Raw Materials For Health Products Xi'an Longze Biotechnology Co., Ltd. , https://www.bestbilberry.com
Crayfish, also known as freshwater crayfish, are native to the United States and have become an important species in freshwater aquaculture. These crustaceans, related to lobsters and shrimp, were introduced to Japan during World War II. Over time, their population expanded significantly, and they eventually became a valuable resource in China. In 2006, Anji County in Zhejiang Province achieved remarkable results with Procambarus clarkii farming, covering 432 mu of land. This report summarizes the trial breeding efforts conducted in a 12-mu pond in Jishan Township, Anji.
**Materials and Methods**
1. **Pond Conditions**: There were five test ponds, each ranging from 2 to 3 acres, totaling 12 acres. The water depth was maintained at 1 meter. The ponds had a steady supply of clean, unpolluted water and were easy to manage. Some areas resembled swamps, with varying shades of vegetation, covering approximately 1/4 of the total area. The walls were constructed using cement bricks and boards to prevent escape, and there was a flat space of over 3 meters inside the walls. Artificial shelters such as bamboo tubes, tiles, and plastic pipes were placed in the ponds.
2. **Preparation Before Stocking**:
- The ponds were drained and dried for one month before stocking. Lime slurry (100 grams per acre) was applied about 10 days prior.
- After filling the pond with 50 cm of water, fermented organic manure (around 300 kg per mu) was added to cultivate natural food sources.
- Aquatic plants such as Vallisneria, Eichhornia crassipes, and Water Lilies were planted, along with some terrestrial grasses. The planting area did not exceed two-thirds of the pond’s total area.
- Snails were introduced as additional animal feed, at a rate of 200–300 kg per acre, and added gradually as needed.
3. **Stocking Shrimp**: Between mid-March and mid-June, 1050 kg of seedlings were stocked into the 12-mu pond. Care was taken during transportation to avoid dehydration and damage.
4. **Feeding Practices**:
- Feed was carefully selected based on the growth stage of the crayfish. During the early stages, diets included insects, cladocera, copepods, and aquatic larvae, supplemented with barley, wheat bran, and bean cake.
- As the crayfish grew, the diet shifted to include wheat bran, bean cake, tender green feeds, pumpkin, hawthorn, and melon skins, along with more animal feed in late summer and early autumn.
- Feeding was done twice daily, with 60–70% of the feed given in the evening. The amount varied depending on weather, water temperature, and activity levels.
5. **Daily Management**:
- Vitamins and immune boosters were added to the feed. Cooked animal waste was used when necessary, and excess grass was removed in summer to maintain water quality.
- Water quality was closely monitored, with dissolved oxygen levels above 5 mg/l, pH between 7–8.5, and transparency around 35 cm. Water was changed every 15–20 days, and lime or photosynthetic bacteria were added regularly.
- Shelling management involved adjusting feeding and water levels to promote molting. High-quality feed was provided immediately after shedding to prevent cannibalism.
- Topdressing with fermented manure was done every half month at 15–20 kg per mu.
6. **Harvesting**: Crayfish reached marketable size within 1–2 months, weighing over 30 grams. Harvesting was done using traps, nets, or by draining the pond.
7. **Breeding Measures**: By the end of 2006, most of the shrimp were harvested, leaving 200 kg in the pond. A large number of broodstock were bred, reaching about 1.5 cm in size and requiring winter protection.
**Test Results**
- Total output from June to December was 2520 kg, valued at 60,480 yuan. Another 1000 kg was harvested, adding 60,000 yuan, for a total of 120,480 yuan.
- Total costs amounted to 56,400 yuan, including wall construction, depreciation, seedlings, pond rent, feed, and electricity. Net income was 64,080 yuan, or 5,340 yuan per mu.
**Discussion and Summary**
- The market price of Procambarus clarkii has been rising, with wholesale prices reaching up to 30 yuan/kg. Demand is high, and the government encourages its farming as part of the national fisheries plan.
- Planting aquatic plants and snails is essential for creating a suitable habitat and providing both plant and animal-based nutrition.
- Timely harvesting of larger individuals helps reduce density and improve growth rates.
- Breeding should focus on females, as males can store sperm for several months, ensuring successful fertilization.
- Fresh feed and properly cooked waste are critical to disease prevention. Dehulling agents should be added to support shell development.
This project demonstrates that Procambarus clarkii farming is a profitable and manageable aquaculture option, offering good returns with relatively low investment.
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