Artificial propagation of bullfrog

Sexually mature male and female bullfrogs are called pro bullfrogs. Female and male parent bullfrogs lay eggs after mating and become bullfrog tadpoles after hatching. after a period of feeding, long feet and shrinking tails, they are abnormal bullfrogs. The main operation techniques of artificial reproduction of commercial bullfrog are as follows:

1. Selection, stocking and cultivation of parent frogs.

Bullfrogs weighing more than 350 grams can reach sexual maturity after 1 year of breeding. Therefore, as long as the frog is strong, sexually mature, disease-free and injury-free bullfrog can be chosen as a parent frog. The number of eggs and the number of eggs laid by the parent frog are positively correlated with the body weight, for example, the 1-year-old female bullfrog weighs 350g can carry 15400 eggs, the 2nd-year-old female frog weighing 385g can carry 38500 eggs, the 2nd-year-old female frog weighing 500g can carry 45000 eggs, and the 2nd-year-old female frog weighing 600g can carry 55000 eggs. 1:1 is the best matching ratio of male and female frogs. The identification method of male and female parent frog: first, look at the skin color of the lower jaw, where the golden color is male, gray and white is female; second, look at the tympanic membrane, where the big is male, and the small is female; third, look at the first finger of the forelimb, where the developed are male, the underdeveloped are female; fourth, listen to the sound and watch the activities, where the sound is loud and active is male, and vice versa.

The selected parent frog should be put into a sterilized spawning pond for intensive cultivation before spawning. The method is:

(1) adequate supply of high-quality feed, daily feeding of palatable animal feed that accounts for more than 10% of the body weight of parent frogs, and live feeding animals are the best.

(2) to create a quiet and concealed environment with fresh water quality without external interference.

2. Spawning

From late April to mid-September, the water temperature is 24-28 ℃, which is the spawning period of bullfrog, but if the water temperature is too high from July to August, bullfrog generally does not lay eggs. People often call early spawning spring spawning and late spawning autumn spawning. When the bullfrog is about to lay eggs, the belly of the female frog expands, and her stomach exceeds her knee while sitting and lying down, and her food intake decreases sharply; the male frog chirps day and night, and after being elected as the heterosexual parent frog and the venue, other male frogs are not allowed to approach. Then male and female frogs follow and hug each other. Finally, the male frog jumps on the female frog's back, hugs the female frog's armpit with the forelimb with marriage tumor, the abdomen is close to the female frog's back, the two orifices are close to each other, sinks into the water, the female frog extends its hind legs, the muscles contract and spawn, and the male frogs ovulate at the same time, and the male frogs are fertilized in vitro. Fertilized eggs continue to gather and form egg blocks, at least thousands or tens of thousands of eggs, floating on the surface in case of water. Bullfrogs usually lay eggs in the early hours of the morning when it is sunny or rainy, and they are laid in a quiet, leeward, pedestrian-sparse pool with a depth of about 35 centimeters and a little aquatic plants. Soon after the bullfrog eggs are produced, the nucleus of the bullfrog will shift automatically, all the black animals will move to the top, and the gray plants will move below. Bullfrog eggs will gradually soften after absorbing water. In order to prevent the egg membrane from softening and sinking into the bottom of the pond to be destroyed and swallowed by fish or other enemies, it should be fished out in time for hatching.

1. Collecting egg blocks

Patrol the pond in the early hours of every morning to find eggs and collect them in time. When patrolling the pond, one should take a light step so as not to disturb the bullfrog that is laying eggs; second, observe carefully in order to find the egg block and pick it up in time. The method of fishing is as follows: people stand in the water, first cut and pick out all the weeds connected to the egg block around and under the egg block with scissors, and then use the basin to start from the edge of the egg block and gently put the egg block into the basin and transfer it into the incubator or incubator to hatch.

2. Incubation

The commonly used hatching tools are large wooden pots, cement ponds, soil ponds and cages, and the hatching effect of cages is the best. The operation method of cage hatching is:

(1) clear pool irrigation

Before hatching, the ponds were strictly disinfected to kill harmful bacteria and enemies, and then poured into rivers, lakes and ponds with fresh water quality, non-toxic pollution, few zooplankton, high oxygen content and neutral pH value. The depth of irrigation is about 1 meter, which is easy to install hatching cages.

(2) releasing eggs

Gently pour the newly collected eggs into the pre-installed incubator, then gently remove the overlapping clumps of eggs with smooth small bamboo sticks, and then put a thin layer of sand under the egg blocks to wash away the sediment, floating water plants, to prevent the eggs from sinking, dense clumps and death due to lack of oxygen. It is best to cover the incubator with a canopy against rain and sun, and set up a bridge board for inspection, feeding and leaving.

(3) hatching density

It is appropriate to lay 6000 eggs per square meter. A 2-square-meter cage can lay 1-2 nests of eggs.

3. Daily management

(1) eggs laid on the same day can be hatched in the same incubator, but eggs laid on different days cannot be hatched in the same cage. Because the first hatched bullfrog tadpoles will suck the unshelled frog eggs.