What are the advantages of using extruded floating feed to farm the four major Chinese carps?

Farming grass carp with extruded floating complete compound feed has many advantages, such as lowering costs, protecting the aquaculture water environment, and high utilization rate. In countries with advanced aquaculture technology such as the United States and Japan, to meet the needs of the environment and fishery production, floating aquatic feed has been widely used since the 1980s.

In recent years, China has also vigorously promoted the use of floating aquatic feed, developing rapidly, and many famous, special and high-quality aquatic products have already used it in large quantities, but in the use of extruded floating fish feed to farm the four major Chinese carps, there is still a relative lack.

I. What is extruded floating feed?

Extruded floating feed is based on the original complete pellet feed formula, improved, cooked and stirred at a higher temperature and in a larger pressure space than pellet feed production, and then released into a normal air environment, so it naturally expands, and each feed pellet produces more loose small pores; feed of the same volume is lighter in weight, so after suitable processing, it will float on the water surface. Just like popcorn, it only makes the feed more fragrant, crisp and palatable and improves the conversion rate; it is not, as some people say, made by adding some kind of chemical leavening agent.

II. Why is floating fish feed quickly accepted for use in other special aquaculture, while the use of extruded floating feed to farm the four major Chinese carps progresses slowly?

The ultimate reason is still the issue of economic benefit. Because the price of special aquatic products is relatively high, producing corresponding feed products at a relatively high price can also be accepted by users. But the four major Chinese carps, after all, are not very high in price, with a small profit margin, and farmers are unwilling to increase costs. Ensuring feed quality while also achieving a price acceptable to farmers, and making a product that truly brings benefits after users use it, is indeed harder than producing pellet feed; there are not many manufacturers that can truly take all factors into account and provide farmers with a relatively good and beneficial extruded floating feed product. Therefore, progress in using floating extruded feed in the farming of the four major Chinese carps has been slow.

III. How should extruded floating feed be selected?

Relatively speaking, the production cost of extruded floating feed is somewhat higher than that of pellet feed, so when selecting extruded floating feed for farming the four major Chinese carps, in addition to choosing well-known brands, quality and price should also be considered comprehensively, and a feed variety of upper-middle level should be chosen. In terms of protein content, it is best to choose varieties with a protein content between 20% and 30%. Although feed with too low a protein content has a lower price, because the processing cost of extruded feed is relatively high, the content of usable nutrients is relatively low, which will increase farming costs; truly usable high-protein feed is rather expensive, and the nutrient content in grass carp excrement will also be relatively high, causing waste. In terms of price, one should choose a variety slightly more expensive than the middle- and high-grade pellet feed used on a large scale in the market.

IV. What benefits are there in using extruded floating feed to farm the four major Chinese carps?

First, feed utilization rate is high. Because extruded feed must be produced through a higher processing temperature and a longer cooking time than pellet feed, its degree of cooking is better, and it can change the structure of components in the feed that cannot be absorbed, making them digestible and absorbable, and eliminating harmful substances in the feed. Just as humans digest and absorb most cooked food better, after the same pellet feed is extruded, the absorption and utilization rate by grass carp increases by more than 30%, and good extruded floating grass carp feed is as fragrant and crisp as biscuits, with good palatability for grass carp and better feeding. Second, it is easy to manage. Extruded floating feed can float on the water surface for a long time, with a floating time of more than 10 hours, making it convenient to observe the fish's feeding situation and control the feeding amount; human waste can be reduced to zero, and it is convenient to feed, saving a lot of time and improving labor production efficiency. Third, disease prevention is good. Harmful bacteria such as Escherichia coli, mold, and Salmonella in the material are completely killed by high temperature and high pressure during the extrusion process, reducing infection of intestinal diseases in the four major Chinese carps and reducing the occurrence of disease. Because floating fish feed floats on the water surface, the four major Chinese carps can only feed at the water surface, so they will not stir up the sludge at the bottom of the pond that contains large amounts of bacteria, reducing infection opportunities; moreover, the surface water of the aquaculture pond is rich in dissolved oxygen and has few harmful substances. In such an environment, the four major Chinese carps not only feed better, but their disease resistance is also enhanced, and they grow more healthily and rapidly. Fourth, water quality is better maintained. Because extruded floating feed has a higher digestion and absorption rate than pellet feed, the feed coefficient is low, the nutrient content in fish excrement is lower, and there is less powder, which can avoid residual bait in the water body, thus greatly reducing pollution of the water environment and providing an extremely favorable guarantee for the four major Chinese carps to grow in a better water environment.

V. How should feed for overwintering grass carp be selected?

Under normal circumstances, after the water temperature drops in winter, grass carp feed very little or do not eat pellet sinking feed, which limits their growth; if pellet sinking feed is put in, it easily causes waste, and if no feed is put in, it limits the growth of the fish. Through the author's large-scale experiments, it was found that when grass carp are farmed with floating feed, on sunny days when the water temperature drops to 15°C, they can still have a feeding amount of 2%-4%, and the grass carp grow relatively well. Therefore, choosing floating feed in seasons with lower water temperature is a very good feeding method for farming the four major Chinese carps.