| Krill meal is a high-quality protein source,and its nutritional value is similar to fish meal.The research objects of this paper are rice field eel(Monopterus albus)and yellow catfish(Peltobagrus fulvidraco),and in this paper we have discussed the effects of krill meal on growth,body composition,intestinal digestive enzymes,serum biochemistry and immune antioxidant capacity of rice field eel and yellow catfish when we replaced different proportion of fish meal.In this experiment,fish meal and soybean meal were the main protein sources,fish oil was the fat source,and alpha-starch was the sugar source and adhesives.The experiment is divided into 10 groups,three replicates per group,and 50 fishes in each cage,a total of 30 cages.The experiment lasted 8 weeks,and the results are as follows:Experiment 1:The basic feed was used as RM0 group.Antarctic krill meal was used to replace 2.5%(RM2.5),5.0%(RM5),7.5%(RM7.5)and 10%(RM10)fish meal in the basic feed respectively,and five kinds of feed with equal nitrogen and lipid were prepared.The experiment was carried out on rice field eel with initial body weight(25.00±0.03)g.Results are as follows: 1)Compared with RM0 group,there were no significant difference in feed coefficient,survival rate,condition factor and hepatosomatic index(P>0.05),but the weight gain rate and specific growth rate increased.Furthermore,the R5,R7.5 and R10 groups were significantly higher than RM0 group(P<0.05),among which RM7.5 group had the best effect and viscerosomatic index was significantly lower than RM0 group(P<0.05).The moisture,crude protein and crude fat showed no significant differences among all treatments(P>0.05).(P>0.05).The crude ash content of RM2.5,RM5 and RM7.5 groups were significantly higher than that of RM0 group(P<0.05).The activity of digestive enzymes in intestinal tract increased first and then decreased,and trypsin reached the maximum in RM2.5 group and was significantly higher than that in other groups(P<0.05).Lipase reached the maximum in RM5 group,but there was no significant difference with other groups(P>0.05).Amylase reached the maximum in RM7.5 group,and significantly higher than RM0 group(P<0.05).2)The glucose content of each group was significantly higher than that of RM0 group(P<0.05).The total cholesterol content increased first and then decreased,reaching the maximum in RM2.5group(P<0.05).The triglyceride content of RM5 group was significantly lower than that of RM0 group(P<0.05).There was no significant difference among other groups(P>0.05).Compared with RM0 group,GOT activity had no significant effect(P>0.05),GPT activity in RM10 group was significantly higher than that in other groups,and there was no significant difference between other groups(P>0.05).Complement 4 and immunoglobulin M did not change significantly(P<0.05).Complement 3 content and alkaline phosphatase activity increased first and then decreased.Complement 3 content reached the maximum in RM5 group and was significantly higher than that in other groups(P<0.05).Alkaline phosphatase activity reached the maximum in RM2.5 group and was significantly higher than that in RM0group(P<0.05).Superoxide dismutase activity increased first and then decreased,and reached the maximum in RM5 group and was significantly higher than that in RM0 group(P<0.05).There was no significant difference in catalase activity and malondialdehyde content compared with RM0 group(P>0.05).In conclusion,substitution of krill meal for 5-7.5% fish meal can improve the growth performance of rice field eel,without affecting the nutrient composition of fish body,improving the metabolic level and enhancing its immune and antioxidant capacity.Experiment 2:The basic feed was used as RP0 group.Antarctic krill meal was used to replace 2.5%(RP2.5),5.0%(RP5),7.5%(RP7.5)and 10%(RP10)fish meal in the basic feed respectively,and five kinds of feed with equal nitrogen and lipid were prepared.The experiment was carried out on yellow catfish with initial body weight(10.51±0.03)g.Results are as follows: 1)Compared with RP0 group,there was no significant difference in weight gain rate,specific growth rate,feed coefficient and survival rate(P>0.05);viscerosomatic index increased first and then decreased,and RP2.5 group was significantly higher than RP0group(P<0.05),while hepatosomatic index and condition factor did not change significantly(P>0.05).The activities of intestinal amylase and lipase were not significantly affected(P>0.05),but the activities of trypsinase in all substituted groups were significantly decreased(P<0.05).There was no significant difference in moisture,crude fat and crude ash,but crude protein in RP2.5 group was significantly higher than that in other groups(P<0.05).2)Compared with RP0 group,the contents of triglyceride,blood sugar,total cholesterol and GPT activity were significantly increased(P<0.05).GOT increased,and the activity of RP10 group was significantly higher than that of RP0 group(P<0.05).Thecontent of complement 3increased significantly(P<0.05),but the content of complement 4 increased slightly(P>0.05).The content of immunoglobulin M increased first and then decreased,and the content of RP5 group was significantly higher than that of RP0 group(P<0.05).Alkaline phosphatase activity showed a downward trend.When the substitution ratio exceeded 5%,the activity decreased significantly(P<0.05).There were no significant changes in superoxide dismutase,catalase activity and malondialdehyde content(P>0.05).In conclusion,the substitution of krill meal for fish meal has no negative effect on the growth,nutrient composition,intestinal amylase and lipase activity of yellow catfish,and can improve its immune capacity,without negative impact on antioxidant capacity,but it will increase the burden on the liver of yellow catfish. |
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