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1. The number of broodstock.
The amount of broodstock needs depends on the scale of production. Usually 1800 eggs per kilogram of female eggs, per kilogram of male fish can extract 10 milligrams, every 10,000 eggs need semen 5-10 ml. If 10 milliliters of semen are needed for every 10,000 eggs, taking into account factors such as fertilization rate, the ratio of male to female broodstock rearing should be 3:1 or 4:1.
2. The temperature of the water raised by the broodstock.
The suitable water temperature for breeding broodstock is 4°C-13°C. Water temperature does not exceed 12°C during the first 6 months of spawning to help obtain good eggs. If the annual water temperature is between 16°C and 17.5°C, the female fish can be bred but the eggs are not refined.
3. Feeds raised by broodstock.
Feeding broodstock should have a histological protein content of more than 40%, a fat content of less than 6%, a carbohydrate content of less than 12%, and a balance of essential amino acids in the feed. Crustaceans are a good feed for broodstock. Adding crayfish, adding dry yeast, a variety of vitamins, and carotenoids all help increase the quality of the eggs.
(II) Artificial insemination
1. Male and female identification.
The rainbow trout's male has a small head, a pointed snout, a curved upper mandible hook, a high body, a non-inflated abdomen, a shallow fork, and a white reproductive hole. The female body is slender, with rounded blunt snouts, upper and lower jaws of equal length, and enlarged lower abdomen. The genital hole protrudes slightly pink and the tail is dark red.
2. Maturity identification.
The maturity of the male fish is recognized by the ability to extrude semen. The maturation of females often depends on the sense of touch. The abdomen of the female is enlarged and soft, and the genital hole is swollen and protruded outwards. If the tail is lifted up, the outline on both sides is obvious. Mature eggs from the ovarian fall into the body cavity, if the residence time is too long, the fertility rate will decline, it is timely to pick eggs, prevent excessive maturation, generally from the ovary discharged into the body cavity of the first 4 days of egg quality is best, a few The best spawning period is still within 7 days, so the females are usually selected once every 7 days.
3. Semen collection.
There are two kinds of sperm extraction, one is to squeeze male sperm directly on the eggs, every 8-10 female eggs, with 3 male sperm can be. The other is to store the semen in a container such as a beaker, place it in a cool place below 8°C, and add it to the egg with a straw every time it is needed. After a few days, the males that have collected the sperm can be repetitively harvested.
4. Oviposition and insemination.
Using the squeeze method, one person holds the female's head in the hand while the other person holds the tail with his left hand. The head is upward and the back is facing the operator. The abdomen is aligned downward with the hole in the receiving ovary. After the fish is calm, With your right hand, follow the direction of the genital hole from the abdomen and gently squeeze it from the top to the bottom. Before fertilization, the egg is treated with an isotonic saline solution (sodium chloride 90.4 g, potassium chloride 2.4 g, calcium chloride 2.6 g, dissolved in 10 liters of water in turn, and the temperature of the water is adjusted to above 4°C. ) Wash, then add semen insemination. Each 10,000 eggs are thoroughly stirred for 1-2 minutes with 5-10 ml of semen, so that the eggs are fully contacted, then a small amount of fresh water is added, and the mixture is rapidly and uniformly stirred for 1-2 minutes. After confirming that all the remaining sperm have lost their insemination ability, Then change the water several times, let stand for 1 hour, wait for the eggs to fully absorb water and then incubate.
(III) Incubation The fertilized eggs start to absorb water after encountering fresh water. The egg membrane and the yolk membrane are separated, and the peritoneal cavity appears, and the egg membrane begins to harden.
1. Equipment incubators mainly include incubators and incubators.
(1) Incubation room. Since egg collection, insemination, and hatching of eggs are performed under direct sunlight, and the operation period is mostly in winter, when the temperature is below 0°C, fish eggs are easily frozen. Therefore, there must be an incubator for hatching eggs. In addition to placing the incubator and picking the eggs in the room, there are also water supply and drainage systems, as well as operating sites for egg collection, insemination and egg-picking. Several small fish ponds can be constructed under conditional conditions. Broodstock.
The area of ​​the incubator room is determined according to the type of incubator used. If the Atkins horizontal incubator is used, it is generally 40-50 square meters when hatching 500,000 fertilized eggs, and 70-90 when hatching 1 million fertilized eggs. 90 square meters, if a vertical incubator is used, the above hatchery area can be halved.
(2) Incubator. At present, there are three main types of incubators, namely horizontal, vertical and barrel types. The water supply method is also divided into three kinds: flowing water, showering and soaking. The domestic Atkins horizontal incubator is mostly used, which mainly consists of hatching tanks, hatching trays and stents. The hatchery trough is made of wood or plastic, and the trough is divided into 4 compartments. Each 8-10 trays are stacked in a rack and placed in a grid. Each egg contains 3000 eggs and each tank can incubate 100,000-200,000 fertilized eggs. Usually two or three tanks can be connected in series with a flow rate of 20-40 l/serving.
(3) Oviposition and picking eggs. Oviducts are used for picking ovates (porous aluminum or plastic basins that require quick water leakage but not oozing), ovum basins, fertilization basins, towels, nylon gloves, and fish stands. Egg-picking requires an egg-picking station, egg picking, picking eggs, and feathers.
2. management.
The suitable incubation water temperature for rainbow trout is 7°C-13°C. The optimum water temperature is 8°C-10°C. If hatching in water above 13°C, the hatching rate will decrease and the deformity will increase. When hatching at low temperature, the incubation period will be prolonged and the effect will be poor. Even after the eyes start, hatching is possible even in water at 18°C.
Oxygen from the fertilization to the pre-eyelid stage requires less oxygen, and the amount of oxygen needed increases after the eyeball is emitted. The oxygen consumption per hour per 100,000 oocytes is close to 500 ml, and the amount of oxygen consumed after hatching is 2 - 3 times, the appropriate amount of oxygen for hatching water needs to be more than 6 mg/L. It needs to be capped.
If a barrel-type incubator is used for hatching, the egg volume per barrel varies from 50,000 to 120,000. After the eggs are inflated, the eggs are inflated and incubated in barrels. The water needs to be filtered and the water injection volume per barrel is 4-6 liters/min. For waterproof mold, it is disinfected once every 3-4 days with malachite green, and the concentration of 1:200,000 is injected into the barrel from the water injection port and lasts for one hour each time. After the incubation temperature reached 220°C, the dead eggs were picked out and the eggs were picked up with special egg-picking tanks and picking eggs.
(D) Eye eggs transport Rainbow trout eggs are generally transported after the eye-opening period. The hatchery trays can be placed in specially made containers with lids. Wet wet gauze was first laid on the hatchery trays, and about 3,000 ophthalmic eggs were mounted on each plate. The eggs were covered with aquatic plants or foam plastic sheets to keep them moist. Each 5 disks are bundled together with a string and placed in a box. The space around the box should be properly fixed and placed in an ice bag to prevent the water temperature from becoming excessively high. The temperature inside the box is preferably 5°C to 10°C. According to the experience of relevant production units, the temperature inside the box is between 2°C and 13°C. After 50 hours of transport, the survival rate of the ovum is more than 96%. Drip every 4 hours during transportation.
(e) When the management temperature of the hatched larva is appropriate, it takes more than 20 days from fertilization to hatching of larvae.
The newly hatched fry is called larvae and is generally 15-18 mm in length. At this time, the larvae should be placed in a specially designed and well-equipped facility. If placed in an Atkin incubator (30 centimeters by 30 centimeters by 2 centimeters larvae feeding tray), it is advisable to put 1,500 tails per tray. If larvae are hatched in a vertical incubator, they are kept in their original position and do not need to be moved. If the incubator is too small, the larvae may be placed in a small mud pool in the hatchery, or placed in a wire-stitched cage, and placed in an open channel, but exposure to direct light must be avoided. During this period, the larvae were lying under the water, and their development depended on the nutrition of the yolk sac, and the amount of water injection should be maintained at 20 liters/minute or more per 100,000 tails. Prevent the egg membrane from obstructing the flow of water to control the amount of water, and remove the dead seedlings in time to maintain the cleanliness of the breeding environment.
Rainbow trout breeding management method
(1) The rearing density of broodstock broodstock should be properly controlled according to the area of ​​the pond, the quality of the water, and the amount of water, usually 5-10 kg/m3. Male and female new fish were bred, and broodstock of different age groups were bred.