Detailed explanation of key points of bullfrog farming technology, master scientific farming methods

I. Efficient commercial bullfrog farming technology

    The rearing of commercial frogs refers to the process of raising metamorphosed juvenile frogs into commercial frogs. It is the last stage of the entire bullfrog farming process and also the most critical production procedure determining success or failure. At present, commercial frog farming can be divided into two methods: intensive farming and extensive farming. Extensive farming means enclosing a relatively broad area with escape-prevention facilities, placing juvenile bullfrogs in this natural environment to feed on natural bait and grow naturally, and harvesting them for sale once they reach commercial size. Intensive farming, by contrast, requires digging smaller artificial ponds, using artificial feeding, and carrying out high-density fully artificial farming. This farming method has high yield and survival rate and is the farming method commonly adopted today. The following focuses on introducing this farming method.

(1) Construction of the rearing site

(1) Frog-rearing ponds. For commercial frog rearing ponds, earthen ponds are generally dug. To save farmland and costs, they can be made by slightly and modifying ponds, lotus ponds, and small water-collection pools. The location should be chosen in flat terrain with abundant water sources, with an area of 100 sq m to 300 sq m, a pond depth of 0.8 m to 1 m, and a water storage capacity of 30 cm to 40 cm. The earthen pond must be surrounded with netting to prevent frogs from escaping. For high-yield intensive farming, specially built cement ponds may also be used, with an area of 15 sq m to 30 sq m. The pond depth is 1 m, and the water storage depends on the size of the frogs. They are made of poured concrete, with the pond bottom and walls smoothed with cement. The slope of the pond bottom should be relatively large to ensure that one end has deeper water, which is the main habitat for the frogs, while the other end is shallower and often exposes the pond bottom, making it convenient for the frogs to come there to feed and rest. The pond bottom should also slope toward the drainage outlet to ensure the pond water can be drained dry. To prevent frogs from escaping, the top of the surrounding pond walls should be poured or built into an inward 10 cm lip. Cement ponds have high yields. At present, domestic production can reach 15 kg of frogs per sq m, making them suitable for intensive high-yield frog farming.
(2) The micro-environment of the frog-rearing pond. To ensure that bullfrogs can grow and develop well, a good ecological environment should be created for them. Some aquatic plants such as lotus, arrowhead, and sweet flag can be planted in the frog pond, which is suitable for bullfrogs to inhabit. On the land and slopes in the frog pond, flowers, grasses, and shrubs should be planted to facilitate bullfrogs resting there and to attract insects as frog bait. To prevent the effects of high summer temperatures on bullfrogs, a half-pond shade shed should be built on the south bank of the frog pond in spring, and some climbing plants such as pumpkin, loofah, and grape should be planted to climb onto the shade shed, allowing bullfrogs to come there to rest during the hot season. Through such arrangements, the ecological environment of the entire frog-rearing pond becomes more suitable for the life and growth of bullfrogs.
(3) Cleaning and disinfection of frog-rearing ponds. Newly built cement ponds should be filled with water and soaked for 15 days before use for dealkalization. When juvenile frogs are to be stocked, the old water should be drained and replaced with new water before stocking. For earthen ponds, if newly dug, they should also be filled with water and soaked for 5 to 7 days before use to remove excessive heavy metal salts. Before stocking, cement ponds should also be coated and scrubbed on the bottom and walls for disinfection with bleaching powder at a concentration of 1 mg per liter or quicklime solution at a concentration of 20 mg per liter. For earthen ponds, 90 g to 110 g of quicklime per sq m or 7.5 g to 15 g of bleaching powder should be dissolved in water and splashed for disinfection.

(2) Stocking of juvenile frogs, bait, and rearing management

The stocking rate of juvenile frogs should be determined according to multiple factors such as frog size, bait conditions, and rearing management level. Earthen ponds generally stock newly metamorphosed juvenile frogs (4 g to 5 g): 100 to 120 per sq m; the stocking rate for cement ponds can be increased by 1 to 2 times.
(1) Artificial bait for frogs. In high-density intensive farming, natural bait alone can no longer meet the needs, so artificial bait must be fed. At present, the artificial bait used in frog farming mainly includes insects attracted by light; live baits such as artificially cultured earthworms and fly maggots; and artificially produced compound pellet bait. Artificial compound pellet bait can be formulated into bait of different specifications and particle sizes according to the different developmental stages and sizes of frogs. The feed conversion ratio and cost are relatively low. In addition, some drugs can be appropriately added during formulation, which can also play a role in disease prevention and control. Experiments show that as long as starting from newly metamorphosed juvenile frogs, live baits such as earthworms and small fish and shrimp are fed together with static baits such as pellet bait, so that the static bait is activated under the driving effect of the live bait, juvenile frogs can eat static bait, and the effect is very good. This solves the key problem for intensive bullfrog farming.
Under artificial rearing conditions, the food intake of bullfrogs varies with temperature, frog size, and bait type. The feeding amount is roughly controlled at between 5% and 15% of the total body weight of the frogs.

(2) Rearing management. Under artificial intensive rearing conditions, bullfrogs have a large food intake and also produce a lot of feces, which easily pollutes and deteriorates water quality, thereby causing disease. This phenomenon is more prominent when rearing in cement ponds. Therefore, cement ponds should be scrubbed frequently, the pond water should be changed regularly, and from mid-April to mid-to-late October, they should be disinfected every 15 days with quicklime at a concentration of 20 mg per liter or bleaching powder at a concentration of 1 mg per liter. When the water temperature rises above 32 °C, bullfrogs will show reduced appetite, and if it continues to rise to 35 °C, death may occur. At this time, in addition to using climbing plants for shade, new water at a lower temperature from outside rivers should be added when necessary. All measures should be taken to keep the pond water temperature below 32 °C and ensure the normal life and growth of the frogs.