Raising yellow eels (Monopterus albus) on livestock and poultry manure: turning waste into treasure with high returns

The new static-water, soil-free ecological breeding technology for yellow eels and loaches invented by Dr. Zhou Wenzong is suitable for migrant workers returning home to start businesses, and also suitable for rural specialized households to diversify their operations using existing resources. The project was first promoted in Yangxin County, Hubei Province in 2006, and Zhou Wenzong was awarded the honorary title of "Son of Yangxin" by his hometown. After seeing reports on Dr. Zhou Wenzong's deeds of "giving back" to his hometown's agriculture, Ji Guangwen, director of the Henan Provincial Fisheries Bureau, led aquatic product officials from provincial-administered cities and key fishery counties to Dr. Zhou Wenzong's demonstration base in January 2007 to inspect and learn, and specially invited him to Henan to promote the technology on a tour and assist in building bases. This project has a unique "ecological circular food chain," forming a relatively closed system of multi-level energy use, rational energy conversion, and material recycling and regeneration. The problem of disposing of livestock and poultry manure that has long troubled farmers is easily solved, becoming a good renewable resource and being converted into organic feed, which can solve the two major problems of resource shortage and environmental pollution, and realize the self-recycling utilization of livestock industry resources. CCTV Channel 7's "Science and Technology Garden" broadcast on June 10, 2009 the popular science series "Science and Technology on the Chain (2): The Cow Dung Chain," introducing how Dr. Zhou Wenzong helped Wang Shuizhang, a cattle farmer in Zhengzhou City, Henan Province, use biogas residue and biogas slurry to raise loaches and grow vegetables and fruit trees. Cow dung was used to raise earthworms and free-range chickens and produce eggs. According to reports, through resource utilization, cow dung turns harm into benefit and waste into treasure, not only achieving zero emissions, but also extending and increasing value through the ecological chain and recycling. Over a year, the benefits generated from processing cow dung alone were greater than what Wang Shuizhang earned from simply raising cattle.
I. Composition analysis of livestock and poultry waste
(1) Composition analysis of cow dung
Cow dung contains 14.5% organic matter, 0.30-0.45% nitrogen, 0.15-0.25% phosphorus, and 0.10-0.15% potassium, making it a valuable resource that can be used by the crop farming industry as a source of soil fertilizer. The organic matter and nutrient content of cow dung are the lowest among various livestock, with a fine and dense texture, relatively high water content, slow decomposition, and low heat generation, making it a slow-release fertilizer. The nutrient content of cow dung itself is much lower than that of chicken manure and pig manure (the contents of nitrogen, phosphorus, and potassium are all lower). In addition, cow dung is a cold organic fertilizer and decomposes more slowly than chicken manure and pig manure, so its fertilizer effect is much slower than that of chicken manure and pig manure.

(2) Composition analysis of pig manure
Pig manure contains 15% organic matter, and its total nutrient content is not high: nitrogen 0.5-0.6%, phosphorus 0.45-0.5%, and potassium 0.35-0.45%. Pig manure has a relatively fine texture and fairly complex composition, containing proteins, fats, organic acids, cellulose, hemicellulose, and inorganic salts. Pig manure contains relatively more nitrogen and has a small carbon-to-nitrogen ratio (14:1), so it is generally easily decomposed by microorganisms, releasing nutrients that can be absorbed and used by crops.

(3) Composition analysis of chicken manure
Chicken manure is rich in nutrients. According to relevant measurements, chicken manure contains: dry matter 89.8%, crude protein 28.8%, crude fiber 12.7%, digestible protein 14.4%, nitrogen-free extract 28.8%, phosphorus 2.6%, calcium 8.7%. Histidine 0.23%, methionine 0.11%, leucine 0.87%, lysine 0.53%, phenylalanine 0.46%. Through proper processing and utilization, it can become a very good green organic fertilizer or chicken manure feed. As a farmyard fertilizer, chicken manure has a higher fertilizer effect than pig manure, cow dung, and others. Each ton of sticky wet chicken manure contains plant nutrients of 11.35 kg nitrogen, 10.44 kg phosphorus (P2O5), and 5.45 kg potassium (K2O). Because chicken manure contains large amounts of organic matter, it can also be used as a raw material for producing biogas, generating energy for use.
From the above analysis data, it can be seen that livestock and poultry manure all contain rich undigested feed components, as well as amino acids and trace elements such as phosphorus, calcium, copper, zinc, manganese, sodium, and potassium generated after passing through the digestive tract. This is the prerequisite for converting them into organic feed through biological fermentation.

II. The ecological circular food chain of this ecological breeding project
First link: biological fermentation treatment of livestock manure
After drying, anaerobic fermentation for biogas production, or composting treatment of livestock and poultry manure, integrated planting and breeding can be implemented. This can not only reduce the pressure of manure on the environment, but also improve soil fertility and the quality of agricultural products, save costs in the crop farming industry, and improve overall ecological, environmental, and economic benefits. Poultry and livestock manure cannot be used to raise earthworms without fermentation, but fresh cow dung dried to 30% dryness can be used directly to raise earthworms. If rotten melons, fruits, rotten vegetable leaves, and the like are mixed with cow dung, the effect of raising earthworms will be even better.

Second link: fermented pig and cow manure becomes earthworm bait
Generally, each ton of manure material can produce 60 kg of earthworms. Generally, consuming 40 jin of cow dung will grow 1 jin of earthworms. Fermented pig manure is also a good feed for earthworms and has a good effect on the growth and development of earthworms. The pig manure of 1 pig can breed and grow 10 kg of earthworms.

Third link: earthworms become bait for yellow eels and loaches
Earthworms are easy to raise, reproduce quickly, and have a protein content as high as 65-70%, making them very good protein feed. They contain 8-9 kinds of amino acids essential to the human body, and also contain 9-10% umami-tasting glutamic acid, with relatively low fat content. Because raising earthworms requires no cost, using them to replace fishmeal can save money on the one hand, and on the other hand earthworm meal has seven or eight percentage points more protein than fishmeal. Furthermore, earthworms are the fresh live bait that yellow eels love most to eat. More than 60% of the weight gain of yellow eels depends almost entirely on the nutrition of earthworms. Because the demand for raising eels is large, artificial collection alone is far from meeting the need. Vacant land beside ponds can be used for artificial cultivation, using cow, pig, and other livestock manure to raise earthworms. About every 10 kg of manure used as base material can grow 500 g of earthworms, and using 3-5 kg of earthworms to feed yellow eels can grow 1 kg of eel meat. Artificially raised earthworms can be harvested and used throughout the year.
Earthworms are the most suitable food for yellow eels, because earthworms contain protein, and yellow eels grow fast and well after eating them. In the hot summer season, fish and shrimp spoil if not eaten, but earthworms can survive and regenerate even if not all are eaten.

Fourth link: livestock and poultry manure is converted into earthworm castings after passing through the earthworm gut
Livestock and poultry manure is converted into earthworm castings after passing through the earthworm gut, achieving increased efficiency and value. The various nutrient components of worm castings are far higher than those of the original manure, containing 23 kinds of amino acids and earthworm enzymes, odorless and tasteless, with uniform particles and strong air permeability and water retention capacity.
Nutrient components of earthworm castings: moisture 13.70%; crude ash 58.22%; crude protein 8.96%; crude fiber 2.73%; crude fat 0.10%; nitrogen-free extract 16.29%; calcium 1.70%; phosphorus 0.58%. Mineral content of earthworm castings: iron 3161 μg/g; copper 20.4 μg/g; manganese 222.0 μg/g; zinc 3.0 μg/g; magnesium 8336.7 μg/g.

Fifth link: worm castings returned to the field give rise to organic ecological farms (vegetable gardens, orchards, tea gardens)
The nutrient components and mineral content of earthworm casting material are higher than those of feed such as ryegrass. It can be processed into feed to raise cattle, pigs, chickens, ducks, fish, and the like, and can also be processed into organic compound fertilizer. It is a high-quality flower fertilizer and farmyard fertilizer. Earthworm castings can be used to develop pollution-free vegetables. Earthworm castings have a very high organic component and are easy for crops to absorb.

Sixth link: fruit and vegetable scraps and earthworms become feed for pigs and cattle
After establishing the above food chain, 70% of the feed for yellow eels is provided by the food chain, and you only need to supplement 30% of the feed. Establishing the food chain can save you a large amount of breeding costs. Raising earthworms on livestock and poultry manure, then using earthworms to feed yellow eels and loaches, is a low-cost ecological circular technology, so that breeding requires no purchased feed and planting requires no purchased fertilizer, and all products are ecological foods, which is equivalent to turning waste into treasure.