FIELD OF THE INVENTION

The present invention belongs to the field of feedstuff formulation for aquaculture of herbivorous and omnivorous species, particularly for aquaculture of echinoids. STATE OF THE ART

The exploitation of fishery resources has increased dramatically in recent years, particularly due to the growth in processing industries.

As regards demand for sea urchin gonads, growth is so high that it has led in recent decades to overfishing of natural populations. Initially the "culture of the sea urchin" was just a "tasty whim" of a few people and focused only on the fresh product consumed in summer (especially in Italy). Today, those who consume this product throughout the year are increasing in number both in Italy and worldwide. In recent years the growth in demand and price on the one hand, and the attempt by the scientific community to protect natural sea urchin populations on the other, have led to intensifying the farming of this species. The main consumer of sea urchin gonads is Japan, where sea urchins are used to prepare expensive sushi. The country that mainly exported to Japan in the 1970s, 80s and 90s was the US (California). Sea urchins have in fact been a major export item of California, thanks to steady demand from Asia.

The sea urchin fishery began in the US in the seventies with a federal program to promote this activity and it became increasingly profitable in subsequent years, with the growth of the yen against the dollar. This led to a goldrush mentality, with about 500 licensed sea urchin divers in California. Maintained over the years, such exploitation has led to depletion of sea urchin stocks.

Several scientific papers have focused on feedstuff formulation for farming different echinoid species. What has so far been noted is that many feeds cause changes in the organoleptic characteristics of the product; others change gonad coloration so that the final product is unmarketable. In addition, most feedstuffs have macroalgae as the principal ingredients, causing a potentially negative impact on marine ecosystems. However, these studies were not carried out on the Mediterranean sea urchin Paracentrotus lividus, nor did they include terrestrial vegetables among the main ingredients.

To date, there is no commercially used artificial feed for fattening echinoids and related species under farming conditions. The only information available regards the use of macroalgae of the genus Macrocystis and Ulva for the farming of the Pacific sea urchin Loxechinus albus. This feed cannot be used for the Mediterranean sea urchin P. lividus due to the scarcity of these macroalgal species in the Mediterranean Sea, while the use of similar algae species would have a significant impact on the marine ecosystem. Feed commonly used in fish farming is not appropriate for feeding P. lividus, because: (1 ) the echinoids have a different physiology from that of teleosts, (2) it is impossible for sea urchins to graze on the commercial pelleted feed commonly used for fish, (3) commercial pelleted feeds are inadequate for sea urchins from a nutritional point of view.

Similar problems to those identified above for echinoids also occur in the aquaculture of herbivorous or omnivorous species which are commercially important for their organoleptic properties.

The purpose of this invention is to provide a feedstuff formulation with a suitable nutrient content for the aquaculture of echinoids and other herbivorous and omnivorous species wherein the main ingredients are of terrestrial origin and the formulation adequately preserves the organoleptic properties of wild sea urchins. SUMMARY OF INVENTION

The present invention solves the problems outlined above by providing a feedstuff for aquaculture of echinoids and herbivorous or omnivorous species, said feedstuff formulation includes egg albumen and ground vegetal material of the genus Lactuca as its main ingredients. The feed is suitable for application in the aquaculture of herbivorous or omnivorous species, particularly of sea urchins and related species. The aim is to obtain a high quality product, in both increased production of edible tissue and maintenance of the organoleptic characteristics of the wild organisms, such as taste, smell and color.

In the experiments carried out on Paracentrotus lividus and Sphaerechinus granulans, the feed was shown to possess properties that guarantee maintenance of the organoleptic characteristics of the animal reared, while ensuring a nutrient content that can generate much greater quantities of edible tissue with an average ratio of about 2-5 to 1 with respect to wild organisms. The feed is produced from natural sources and discard materials from food farming can be used. This process helps keep production costs low, with the return to a productive cycle of waste materials otherwise destined for pulping.

The food of the invention has a high resistance to water and does not flake on prolonged contact with water, thus avoiding dispersal in the environment and ensuring a low environmental impact as well as good conversion efficiency into edible tissue.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 shows photos of the artificial feedstuff invention.

FIGS. 2 and 3 show graphs of gonad weight, gonad-somatic index, IGS, and total weight of specimens of wild sea urchins and sea urchins fed with the artificial feedstuff of the invention.

FIG. 4 shows photos of sea urchins fattened in tanks with the artificial feedstuff of the invention.

DETAILED DESCRIPTION OF INVENTION

The main ingredients means the two ingredients present in greatest quantity in proportion to the total weight of the composition. The amounts are calculated using the uncooked ingredients.

The feedstuff of the invention is made with uncooked natural components mixed together in well-defined proportions and subject to cooking in order to obtain a compound (or "cookie") which has a high persistence in water (3-5 days depending on water temperature).

The feed produced from the composition of the invention is preferably subject to cooking, thus obtaining a compound (or "cookie") with a homogeneous plastic consistency maintained even when immersed in water. This "cookie" maintains its consistency in water for 3-5 days, depending on water temperature.

For the purposes of the present invention fresh egg albumen is preferably used. Egg albumen may also be reconstituted, for example from lyophilized egg albumen rehydrated with water (10-20% freeze-dried albumen + 20% water). W

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Of the vegetal material of the genus Lactuca the preferred species is L sativa, but other commercially available edible species can also be used profitably, also in mixtures, in the preparation of the invention. Among the varieties of lettuce that can be used are Lactuca sub. crispa, Lactuca sub. capitata; Lactuca sub. longifolia, Lactuca sub. secalina. Both fresh leaves and fresh discard can be used to obtain the same results.

The composition preferably includes other ingredients that contain fat, carbohydrate and protein of fish or plant origin. In detail, these additional ingredients are fish meal (preferably herring or sardine or other kinds of flour), soybean meal, wheat flour, fish oil (preferably herring or sardine), maize flour and soybean oil.

The feed preferably does not contain macroalgae.

The feedstuff of the invention as above described is preferably obtained by cooking a mixture of the following uncooked ingredients:

45-55% Egg albumen, fresh or reconstituted

30-40% Lactuca sativa

4-6% Fish flour (herring, sardine and other kinds of flour)

3.8-4.2% Soybean seed flour,

2.8-3.5% Wheat flour,

2.4-3.0% Fish oil (herring or sardine),

0.7-1.2% Corn flour,

0.8-1.3% Soybean Oil,

where the percentages are percentages by weight of the total weight of the mixture of raw ingredients.

A further object of this invention is a method for preparation, which is by cooking a homogeneous mixture of the raw ingredients. The mixture can be cooked in an oven for 2-20 minutes at 60-120 °C or in a microwave oven at 500-1000 W for 2- 15 minutes.

The homogeneous mixture of raw ingredients can be obtained using any potential means of grinding and mixing the ingredients, preferably a blender.

To cook the homogeneous mixture, the mixture is preferably placed in a box with a flat bottom to a final layer 2-5 mm thick, preferably about 2 mm. Once cooked, the final product looks like a baked cookie of plastic consistency which can be cut into pieces of any shape.

The composition of the invention is useful for aquaculture of echinoids, preferably P. lividus, S. granulans, Loxechinus albus and Strongylocentrotus intermedius and other herbivorous or omnivorous species, with similar food requirements, including:

- freshwater species selected from the group consisting of:

• Cyprinidae;

• Cichlids with particular focus on the genus Oreochromis spp. and Symphysodon spp.

• Loricariidae;

• Caridina;

- Marine species: herbivorous and omnivorous species, including:

• Mugilidae;

· Shellfish (except filter feeders) with particular focus on the genera: Haliotis spp. and Concholepas spp.

• Penaeid crustaceans.

The nutritional protocol for echinoids and other invertebrates requires that the feed of the invention is preferably administered weekly, in amounts of 1-4 grams per specimen (average size 40 g).

The nutritional protocol for herbivorous or omnivorous fish species requires that the feed of the invention is preferably administered daily, in amounts of 2-6% of body weight in relation to size.

In light of the experimental results obtained, the nutritional protocol for farmed organisms consists of an artificial feedstuff made of raw, natural, low-cost materials, which in the case of the sea urchin supports an increase in gonad weight of 2 to 5 times compared to wild specimens of the same size, while maintaining the organoleptic characteristics.

Due to the excellent growth performance obtained using the feedstuff, reduced production costs are expected, since a single sea urchin would produce a quantity of edible tissue equal to that of three wild sea urchins or sea urchins fed on alternative diets. This result is obtained without compromising the organoleptic characteristics of the final product. This nutritional protocol would also result in reduced costs of feeding the farmed animals, as the highest percentage of substances making up the feed comes from food industry waste. In addition, the feedstuff has a high resistance to water, ensuring a low environmental impact. The present invention can be better understood in light of the following experimental examples.

EXPERIMENTS

Example 1 - Feedstuff preparation

Raw composition: 50% egg albumen, 33.3% Lactuca sativa, 4.8% fish flour (herring), 4.2% soybean seed flour, 3.2% wheat flour, 2.7% fish oil (herring), 0.9% corn flour, 1.1 % soybean oil.

The different ingredients were mixed together, in the above proportions, using a blender. Once homogenized the mixture was placed in a box with a flat bottom, filled to achieve a thickness of 2 mm. Subsequently the mixture was cooked at a temperature of 100 °C for 10 minutes. After cooking, the mixture, which assumed an elastic texture, was cut into squares 4 cm long ready to be fed to the echinoids. The feed can be stored at -20 °C for 3 months. Figure 1 shows photos of the feed obtained using the method described above. Example 2 - Paracentrotus lividus feeding experiments

Laboratory feeding experiments lasting three months each were carried out to verify the efficacy of the feedstuff for sea urchin gonad growth. During the experiments the feedstuff was used to feed sea urchins and resulted in an excellent growth performance calculated from gonad weight, gonad-somatic index, IGS, and total weight (Figures 2, 3).

The food was administered on a weekly basis with amounts equal to 2 grams per individual. In Figure 4 photos of the gonads of specimens fattened with this nutritional protocol are shown. From the photo it is possible to see that the color of the gonads remained unchanged.