Effect Of Dietary Carbohydrate Source And Level On Growth And Metabolism Of Monopterus Ablus

In this paper,the apparent digestibility of seven different carbohydrate source diets and the effects of different carbohydrate source and carbohydrate level diets on the growth and metabolism of Monopterus ablus were studied,in the purpose of providing reference basis for selecting appropriate carbohydrate source and carbohydrate level in the dietary of Monopterus albus.The main research results are as follows:1.Apparent digestibility of seven carbohydrate source diets and their effects on the growth and metabolism of Monopterus albusThe effect of seven diets with different carbohydrate sources（glucose,sucrose,corn starch,wheat meal,rice flour,tapioca starch and potato starch）on the apparent digestibility coefficients and the growth performance of effect mechanisms were studies in Monopterus albus（M.ablus,initial body weight of 21.08±0.43g）.The experiment was divided into 7groups,with 4 replicates in each group and 20 M.ablus per replicate.Seven kinds of diets with 30%different carbohydrate sources were formulated to contain fish meal,soybean protein concentrate and casein as protein sources,fish oil and soybean oil（1:1）as lipid sources,and Y₂O₃ was added as exogenous indicator.The breeding cycle was 60 days,the feces were collected by siphon method for determination after feeding for 4 weeks.The growth performance of M.ablus in wheat meal and rice flour groups was the best,and tapioca starch and potato starch groups were better than sucrose and glucose groups,the glucose group had the worst growth performance.As for the ADC of crude protein and crude fat,wheat meal and rice flour groups were higher than tapioca starch and potato starch groups,and the glucose and sucrose groups were the lowest.No effect of dietary carbohydrate on the activities of gastric digestive enzymes was noticed among all groups,and the activities of digestive enzymes in hepatopancreas and intestines were higher in wheat meal and rice flour groups.The Liver glycogen deposition of M.ablus in glucose and corn starch groups was lower than other five groups.The peak time of blood glucose in M.ablus fed with different carbohydrate sources diets were different,most of which occurred at 3 h to 6 h after meal.Among them,the peak time of blood glucose in corn starch,rice flour and potato starch groups appeared at 3 h after meal,and sucrose,wheat meal and tapioca starch groups appeared at 6 h after meal.The blood glucose concentration of sucrose group remained at a high level 3 h to 6 h after meal,and the potato starch and tapioca starch groups maintain a high blood glucose concentration for a long time.Besides,the blood glucose concentration of M.ablus in glucose group was always maintained at the lowest level,and the peak appeared at 1h after meal.As consider of growth performance and apparent digestibility coefficients,wheat meal and rice flour were more suitable as dietary carbohydrate sources for M.ablus among the seven kinds of dietary carbohydrate sources.2.Effect of dietary carbohydrate level on growth and metabolism of Monopterus albusAs the results of seven carbohydrate source diets for M.albus,seven different gradients（8%,12%,16%,20%,24%,28%,and 32%）of wheat flour were added to formulate seven isonitrogenous and isolipid diets with different starch levels,then fed M.albus for 60 days,respectively,and 4 duplications were contained in each group.The optimal dietary carbohydrate supplemental level of M.albus was determined from the aspects of growth performance,body nutrient composition,digestive enzyme activity,liver and serum biochemical indexes and intestinal microstructure.The results showed that:（1）The weight gain rate,specific growth rate and protein efficiency ratio all showed a trend of first increasing and then decreasing with the increase of dietary carbohydrate level.M.albus showed better growth performance in the 16%and20%groups,and the survival rate of 32%group was significantly decreased（P<0.05）.（2）The optimal dietary carbohydrate supplemental level of M.albus was 16.21%-19.29%by the regression analysis basing on the weight gain rate,specific growth rate and protein efficiency.（3）Dietary carbohydrate level had no significant effects on the visceral body index,liver body index,intestinal index and carcass percentage of M.albus,but the fatness of 8%group was significantly lower than 16%and 20%groups（P<0.05）.（4）The intestinal protease activities of M.albus in 16%and 20%groups were significantly higher than that in8%and 32%groups（P<0.05）,but the hepatopancreas protease and pepsase activities showed no significant effects in each group.The gastric lipase in 8%and 12%groups was significantly lower than other 5 groups（P<0.05）,but the intestinal and hepatopancreas lipase activities showed no significant difference in each group.The hepatopancreas amylase in 32%group was significantly higher than 8%and 12%groups（P<0.05）,and the intestinal amylase in 24%group was significantly higher than 8%group（P<0.05）,but there was no significant difference between other groups（P>0.05）.The overall gastric amylase activities were lower,but showed no significant difference in each group（P>05）.（5）The activities of glutamic pyruvic transaminase（GPT）and glutamic oxalacetic transaminase（GOT）in liver of M.albus were firstly increased and then decreased with the increase of dietary carbohydrate level,but the difference was not significant（P>0.05）.The liver hexokinase activity of 32%group was the highest,but the difference was not significant（P>0.05）.The GPT activity and malondialdehyde（MDA）content in serum were significantly decreased first and then significantly increased with the increase of dietary carbohydrate level.The GOT activity and insulin content in serum were also decreased first and then increased with the increase of dietary carbohydrate level,but the difference was not significant（P>0.05）.（6）The contents of crude protein and fat in whole body of M.albus in 8%group were lower than other 6groups,but the difference was not significant.And the liver nutrition showed no significant difference among all groups.In conclusion,the utilization effect of cereal starch is better than potato starch on M.albus,and the small molecule carbohydrate diet resulted in the worst growth performance of M.albus.The optimum supplemental level of wheat flour was 16.21%-19.29%based on the evaluation indexes of growth performance,feed conversion ratio and protein efficiency.Furthermore,the supplemental level of dietary wheat meal should not be higher than 24%considering of intestinal digestive enzyme activity in M.albus.