Detailed Explanation of Turtle Egg Incubation Methods and Technical Points

Using the "@#@238@#@Automatic Heating and Temperature Control Device for Greenhouses" (China Patent 95239104.X) for turtle egg incubation, the sand temperature is controlled at 32°C, the relative air humidity is adjusted to 80%, the interstitial sand humidity is around 10%, and ventilation is provided at appropriate times. Hatchlings emerge in about 50 days, with a hatching rate of 88%-98%. From 1997-1998, a research institute in Suzhou used this "automatic heating and temperature control device" to conduct temperature-controlled breeding experiments on the yellow-margined box turtle (Cuora flavomarginata). The device uses a single-phase power supply, 1-4KW, adjustable, controlling the sand temperature at 28-32°C and humidity at 80%-85%. A total of 1079 turtle eggs were provided for incubation, 950 hatched, giving a hatching rate of 88%. 1. Incubation facilities: The incubation room can be newly built or converted from an old building. The area is generally 10-30 sq m, with a height of 2.5-3 m. The ceiling is sealed with foam boards, and the four walls indoors are best also lined with foam boards for insulation. A 40-60 cm wide walkway is set up in the middle or on one side of the room. Cement pools are built on the ground on both sides of the walkway, with the pool bottom smoothed, a pool depth of 20 cm, and 10 cm of water stored. New cement pools must be repeatedly soaked in clean water before use to remove alkalinity. It is best to lay a layer of sponge on the pool bottom so that hatchlings falling naturally into the water upon emergence are not injured. The incubation rack is made of angle iron or wood. It is set up in multiple tiers, with each tier about 20 cm apart. The rack height is about 1.5 m; if too high, it is inconvenient to operate. The incubation trays placed on the incubation rack use plastic turnover boxes 8-10 cm high, with dozens of holes drilled in the bottom and around the sides to facilitate ventilation. A simpler method is: do not use an incubation rack. Stack the incubation trays layer upon layer, and place bricks on the four corners on top of each tray to separate the trays from one another. The gap between each layer is 10 cm. To keep the indoor air fresh, install one bidirectional ventilation fan at the top of each of the north and south walls of the incubation room. When installing the temperature control device, pay attention to even distribution of the heaters. Keep a certain distance between the incubation rack and the heaters. Generally, heaters are installed on the four walls, 70 cm above the ground, to heat the air during incubation. 2. Turtle egg incubation. One method is the sand-laying incubation method: spread fine sand with a particle size of 0.6mm about 3 cm thick in the incubation tray. Place a layer of turtle eggs on it, then spread another 2 cm thick layer of fine sand on top. The turtle eggs are arranged 1 cm apart. Generally, about 100 turtle eggs are placed in each box. Another method is the sand-free incubation method: the incubation medium uses sponge and foam board. First, place a 2.5 cm thick sponge at the bottom of the incubation tray, then place a foam board 1.5 cm thick on top, drill holes about 2 cm in diameter (according to the size of the turtle eggs) every 2 cm on it, and arrange the fertilized turtle eggs with the animal pole facing up to fill it, and finally place a thin sponge 1 cm thick on top. This sponge is required to be soaked in water and squeezed dry until it no longer drips. The moisture content of the upper and lower sponges is controlled at 45% and 80% respectively. During incubation, the "temperature control device" automatically heats, controlling the air temperature at 34°C and the sand temperature at 32°C. When the natural air temperature is higher than 37°C, the sand temperature is rarely higher than 33°C. Therefore, temperature-controlled incubation of turtles does not require cooling. The relative air humidity, through air heating and evaporation of water from the cement pool below the incubation rack, can generally already meet the requirement of 80% relative humidity. Because the air circulation in the incubation room is relatively fast, the sand also loses water relatively quickly, so more attention should be paid to replenishing the water in the sand. The interstitial sand humidity is mainly achieved by manual spraying or sprinkling. Sprinkling should follow the principle of small amounts and frequent applications. This is to avoid too much water being sprinkled at one time, making the sand humidity too high, restricting ventilation conditions, and affecting the normal development of turtle embryos. Especially in the late stage of embryonic development, attention should be paid to the stability of environmental ecological conditions. During incubation, spray water on the sand at regular intervals. The amount of water sprayed should be determined according to the dryness and wetness of the sand, with the aim of keeping the sand humidity at 10%. The sprayed water must be clean; if the water is relatively dirty, it can easily cause the growth of mold and various other pathogens. When it is found that the surface of the turtle eggshell is not smooth, is sticky, and has black spots on the eggshell, it indicates contamination by miscellaneous bacteria, and the eggs should be removed promptly to prevent the spread of pathogens. Eggs infected with pathogens basically cannot complete normal embryonic development. 3. Hatchling emergence. Generally, emergence is natural. When the embryo completes development, at emergence it first uses the snout to break through the eggshell, extends the head, then uses the forelimbs to support the whole body and emerges from the shell. Therefore, when the accumulated temperature reaches about 38000°C and the hatchlings are emerging, move the incubation tray to the lowest layer, closer to the pool water on the ground, so that newly hatched turtles can easily fall into the water. Alternatively, place a plastic basin under the incubation tray, with water in the basin, so that hatchlings fall naturally into the basin after emergence. Hatchlings mostly emerge in the evening and around 3:00-9:00 before and after dawn. Another method is artificially induced emergence. When the accumulated temperature reaches about 38000°C and the hatchlings have not yet emerged, immerse the same batch of turtle eggs about to hatch into warm water at 20-30°C to stimulate the hatchlings to emerge. They can emerge after 10-15 minutes. If they have not emerged after 20 minutes, they should be put back in place to continue incubating. This method can concentrate hatchling emergence and facilitate management, but it may cause adverse effects on the later growth and development of the hatchlings, so it is not advocated. In addition, there are also the cooling emergence method, the air exposure method and the shell-peeling method (suitable for weak turtles). These methods all share a common drawback: they cause great stimulation to hatchlings that could emerge normally, causing some hatchlings whose yolk has not yet been fully absorbed to emerge early. After emergence, they cannot normally absorb the yolk material and are prone to infection and disease, which easily causes death. After hatchlings emerge, some umbilical cords have already been rubbed off, while others have not yet fallen off, but the yolk requires 2-3 days to be completely absorbed. Newly emerged hatchlings stretch out in the water for several minutes. The initial weight of hatchlings is generally 70%-75% of the egg weight. At the time of hatching, the Chinese pond turtle (Mauremys reevesii) generally has a carapace length of more than 2.6 cm, a width of more than 2.2 cm, and a body weight of more than 3.5 g (most are 2.8-6.1 g); the yellow pond turtle (Mauremys mutica) weighs 6.5-9 g; the painted turtle (Trachemys scripta) has a carapace length of more than 3 cm and a body weight of 6-8 g.