Detailed Explanation of Artificial Breeding Technology for the Chinese Brown Frog
The Chinese brown frog is a precious wild animal endemic to China, a valuable Chinese medicinal material, a nourishing delicacy and a delicious food. The Chinese brown frog is also a guardian of the forest and plays a role in promoting increased forestry production and income and protecting the forest ecological environment. Northeast China is rich in forest resources, with a suitable environment, good vegetation and abundant water resources, so semi-artificial breeding of the Chinese brown frog has gradually developed in mountainous areas. However, in the process of semi-artificial breeding of the Chinese brown frog, the problem of low return rate has always troubled Chinese brown frog breeders. This article introduces semi-artificial breeding technology for the Chinese brown frog, including the selection and construction of Chinese brown frog breeding sites; hatching methods; rearing and management of tadpoles; recapture of Chinese brown frogs; management during the overwintering period, etc., and explains various measures to increase the return rate of Chinese brown frogs at each growth stage.
The Chinese brown frog (Rana chensinensis) belongs to Amphibia, Anura, Ranidae, Rana. It is a precious wild animal endemic to China with high nutritional value. Its oviduct (frog oil) is a valuable Chinese medicinal material, with the functions of tonifying deficiency and reducing fever, benefiting the liver and kidneys, and nourishing lung yin. It mainly treats diseases such as essence depletion and strain, and neurasthenia. Its meat is tender and delicious, making it a fine dish at banquets. Its eggs, head, skin and other parts are excellent raw materials for making beauty and health care products. Semi-artificial breeding of the Chinese brown frog has opened up a new path to wealth for people in the forest regions of Northeast China.
1 Selection of breeding sites
1.1 Terrain The terrain should be relatively flat to facilitate irrigation and drainage. The soil conditions should be clay and loam with low permeability and strong water retention, which is conducive to water storage and retention in the pond. This is the prerequisite for maintaining stable water temperature and also a necessary condition for tadpoles to metamorphose early. Breeding sites are best concentrated in one area for easy management.
1.2 Water source The water source should have sufficient volume and be free of pollution to ensure the water supply for the breeding site. In addition, the breeding site should preferably be near the release site, combining breeding and release, which saves a great deal of manpower and material resources.
2 Construction of breeding sites
2.1 Spawning and hatching ponds Spawning and hatching ponds should be built on flat terrain close to a water source. Generally, the pond depth is around 40 cm, and the pond bottom should be level, with stones, gravel and other debris removed, which helps raise the water temperature. A water inlet is set at the upper part of the pond, and a drainage outlet is set at the lower part. The water inlet and drainage outlet are arranged diagonally to speed up the renewal of pond water. The outlet is blocked with a sand net to prevent tadpoles from swimming out with the water. For hatching ponds with high permeability, plastic film can be used to cover the pond bottom. To reduce costs, small pieces of used plastic film can be overlapped to cover the pond bottom, then compacted with soil and soaked with water. The work of building hatching ponds is best completed in summer and autumn so as not to affect spring hatching.
2.2 Egg stage management Before seed frogs spawn, randomly place some branches in the spawning and hatching pond to stabilize the egg masses. During this period, slow the water flow as much as possible to maintain the pond water temperature. The pond can also be filled with water in advance, and the inlet and outlet closed. After the Chinese brown frog spawns, if frost occurs, frog eggs can be covered with straw curtains and other materials to protect them. During drought with little rain, the egg masses should be turned regularly, and the egg masses can also be pressed into the water to keep them moist. For egg masses that sink to the bottom, scoop them out with a net, rinse off mud and sand with clean water, then insert a wooden stick under the egg mass to lift it up, and turn it 1-2 times per day.
3 Rearing of tadpoles
To raise Chinese brown frogs well, tadpoles must first be raised well. To increase the survival rate of tadpoles, the following points must be achieved: 1) Sufficient feed and balanced nutrition. 2) Appropriate density and consistent age class. 3) Reasonable water changes and maintenance of water temperature. 4) Prevention of disease, insect pests and natural enemies. Only by achieving the above points can a foundation be laid for raising Chinese brown frogs well.
In actual management, temporary tents can be built and stoves set up to prepare feed. Newly hatched tadpoles do not feed and live on the egg membrane. After one week, feed them cooked soybean cake, corn and other concentrated feed. Note that the feed must be cooled before feeding. When feeding, it must be distributed evenly to avoid some tadpoles being unable to get food. The times when tadpoles like to eat are generally 8:00 and 16:00 each day, so it is best to feed at these times. When feed is added, if most tadpoles quickly gather on the feed to eat, it proves that the tadpoles are already in a hungry state, indicating that the amount of feed is insufficient and the feeding amount should be appropriately increased.
After the forelimbs grow out and before the tail disappears, tadpoles stop feeding on concentrated feed and mainly feed on live animal food. During this period, try to avoid walking along the pond edge, so as not to disturb the tadpoles, and especially avoid stepping on small frogs that have already come ashore.
The water temperature in the pond should be kept between 10-24°C. If the water temperature is too low, tadpoles grow slowly; if the water temperature is too high, it will cause tadpole death. The time for changing water should preferably be after 16:00 each day, because at this time the water temperature in the river and in the pond differs little, which can keep the pond water temperature relatively stable. Through regulation by water changes, in addition to maintaining the pond water temperature, it can also ensure that the pond water has sufficient oxygen and nutrients. Irrigate shallowly on sunny days and deeply on cloudy days. Master the timing of water changes as appropriate, and also adjust the pond water depth at any time according to the weather and the pond's environment to suit tadpole growth. As tadpoles gradually grow larger and the air temperature rises, the rate of pond water replacement should be accelerated to increase the oxygen and nutrient content of the pond water and ensure normal tadpole growth.