The Effects Of Different Plant Protein Sources On Growth And Delaying The Sex Reversal Of Monopterus Albus

Rice field eel, Monopterus albus, a scaleless, finless, gills degraded freshwater bony fish, is regarded as a good candidate for freshwater culture for its delicious meat and high market value. Cage culture is an effective artificial cultivation model for M. albus. Because it has a special phenomenon of sex reversal, the artificial breeding of the M. albus has become a critical step during the culture. The present study was conducted to determine the effects of different dietary plant protein sources on growth and sex reversal in M. albus. The main results are as follows:1. A2-month feeding experiment was conducted to evaluate the effects of different dietary plant protein sources on growth performance in rice field eel, M. albus. Eels (mean weight:12.56±1.17g) were fed with three diets with protein concentration of46%containing soybean meal, rapeseed meal, cottonseed meal and fish meal, fermented soybean meal as the main protein source. The results showed that eels in the cottonseed meal group (CMP) had maximum growth performance, and its weight gain, specific growth rate, protein efficiency ratio and feed conversion ratio were145.01%,1.47%,88.2%and2.46, respectively. Eels in the soybean meal group (SMP) showed lower growth performance than CMP but higher than that in rapeseed meal group (RMP). Hepatosomatic index, viscerosomatic index and condition factor showed no significant differences among three groups. Eels from SMP showed the greatest crude protein content in muscle, significantly higher than that in CMP and RMP. Crude fat content of eels muscle in RMP were significant higher that in SMP and CMP. No significant differences were observed in ash content of muscle between SMP and RMP, but significantly higher than in CMP.2. A1year feeding experiment was conducted to evaluate the effects of different plant protein sources in higher dietary protein on delaying the sex reversal in rice field eel, M. albus. The female eels (tested by biological biopsy) were fed with three diets with protein concentration of46%from soybean meal, cottonseed meal and rapeseed meal in tanks (75cm diameter,55cm water depth) for1year. The control groups were fed40%dietary protein. The results showed that eels in CMP and SMP had higher serum E2concentrations and GSI, compared to that in RMP. The ratio of female eels in SMP, RMP, CMP and control were80.23±3.27%,70.74±4.85%,85.78±2.12%,78.16±2.37%, respectively. The gonadal developments of eels which have reversed to the male have completed. The results indicated that, compared to soybean meal and rapeseed meal, dietary cotton meal delayed the sex reversal of eels more effectively.