Effects Of Cecropin,β-Carotene And Vitamin Eon Growth Development Of Rana Zhenhaiensis Tadpoles

China is one of the countries with the longest aquaculture industry.With the development of aquaculture industry,intensive and high-density cultivation mode has become the main cultivation mode,which leads to the decline of self-purification ability of water,serious water pollution,and animals are easy to be infected with diseases and slow growth.In this study,Rana zhenhainesis tadpoles were taken as the experimental object,and different concentrations of cecropins,β-carotene and vitamin E were added.The purpose was to:(1)influence of feeding cecropin,β-carotene and vitamin E on the growth performance of R.zhenhainesis tadpole;(2)compare the effects of different cecropin,β-carotene and vitamin E on the physiological and biochemical indexes of R.zhenhainesis.The main research results are as follows: 1.Effect of cecropins on the growth and development of R.zhenhaiensis tadpolesIn this work,we investigated the effects of cecropins on the growth performance and enzyme activity of R.zhenhaiensis tadpoles.Five hundred R.zhenhaiensis tadpoles(Gosner 26~27)were randomly allocated to 5 groups with 5 replicates per group and 20 tails per replicate.Tadpoles were fed the basic diet supplemented with 0,1.0,2.0,4.0 and 8.0 mg/g cecropins cecropin,respectively.The results as showed as follows:(1)the concentration of cecropins was significantly negatively correlated with the developmental stage,but not body length of the R.zhenhaiensis tadpoles.(2)The metamorphic rate was 94.6%,there were no significant differences among the treatments.(3)Metamorphic time,body length and body mass at metamorphosis were positively correlated with the concentration of cecropins.(4)But jumping distance of froglet at metamorphosis was not significantly correlated the concentration of cecropins.(5)The concentration of cecropins was negatively correlated with the SOD activity of the thigh muscle of froglet at metamorphosis.These findings showed that within the concentration range of this experiment 8mg/g cecropins can slow down development rate,prolong metamorphic time,form larger size at metamorphosis in R.zhenhaiensis and the fitness of froglets.2.Effects of β-carotene on the growth performance of R.zhenhaiensis tadpolesThe experiment was conducted to evaluated the effect of dietary β-carotene supplementation on the growth performance and enzyme activity for R.zhenhaiensis tadpoles.Two hundred and eighty-eight tadpoles(Gosner 25~26)were randomly allocated to 4 groups with 3 replicates per group and 24 tails per replicate.Tadpoles were fed the basic diet supplemented with 0,50,500 and 1200 mg/kg β-carotene,respectively.The experiment ended when R.zhenhaiensis tadpoles complete metamorphosis.The results show as follow:(1)The body weight,snout-vent length and tail length of tadpoles between the groups were no significant difference,but significant difference was found in the Gosner development that the control group significantly faster than the β-carotene groups.(2)The weight gain rate,specific growth rate and metamorphosis rate between the groups were no significant difference,but the metamorphosis time of the control group was significantly shorter than the β-carotene treatment groups and the metamorphosis time shortened with the increase of β-carotene concentration.(3)Snout-vent length,head length,length of lower arm and hand and hindlimb length of the froglets between the groups were significantly different that the control group were smaller than other groups,but the weight was not significantly different.(4)The average jumping distance of froglets between the groups was significant difference and the 50 and 500mg/kg β-carotene groups were significantly greater than that the 1200 mg/kg β-carotene and the control group.(5)Catalase(CAT)activity of froglets liver had significant difference,and 50 mg/kg β-carotene group was significantly higher than other treatment groups,but total superoxide dismutase(T-SOD)activity had no significant difference.In conclusion,within the concentration range of this experiment 500 mg/kg β-carotene in the feed can significantly slow down the early development of R.zhenhaiensis tadpole,prolong the metamorphosis time,form larger froglets,significantly enhance the accumulation of energy,the motor performance of froglets,and the fitness of froglets.3.Effects of vitamin E on the growth performance of R.zhenhaiensis tadpolesThe experiment was conducted to evaluated the effect of dietary vitamin E supplementation on the growth performance and enzyme activity for R.zhenhaiensis tadpoles.Two hundred and eighty-eight tadpoles(Gosner 25~26)were randomly allocated to 4 groups with 3 replicates per group and 24 tails per replicate.Tadpoles were fed the basic diet supplemented with 0,50,500 and 1200 mg/kg vitamin E,respectively.The experiment ended when R.zhenhaiensis tadpoles complete metamorphosis.The results show as follow:(1)The body weight(P=0.12),snout-vent length,tail length and the Gosner of tadpoles between the groups were no significant difference.(2)The weight gain rate,specific growth rate and metamorphosis time between the groups were no significant difference,but the metamorphosis rate of the control and 50 mg/kg vitamin E group was significantly higher than 500 and 1200 mg/kg vitamin E group.(3)The head length of froglets in the control group was significantly smaller than the vitamin E treatments,but there was no significant difference between the vitamin E treatments.Length of lower arm and hand of froglets in 50 mg/kg group was significantly larger than the control group.Hindlimb length and the weight of 500 mg/kg vitamin E group is larger than 50 mg/kg group,but the other group was no significant difference.Body length and average jumping distance was no significant difference.(4)Catalase(CAT)activity and total superoxide dismutase activity of froglets liver were not significant,but malondialdehyde(MDA)content was significant difference.MDA content in the 50 mg/kg vitamin E and the control group were significantly lower than that the 500 and 1200 mg/kg vitamin E group,and MDA content in the 500 mg/kg vitamin E group was the highest.In conclusion,within the concentration range of this experiment 50 mg/kg of vitamin E into the feed significantly increased the head length and length of lower arm and hand of froglets,reduced the content of MDA in the liver,and enhanced the antioxidant capacity of froglets.