form of pellets of the above-mentioned type, whereby they are not affected by the waves of the sea.

[0040] As mentioned above, the “sinking speed” problem is solved by loading or coating the fish feed pellets with a coating oil comprising at least 10% w/w microbial oil, preferably at least 50% w/w microbial oil.

[0041] In particular, the invention provides a quick-sinking fish feed in the form of pellets, which is characterized in that the pellet is coated or loaded with a coating oil containing at least 10% w/w microbial oil, preferably at least 50% w/w microbial oil.

[0042] In preferred examples the coating oil comprises 50 or 100% w/w microbial oil. If the coating oil comprises 50 w/w microbial oil, the coating oil is for example a 1:1 mixture of microbial oil and rapeseed oil.

[0043] The present invention also provides a method of modulating the sedimentation or sinking speed of dry fish feed pellets by admixing the coating oil with a variable ratio of at least two different oil-sources selected from microbial oil vegetable oil, and fish oil.

[0044] Examples of coating oil mixtures with variable ratios of selected oil sources for modulating the sinking/sedimentation speed are:

TABLE-US-00001 Vegetable oil:Microbial oil 1:1; 2:1; 5:1; 10:1; 15:1; 20:1; 25:1; 1:2; 1:5; 1:10 Fish oil:Microbial oil 1:1; 2:1; 5:1; 10:1; 15:1; 20:1; 25:1; 1:2; 1:5; 1:10

[0045] For modulating the sinking/sedimentation speed of fish feed pellets vegetable and fish oil are used to finetune, i.e. reduce the pronounced sinking speed effect surprisingly observed for the microbial oil, in particular algal oil.

[0046] The present invention provides a new and simple process of pronouncedly increasing the sinking speed of fish feed in the form of pellets of the above-mentioned type, whereby they are not affected by the waves of the sea.

[0047] With a view to providing the pellets according to the invention, the pellets are loaded or coated with a coating oil rich in PUFAs, wherein the oil comprises at least 10% microbial oil, preferably algal oil.

[0048] In a preferred embodiment, the microbial oil is an oil derived from a species of Schizochytrium sp. ATCC PTA-10208, as for example the commercial oil product available under the Trademark Veramaris®.

[0049] As mentioned above, the main part of the fish feed is present in the form of pellets which are prepared by so-called extrusion. The extrusion is principally carried out in the following manner: [0050] The dry ingredients are mixed. Immediately before or during the extrusion, part of the fat and water are added, such that the fat content during extrusion is between about 15 and 20t by weight and the water content is slightly above 20 by weight. In the extruder, the material is subjected to vigorous mechanical working in combination with high pressure and high temperature. [0051] This treatment results in an expanded feed of high meltability. At the end of the extruder there is arranged a nozzle, through which the material passes, and after that, a rotary cutter which cuts the material to a suitable size. By varying the size of the nozzle and the speed of the cutter, the size of the feed pellets can be adapted to the fish to be fed. Immediately after extrusion, the pellets are dried, whereupon the remaining amount of fat is added, either by immersion in a hot oil bath or by spraying. Finally the pellets are cooled.

[0052] So far, the preparation of the pellets according to the invention conforms with the preparation of pellets that are known hitherto.

[0053] It may be contemplated that the extruded feed pellet(s) has a DORIS value in the range from 75-100%. The DORIS value is measured on a DORIS tester (Durability on a Realistic Test) (Akvasmart, AKVA group ASA, Bryne, Norway). The DORIS tester is designed to mimic the pellet degradation during pneumatic feeding system. The result is between 0% and 100%, and corresponds to the mass fraction (m/m) of whole pellets after DORIS exposure relative to the initial sample mass.

[0054] It may also be contemplated that the extruded feed pellets of the present invention has a pellet hardness in the range from 20-100N. The pellet hardness is determined on a pellet strength texture analyzer from Stable Micro Systems Ltd, Godalming, More specifically a TA-XT plus Texture Analyzer (TA) from Stable Micro Systems mounted with a cylindrical probe (P/40) was used to determine pellet hardness.

[0055] The feed pellets can be fed to all types of fish, including cold-water fish and shrimp. Some examples are turbot, halibut, yellow tail salmon, trout, bream, bass and tuna. The feed is particularly suitable for feeding salmonids, including Atlantic salmon (Salmo salar), other salmon species and trout, and non-salmonids such as cod, sea bass, sea bream and eel. It is suitable for feeding salmon, trout, bream and/or bass in the fresh water (FW) phase and the in the sea water (SW) phase and in the period after hatching and until slaughter and in all stages, such as fry, fingerlings, parr, smolts and adult fish.

[0056] In a particular preferred embodiment of the present invention, the aquatic animal is a fish or a decapod crustacean.

[0057] The fish may be any kind of fish such as but not limited to a fish selected from the group consisting of salmon, trout, sea bream, sea bass, cod, eel, turbot, halibut, yellow tail, tuna, carp, tilapia and catfish. In a particular preferred embodiment, the fish is selected from the group consisting of salmon, trout, sea bream and sea bass.

[0058] The salmon may be of the family Salmonidae and of the subfamily of Salmoninae. In one embodiment the salmon is selected from the group consisting of the genus Salmo, Oncorhynchus and Salvenis. In a further embodiment the genus Salmo is selected from the group consisting of Atlantic salmon (Salmo salar) and Brown trout (Salmo trutta). In yet an embodiment the genus Oncorhynchus is selected from the group consisting of Chinook salmon (Oncorhynchus tshawytsch), Rainbow trout (Oncorhynchus mykiss), Sockeye salmon (Oncorhynchus nerka) and Coho salmon (Oncorhynchus kisutch). In a further embodiment the genus Salvenis is selected from the group consisting of Arctic charr (Salvelinus alpinus), Brook trout (Salvelinus fontinalis) and Lake trout (Salvelinus namaycush).

[0059] The sea bream may be gilt-head sea bream (Sparus aurata) whereas the sea bass may be European bass (Dicentrarchus labrax)

[0060] In a preferred embodiment of the present invention the decapod crustacean may be shrimp or prawn.

[0061] The shrimp may be selected from the group consisting of Pacific white shrimp (Penaeus vannamei or Litopenaeus vannamei), Whiteleg shrimp (Penaeus vannamei or Litopenaeus vannamei), Black tiger shrimp (Penaeus monodon), Kuruma shrimp (Penaeus japonicas or Marsupenaeus japonicas), Western blue shrimp (Penaeus stylirostris or Litopenaeus stylirostris), blue shrimp (Penaeus stylirostris or Litopenaeus stylirostris), Chinese white shrimp (Penaeus chinensis or Fenneropenaeus chinensis), Oriental shrimp (Penaeus chinensis or Fenneropenaeus chinensis), Indian white shrimp (Penaeus indicus or Fenneropenaeus indicus), Banana shrimp (Penaeus merguiensis or Fenneropenaeus merguiensis), Akiami paste shrimp (Metapenaeus spp.), yellowleg shrimp (Penaeus californiensis or Farfantepenaeus californiensis), brown shrimp (Penaeus californiensis or Farfantepenaeus californiensis), Sao Paulo shrimp (Penaeus paulensis or Farfantepenaeus paulensis), Carpas shrimp (Penaeus paulensis or Farfantepenaeus paulensis), redspotted shrimp (Penaeus brasiliensis or Farfantepenaeus brasiliensis), spotted pink shrimp (Penaeus brasiliensis or Farfantepenaeus brasiliensis) and southern white shrimp (Penaeus schmitti).

[0062] The prawn may be selected from the group consisting of King prawn (Penaeus vannamei or Litopenaeus vannamei), Giant tiger prawn (Penaeus monodon), Giant Freshwater Prawn (Macrobrachium rosenbergii), Giant river prawn (Macrobrachium rosenbergii), Malaysian prawn (Macrobrachium rosenbergii), Kuruma prawn (Penaeus japonicas or Marsupenaeus japonicas), Fleshy prawn (Penaeus chinensis or Fenneropenaeus chinensis), Indian prawn (Penaeus indicus or Fenneropenaeus indicus), Banana prawn (Penaeus merguiensis or Fenneropenaeus merguiensis), Oriental river prawn (Macrobrachium nipponense) and Monsoon river prawn (Macrobrachium malcolmsonii).

[0063] Microbial oils according to the present invention comprise DHA and optionally EPA. The oils may be provided in a variety of forms for use in the aquaculture feed compositions herein, wherein the oil is typically a partially purified or purified oil.

[0064] As mentioned above, the oil producing microorganism can be a wildtype or mutant strain of the species Schizochytrium. Schizochytrium strains are natural sources of PUFAs such as DHA and can be optimized by mutagenesis to be used as microbial source according to the present invention.

[0065] Such a microbe may be cultured and grown in a fermentation medium under conditions whereby the PUFAs are produced by the microorganism. Typically, the microorganism is fed with a carbon and nitrogen source, along with a number of additional chemicals or substances that allow growth of the microorganism and/or production of EPA and DHA. The fermentation conditions will depend on the microorganism used and may be optimized for a high content of the desired PUFA(s) in the resulting biomass.

[0066] In general, media conditions may be optimized by modifying the type and amount of carbon source, the type and amount of nitrogen source, the carbon-to-nitrogen ratio, the amount of different mineral ions, the oxygen level, growth temperature, pH, length of the biomass production phase, length of the oil accumulation phase and the time and method of cell harvest.

[0067] When the desired amount of EPA and DHA has been produced by the microorganism(s), the fermentation medium may be treated to obtain microbial biomass comprising the PUFA(s). For example, the fermentation medium may be filtered or otherwise treated to remove at least part of the aqueous component. The fermentation medium and/or the microbial biomass may be further processed, for example the microbial biomass may be pasteurized or treated via other means to reduce the activity of endogenous microbial enzymes that can harm the microbial oil and/or PUFAs. The microbial biomass may be subjected to drying (e.g., to a desired water content) or a means of mechanical disruption (e.g., via physical means such as bead beaters, screw extrusion, etc. to provide greater accessibility to the cell contents), or a combination of these. The microbial biomass may be granulated or pelletized for ease of handling. Thus, microbial biomass obtained from any of the means described above may be used as a source of microbial oil comprising EPA and DHA. The microbial oil may be finally extracted from the biomass according to methods described in EP 1,513,922 or U.S. Pat. No. 6,750,048.

[0068] A preferred microbial oil according to the invention is a crude oil derived form a strain of the species Schizochytrium comprising oleic acid (18:1n−9) in the range 0.28-229.15 g/kg feed, linoleic acid in the range 0.22-233.24 g/kg feed, alfa-linolenic acid in the range 0.28-225.06 g/kg, arachidonic acid (ARA, 20:4 n−6) in the range 0.03-24.55 g/kg, eicosapentaenoic acid (EPA, 20:5 n−3) in the range 0.03-73.66 g/kg and docosahexaenoic acid (DHA, 22:6 n−3) in the range 0.03-73.66 g/kg.

EXAMPLES

Example 1: Preparation of Pressed Fish Feed

[0069] The main raw materials are ground and mixed. Micro-ingredients are then added to the mixer and the homogenous mix is conditioned by adding water and steam to the mass in a preconditioner. This starts a cooking process in the starch fraction (the binding component). The mass is fed into a pellet mill. The mass is forced through the mill's die and the strings are broken into pellets on the outside of the die. The moisture content is low and drying of the feed is not necessary.

[0070] Additional oil including a fish feed composition according to the present invention is then sprayed onto the surface of pellets, but as the pellets are rather compact, the total lipid content rarely exceeds 24%. The added oil may be fish oil, microbial/algal or vegetable oils, for example rape seed oil or soy oil, or a mixture of oils. After oil coating, the pellets are cooled in a cooler and bagged. The final pressed fish feed contains 10 to 5000 ppm of the composition as described in the invention.

Example 2: Method for Preparation of Extruded Fish Feed

[0071] The main raw materials are ground and mixed. Micro ingredients incl. a fish feed composition according to the invention are added to the mixer. The homogenous mix is conditioned by adding water and steam to the mass in a preconditioner. Additional oil may also be added to the mass at this stage. This starts a cooking process in the starch fraction (the binding component). The mass is fed into an extruder. The extruder may be of the single screw or the twin-screw type. Due to the rotational movement of the mass in the extruder, the mass is further mixed. Additional oil, water and steam may be added to the mass in the extruder. At the end of the extruder, the mass has a temperature above 100° C. and a pressure above ambient pressure. The mass is forced through the openings in the extruder's die plate. Due to the relief in temperature and pressure, some of the moisture will evaporate immediately (flash off) and the extruded mass becomes porous. The strings are cut into pellets by a rotating knife. The water content is rather high (18-28%) and the pellets are therefore immediately dried to approximately 10% water content in a dryer.

[0072] After the dryer, more oil including a feed additive composition according to the invention may be added to the feed by spraying oil onto the surface of the feed, or by dipping the feed in oil. It is advantageous to add the oil to the feed in a closed vessel where the air pressure is below ambient (vacuum coating) so that the porous feed pellets absorb more oil. Feed containing more than 40% lipid may be produced this way. After the coater, the feed is cooled and bagged. Oil may be added at several places in the process as explained above, and may be fish oil, microbial/algal or vegetable oils, by example rape seed oil or soy oil, or a mixture of oils.

[0073] Fish need protein, fat, minerals and vitamins in order to grow and to be in good health. The diet of carnivorous fish is particularly important. Originally in the farming of carnivorous fish, whole fish or ground fish were used to meet the nutritional requirements of the farmed fish. Ground fish mixed with dry raw materials of various kinds, such as fish meal and starch, was termed soft or semi-moist feed. As farming became industrialized, soft or semi-moist feed was replaced by pressed dry feed. This was itself gradually replaced by extruded dry feed.

[0074] Today, extruded feed is nearly universal in the farming of a number of fish species such as various types of salmonid, cod, sea bass and sea bream.

[0075] The dominant protein source in dry feed for fish has been fish meal of different qualities. Other animal protein sources are also used for dry fish feed. Thus, it is known to use blood meal, bone meal, feather meal and other types of meal produced from other slaughterhouse waste, for example chicken meal. These are typically cheaper than fish meal and fish oil. However, in some geographic regions, there has been a prohibition against using such raw materials in the production of feeds for food-producing animals and fish.

[0076] It is also known to use vegetable protein such as wheat gluten, maize (corn) gluten, soya protein, lupin meal, pea meal, bean meal, rape meal, sunflower meal and rice flour.

Example 3: Rate of Descent/Sinking Speed of Different Fish Feed Pellets

[0077] Examples of pellets according to example 2 are loaded/coated with 22% coating oil as follows:

[0078] 22% Algal oil, rich in DHA and EPA (AO)

[0079] 22% Fish oil (FO)

[0080] 22% Rapeseed oil (RO)

[0081] 11% AO & 11% FO

[0082] 11% AO & 11% RO

[0083] 11% FO & 11% RO

[0084] The sinking speed was measured according to standard technique at 4° C. and is shown in table 1.

TABLE-US-00002 TABLE 1 11% AO 11% AO 11% FO 22% AO 22% FO 22% RO 11% FO 11% RO 11% RO Sinking 17.64 12.68 12.2 18.72 15.56 12.4 speed (m/s)