Bullfrog breeding technology video

Abstract: bullfrog originated in North America and was introduced into the interior of China from Cuba and Japan in 1959. At present, China mainly depends on breeding production, with average production all over the country, mainly concentrated in Hunan, Jiangxi, *, Sichuan, Hubei and other places. Commercial frogs are mainly listed in autumn and winter, and the supply sources are mainly from Guangdong and Fujian. Let's take a look at the bullfrog breeding technology video!

Bullfrog originated in North America and was introduced into the interior of China from Cuba and Japan in 1959. At present, China mainly relies on breeding and production, with average production all over the country, mainly concentrated in Hunan, Jiangxi, Sichuan, Hubei and other places. Commercial frogs are mainly listed in autumn and winter, and the supply sources are mainly from Guangdong and Fujian. Let's take a look at the bullfrog breeding technology video!

Breeding techniques of bullfrog

1. The choice of parent frog

There are obvious differences in appearance between male and female bullfrogs whose ① reaches sexual maturity. The diameter of the tympanic membrane of the male bullfrog is significantly larger than that of the eye. There is a well-developed marriage tumor on the inside of the thumb of the forelimb, which is more obvious in the reproductive season. The skin of the throat is golden, the color of the reproductive season is darker, there is a pair of banded vocal sac, can produce a loud sound. The diameter of the tympanic membrane of the female bullfrog is slightly smaller than that of the eye. There is no marriage tumor on the thumb of the forelimb. The skin of the throat is grayish white with black markings and no vocal sac.

The quality of ② parent frog is directly related to the effect of reproduction and the economic characters of offspring. Therefore, the parent frog must be strictly selected. Parents of frogs should be disease-free, injury-free, physically strong and in good shape. The male frog should choose more than 2 years old, the skin of the vocal sac is golden, the marriage tumor is obvious, and the weight is about 300 to 400 grams. The female frog should choose 3 years old, the abdomen is dilated, soft, full of elasticity, the weight is about 400 to 500 grams. The best time to choose a frog is in November before overwintering and in March at the latest. For the parent frogs selected before winter, it is best for the male and female to be raised separately, and the male and female parent frogs will be raised together at the beginning of April of the following year.

2. Male and female ratio

In principle, 1:1 is suitable for the ratio of male and female parent frogs, and it is even better if we can appropriately increase the proportion of male frogs. Too few male frogs will affect the effect of reproduction. However, there should not be too many male frogs. Too many male frogs will cause competition for female frogs, which will affect the normal hugging pairs of male and female frogs, and even cause casualties. Parent frogs are generally stocked according to the standard of one pair for every 5 square meters of water.

3. Spawning and fecundity

① water temperature: when the water temperature rises above 18 ℃, the male frog begins to be in estrus, which is mainly characterized by frequent singing and chasing the female frog. Generally speaking, the female frog is in estrus about 15 days later than the male frog. The female frog shows restlessness in estrus, lingers around the male frog and obeys the male frog. When the bullfrog hugs each other, the male frog crouches on the female frog's back and hugs the female's armpit with his hands.

② hug right: a short hug time of a few hours, a long time can be up to 2 days. When the female frog lays eggs, due to the contraction of the abdomen and the tight pressure of the male frog, the mature eggs in the uterus are continuously excreted out of the body through the cloaca, usually two eggs side by side. At this time, the male frog's rear abdomen is close to the female frog's back and ejaculates at the same time. Sperm and eggs are fertilized in vitro water.

The number of ③: the general spawning time lasts 10-20 minutes. Bullfrog spawning requires a quiet environment, spawning season should not allow idle people to go in and out, so as not to interfere with spawning and cause suspension of spawning. The number of eggs laid by bullfrogs is closely related to age, individual size, nutritional conditions and ecological conditions. The number of eggs laid by frogs weighing 300 to 500 grams ranges from 10, 000 to 50, 000, and the number of eggs per gram of body weight varies from 15 to 109.

Hatching technique of bullfrog eggs

1. Egg collection

After the bullfrog lays eggs, the fertilized eggs can not stay in the spawning pool for a long time, and the eggs should be collected 20-30 minutes after spawning. At this time, the egg membrane outside the fertilized egg has fully absorbed water and expanded, and the fertilized egg can be transposed in the egg membrane, so that the animal of the fertilized egg is facing up, the plant is facing down, and a gray-black egg mass can be seen on the water surface, which is the appropriate time to collect eggs.

In order to ensure timely egg collection, in the spawning season, it is necessary to strengthen the inspection of the spawning pool in order to find the egg block in time. In the evening when the male frog cries frequently, it is especially necessary to observe the situation of the parent frog hugging. Usually the right place to kiss the frog the night before last is the place where the eggs are laid the next day. In this way, the egg mass can be found purposefully to avoid omission.

When collecting eggs, use scissors to cut the aquatic plants that adhere to the egg block, and do not pull hard, so as not to break the egg membrane and affect the hatching. The collected eggs should be quickly moved into the incubator. It is best to put one egg block into one incubator. If the area of the incubator is large, when multiple eggs must be placed, the eggs laid on the same day should be placed to ensure simultaneous hatching, so as to avoid different sizes of tadpoles in the incubation pool and affect the release of tadpoles.

2. Hatching density

The hatching density is directly related to the hatching rate. When incubating in still water in an incubator, only 6000 eggs can be placed per square meter. If hatching with micro-running water or cage, the hatching density can be increased to 8000 eggs per square meter.

3. The environmental conditions needed for hatching

The hatching of bullfrog eggs is closely related to the water temperature. The required water temperature for hatching is 20: 31 ℃, and the optimum water temperature is 25: 28 ℃. The suitable pH of the water for hatching is 6.8-8.5. The oxygen content of the slightly acidic water is less, which will affect the hatching, soften the egg membrane, collapse the egg, and cause the egg to break the membrane and die. The water used for hatching should have sufficient oxygen. Generally, the dissolved oxygen content of the water should not be less than 3 mg / L, which will cause the death of the egg.

4. Management during incubation

Because of the direct sunlight at noon, the temperature of the water is higher, and the temperature is low at night or rainy day, resulting in a large temperature difference between day and night, which affects the hatching rate. A shed should be built above the incubator for shade, and it should be covered at night to keep the temperature stable.

The development of embryos should be observed frequently during incubation, and dead eggs should be removed in time to avoid spreading and affecting water quality. After the tadpoles hatch, due to the dissolution of the egg membrane, it will consume a lot of oxygen in the water, resulting in hypoxia in the water and deteriorating the water quality. At this time, appropriate running water or changing water should be taken.

Newly hatched tadpoles have poor swimming ability and are often sucked on the walls of hatching containers or on aquatic plants. Stir them less so as not to affect the rest and survival rate of tadpoles.