| This study explored the nutrients’apparent digestibility of four kinds of protein sources for Mono Pters ablus,and the optimal protein levels of M.ablus.In order to provide reference for the selection of protein source and the determination of protein level in M.ablus feed,the main results are as follows:1.The study on nutrients apparent digestibility about four kinds of protein sources of M.ablusThe purpose of this study was to explore the apparent digestibility of M.ablus to dry matter,crude protein and crude fat in corn protein meal,expanded soybean meal,chicken meal and blood meal.The experimental feed was based on the ratio of 7:3 between the basic feed and the test ingredients,and 0.2%yttrium trioxide（Y203）was added as the exogenous indicator.M.ablus with an initial weight of（22.43±0.2）g were randomly divided into 5 groups with 4 replicates in each group and 30 fish in each replicate.one group was randomly selected as the control group and fed with basic feed simultaneously,while the remaining four groups were fed with experimental feed respectively.Feces were collected by siphoning after 1 week of feeding.The results showed that the apparent digestibility of rice M.ablus to the dry matter of 4 protein ingredients ranged from 73.90%to 98.55%,the apparent digestibility of crude protein ranged from 88.40%to 95.75%,and the apparent digestibility of crude fat ranged from 81.90%to 83.50%.Blood meal was the highest in all indexes,significantly higher than other groups（P<0.05）,followed by chicken meal,the dry matter apparent digestibility and the apparent digestibility of crude lipid were the lowest in the expanded soybean group（P<0.05）,and the apparent digestibility of crude protein was the lowest in the corn protein powder,significantly lower than other groups（P<0.05）.Among them,the apparent digestibility of nutrients in animal protein ingredients is higher than that of plant protein ingredients,and blood meal is the highest.Among plant protein ingredients,the apparent digestibility of dry matter and crude fat in corn protein ingredients is higher than that of expanded soybean meal,but the apparent digestibility of crude protein is lower than that of expanded soybean meal.During the breeding period,it was found that in the animal protein ingredients,the feed of the blood meal group could inhibit the feeding of M.ablus.Among the plant protein ingredients,the corn gluten meal group was more active in feeding,at the same time,according to the growth conditions during cultivation,the weight gain rate of eel in chicken meal group was better than that in other groups（P<0.05）,and the protein efficiency was second only to that in blood meal group,but higher than that in other groups（P<0.05）..Conclusion:considering the apparent digestibility and growth performance and feeding conditions of M.ablus to the nutrients of the four protein ingredients,chicken meal and corn protein meal are better protein ingredients to replace fish meal.2.Effects of dietary protein level on growth performance of M.ablusThe experiment was aimed to investigate the effects of different dietary protein levels on the growth performance,body composition,body tissue,serum index,liver biochemical index and digestive enzyme activity of Monopterus albus,in order to determine the optimal protein levels.Fish meal was used as the main protein source in the experiment.Seven isoenergetic diets were formulated to contain different levels of crude protein（dry matter）32.74%,38.50%,42.26%,48.35%,52.65%,57.87%and 62.31%,and Monopterus albus were fed for 60d with initial weight of（17.1±0.2g）.There were four repeats set for each treatment,and 30 Monopterus albus for each repeat.The results showed that:（1）Effect of dietary protein levels on growth performance of Monopterus albus:The survival rate was no significantly difference between each experimental group（P>0.05）,which was good in each experimental group;when the dietary protein levels between 32.74%～52.65%,with the increase of dietary protein levels,weight gain rate and specific growth rate will increase together,and there is significantly difference（P<0.05）,when the dietary protein levels between 52.65%～62.31%,with the increase of dietary protein levels,weight gain rate and the change of specific growth rate was not significantlyt（P>0.05）.（2）Effect of dietary protein level on dietary utilization of Monopterus albus:When the dietay protein levels was between 32.74%～52.65%,with the increase of the dietary protein level,the feed conversion ratio downward significantly（P<0.05）.When the dietary protein level was between 52.65%～62.31%,the feed conversion ratio did not change significantly（P>0.05）.when the level of dietary protein was between 32.74%～52.65%,with the increase of dietary protein levels,the protein efficiency ratio increased significantly（P<0.05）.When the level of dietary protein was between 52.65%～62.31%,the change of protein efficiency ratio was not significantly（P>0.05）.（3）Effects of dietary protein levels on body composition of Monopterus albus:The body protein was increasing firstly and then reducing with the increasing of dietary protein levels,there were significantly difference between the experimental groups（P<0.05）.The body lipid content of Monopterus albus decreased significantly（P<0.05）.（4）Effects of dietary protein levels on tissue and body indexes of Monopterus albus:with the increase of dietary protein levesls,the viscerasomatic index and hepatosomatic index of Monopterus albus reduced significantly（P<0.05）,while intestosomatic index and splenic idex showed no significant difference（P>0.05）.（5）Effects of dietary protein levels on nutritional composition in different tissues of Monopterus albus:The level of dietary protein had a significant effect on the nutritional composition of muscle,liver,intestine,skin and kidney of Monopterus albus（P<0.05）,With the increase of dietary protein level,the crude protein content in all tissues showed an increasing trend.（6）Effect of dietary protein level on serum and liver biochemical indexes of Monopterus albus:The activity of GPT and GOT in Monopterus albus serum decreased first and then remained unchanged,with the increase of dietary protein levels,there were significantly difference between experimental groups（P<0.05）;MDA decreased first and then increased with the dietary protein levels,and it was the lowest in the T5 group（P<0.05）;The blood glucose content in T1 group was the highest,which was significantly higher than that in other groups（P<0.05）;The activity of GPT and GOT in liver increased first and then remained unchanged,with the dietary protein levels,there were significantly difference between experimental groups（P<0.05）.（7）Effect of dietary protein level on liver microstructure of M.ablus:low protein level cause damage to liver function of M.ablus,and glycogen accumulated in liver simultaneously.（8）Effect of dietary protein level on digestive enzyme activity in tissues of Monopterus albus:The protease activity in liver,stomach and intestine tissues of Monopterus albus increased first and then remained unchanged,with the increase of dietary protein levels,there were significantly difference between experimental groups（P<0.05）;The lipase activity in Liver of Monopterus albus decreased first and then remained unchanged,with the increase of dietary protein levels,there were significantly difference between experimental groups（P<0.05）,but the lipase activity in stomach and intestinal was not affected by dietary protein level（P>0.05）;The amylase activity in liver and intestine tissues of Monopterus albus decreased first and then remained unchanged,with the increase of dieary protein levels,there were significantly difference between experimental groups（P<0.05）,when there were not significantly difference between experimental groups in stomach（P>0.05）.Conclusion:In the appropriate protein level range,increasing the dietary protein level can promote the growth and the feed utilization of,and improve the immune antioxidant capacity of fish.In the appropriate protein level range,the increase of dietary protein level can promote the growth iand the feed utilization,and the immune antioxidant capacity of Monopterus albus.However,the high level of feed protein will not only increase the cost,but also hinder the growth of Monopterus albus.According to the comprehensive analysis of weight gain rate,protein efficiency ratio,protein retention rate and feed conversion ratio of Monopterus albus,the optimal protein level of diteay for Monopterus albus was 48.51%～52.60%（dry matter）. |
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