A brief discussion on the matching techniques of High-yield Culture Model of Grass Carp in Hunan Province

Teng's Fisheries Business Network-exclusive report by Contemporary Aquatic Magazine:

Hunan Province is one of the main producing areas of grass carp (Ctenopharynodonidellus) in China, and the culture capacity of grass carp is as high as 589000 tons (2013 statistics). The water surface of this area is large, and there are many intensive culture water surfaces, but the yield per mu is generally low, the average amount of feed per mu is less than 1 t per mu, and most of the yield per mu is less than 1000kg. The farming scale of farmers is 10 to 20 mu, and the profit per mu is about 1000 yuan. In order to better promote the upgrading of culture, improve the yield per unit area and culture efficiency, combined with market practice and science and technology, this paper introduces the relevant supporting techniques for popularizing the high-yield culture mode of grass carp in Hunan market. in order to promote the level of culture in Hunan and improve the efficiency of farmers.

1 present situation of grass carp culture in Hunan

In Hunan area, grass crucian carp is mainly mixed with silver carp, in which the yield of grass carp is the highest, but because the farmers are not vaccinated against grass carp, the survival rate of grass carp is generally 50%-80%, and the survival rate of ultra-low grass carp can reach 30%. During the period of culture, not enough attention was paid to the ecological balance of water body, and ammonia nitrogen and nitrite often exceeded the standard, resulting in difficult feeding and serious disease of fish, thus the yield was low and the profit of culture could not be effectively guaranteed. What's more, most farmers grow a large number of ryegrass, Sudan grass and other forage grass, which are mixed with feed during the breeding period. one is that the crude fiber content of the forage grass is high, which accelerates intestinal peristalsis, resulting in the excretion of part of the feed without thorough digestion, and the other is that the fish give priority to feeding, resulting in part of the forage grass rotting in the water, accelerating the deterioration of water quality.

After grass carp has been cultivated, it is the season of autumn and winter. At this time, grass carp are listed in large numbers, which leads to the low price of grass carp, the decline of farmers' enthusiasm for selling grass carp, and the impact of grass carp from other places (such as Guangzhou, etc.), and the fish price is even lower. Seeing that at the end of the year, a large number of grass carp are stored in the pond, helpless, only overwintering, but after overwintering, although the price of grass carp is about improved, but the cup water car salary, grass carp overwintering a lot of fat The benefit of farmers is greatly damaged.

(2) High yield culture model

Different sizes of grass carp and crucian carp mixed culture mode, and with flower silver carp (see Table 1 for details). This model focuses on hot water fish and increases the yield per unit area. From August to September, the fish is sold once or twice a month, and the yield per mu is increased from 500~750kg to 1000~1500kg. Those who are ripe can try to sprint 2000kg.

Table 1 High-yield culture model

3 supporting techniques and conditions 3.1 epidemic disease prevention and control technology

Grass carp injection vaccine technology (this technology is the key to the success of grass carp culture), grass carp Gill rot disease, red skin disease, enteritis disease, grass carp survival rate is low, while grass carp triple vaccine, through grass carp intramuscular injection or intraperitoneal injection, improve the survival rate of grass carp, reduce the risk of disease, so as to improve efficiency. At present, grass carp vaccine mainly comes from local vaccine, and the survival rate of grass carp can reach more than 90% by injecting vaccine. In addition, during the peak period of feeding, the liver and gallbladder protection drugs (such as Gandanshuling, Duowei, Qishen immune Powder, etc.) were taken regularly every month, and the fatness (K) was controlled within 1.9 to 2.4 by adjusting the feeding rate.

Note: K = (W/L3) × 100, where w is body weight (g) and L is body length (cm, rostral to caudal fin base)

3.2 balanced oxygenation technology

Balanced aeration technology, mainly using micro-hole aerator and impeller aerator. During the day, the oxygen produced by photosynthesis is enough to grow the fish, open the impeller aerator, break the water layer and evenly dissolve oxygen up and down the water body; at night, without photosynthesis, algae and fish in the water consume oxygen and need to borrow oxygen from the air, open the bottom to increase oxygen, press the air into the bottom of the water, and when the air overflows from the bottom to the water surface, the oxygen in the air gradually dissolves in the water body to achieve the purpose of increasing oxygen. Oxygen enrichment in the feeding area, because most of the fish body activities are concentrated in the feeding area, the dissolved oxygen in the water body in the feeding area is low, which is not conducive to feed utilization and fish growth, while the microporous oxygen enrichment plate is concentrated in the feeding area to avoid hypoxia in the feeding area and ensure that the dissolved oxygen in the feeding area is always above 4mg/L.

3.3 Precision feeding technique

Precision feeding technology, using expanded material + medium and high grade hard granule 1 ∶ 1 combination feeding, in high temperature and low temperature season (water temperature > 30 ℃ or