The Study On Wintering Technology Of Artificial Breeding Of Rana Chensinensis

Being the critical path to achieve the fully artificial cultivating of the RTC, over-wintering technology is the key issue for fully the RTC artificial breeding industry. In the past, the overwintering technology in china is still in the primary stage, and staying with only simple theoretical researches with no real progress. As the result, without successful over-wintering technology, the breeding plan has been suffered and serious loss been encountered consequently. Therefore, the over-wintering technology is the urgent issue need to be solved.On Oct. of 2003, based on the local research results, four over-wintering modes had been selected and under investigation by the office for the RTC in Tieli. They were: indoor overwintering in dryness;outdoor over-wintering in vault;indoor over-wintering in water;outer over-wintering in water. Also three experimental bases were selected for each of the four modes. The tracking results of these over-wintering modes showed that the indoor overwintering in water mode was the best among these modes. The deep dormancy time for RTC is around 170 days, which is quite closed to that of under natural condition. The body weight drop in this mode is about 5%. The survival rate is above 90%, which is the highest among all other modes. In August 2004, based on the optimized mode of 2003, the indoor optimal overwintering pond with condition controlling mode was constructed by the office for the RTC in Tieli, Later in 2004 and 2005, other facts affecting the RTC over-wintering, such as: density and environmental factors, as well as water quality, were also been investigated and studied.The research results showed that the time differences for RTC entering the over-wintering pond varied with different locations. The RTC were transferred from the pond in the pen to the indoor over-wintering pond under the condition of the outdoor temperature was dropped to below 0°C and indoor water temperature was between 5—6℃. The RTC were captured in the penned pond with circulated flowing water. Then they were transferred to the indoor overwintering pond. In the primary stage of hibernation, the depth of water was kept between 5 and 10 centimeters. It also required that many of the big stone kept being above the water-surface as the transitional stage for the RTC in the pound. The depth of water in the pond would be increased gradually following the temperature drop. The depth of the water in the pound would be increased to between 50⁶0 centimeters, as the RTC was into the stage of deep hibernation. The density was kept about 1500 individuals/m² at this period. If the Oxygen Content in the water was below 6mg/L, the RTC also begun to dieThe research results showed that: the optimal Oxygen Content is around 6⁸mg/L. The optimal flow speed in the pond is between 0.04—0.08m³/min and the optimal ph is about 7. The Fe content is not beyond 0.2⁰.3 mg / L. The calcium carbonate content is more than 150 mg / L. And the CO₂ content should be below 50 mg / L.It also showed that the lights can influence the over-wintering, the dark scattering light isbetter than the strong direct light for RTC. In the stage of deep hibernation for RTC, the lights and noise may cause RTC to active, lead the energy loss and influence survival rate of the RTC. Then during the hibernation period, it is important to seal the windows of the rooms for the indoor pound.