| The nutritive components of duckweed were measured in this paper and its nutritive values were evaluated too. The techniques of the artificial cultivation of duckweed and their applications in cultivating the fingerling of grass carp and breeding the fish were studied. The main results are as follows:1. The duckweed has a high roughage protein contents, which is not only rich in nourishment but has a nice chewy flavor as well. What is more, it reproduces its new individuals in a relative quick speed. And it is a kind of high quality baits to grass carp, Wuchang carp etc. According to the study, the proportion of roughage protein in air-dried duckweed is 30.5%, roughage fiber is 16.5%, roughage ash ratio is 21.02%, roughage fat is 1.98%, calcium is 0.62%, phosphorus is 0.88%. With the lowing of proportion of protein feed and synthesize pigment by adding duckweed powder into forge can decrease the input, increase the quality of products.2. The proportion of protein in duckweed has something to do with the proportion of nourishment in the water. In clear and low-nourishment water, it is not only slow-growing, but has a lower proportion of protein because of the high proportion of fiber, ash ratio and carbohydrate in it. In contrast, in the high-nourishment water, duckweed is not only quick-growing with a high proportion of protein, but has a lower content of roughage fiber and ash ratio. Because of the high proportion of water in fresh duckweed and its growing in the water with some kinds of parasite and germ living in it, the duckweed can not be given directly to animals, which must be processed. In the process of fish-feeding, especially the grass carp-farming, the prevention and treatment of diseases in fish must be taken into consideration.3. Method of the artificial breed of the duckweed. The duckweed grows on the surface of water, sinking at the bottom of water as a sprout to survive winter in the late autumn. The temperature in the water must range from20～30℃. Duckweed can be breed in common pond which is also in special pond. The pond should be a rectangle with 300～600mm. The depth of water is 1.3～1.7 meter. Putting some mud with a depth of 6～10 meters as the source of fertilizer. The pond must be disinfected for seven or ten days. When the pH ratio comes to 7, some fertilizer can be put in with 50～70 kilograms per 100 mm. As base fertilizer, the way of applying fertilizer can be different. Both spilling and piling are available. With piling, the duckweed seed can be planted three days later, but with spilling, the seeds can be planted several hours later. The weigh of seed should better be 5～10 kilograms, Spilling; 5～10 kilograms human excrement per 100mm, or spilling 0.2 kilogram urea and 0.1 kilogram phosphate fertilizer. The duckweed can be harvested in seven or ten days later with 30 percent of the total once.4. The use of duckweed in the grass carp farming. Grass carp is a typical kind of herbivore fish, which is called the first of "the four kinds of fish" as its quick-growing, big size, good taste and high-nourishment. It is the fish to be breed broadly. According to the experiment, use of duckweed can not only cultivate big size grass carp, but has a great effect on farming of grass carp, which is an effective way to decrease the input and increase the economic benefit.5. The prevention and treatment of diseases should be paid highly attention when using duckweed to breed grass carp. These diseases such as rot cheek, enteritis, red skin and blooding are very common in the breeding grass carp which usually occur and spread in the busy season of growth. And a lot of diseases will occur. It will lead to death of fish and cause the great economic loss. We can use quick lime, fish recuperation, Masson pine, garlic etc. to utilize comprehensively so as to prevent the above four diseases.
|
PDF Full Text Request