Effects of elevated temperatures on embryonic development and growth of tadpole and froglet stage of Thai frog (Rana tigerina)

Abstract

Research was conducted to determine the influence of temperature on the embryonicdevelopment, growth, and survival rate of frogs and to provide the basis knowledge onfrogs' temperature tolerance. The experiment to evaluate the ef ect of temperatureonthedevelopment of frog embryos during the time from fertilized egg to hatching includestwoexperiments (i) the ef ect of dif erent elevated temperatures on the development andhatchingof embryos (ii) the ef ects of dif erent elevated temperatures on the survival and developmentrate of tadpoles to the froglet stage. The result show that the weight of frogs was significantlyhigher at 27°C, 30°C and 33°C compared to those frogs raised at 24°C (p<0.05). Theeggswere incubated in dif erent temperatures, the embryo development time was shortenedattreatments of 27, 30 and 33 oC, and the longest embryo development time was inthe24oCtreatment (27.17 hours). The shortest average time at 30 and 33 oC were 15.64and14.95hours respectively. There was a significant dif erence between the treatment of 30 and 33oC compared to those at the 27oC treatment (19.37 hours). Survival rate and feedconversionratio (FCR) were evaluated at the end of the experiment. The results showed that after15days, the growth rate in the 27, 30 and 33oC treatments was significantly higher (p<0.05)than those at the 24oC treatment. The highest growth was observed in the 33oC treatment(1.628±0.06g). Similarly, after 30 days, the growth rate of froglet weight was recorded(5,540±0.47 g), significantly dif erent (p <0.05) compared to those of all other treatments.Survival rates ranged from 62% to 79% and were not significantly dif erent (p>0.05) amongtreatments. In contrast, the percentage of female frogs reached the highest valueat thetreatment temperature of 30°C (86.67%) and the lowest value at the treatment of 24°C(43.33%), but there was no significant dif erence between them.