| Generally agreed that with rapid expansion of aquaculture, raw materials like fish meal(FM)from marine fisheries may not be able to sustain the needs of aquaculture in not too distant future.This is because the global demand for these raw materials for aquafeeds has increased steadily despite the static global production levels and may not be able to meet the demand in the near future.Consequently,replacement of these popularly used feed ingredients in aquafeeds with economically viable and sustainable alternatives have become more than casual considerations. Hermetia illucen larvae meal(HM),which includes high level of protein and lipids and has a good balance of all of the essential amino acids,has a great potentials in aquatic feed. This experiment was conducted to assess the nutritional value of hermetia illucen larvae meal(HM), then obtained the apparent digestibility coefficient(ACD) and digestibility coefficient in vitro of HM in carp, finally we invatigated optimum supplemental levels of HM in Jian carp(Cyprinus carpio var. Jian) diets via the effect of replacement of fish meal with HM on growth performance, body composition, intestinal protease activity and health status. The results shows that:(1) The nutritional components analysis showed that the CP of HM in the experiment was 41.76% and the CL was 30.05%. The amino acid composition of HM was balanced.(2) To test digestibility coefficient in vitro of HM in Jian carp, the enyme was extracted from the intestine of Jian carp. The dry matter digestibility coefficient in vitro of HM similar to the fish meal(32.63%) in juvenile Jian carp was 29.93%. The CP and CL digestibility coefficient in vitro of fish meal was significantly higher than HM in Jian carp(P<0.05).(3) To test the apparent digestibility coefficient(ACD) of HM in carp, the experimental fish were randomly divided into two groups(fish meal group and HM group) with 4 replicates per group and 18 fish per replicate in recirculating aquaculture system for 4 weeks.The fish in fish meal(FM) group was fed experimental diets consisted of 70% basal diet and 30% FM,and the fish in HM group was fed experimental diets consisted of 70% basal diet and 30%HM. The fecal samples were collected to test the conventional composition.We found that the ADC of DM(61.28%), CP(82.53%), CL(86.02%) for HM were lower than FM in carp. The ADC of CP for HM was significantly lower than FM(P<0.05).(4) To invatigate optimum supplemental levels of HM in Jian carp(Cyprinus carpio var.Jian) diets, 0%, 25%, 50%, 75%, 100% of fish meal protein were substituted by HM to formulate five isonitrogenous and isolipidic diets(crude protein 36% and crude lipid 6%).The experimental fish with same size were randomly allotted to five groups with triplicate of tanks(18 fish per tank) in in recirculating aquaculture system for 8 weeks. At the end of the feeding trial,(1) survival rate of experimental fish was 100%. The final weight(FW), weightgain rate(WGR) and special growth rate(SGR) of fish was the highest in 75% HM group, but no significant was found among groups(P>0.05). The HM in diets had no effect on the growth, feed efficiency rate(FER), ADCs of juvenile Jian carp(P>0.05). The ADCs of CP and CL in HM groups had a slight down trend with increasing HM levels, but no significant was found among groups(P>0.05). The protein converting rate(PCR) in the HM groups were higher than the FM group. The PCR of T2 and T3 groups were significantly higher than the FM group(P<0.05).(2) The HM in diets had no effect on the conventional composition of whole body, muscle and hepatopancreas for juvenile Jian carp. However, the CP of whole body and muscle had a slight up trend and the CL of whole body and muscle had a slight down trend with increasing HM levels. The fatty acid composition analysis showed that C12:0 has a significant increase in muscle and hepatopancreas with the increasing HM levels(P<0.05).The C18:2n-6 and C18:3n-3 had a significant decrease in muscle and hepatopancreas with the increasing HM levels(P<0.05). The fatty acids composition of muscle and hepatopancreas were in accordance with the fatty acid composition of diets.(3)The hepatosomatic index(HSI) and Kidney index(KI) in 75% replacement level were significantly higher than the FM group(P<0.05).(4) No significant were found between the control group and treatment group for biochemical indices of serum(P>0.05). Neverthless,the secrum T-AOC was significantly lower than other groups in 100% replacement level and secrum MDA was significantly in 100% replacement level higher than FM group(P<0.05).Conclusion: The supplement of HM in juvenile Jian carp diets to replacement the fish meal protein has no effect on the growth, FCR, body composition and biochemical indices of serum. However, the high replacement levels(75% and 100%) are harmful to healthy of juvenile Jian carp. It is possible to replace below the 75% level of the dietary FM protein with HM in formula feed of Jian carp. |
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