Crab breeding, especially stage IV (larvae) to macrolarvae stage, adequate supply of palatable bait is the key to improving the survival rate. In production, artificially cultivated animal feeds not only occupy water but also have high costs.
Insufficient food can also kill each other. The use of artificial and alternative bait, poor quality, poor palatability, easy to cause water pollution, low survival rate of seedlings. The city of Dezhou was rich in freshwater zooplankton. In the late 1980s, Liaoning Province used to purchase shrimp for seedlings, and Hubei and Liangshan counties used for breeding of leather beard carp. Since 1993, we have used zooplankton as a bait for crab breeding for six consecutive years at the Dongping Lake Crab Testground, and have promoted it to eight fields such as Shouguang, Lijin and Rongcheng.
I. Zooplankton fishing and processing
Dezhou City, Shandong Province has 1,147 acres of water surface, which is eutrophic due to the large amount of sewage injected into the city. Promotes zooplankton bloom in water. Although fish farming consumes a portion, it is still surplus. The masses trawl 120 screens
Fishing, fresh catches of more than 2,000 tons throughout the year. Mainly rotifers (20%), Cladocera (70%), nauplii, and dart blister (10%). There are two types of dry processing and fresh freezing. Dry method: Wash impurities immediately after fishing, in cement
Or tar dry on the ground for a day (4 to 5 kilograms of dry 1 kilogram of dried product), sold through a sifting and bagging (above 50% of crude protein content); Fresh-frozen method: Acquired by the Fisheries Department, freshwater rinsing, plate freezing, and storage in cold storage .
Second, feeding method
Fresh frozen zooplankton were crushed and frozen before being fed directly into the water and naturally opened to feed the crabs. Dry products should be inspected for moldy deterioration, crushing individual cohesive blocks, sieving, removing impurities, direct feeding or adding a small amount of water
Wet feeding.
1. Feeding larvae. When (氵蚤) develops to stage IV, the food intake is large. At this time, the amount of frozen halves, rotifers or egg yolks, fish gizzards, bean cakes, etc. can be reduced, and dry or frozen zooplankton can be added. (Pupae) young to V, can all feed zooplankton. Feed 12 times a day, every 2 hours. The feeding amount is 150-200 g/million seedling days for dry products, and 300-400 g/million seedlings for fresh frozen products.
2, bigeye larvae feeding. After V stage (larvae) were young to large larvae, they were all fed to zooplankton. The first day of feeding was 20 grams per cubic meter of dried water and 12 feedings. The next day, 30 grams of dry product per cubic meter of water,
On the third day, 40 grams of dry product per cubic meter of water. After the fourth day, increase by 10% daily. Three times the weight of the dried product is fresh.
3, feeding crabs. Out of the pool big eye larvae bred into 3-5 period barbed crabs, to adjust the amount of feeding along with the metamorphosis of crab seedlings. Within a week, fresh frozen zooplankton is fed at a rate of 150-200% of the weight of the bigeye larvae. Large-eyed larvae metamorphosis into juvenile crabs, to increase the amount of feeding to prevent mutual killing, in the case of normal survival rate, generally 200 to 400% of the weight of large-eye larvae fed fresh product zooplankton. If you feed dry products, you can feed them by 1/4 to 1/3 of the fresh product's weight. Regardless of feeding fresh and dried products, they should be evenly fed to aquatic plants in shallow water areas. In the first week, 4-6 shots a day, 2 shots in the second week. Afternoon feeding accounts for 2/3 of the daily feed.
Third, feeding effect
Stage IV (Aphid) young bred to 3-5 stage crabs, strict requirements on food and water quality. Many years of practice have proved that the use of zooplankton as a substitute feed has a significant effect.
1, easy to control the water quality. Zooplankton, especially dry products, do not easily precipitate in water. In the past, we used egg yolks, surimi, soy milk, and bean cakes as surrogate baits. When the big-eyed larvae emerged from the pond, 2 cm thick bait was deposited on the bottom of the pond. Even if you increase the amount of water, the water quality is not as easy to control as zooplankton substitutes.
2, reduce production costs. A total of 11 days from the IV stage (larvae) to large eye larvae emerged. Before 1993, the experimental field was fed with conventional feeds every year. According to the current price of Shandong, the feed cost was about 7,000 yuan. After 1993, the investment was changed to floating
Each year, about 300 kg of dry products are weighed. Calculated at 7 yuan/kg, the bait cost is 2,100 yuan, saving 70%. What's more important is to save water for animal feed, reduce water exchange, increase survival rate, and reduce production costs.
3, reduce labor intensity. Zooplankton is easy to store, pick up and feed, and it is very convenient. It eliminates the hassle of other substitute baits and also reduces the labor intensity of changing water to regulate water quality.
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