Brazilian artificial breeding technique
The Brazilian scientific name Prochilodus scrofa, also known as South American salmon, is native to the Paraná River system in southern Brazil and is the main freshwater economic fish in Brazil. The fish was established in 1996 by the Zhejiang Institute of Freshwater Fisheries. First introduced into China, and artificially propagated successfully in June 1998, obtaining seedlings in small quantities. The Guangxi Fisheries Research Institute introduced seedlings in 1998. After two years of pond aquaculture and broodstock breeding, it was artificially propagated in 2000 and succeeded.
1 Materials and Methods
1.1 Selection and cultivation of broodstocks On 2 July 1998, the Guangxi Fisheries Research Institute introduced 1000 pigs of 2-3 kilograms of body length, 2-3 centimeters in length, and was stocked in Nama Base Fishpond and shrimp polyculture, after more than 90 days. After rearing, shrimp was collected on the dry pond on November 14th. A total of 559 brazilian tapirs were obtained. The average body weight was 0.35 kg and the largest individual was 0.5 kg/tail, and then moved to the 5th pond to continue cultivation for the winter. In 1999, under careful feeding and management, the broodstock was then selected for natural wintering in the pond. Daily water temperature records, regular water to maintain a certain level to ensure the broodstock smooth winter, spring 2000, the water temperature rise, start daily feeding, lower the water level for the broodstock to receive light, flush every 2 hours, once a day, to stimulate the broodstock Gonadal development, from time to time check the extent of gonad maturation. In March 2000 fishing inspection, a total of 321 broodstock were selected, with an average weight of 1.3 kg and a maximum of 1.8 kg.
1.2 selection of mature individuals in Nanning, Guangxi in late April early May, water temperature 25-27 °C can be culled broodstock choice. Males are generally smaller than females, and have a tangled touch on the body surface, especially on the sides of the anal fin. Roughness is evident on both sides of the anal fin base. The vents are recessed, smaller, and have 2 holes. The abdomen does not inflate. Milky semen flowed out or lined with fine spots. Females are larger than males, with a slightly rough body surface, protruding vents, and indifferent abdomen enlargement. There are 3 holes, and the larger, round, ruddy, mature broodstock can extrudate loose eggs. Grain, egg gray or light yellow, good gloss.
While selecting the broodstock, a part of the immature female broodstock is cooked with a needle, and the injection dose is 0.3 μg LRH-A2/kg, which is then returned to the pro-fish pond for further cultivation.
1.3 Artificial Fertility 1 Carefully select the mature broodstock, male to female ratio 1:1.5 or 1:2, transfer to the holding box in the urine production basin with the brood clips, separate male and female. In general, broodstock should be injected once for mature broodstock. In the water temperature 25 ~ 27 °C, 18:00 ~ 23:00 injection, the next morning can lay eggs. The male fish dose is 50% of the female fish, and the oxytocculum is injected into the body cavity, and the angle of the phosphorus-free depression at the base of the pectoral fin is 450 points. The depth of the needle is 0.3-0.5cm. Generally, it is appropriate for each fish to be 1-3ml. . Based on the urine test design of the first batch of 8 broodstocks on April 29th, 2000, the final selection of a good mixture of oxone and luteinizing hormone-releasing hormones was conducted and one injection was used for oxytocin production.
2 Spawning. After the oxytocic injection of broodstock into the same spawning pool, and continuous flushing microfluidic state, the water temperature 26-28 °C, after 12 to 16 hours, you can see the female was tightly forced by several male and female fish, Friction of the abdomen of the female and a haha ​​sound, sometimes with the head hitting the female, or even lifting the female out of the water. At this time, the female and the male rapidly move their bodies, or the abdomen is bent near the tail, twisting together and trembling The abdomen spawned and spawned, and the fertilized eggs were floating. Take the volume method to use a bowl number, and then multiply the number of eggs per unit container to obtain the amount of eggs laid.
3 Postpartum broodstock care: When the post-partum broodstock is removed from the spawning pool, rubbing wounds with chlortetracycline ointment on wounded broodstock to prevent water mould and ulceration. At the same time, each broodstock was injected with 1.5 to 2 ml of 50 mg of normal saline of rehabilitation agent, 100 ml of glucose, and 10 ml of chloramphenicol (250,000 units/2.5 ml)] and placed in a postnatal broodstock cultivation pond for careful feeding and management.
l. 4 Incubation In this experiment, the eggs in the egg collection box are incubated in the hatchery ring, with a water temperature of 26-27°C, dissolved oxygen of 6.9 mg/L, a pH of 8.2-8.6, and a flow rate of 0.23 M/s. The fry was filmed after 13 hours and 35 minutes. The body length was 4.46mm when the film was released. When the yolk sac disappeared, it took 60-72 hours to swim. The fry found the waist point (the average length was 5.99mm and the average weight was 0. 22mg) out loop for incubation.
1.5 Embryonic development of Brazilian quail embryos was observed continuously using a 16160/0.17 electro-optic binocular dissection microscope. Timings and characteristics were recorded. The entire process of embryonic development was observed continuously using a Nissan dissection microscope camera. Embryos take pictures. Use a vernier caliper to measure egg diameter and embryo length. 2 Results 2.1 The artificial breeding of brazilian bran was successful in Guangxi and a certain scale of production was formed. In April and June of the year of 2D0, a total of four batches of broodstock were spawned, including 145 males and 104 females. (Another body with a length of 35 coffee and a female weight of 900 g was examined. The number of fertilized eggs was 1.74105 capsules). The total number of eggs retrieved was 7.3 million, the average fertilization rate was 76.5%, and 4.54 million seedlings were obtained. The hatching rate was 68%. See Table 1 for details.
2.2 Embryonic development of Brassica juncea: Members of the project team conducted continuous observation and photomicrographs of the embryonic development of Brassica juncea, and recorded the timing and characteristics. Mature Brazilian quail eggs are spherical, yellow-brown, floating eggs, non-adhesive, egg diameter 1.40-1.50mm. The embryonic development rate of Brassica rapa is fast, and the fertilized eggs have a filming time of 13 hours and 35 minutes at a water temperature of 26-27°C. A preliminary understanding of the basic rules of the embryonic development of Brassica indices under artificial propagation conditions, and according to the results of photographing, depicts the embryonic developmental sequence of Brassica rapa. See Table 2 for details.
Table 1 Artificial Breeding of Brazilian Eel Seedlings Table Induction Production Batch Employing Time Spawning Number of Breeding (10,000) Fertilization Rate (%) Emergence (10 000) Hatching Rate (%)
♀ ♂
1 April 229 8 8 25 75.4 5 26.5
2 May 4 31 64 250 73.5 150 81.6
3 June 13 19 16 105 76.5 65 80.9
Total 104 145 750 76.5 454 68.0
3 Discussion
(1) From the time of the initial hatching to sexual maturation in Brazil, it takes a month in Nanning, Guangxi. Mature individuals are generally more than 600g, females are heavier than males, and Brazilian eggs have a greater amount of eggs, spawning 18-25 million eggs per kilogram of broodstock. Injecting oxytocic agents can induce natural spawning and fertilization of the broodstock in the spawning pool. The average egg diameter after water absorption is 2.28 mm and the maximum outer membrane diameter is 3.94 mm.
(2) At a water temperature of 26 to 27°C, the number of hatchings in Brazil is 815 minutes (13 hours and 35 minutes). At the same water temperature, the incubation time of the freshwater whitefish, which is a species of the same species, was 21 hours and 58 minutes [1]. The number of hatching times in Brazil was 8 hours and 23 minutes less than that of freshwater whitefish. At the water temperature of 27°C, the hatching times of grass carp and abalone were 23:00 and 28:15 respectively [2], which were greater than the hatching time of Brazilian carp. The developmental speed of fish embryos is mainly affected by environmental factors such as genetic factors and water temperature. In this experiment, the water temperature 26-27 °C, dissolved oxygen 6.9mg / L, pH 8.2-8.6, water flow 0.23m / s, indicating that the environmental conditions are suitable [3], according to the Brazilian salmon fry As a result of the cultivation, it has been demonstrated that the growth and development of larvae is normal, so that the rate of embryonic development in Brazil reflects its genetic characteristics.
(3) The pH value of the incubation water used in this experiment is 8.2-8.6. Whether the high alkalinity of shellfish water has influence on the embryonic development of Brassica rapa is yet to be studied.
(4) The authors observed embryo malformations under the conditions of this experiment, if the incubation temperature is above 28°C, the malformation rate is higher. The author believes that the temperature of incubating Brazilian bran in production should be controlled below 28°C, and the optimal incubation temperature is 25-27°C.
references
[1] Zhang Zhongying et al., Biology and Artificial Breeding of Freshwater Whitefish, Freshwater Fisheries, 1991(4): 3-6.
[2] Liu Jiankang, Chinese Freshwater Fish Breeding, 1992. Science Press, Beijing
[3] Lei Huiyi et al., Pond Fish Education, Science Press, 1981
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