In autumn, the weather turns cool gradually. As the saying goes, "one autumn rain, one cold", prawns are very sensitive to changes in the environment. In case of sudden changes in weather, algal blooms and hypoxia, they are prone to stress reactions.
Temperature is very important for all organisms, because biological physiological and biochemical processes need to be carried out at a certain temperature. From dinosaurs to bacteria and viruses, from microorganisms to plants and animals, the growth, reproduction, immunity and other physiological stages of various organisms will be affected by temperature.
Penaeus vannamei is particularly sensitive to changes in the environment, and it is difficult to make adjustments in a short period of time. Therefore, heavy rain and other weather, seasonal changes in water temperature and other periods of large amplitude are also periods of high incidence of diseases of Penaeus vannamei. Prawns are prone to slow feeding, white spot syndrome, red body, molting failure, yellow gills, black gills, intestinal thinning, tail section whitening, swimming in the pond or even stealing death, causing significant losses to the breeding.
What aspects should we pay attention to and prevent from the impact of large temperature difference between day and night on aquaculture?
01. Bubble disease caused by large temperature difference
The temperature difference between day and night is large. At this time, the gas solubility in water changes greatly. The water temperature rises in the day, and the dissolved gas is easy to be supersaturated, leading to bubble disease, causing gas damage to cultured animals, and secondary infection with various diseases.
02. Causes stress on prawns
The temperature difference changes greatly, and the stress on the breeding animals is large, resulting in the decline of disease resistance and the susceptibility to disease.
03. The pond is easy to reverse
At the same time, the temperature difference is large, and the convection between the upper and lower water bodies is intensified, which makes the pond very easy to reverse to the bottom. The dirt at the bottom enters the water body, causing the breeding of various harmful pathogens such as bacteria and parasites.
In view of the above problems, pond management is particularly important. Specifically, we can:
01. Strengthen oxygenation
Open more aerators, and it is better to install "small flying saucer" in the pond where conditions permit, so as to accurately grasp the time of gas supersaturation and precise aeration. When the temperature difference becomes large, the pond water body is prone to thermocline. When the sun comes out in the daytime, the temperature of the upper water body rises rapidly, while the temperature of the lower water body rises slowly. In the evening, due to the influence of strong wind, the temperature of the upper water body drops rapidly, and the lower water body drops more slowly. Because the density of the lower water body is larger than the lower water body, the vertical convection forms, which rolls up the toxic substances at the bottom, increases the chemical oxygen consumption of the pond, makes the dissolved oxygen in the water body drop down, and even makes the fish and shrimp poisoned. If it rains, the situation will be more serious. Therefore, it is suggested that in sunny afternoons, oxygen should be added in turn to mix the upper and lower water bodies and reduce convection at night. If there is a thunderstorm or a sudden north wind, you need to open more oxygen dispensers at night; In case of typhoon, the water level of the shrimp pond shall be lowered appropriately, and oxygen enrichment shall be strengthened. During the rainstorm, particulate oxygen can be sprinkled dry, and the surface water of the pond shall be drained in time.
02. Effective detoxification and stable water quality
In addition to increasing oxygen in advance before and after cooling, it is particularly important to use detoxification products. Use Shuilishang products together to remove toxins and relieve stress.
03. Supplement nutrition and improve physical fitness
The weather changes greatly, causing great changes in water quality, and the shrimp is prone to enteritis, slow feeding, body color deterioration and other stress reactions. Therefore, it is recommended to regularly add high stable VC (high stable VC), immune polysaccharide (biotin), liver protection and growth promotion products (liver and intestine), complex protein small peptide (really fast), etc. to the feed to improve the anti stress reaction ability of the object. It should be fed regularly, scientifically and appropriately. The scientific use of the product can enhance the resistance of shrimp, reduce stress, promote the growth of shrimp, and restore the vitality of shrimp.
04. Frequent base correction and prevention of reverse base
The bottom of shrimp should be raised first. If the bottom is improved, half of the breeding will be successful. You can use EM bacteria, bacillus, lactobacillus and the like (Shiba, live enzyme, Shibao) to maintain the ecological balance of water by absorbing and transforming organic substances in the water, such as feed residues, fish excrements, etc. This can not only improve the bottom, but also play a role in algae and bacteria culture.
05. Pay attention to controlling feed feeding
In autumn, the intake of prawns increases in the morning and evening, but the appetite is weak at noon. It is suggested that the farmers should adjust the feeding proportion of each meal reasonably according to the feeding situation of shrimp, so as to improve the feed utilization rate; In case of strong rainfall, it is better to stop feeding immediately to avoid excessive residual bait polluting the pond bottom; During the molting period of prawns, the feed will be reduced, and the farmers should also pay attention to reducing the feed properly; In South China, when the weather is still hot and hot, the metabolism will be more vigorous, and the feed will deteriorate faster and faster in the water. The feed should be small for many times to avoid the bacterial enteritis disease of prawns caused by eating the deteriorated feed. But at the same time, if the shrimp is hungry for a long time, the liver function will be seriously damaged, and the repair and metabolism of liver cells will be hindered. Therefore, it is OK to stop feeding, but not too long.