Text | Zhejiang Haida Huang Tao
Introduction: From less than 800 catties to 1800 catties, it took only 2 years!
1. Sheds in different regions have their own characteristics
Since 2020, the rapid development of small sheds across the country is mainly due to the high cultivation rate and strong replicability of this model. However, the farming environment is different in each region.
Taking Shaoxing, Zhejiang Province as an example, the salinity of aquaculture water sources in this region is low, generally below 5‰. Two years ago, Shaoxing sheds also attracted many new and old farmers to invest. It may be that there has been a high-yield experience in Jiangsu, and many farmers have set the output target to 1,800 catties for the first shrimp. But contrary to expectations, the output of the first shrimp is basically less than 800 catties, and the highest individual sheds are 1200 catties. Farmers' confidence has been severely hit, and it is generally believed that low-salinity sheds will not produce high yields.
In addition, the price of shrimp during the peak period of shrimp sales in June and July this year was 1.5 yuan per catty lower than that of the same period last year (Figure 1).
Figure 1
Second, the experience of the masters is shared, and the low salinity shed can also be high-yielding
Fortunately, under the conditions of the same natural environment such as climate, soil quality, and water source, after two years of continuous exploration, some breeding masters have been able to raise 1,800 catties of shed production more stably. In order to reveal the hidden logic behind the high yield of low-salinity sheds, the technical service team of Haid visited and investigated a number of breeding masters with a shed yield of 1,800 catties and a shrimp seedling recapture rate of more than 9 percent, to understand and learn from their successful experience.
Next, this article will combine the breeding data monitored in 2024 and the survey results of high-yield farmers, and summarize and share some key points to support the high yield of low-salinity sheds for the reference of the majority of farmers.
No.1 Environmental regulation
1. Salinity adjustment
The water source of the outer rivers in Shaoxing area is generally fresh water, and the salinity of well water is only 2‰-6‰. The survey found that high-yield farmers all use well water to raise shrimp throughout the whole process, and the salinity of the aquaculture water has always been maintained at more than 4‰. This is consistent with the conclusion of our small water experiment with P10 shrimp seedlings. In the 6 h of the experiment, only 48% of the shrimp seedlings in the river water group (0.1‰) survived, and the survival rate of shrimp seedlings in the well water group (3.6‰) and the river well water mixing group (1.8‰) was 98%. After 48 h of the experiment, the survival rate of shrimp seedlings in the well water group (3.6‰) was the highest (88%), and the survival rate of shrimp seedlings in the river water group (0.1‰) was less than 3% (Fig. 2). It can be seen that salinity has a great impact on the survival of shrimp seedlings, and it is recommended to breed in whole well water, and test the salinity before releasing seedlings to ensure that all sheds are above 4‰.
Figure 2
2. Water temperature control
We all know that the increase in temperature decreases the dissolving capacity of oxygen in water, on the contrary, the metabolism of organisms in water increases, the respiratory rate increases, and the oxygen consumption increases, and the comprehensive result is that the higher the water temperature, the lower the dissolved oxygen. We continuously monitored the water temperature and dissolved oxygen changes in the same shed for 10 days, and analyzed the data at 6 and 16 o'clock every day, and found that the dissolved oxygen decreased by 0.2 mg/l for every 1°C increase in water temperature (Figure 3). High-yielding farmers usually adopt methods such as increasing the amount of water and covering the shade net to control the water temperature below 32°C to ensure that the dissolved oxygen is in a relatively safe range.
Figure 3
No.2 Management Operations
1. Precise feeding
"How many pounds of feed have you fed? How old are shrimp? It should be the most common opening sentence for greetings between farmers. It can be seen that the size of shrimp and the amount of feed are the breeding links that everyone is more concerned about. Asking others about their feeding amount compared to their own can effectively avoid the problem of slow growth of shrimp seedlings caused by too little feeding, and waste and deterioration of water quality caused by too much feeding. The feeding data provided by the high-yield farmers and their final pond clearing data were combined and analyzed, and it was found that even though there were differences in seedling stocking density and recapture rate, their daily feeding amount was basically about 9 kg/10,000 (actual surviving seedlings).
Table 1
2. Replenish the shrimp
Minerals are indispensable in shrimp farming and are involved in many physiological and metabolic processes. However, the mineral content of low-salinity water sources is generally low. In order to maintain the stability of the breeding environment and help the healthy growth of shrimp seedlings, many farmers will regularly use mineral replenishment animal protection products. We selected 3 sheds to carry out continuous monitoring of calcium, magnesium and potassium content for 2 months and 2 days (Fig. 4), combined with the analysis of the dosage of calcium chloride, magnesium chloride and potassium chloride in the process, it was concluded that the average daily use of calcium chloride was 0.95 kg, 3.65 kg of magnesium chloride and 0.84 kg of potassium chloride, which could basically make up for the consumption of calcium, magnesium and potassium elements in the water body during the cultivation process of low-salinity sheds.
Figure 4
3. Prevention and control of sub-salt
When it comes to low-salinity shrimp farming, many farmers will immediately think that the problem of sub-salt is not easy to handle. If you want to raise high yields in low-salinity sheds, the prevention and control of sub-salt in the turbidity period is a skill that must be mastered. The turbidity period generally occurs about 25 days after the seedlings are released, when the shrimp seedlings basically reach 3 cm, and the feeding desire and bottom picking ability are enhanced, resulting in the sediment at the bottom of the pond turning up, the water becoming turbid, the algae survival difficult, the pH and dissolved oxygen of the water body decreasing (Fig. 5), the gradual accumulation of ammonia nitrogen, and then the soaring of sub-salt.
Here, taking the practical effect as an example (Figure 6), we share a set of practical sub-salt prevention and control plans that are effective in 5 days: 1. Fertilizer: fungus and algae Wang 2 kg/shed + algae paste 1 kg/shed [2 days/time]; 2. Supplement: shrimp multi-treasure bubble fungus 10 kg/shed + bud speed net 0.5 kg/shed, 3102 3 kg/shed + brown sugar 3 kg/shed [2 days/time]; 3. Emergency: 0.5 bags/shed [for 3 days].
Figure 5
Figure 6
4. Vibrio prevention and control
For small shed farmers, vibrio prevention and control should be no stranger, it can be said that it has become a part of the daily operation of many farmers, and everyone is estimated to have a different method. The operation methods of high-yield farmers in the prevention and control of Vibrio are also different, including regular use of Vibrio drugs, regular disinfection, and antibacterial bacteria, and these methods also have certain effects.
We have done many follow-up experiments on the effect of disinfection and vibrio on the bottom of the beautiful bottom, and the results show that the vibrio bacteria will start to breed again after 2 hours of disinfection, and can multiply rapidly within 1 hour (Figure 7). Therefore, it is more appropriate to replenish bacteria 2 hours after using a beautiful bottom disinfection. At the same time, it is recommended to use disinfection methods to treat Vibrio farmers, according to the continuous sterilization effect of different disinfectants, choose the right time to replenish bacteria can achieve twice the result with half the effort.
Figure 7
"Difficult things in the world must be done easily; The big things in the world must be done in detail. "Behind every successful person, it is the details that play a decisive role, and only by perfecting the small details can we achieve great things. The era of "profiteering" of small shed white shrimp farming has passed, and if you want to make a profit, you must achieve stability and high yield. The competition is about grasping the details and having a good attitude. Through the comprehensive advantages of feed, animal protection, seedlings and breeding technology services, Haid will help farmers to reduce costs and increase efficiency.
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