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Impacts of the unsaturation degree of long-chain fatty acids on the volatile fatty acid profiles of rumen microbial fermentation in goats in vitro

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Journal of Integrative Agriculture 2016年第12期15卷 2827-2833页

作者： GAO Jian WANG Meng-zhi JING Yu-jia SUN Xue-zhao WU Tian-yi SHI Liang-feng College of Animal Science and Technology Yangzhou University Grasslands Research Centre AgResearch Ltd.

This study investigated the impacts of the degree of unsaturation （unsaturity） of long-chain fatty acids on volatile fatty acid （VFA） profiles of rumen fermentation in vitro. Six types of long-chain fatty acids, including stearic acid （C18：0, control group）, oleic acid （C18：1, n-9）, linoleic acid （C18：2, n-6）, a-linolenic acid （C18：3, n-3）, arachidonic acid （C20：4, n-6） and eicosapentaenoic acid （C20：5, n-3）, were tested. Rumen fluid from three goats fitted with ruminal fistulae was used as inoculum and the inclusion rate of long-chain fatty acid was at 3% （w/w） of substrate. Samples were taken for VFA analysis at 0, 3, 6, 9, 12, 18 and 24 h of incubation, respectively. The analysis showed that there were significant differences in the total VFA among treatments, sampling time points, and treatment×time point interactions （P〈0.01）. a-Linolenic acid had the highest total VFA （P〈0.01） among different long-chain fatty acids tested. The molar proportion of acetate in total VFA significantly differed among treatments （P〈0.01） and sampling time points （P〈0.01）, but not treatment×time point interactions （P〉0.05）. In contrast, the molar proportion of propionate did not differ among treatments during the whole incubation （P〉0.05）. However, for butyrate molar proportions, significant differences were found not only among sampling time points but also among treatments and treatment×time point interactions （P〈0.01）, with eicosapentaenoic acid having the highest value （P〈0.01）. Additionally, no statistically significant differences were found in the acetate to propionate ratios among treatments groups （P〉0.05）, even the treatments stearic acid and a-linolenic acid were numerically higher than the others. The inclusion of 3% long-chain unsaturated fatty acids differing in the degree of unsaturation brought out a significant quadratic regression relation between the total VFA concentration and the double bond number of fatty acid. In conclusion, the a-linolenic acid with 3 double

关键词： volatile fatty acid unsaturation degree long-chain fatty acid in vitro fermentation

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Variations in the effective and bankfull discharge for suspended sediment transport due to dam construction

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Frontiers of Earth Science 2022年第2期16卷 446-464页

作者： Fan CHEN Li CHEN Wei ZHANG Jing YUAN Kanghe ZHANG State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China Changjiang Institute of Survey PlanningDesign and ResearchWuhan 430010China Bureau of Hydrology Changjiang Water Resources CommissionWuhan 430010China

A varied class method is applied to calculate the effective discharges and their variations after the Three Gorges Dam(TGD)construction based on the mean daily flow discharge and suspended sediment concentration field data from 1981 to *** comparison,the bankfull discharges are also determined according to the cross-section profiles and flow discharge-stage *** results show that a bimodal effective discharge curve usually exists at the fixed sites,which generates two effective discharges(Q_(e1) and Q_(e2))within the moderate flow *** the quasi-equilibrium circumstances of the pre-dam period,effective discharges are closely related to the mean annual runoff,with a narrow range of regional variations in occurrence *** analyses draw the conclusion that the relatively higher unsaturation degrees of the pre-dam effective discharges caused by dam interception and riverbed coarsening are the primary cause of the increase in effective discharges from Yichang to Shashi,while the more frequent low and medium discharges due to flow regulation drive the decrease in effective discharges from Jianli to *** slightly elevated flood levels and descending bankfull levels collaboratively result in the decrease of bankfull discharges from Yichang to Shashi,while the lowered bed elevation causes the increase in bankfull discharges from Luoshan to ***,the bankfull discharge in the Middle and Lower Yangtze River is larger than effective discharge and approaches the 1.5-year recurrence interval discharge.

关键词： effective discharge bankfull discharge unsaturation degree flow-sediment regimes Middle and Lower Yangtze River Three Gorges Dam

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