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(I) It is generally preferable to infuse a round funnel with a funnel formed at the bottom of glass or plastic so that the air diffusion from the bottom is uniform, so that all eggs can be kept in suspension and the hatching rate can be increased. This method is suitable for small-scale hatching. . The maximum hatching rate can be obtained when the water temperature is between 20°C and 30°C, and the fastest hatching occurs at 30°C. At the same time, dissolved oxygen is maintained in a near-saturated state and sufficient sunlight can increase egg hatchability and hatching speed. Cement tanks are used for large-scale hatching. The amount of Artemia eggs can generally be put in a ratio of 3-5 grams of Artemia eggs per liter of water, and the quality of Artemia eggs can be increased. During the incubation, the concrete pool should be inflated with air stone. It is usually advisable to place 1-2 per square meter. Care should be taken to evenly distribute the rock, especially the pool corners should be inflated, as the bottom of the concrete pool is generally large and flat, and the inflated eggs are easily piled into the corners of the pool and affect hatchability. When the water temperature was between 26°C and 30°C, macroscopic larvae could be hatched from Artemia eggs 24 hours later.
(B) factors affect the hatching rate For the same batch of Artemia eggs, the pH of the hatchery water, salinity, radon gas level, illumination, incubation time are all important factors affecting the hatching rate.
1. When the pH of Artemia hatches, the pH of the incubation water is required to be 7.5-8.5 and hatched. The light on the surface of hatching fluid is 2000 lux. In between, the optimum pH is 8, and appropriate amount of baking soda can be added to the water for adjustment.
2. The practice of salinity shows that the optimum salinity for hatching is 20 ‰, and the effect of low salinity is lower than that of high salinity.
3. Temperature and temperature not only affect the hatching, but the month. Affect the hatching speed. The appropriate degree of incubation is 28°C to 31°C, and the appropriate amount is 30°C. It should not exceed 32°C, nor should it be lower than 26°C.
4. Inflation should be fully, evenly, slowly and safely aerated during incubation (requiring incubation water containing more than 2.5 mg/L oxygen) and agitate the pool water to avoid excessive foaming and dead spots in the incubator. Excessive helium may cause death of some eggs and larvae due to violent rolling of the water body; however, if helium is not enough, larvae and larvae will die due to lack of oxygen.
5. The photoperiodic Artemia larvae have a phototaxis effect, and the light contributes to the embryonic development and membrane hatching of the Artemia, and the illumination of the hatching fluid surface is 2000 lux.
6. The hatching time of a reasonable hatching time should be fully hatched with Artemia eggs as a principle. The hatching time is too short to fully hatch the Artemia eggs and affect the hatching rate. For Artemia eggs with a hatching rate of more than 70%, hatching time should be within 24 hours, especially for Artemia eggs produced in the Great Salt Lake of the United States. For Artemia eggs with hatchability below 70%, hatching time can be extended to 27 to 36 hours.
7. The density is generally 4-6 kg per cubic meter of water. If the density is too high or too low, the hatching rate will be affected.
8. Freshwater activated Artemia eggs are sterilized and rinsed with water in the net, and soaked in clean water at 26°C to 28°C for 2 to 3 hours to stimulate germination of dormant eggs, shorten hatching time, and speed up hatching.
9. Disinfection: Before hatching, use Malachite green or bleaching liquid to dip into Artemia eggs for 20 minutes to kill germs, reduce infection, and increase hatching rate.
10. The purchased Artemia eggs need to be frozen at -20°C to 25°C for 10 to 20 seconds, and then transferred to a low-temperature freezer for sealed storage. Generally, they can be preserved for 2 to 3 years. Before 7 to 10 days before hatching, Artemia eggs should be thawed in places with ventilation, light protection, and room temperature kept within 20°C to obtain the ideal hatching effect.
(V) Quality identification of dormant eggs National industry standards provide a clear definition of the quality of Artemia eggs and are the basis for identifying the quality of dormant eggs.
1. Comprehensive identification scale A certain amount of Artemia eggs are hatched as usual, and the hatched Artemia is weighted after removing egg shells and impurities (wet and heavy is drained until no water is dripped). The weight obtained is divided by the weight of dried eggs from the insects, which is generally of good quality. Artemia eggs have a weight ratio of 2.5 or less, and inferior Artemia eggs are around 1.5.
2. The sensory index was randomly sampled, and a small amount of Artemia eggs were evenly placed on a glass slide. Microscopy was used to observe: 1 A generalized Artemia egg is like a hi-hat ping-pong. If it is round, it is a wet egg or an empty egg. One end of the egg has a depression, hemispherical, visible to the naked eye as a tan, yellowish brown, grayish brown, shiny, no mildew odor, feel soft, no adhesion, no wet flu, smooth egg surface, such eggs are High quality eggs. 2 Observe the attachments on the outside of the egg shell to see if there are any crystalline substances and if there is any foreign matter attached. In general, eggs of good quality have no crystalline substances or other impurities outside the shell, or occasionally or rarely ruptured eggs, egg shells, and other foreign particles. If the crystalline substance or impurities are too much, it means that the eggs are not washed or precipitated after they are picked up, and are inferior eggs. 3 observe the egg breakage rate. The breakage rate of eggs is inversely proportional to the quality of the eggs. The higher the breakage rate, the worse the quality of the eggs. The breakage rate of fresh eggs is generally very low, but the egg breakage rate is very high. 4 Observe the diameter of the egg. Smaller egg diameters and uniform size lead to better egg quality. If egg sizes vary, most are untreated fresh eggs.
3. In the hatchery Feng, take more than 100 eggs in a dissecting microscope, set 5 parallel samples, and place them in 500 ml beakers that contain 200 ml of natural water. During incubation, the pH was adjusted to 8-9 with sodium bicarbonate, the incubation temperature was controlled at 28°C, and the light intensity was 5,000 lux. After 48 hours, the number of nauplii was counted with iodine solution and the hatching rate was calculated. In general, the hatchability of Artemia eggs is more than 90% of A grade, and 70% of C grade.
4. Impurities were soaked in saturated saline and fresh water, washed, and dried to obtain a reduced weight. The percentage of impurities was calculated. The impurity content of imported Artemia eggs is generally about 0.03%, and the content of impurities in domestic Artemia eggs is relatively large.
5. Moisture samples were dried in a drying oven at 35°C for 2 hours to obtain the lost water content and the juice was calculated as the percentage of moisture. The moisture content of imported Artemia is 6% to 7% for Grade A, and 7.3% for Grade C. The moisture content of domestic Artemia eggs is also higher.
6. The number of grains per gram of eggs imported into the Artemia eggs per gram of eggs is generally 270,000 to 290,000 for Class A and 230,000 for Class C. If the moisture and impurities are high, the number of grains per gram is reduced accordingly.
7. Bacteria detection Artemia hatched, placed on a slide, drop 1 drop of clear water, cover glass and Artemia microscopic examination (magnification of the lens is 640X), check the amount of bacteria in the brine shrimp. If there is a small amount of bacteria, it is normal. If there are a lot of bacteria in the body, it should not be used.
8. Incubation time was determined during hatching of Artemia eggs, and the hatching time of Artemia was observed. The incubation time of good Artemia eggs is 18 to 20 hours. The shorter the incubation time, the better the egg quality. If the hatching time exceeds 24 hours, eggs are generally laid every other year. The longer the hatching time, the worse the halo of eggs.
Hatching of dormant eggs
Incubation of dormant eggs is commonly used in shrimp and crab breeding in late winter and early spring.
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