A 9-week feeding trial in floating freshwater cages(1.0 m×1.0 m×2.0 m) was conducted to study the effects of different dietary levels of protein and starch on growth,body composition,and gene expression of e...A 9-week feeding trial in floating freshwater cages(1.0 m×1.0 m×2.0 m) was conducted to study the effects of different dietary levels of protein and starch on growth,body composition,and gene expression of enzymes in common carp,Cyprinus carpio(mean body weight,36.12±1.18 g) to evaluate the protein-sparing effect of dietary carbohydrate.Four diets were formulated with corn starch as the carbohydrate source to obtain corn starch levels of 6.5%,13%,19.5%,or 26%and protein levels of 30.5%,28.2%,26.4%,and 24.2%.The results showed no differences in growth performance of fish fed the diets with different protein and corn starch levels,but body composition and glucose metabolic enzyme activity of carp were significantly affected by the different diets(P<0.05).Weight gain,specific growth rate,and the feed conversion ratio were not different in fish fed the different dietary treatments.Protein efficiency ratio increased significantly as corn starch level increased(P<0.05).Whole-body crude lipid composition increased with increasing dietary corn starch level(P<0.05).Glucokinase(GK),hexokinase,and pyruvate kinase(PK) activities increased significantly with increasing dietary corn starch level(P<0.05),whereas glucose-6-phosphate(G6Pase) activity decreased with increasing dietary corn starch level(P<0.05).GK gene expression was significantly higher in fish fed the high-corn starch diet than those fed the low-corn starch diet(P<0.05).G6 pase gene expression tended to decrease with increasing starch level(P>0.05).In summary,the results indicate a protein-sparing effect by substituting carbohydrate in the diet of common carp.展开更多
Investigating the effects of residue chemical composition on soil labile organic carbon （LOC） will improve our understanding of soil carbon sequestration. The effects of maize residue chemical composition and soil w...Investigating the effects of residue chemical composition on soil labile organic carbon （LOC） will improve our understanding of soil carbon sequestration. The effects of maize residue chemical composition and soil water content on soil LOC fractions and microbial properties were investigated in a laboratory incubation experiment. Maize shoot and root residues were incorporated into soil at 40% and 70% field capacity. The soils were incubated at 20 ℃ for 150 d and destructive sampling was conducted after 15, 75, and 150 d. Respiration, dissolved organic carbon （DOC）, hot-water extractable organic carbon （HEOC）, and microbial biomass carbon （MBC） were recorded, along with cellulase and β-glucosidase activities and community-level physiological profiles. The results showed that the cumulative respiration was lower in root-amended soils than in shoot-amended soils, indicating that root amendment may be beneficial to C retention in soil. No significant differences in the contents of DOG, HEOC and MBC, enzyme activities, and microbial functional diversity were observed between shoot- and root-amended soils. The high soil water content treatment significantly increased the cumulative respiration, DOC and HEOC contents, and enzyme activities compared to the low soil water content treatment. However, the soil water content treatments had little influence on the MBC content and microbial functional diversity. There were significantly positive correlations between LOC fractions and soil microbial properties. These results indicated that the chemical composition of maize residues had little influence on the DOC, HEOC, and MBC contents, enzyme activities, and microbial functional diversity, while soil water content could significantly influence DOC and HEOC contents and enzyme activities.展开更多
基金Supported by the Key Technology R&D Program of Tianjin(No.13ZCZDNC00900)the Tianjin Research Program of Application Foundation and Advanced Technology(No.14JCQNJC15100)+2 种基金the Tianjin Innovative Research Team(No.TD12-5018)the Tianjin Key Laboratory of Animal and Plant Resistancethe National Natural Science Foundation of China(No.31402313)
文摘A 9-week feeding trial in floating freshwater cages(1.0 m×1.0 m×2.0 m) was conducted to study the effects of different dietary levels of protein and starch on growth,body composition,and gene expression of enzymes in common carp,Cyprinus carpio(mean body weight,36.12±1.18 g) to evaluate the protein-sparing effect of dietary carbohydrate.Four diets were formulated with corn starch as the carbohydrate source to obtain corn starch levels of 6.5%,13%,19.5%,or 26%and protein levels of 30.5%,28.2%,26.4%,and 24.2%.The results showed no differences in growth performance of fish fed the diets with different protein and corn starch levels,but body composition and glucose metabolic enzyme activity of carp were significantly affected by the different diets(P<0.05).Weight gain,specific growth rate,and the feed conversion ratio were not different in fish fed the different dietary treatments.Protein efficiency ratio increased significantly as corn starch level increased(P<0.05).Whole-body crude lipid composition increased with increasing dietary corn starch level(P<0.05).Glucokinase(GK),hexokinase,and pyruvate kinase(PK) activities increased significantly with increasing dietary corn starch level(P<0.05),whereas glucose-6-phosphate(G6Pase) activity decreased with increasing dietary corn starch level(P<0.05).GK gene expression was significantly higher in fish fed the high-corn starch diet than those fed the low-corn starch diet(P<0.05).G6 pase gene expression tended to decrease with increasing starch level(P>0.05).In summary,the results indicate a protein-sparing effect by substituting carbohydrate in the diet of common carp.
基金supported by the National Key Research Program of China(Nos.2016YFD0200107and 2016YFD0300802)the National Natural Science Foundation of China(No.41271311)+1 种基金the Earmarked Fund for China Agriculture Research System(No.CARS-03)the Science and Technology Service Network Initiative of Chinese Academy of Sciences(Nos.KFJ-SW-STS-142-03 and KFJ-EW-STS-083-2)
文摘Investigating the effects of residue chemical composition on soil labile organic carbon （LOC） will improve our understanding of soil carbon sequestration. The effects of maize residue chemical composition and soil water content on soil LOC fractions and microbial properties were investigated in a laboratory incubation experiment. Maize shoot and root residues were incorporated into soil at 40% and 70% field capacity. The soils were incubated at 20 ℃ for 150 d and destructive sampling was conducted after 15, 75, and 150 d. Respiration, dissolved organic carbon （DOC）, hot-water extractable organic carbon （HEOC）, and microbial biomass carbon （MBC） were recorded, along with cellulase and β-glucosidase activities and community-level physiological profiles. The results showed that the cumulative respiration was lower in root-amended soils than in shoot-amended soils, indicating that root amendment may be beneficial to C retention in soil. No significant differences in the contents of DOG, HEOC and MBC, enzyme activities, and microbial functional diversity were observed between shoot- and root-amended soils. The high soil water content treatment significantly increased the cumulative respiration, DOC and HEOC contents, and enzyme activities compared to the low soil water content treatment. However, the soil water content treatments had little influence on the MBC content and microbial functional diversity. There were significantly positive correlations between LOC fractions and soil microbial properties. These results indicated that the chemical composition of maize residues had little influence on the DOC, HEOC, and MBC contents, enzyme activities, and microbial functional diversity, while soil water content could significantly influence DOC and HEOC contents and enzyme activities.
