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Yesterday, I talked about why we need carbon sources in aquaculture, and today the editor-in-chief of the Fisheries Research Society will give you a detailed list of the demand for carbon sources in various breeding models, as well as what kind of carbon source is more suitable for us in aquaculture.
Among the various aquaculture models, the demand for carbon sources, in order of needs from small to large, is as follows:
Ponds without aerators with large water surfaces have the least demand for carbon sources (e.g., an area of thousands of acres);
the second is an ordinary small water surface soil pond (such as a soil pond of hundreds of acres and dozens of acres);
the third is to intensively raise small-area earthen ponds, Fujian winter shed breeding earthen ponds;
The fourth is the high-level pool (there are many aerators), and then there is the Rudong shed, and the largest demand for carbon sources is the factory cement pool aeration tank.
Why is there such an order? This is determined by the characteristics of the microorganisms themselves, microorganisms need carbon nutrition, trace element nutrition, and the reproduction of microorganisms requires aeration and oxygenation.
From the above order, we know that the natural extra-large water surface of the earthen pond (thousands of acres), the large water surface of its water body self-purification ability is extremely strong.
The sediment of the soil pond itself is rich in a large amount of carbon nutrients and trace element nutrients, and there is no aerator in this large water surface, and most of the breeding density is the lowest in such a large water surface.
Therefore, this determines that the first does not need to splash too many microorganisms, the second does not need too many carbon sources, and the absence of an aerator also determines that it is impossible to splash too many microbial products.
The factory aeration tank is the breeding mode that requires the most carbon sources, because the aeration tank is very dissolved oxygen;
This is a prerequisite for a large number of microbial products, because all microorganisms entering the water need to consume oxygen (but different bacteria need different degrees of oxygen);
Second, the breeding density of factory aeration tanks is the highest among all farming models, which also determines that there will be a large amount of total nitrogen in the water body, so this determines the need for more carbon sources to balance the carbon to nitrogen ratio.
It is said that in some factory aeration tank culture, the biofloc technology is used, and the carbon source such as molasses is sprinkled every day, which is equal to the amount of feed invested;
The results show that the type of carbon source will affect the structure, composition, nutrient composition and stability of biological flocs, and then affect the growth and survival of farmed organisms, and the cost of different carbon sources also determines the utilization value of biological flocs.
The Fisheries Research Society found a paper on the experimental analysis of three commonly used carbon sources of glucose, sucrose, and molasses by consulting the data:
It was concluded that the suitable carbon source for the formation of biofloc in the shrimp farming system was sucrose, and the suitable amount of sucrose was 75% of the daily feeding amount.
This may be because glucose, as a monosaccharide, is easily absorbed and metabolized by bacteria, which can quickly promote the growth and reproduction of bacteria, but it is easily affected by the amount and time of addition, resulting in the instability of the bioflocs formed.
Although molasses is the fastest to form flocs and has low cost, it contains more impurities, and the practical application has higher requirements for dissolved oxygen in water.
Sucrose is easily absorbed and utilized by heterotrophic microorganisms in the aquaculture water, which can quickly form bioflocs and exist stably in the aquaculture water.
When the sucrose addition reached 75% of the daily feeding amount, the number of heterotrophic bacteria did not increase, but the 100% sucrose addition rate was beneficial to keep the number stable, but the 50% sucrose addition could not maintain the stability of the number of heterotrophic bacteria.
Therefore, we can give priority to sucrose when supplementing the carbon source of the water body, which is more effective.