AU2011225157B2 - Tuna-hatchling formula feed - Google Patents

Abstract

Disclosed is a formula feed preferred by fish hatchlings of the scombridae family that includes bluefin tuna, at approximately 20 - 70 days after hatching, or approximately 20 - 200 mm in length. The formula feed provides a chewy texture with a break resistance at a range of 10 - 200 g/mm by adding, heating and cooling a gelling agent such as gelatin or guar gum to formula feed conventionally used in marine fish formula feed. This may also be dried.

Description

DESCRIPTION [Title of the Invention] TUNA-HATCHLING FORMULA FEED [Technical Field] [0001] 5 The present invention relates to a formula feed suitable for fry of bluefin tuna and the like. [Background Art] [0002] In recent years, in natural fish catch, there is an lo international movement to regulate the fish catch of bluefin tuna in view of decreasing resources and biotic conservation. For example, natural tuna resources-international administering authorities (Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and 15 Central Pacific Ocean, International Commission for the Conservation of Atlantic Tunas) determined the Atlantic or Mediterranean tuna catch quata to be 40% reduction in 2010 from that in 2009, bigeye tuna catch quata to be 40% reduction over 3 years from 2009, and southern bluefin tuna catch quata 20 to be 20% reduction in 2010 and 2011. The regulations of tuna catch quata is feared to be further extended worldwide in the future. [0003] Under such circumstances, the demand for tuna farming is 25 increasing more and more. Currently, not less than 95% of the fries for bluefin tuna farming is natural young of bluefin tuna (15-25 cm) caught in the sea around Japan, and the. bluefin tuna culture industry can be said to depend on the naturally-developed fries. 30 [0004] Several years ago, the Fisheris Laboratory of Kinki University succeeded in a complete culture of bluefin tuna (patent document 1); however, the supply system that meets the demands for domestically-cultured tuna has not been 35 established. This is caused by the facts that the survival rate after processes from egg to young blue fin tuna is not more than a few percent; feeding operation, feeding cost, preservability of feed and the like are inefficient since bluefin tuna larval fish is cultivated by feeding freshly 5 hatched larval fish of red seabream and the like, and bluefin tuna fry is cultivated by feeding whitebait of Japanese sand lance (silver anchovy) and the like.; and further, large-scale production is difficult due to the low survival rate. Therefore, the development of a formula feed for bluefin lo tuna fry that can increase the survival rate has been desired. [0005] Heretofore, a wide variety of formula feeds for cultured fish have been developed and commercially supplied. In particular, many of the formula feeds for the fries of 15 Japanese amberjack, red seabream, takifugu, flounder and the like, which provide high production values, have superior characteristics such as low cost, easy handling and quality preservation since they are dry pellets, rapid growth and the like. 20 [00061 However, there is no successful case of cultivation of bluefin tuna fry only on conventional formula feed, and whitebait of Japanese sand lance and the like is necessary as a feed for larval fish to young bluefin tuna. This is because 25 it is almost impossible to make fry eat formula feeds. [0007] Conventionally, cultivation of bluefin tuna fry is technically possible by feeding whitebait of Japanese sand lance or anchovy. However, supply of whitebait of these fish 30 species is not stable, since the resources may change drastically. Furthermore, whitebait free of other fish mixed therein and whitebait having a size suitable for tuna fry are expensive and valuable, since available areas and season are limited. In the years ahead, moreover, the route of whitebait 35 supply may change and its price may drastically increase due 2 to the influence of global warming and the like. In addition, whitebait has disadvantages in that the nutrition components thereof vary greatly and modification to achieve nutritional value suitable for bluefin tuna fry is difficult, the fry may 5 be infected with a disease derived from whitebait and the like. [0008] Given such situation, the cultivation system of tuna fry is desired to quickly depart from the dependency on the use of whitebait for feed. Particularly, it is necessary to develop 10 an artificially producible formula feed, rather than a natural feed, for the cultivation of tuna fry that requires a large amount of feed. [0009] In addition, tuna fry requires 4-7 times of feeding per 15 day. Since whitebait shows poor quality preservability, it is preserved as a frozen block. For feeding, the block needs to be thawed, which complicates the operation to feed tuna fry. [0010] As a feed for fry of the fish belonging to the genus 20 Thunnus, which is other than natural feeds such as whitebait and the like, a solid feed containing a shell made of guar gum, gelatin and the like, and fish food has been suggested (patent document 2). This feed is for young tuna (total length not less than about 25 cm, body weight not less than about 300 g, 25 about 80-90 days after hatching), and is not intended for freshly-hatched larval fish to fry having total length of not more than 25 cm. [0011] As a feed for fry of the fish belonging to the genus 3o Thunnus, which is at least about 20 days after hatching, a feed for the fish belonging to the genus Thunnus has been suggested, which contains a defatted enzyme-treated fishmeal, polar lipid animal fats and oils or plant fats and oil as lipid sources, active starch as a carbohydrate source and 200 35 mg/kg or above of vitamin C (patent document 3). 3 However, when directly used, the feed is poorly eaten by fry as compared to natural feeds, and therefore, addition of glutamic acid, stidine and inosinic acid-phosphoric acid as ingestion promoting substances is necessary. Such additives are expensive 5 for materials for feed for fish. [Document List] [patent documents] [0012] patent document 1: JP-A-2006-75021 10 patent document 2: JP-Al-2006-90866 patent document 3: JP-A-2008-148652 [SUMMARY OF THE INVENTION] Problems to be Solved by the Invention [0013] 15 The labor in the production of seeds of many marine fish is saved by using formula feeds. The formula feeds permitting preservation at ambient temperature or in a refrigerator can be used immediately after taking out from the storage. An automatic feeder can also be used. On the other hand, biological feed 20 (rotifer, brine shrimp and the like) and frozen feed (krill, whitebait) require culture and thawing, show low preservability, and are difficult for mechanization of feeding. [0014] In the present invention, many experiments were conducted in 25 an attempt to solve the above-mentioned problems, feed preference of bluefin tuna fry was studied, and a formula feed that bluefin tuna fry prefers regardless of the materials of the feed was newly developed by devisal of the texture of the feed. [0015] 30 The present invention as claimed herein is described in the following items 1 to 9: (1) A formula feed for tuna fry of around 20-70 days after hatching or with a total length of about 20-200mm, which has a diameter of 0.5 - 10.0 mm and a gummy texture, i.e., a smooth and 4 6402256_1 (GHMatters) P91394.AU JESSIEL slippery surface, a little sliminess in water, and chewy elasticity, and is obtained by adding a gelling agent approved as a food additive to a fish feed material to achieve a gummy texture. 5 (2) The formula feed for tuna fry of (1), wherein the gummy texture is a rupture strength of 10-200 g/mm. (3) The formula feed for tuna fry of (1) or (2), wherein the gelling agent is approved as a food additive, for example, gelatin, guar gum and the like. 10 (4) A formula feed for tuna fry, which is obtained by drying the formula feed for tuna fry of any one of (1) to (3). (5) The formula feed for tuna fry of any one of (1) to (4), wherein the tuna fry is a fry of a fish belonging to the genus Thunnus. 15 (6) A method of breeding a tuna fry, which comprise feeding a tuna fry of around 20-70 days after hatching or with total length of about 20 - 200 mm with the formula feed for tuna fry of any one of (1) to (4). (7) The method of (6), wherein the tuna fry is a fry of a fish 20 belonging to the genus Thunnus. (8) Use of the formula feed for tuna fry of any one of (1) to (4), for feeding a tuna fry of around 20-70 days after hatching or with total length of about 20 - 200 mm. (9) The use of (8), wherein the tuna fry is a fry of a fish 25 belonging to the genus Thunnus. [0016] The present invention targets fry of a fish belonging to the genus Thunnus including bluefin tuna, and of around 30-70 days 30 after hatching or with total length of about 20 - 200 mm. [0017] Many of the formula feeds for marine fish are conventionally dry crumbles (pellets), and bluefin tuna fry do not eat most of 5 6402256_1 (GHMatters) P91394.AU JESSIEL them. Interestingly, however, the fry ingest food which is slippery, soft and has chewy texture such as Japanese wheat noodles (spaghetti) and gummi candy (gummy), which the inventors empirically knew. Thus, they investigated by trial and error to 5 arrive at a feed which has such texture, is superior in nutrition and, further economical. [0018] As a result, they have successfully produced an ideal feed by mixing a gelling agent such as gelatin, guar gum and the like with 10 a feed material, and heating and cooling the mixture. As the feed material, fish meal, soybean protein and the like, which are conventionally used for feed for marine fish, can be used, and vitamins and minerals can be added as necessary. [0019] 15 The "gummy texture" in the present invention means a rupture strength within the range of 10 - 200 g/mm, more preferably 40 60 g/mm. Juvenile tuna likes to ingest any feed having elasticity of this level. A feed having a rupture strength exceeding 200 g/mm is too 20 hard, impairs the "gummy texture" in the context of the 5a 6402256_1 (GHMatters) P91394.AU JESSIEL present invention and decreases feed eating. A feed having a rupture strength of less than 10 g/mm has poor shape retentability and causes water pollution. In cases where the formula feed of the present invention 5 is dry, the formula feed is preferably ingested by juvenile tuna as is the case with undried feed, as long as a rupture strength of the surface of the feed can be achieved within the range of the present invention within one minute after immersion in water. 10 When drying a formula feed having a rupture strength within the range of the present invention, the rupture strength of the dry feed is desirably adjusted within the range of 300 - 900 g/mm. A feed having a rupture strength higher than this range shows poor reconstitution in water, and 15 is wasted since it sinks before eaten by tuna. Conversely, a feed having a rupture strength lower than this range easily causes clogging of an automatic feeder. The feed of the present invention dried to meet the above range allows penetration of water to the inside within 5 20 minutes maximum after immersion in water at 20 0 C, the rupture strength falls within the range of 10 - 200 g/mm like before drying. [0020] The "rupture strength" in the present invention is a 25 numerical value determined by "stress at rupture/dent". Here, the stress at rupture and dent are the values measured using SUN RHEO TEX SD700 (manufactured by SUN CHEMICAL CO., LTD.) as a measuring apparatus and a spherical plunger (diameter 5 mm) under the conditions of plunger speed 60 mm/min, plunger 30 weight 35 g. The measurement method includes perpendicularly pressing the plunger against the measurement target, and measuring the force necessary for the measurement target to lose resistance and become ruptured [=stress at rupture (g)] and the distance [=dent (mm)] at the time of rupture. Since a 35 positive proportional relationship exits between the stress at 6 rupture and the dent, the stress at rupture was divided by the dent and the coefficient thereof was taken as the rupture strength (g/mm). [Effect of the Invention] 5 [0021] Using the formula feed of the present invention, the following have been enabled: the eating amount is high even after feeding of whitebait of Japanese sand lance and the like is stopped and the feed is changed to the formula feed; 10 decrease of growth rate is within an acceptable level; and a survival rate higher than that of a mince feeding group can be achieved when a stress caused by transfer is applied. [00221 In addition, the formula feed is superior to 15 conventionally-used whitebait in many aspects in that the main ingredient (fish meal) is economical and stably supplied, the feed after being molded can be stored in a refrigerator, and additives such as nutritional enrichment and the like can be added with ease during production. Furthermore, since gelatin 20 (collagen) as an additive to improve texture has advantages in that, being a protein, it is a digestible substance, its health food-like image has been socially established, since guar gum (water-soluble plant fiber) is also widely used as a food additive and addition of a novel substance is not 25 necessary, the formula feed does not require a particular safety certification, and the like. [Brief Description of the Drawings] [0023] Fig. 1 shows the number of dead fish in each feed group 30 in Experiment 3. Fig. 2 shows the body weight of each feed group 7 days later in Experiment 3. Fig. 3 shows the degree of obesity of each feed group 7 days later in Experiment 3. 35 [Description of Embodiments] 7 [Examples] [0024] Experiment 1 <Feed eating activity> To examine feed eating activity of tuna fry, the 5 following feeds were prepared, and fed to tuna fry (1200, total length 80 mm, after keeping in a 10 m fish preserve for 2 weeks). The composition of each feed is as shown in Table 1. The tuna fry were cultivated only on Japanese sand lance whitebait for the 2 weeks in the fish preserve, and were not 1o fed with a formula feed at all. [0025] (1) Commercially available feed for marine fish: trade name "OTOHIME-S2" (manufactured by Marubeni Nisshin) Actually used for many fish species such as red seabream, 25 takifugu and the like. Beads (pellet or crumble)-like dry feed, usable for automatic feeder. (2) Crumble feed: dry crumble feed (diameter 1 mmo, length 2 3 mm) made from materials imaginably good for fish, disregarding the cost of the materials, and usable for 20 automatic feeder. (3) Gummy feed: A feed (diameter 1 mmo, length 2 - 5 mm) having a chewy texture produced by adding gelatin to the materials of the above-mentioned crumble feed. Easily fused at a high temperature (32*C or higher), and unusable for automatic feeder 25 under the midsummer scorching sun. (4) Low cost gummy feed: A feed (diameter 1 mm#, length 2 - 5 mm) having a chewy texture produced by removing expensive materials from the materials of the above-mentioned crumble feed and adding gelatin. Easily fused at a high temperature 30 (32*C or higher), and unusable for automatic feeder under the midsummer scorching sun. (5) Low cost gummy (guar gum) feed: A feed (diameter 1 mm#, length 2 - 5 mm) having a chewy texture produced by removing expensive materials from the materials of the above-mentioned 35 crumble feed and adding guar gum (10%) instead of gelatin. 8 Easily fused at a high temperature (32*C or higher), and unusable for automatic feeder under the midsummer scorching sun. (6) Low cost gummy (dry) feed: A feed produced by drying the 5 low cost gummy feed of the above-mentioned (4) in an air conditioned room (temperature, 25*C) for 6 hr. Resistant to fusion at a high temperature, and usable for automatic feeder. (7) Japanese sand lance whitebait: most general feed for cultivation of tuna fry. With proven good performance for lo growth. Sold in frozen block, and fed by sowing by hand after thawing. Poor preservability, desirably thawed and adjusted for each feeding. Unusable for automatic feeder. [0026] The above feeds were given to tuna fry, and the feed 15 eating activity was compared. The results are shown in Table 2. The feed eating activity was evaluated based on the definition shown under the Table. It was observed that even when the eating of the commercially available formula feed for marine fish (trade 20 name: OTOHIME-S2) was found, the fish that showed feed eating spit out the feed after swallowing once. The dry crumble feed was free of spitting out behavior, and considered to have been swallowed. However, a continuous feed eating behavior was not observed. 25 In contrast, all gummy feeds induced active feed eating by the fish, where the fish dashed particularly toward the feeds many times, and a continuous feed eating behavior was found. Jumping due to excitement was also observed. With the frozen Japanese sand lance whitebait, the feed 30 eating behavior was still more active, and jumping near the water surface was active. A continuous feed eating behavior accompanying dash movements with splashing was observed. [00271 Since dry crumble feed and gummy feeds had almost the 35 same constituent components and ratios thereof, and are 9 different only in the presence or absence of gelatin. Thus, the only difference between them is being gummy or crumble. It is therefore considered that the texture is considerably important for the feed eating by tuna fry. Since 5 the same results were 'also obtained with the low cost gummy feed free of trace expensive materials (lactoferrin, astaxanthin and the like), the same effect is expected with gummy feeds even when trace expensive materials are not contained. Furthermore, by comparison of the feed eating 1o activity of the feed produced by replacing gelatin in the low cost gummy feed materials with guar gum, the feed eating activity did not decrease at all even after changing the components. [0028] 15 From the foregoing, the trace expensive materials are not necessary for the feed eating activity of bluefin tuna fry, and the feed preferred by bluefin tuna fry should importantly have a chewy texture by the addition of gelatin, guar gum and the like. 20 The gummy (dry) feed is obtained by drying a low cost gummy feed in a room with running air-conditioner (25 0 C) for 6 hr. The texture thereof is very similar to crumbled instant noodle, and more like a crumble feed than a gummy feed. When immersed in water, the surface immediately gets slimy to some 25 extent. This is considered to be attributable to the high hydrophilicity of gelatin (containing collagen as a main component). [0029] According to this experiment, the gummy (dry) feed showed 30 the same feed eating activity as the gummy feed. This means that the gummy feed does not show decreased feed eating even after drying, and drying enables conventional feeding by an automatic feeder (note) generally used for other marine fish. In other words, the gummy feed can drastically save the labor 35 of conventional feeding operation by drying and using an 10 automatic feeder. [0030] Table 1 ratio (weight ratio) of materials used for each formula feed gummy feed low cost gummy cre (with trace feed (without material) trace material) fish meal 400 390 450 squid powder 100 80 85 krill meal 50 40 43 soybean protein 50 50 bonito stock extract residue squid liver oil 100 100 106 soybean lecithin 55 45 46 cholesterol 10 10 unsaturated fatty 10 10 acid vitamin mixture 30 29 29 sodium-calcium L ascorbic acid-3- 2 2 monophosphate choline chloride 1 1 mineral mixture 40 40 40 astaxanthin 1 1 lactoferrin 1 1 activated gluten 50 - gelatin powder - 114 114 total 1000 1000. 1000 5 [00311 Table 2 feed eating activity of each feed by bluefin tuna fry kind of feed feed eating activity commercially available formula feed for + marine fish (trade name: OTOHIME-S2) dry crumble + gummy (with astaxanthin, lactoferrin) +++ low cost gummy +++ low cost gummy (guar gum) +++ low cost gummy (dry) +++ Japanese sand lance whitebait 11 definition of feed eating activity -: no eating ±: eating is observed but spit out +: eating is observed but not active or continuous ++: continuous eating but not active +++: swims slower than ++++ but continuously eats well frequent dashing toward food and feed eating jumping due to excitement is also observed ++++: active jumping near water surface and active and continuous eating with splashing continuous dashing for feed eating [0032] Experiment 2 <swarming and feed eating > An experiment regarding the influence of the feed used 5 for cultivation on the swarming and feed eating was performed. [0033] Bluefin tuna fry cultivated on Japanese sand lance whitebait were further cultivated on Japanese sand lance whitebait, dry crumble and low cost gummi for 11 days, and the 1o feed eating activity observed when fed with each feed used in Experiment 1 was compared. The results are shown in Table 3. 12 [0034] Table 3 influence of diet used for cultivation on swarming and feed eating cultivation diet .feed cu o kind of feed swarming eating activity Japanese sand lance whitebait Japanese sand lance whitebait group dry crumble + low cost gummy +++ +++ low cost gummi (using guar gum) low cost gummy (dry) +++ +++ dry crumble Japanese sand lance group whitebait dry crumble +++ +++ low cost gummy +++ +++ low cost gummi (using guar gum) low cost gummy (dry) +++ +++ low cost gummy Japanese sand lance group whitebait dry crumble ++ +++ low cost gummy +++ ++++ low cost gummi (using guar gum) low cost gummy (dry) +++ ++++ 5 The definition of feed eating activity is the same as in Experiment 1. definition of swarming -: no swarming +: swarming is observed ++: 70% of fry near the feeding place swarm ++: 100% of fry near the feeding place swarm 10 [0035] In the Japanese sand lance whitebait group, swarming was observed for any feed, but the dry crumble was not ingested. While swarming and eating activity were high for the low cost 13 gummy feed, they were the strongest for the Japanese sand lance whitebait. In the dry crumble group, swarming was observed for any feed, but eating was active for the feeds other than Japanese 5 sand lance whitebait. In the low cost gummy group, swarming and active eating were observed for any feed. [00361 The above results show that cultivation on Japanese sand lo- lance whitebait or dry crumble results in the presence of feeds that are not eaten by fry. On the contrary, cultivation on low cost gummy feed results in active eating of any feed. This means that fry cultivated on low cost gummy feed can be fed with any other feed from any time, which is considered to 15 enable change of feeds and use of an automatic feeder for a certain period (e.g., only daytime or only afternoon of a day and the like), in consideration of the economic efficiency and labor of fry cultivators. Drastic change of a component of any conventional feeds requires a period for making fish eat a new 20 feed and a conditioning period. Therefore, the feed of the present invention is innovative. Particularly, the flexibility permitting radical change of feed components according to the condition of cultivated fish and environment (water temperature, sunshine and the like), without requiring a 25 period for making fish eat a new feed or a conditioning period is absent in conventional feeds. A feed eating activity equivalent to that of the gummy feed was observed for the gummy feed using guar gum. [0037] 30 From the above, the feed preferred by bluefin tuna fry should importantly have a chewy texture of gelatin, guar gum and the like, in accordance with the results of Experiment 1. The same results as for the gummy feed were also obtained for the gummy (dry) feed. 35 It is also shown here that the gummy (dry) feed can be 14 used as an alternative to the gummy feed. [0038] Experiment 3 <survival rate> Bluefin tuna fry (total length: 45 mm) were housed in 6 5 onshore fish preserves (2x2x2 m) by 200 fry each. One fish preserve was not fed, and other fish preserves were fed with Japanese sand lance whitebait, dry crumble and low cost gummy feed. Seven days later, the experimental fishes were taken out and the body length, body weight and obesity degree (100,000 x lo body weight (g)/cube of body length (mm)) were measured. In addition, dead fish were taken out and counted every day. The fish were fed every 2 hours during 7:00 - 19:00. [0039] The number of dead fish was the highest on day 3 in all 15 fish preserves (Fig. 1), and decreased thereafter. The number of dead fish was the lowest in the fish preserve fed with a low cost gummy feed. This shows that the low cost gummy feed has an effect to decrease the death rate after transfer. [0040] 20 The body weight at 7 days from the start of the experiment (Fig. 2) showed a significant increase from that at the start of the experiment in any fish preserve (ANOVA, P<0.05). The growth amount was the highest in the Japanese sand lance whitebait group and the low cost gummy group, 25 followed by the dry crumble. The same results were also obtained for the obesity degree (Fig. 3). These results show that feeding of a low cost gummy feed is expected to afford a growth rate equivalent to that of Japanese sand lance whitebait, and does not decrease the obesity degree. 30 [Industrial Applicability] [0041] The present invention enables efficient production and improvement of the survival rate of bluefin tuna fry. As a result, bluefin tuna fry is stably supplied in a large amount 35 to fish farmers, which contributes to the realization of 15 complete bluefin tuna cultivation independent of the natural resources. In the claims which follow and in the preceding 5 description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated 10 features but not to preclude the presence or addition of further features in various embodiments of the invention. It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a 15 part of the common general knowledge in the art, in Australia or any other country. 16 6402256_1 (GHMatters) P91394.AU JESSIEL

Claims (10)

1. A formula feed for tuna fry of around 20-70 days after hatching or with total length of about 20 - 200 mm, which 5 has a diameter of 0.5 - 10.0 mm and a gummy texture, and is obtained by adding a gelling agent approved as a food additive to a fish feed material to achieve a gummy texture. 10

2. The formula feed for tuna fry according to claim 1, wherein the gummy texture is a rupture strength of 10 200 g/mm.

3. The formula feed for tuna fry according to claim 1 or 15 2, wherein the gelling agent is gelatin or guar gum.

4. A formula feed for tuna fry, which is obtained by drying the formula feed for tuna fry of any one of claims 1- 3. 20

5. The formula feed for tuna fry according to any one of claims 1-4, wherein the tuna fry is a fry of a fish belonging to the genus Thunnus. 25

6. A method of breeding a tuna fry, which comprise feeding a tuna fry of around 20-70 days after hatching or with total length of about 20 - 200 mm with the formula feed for tuna fry of any one of claims 1-4. 30

7. The method according to claim 6, wherein the tuna fry is a fry of a fish belonging to the genus Thunnus. 17 6402256_1 (GHMatters) P91394.AU JESSIEL

8. Use of the formula feed for tuna fry of any one of claims 1-4, for feeding a tuna fry of around 20-70 days after hatching or with total length of about 20 - 200 mm. 5

9. The use according to claim 8, wherein the tuna fry is a fry of a fish belonging to the genus Thunnus.

10. The formula feed for tuna fry of claim 1, the method of breeding a tuna fry of claim 6, or the use of claim 8, 10 substantially as hereinbefore described with reference to any one of the Examples. 18 6402256_1 (GHMatters) P91394.AU JESSIEL