The present experiment was conducted to determine the effects of Molasses-Urea Supplementation （MUS） on weight gain, ruminal fermentation and major microbial populations in sheep on a winter grazing regime in Inner ...The present experiment was conducted to determine the effects of Molasses-Urea Supplementation （MUS） on weight gain, ruminal fermentation and major microbial populations in sheep on a winter grazing regime in Inner Mongolia. Total 40 sheep, allowed free consumption of MUS after grazing, served as a treatment group, while 30 sheep, fed only by pasture grazing, served as a control group. Ruminal fermentation parameters, consisted of pH, Bacterial Crude Protein （BCP） and ammonia nitrogen （NH3-N） were measured. In addition, numbers of five symbiotic bacteria were investigated. The results showed as follows： the average daily weight gain, concentration of NH3-N and numbers of protozoa were significantly higher （p〈0.05） in the treatment group than those in the control group. Contrastingly, no significant difference was found in BCP concentration and pH between the two groups. At the end of the experiment, the populations of Selenomonas ruminantium, Anaerovibrio lipolytica, Fibrobacter succinogenes, Ruminococcus flaveciens and Ruminococcus albus in the treatment group were significantly higher than those of the control group （p〈0.05）. These results demonstrated that greater weight gain could be induced during winter in Inner Mongolia by improved nutritional status through promotion of microbial populations using urea and sugar.展开更多
Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper...Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.展开更多
基金Supported by the National Nature Science Foundation of China(31460615)the Modern Agroindustry Technology Research System(CARS-39)
文摘The present experiment was conducted to determine the effects of Molasses-Urea Supplementation （MUS） on weight gain, ruminal fermentation and major microbial populations in sheep on a winter grazing regime in Inner Mongolia. Total 40 sheep, allowed free consumption of MUS after grazing, served as a treatment group, while 30 sheep, fed only by pasture grazing, served as a control group. Ruminal fermentation parameters, consisted of pH, Bacterial Crude Protein （BCP） and ammonia nitrogen （NH3-N） were measured. In addition, numbers of five symbiotic bacteria were investigated. The results showed as follows： the average daily weight gain, concentration of NH3-N and numbers of protozoa were significantly higher （p〈0.05） in the treatment group than those in the control group. Contrastingly, no significant difference was found in BCP concentration and pH between the two groups. At the end of the experiment, the populations of Selenomonas ruminantium, Anaerovibrio lipolytica, Fibrobacter succinogenes, Ruminococcus flaveciens and Ruminococcus albus in the treatment group were significantly higher than those of the control group （p〈0.05）. These results demonstrated that greater weight gain could be induced during winter in Inner Mongolia by improved nutritional status through promotion of microbial populations using urea and sugar.
基金Projects(52022113,52278546)supported by the National Natural Science Foundation of ChinaProject(2020EEEVL0403)supported by the China Earthquake Administration。
文摘Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.
