[Objective] The paper was to study the dynamic changes of forage nutrient substance fermentation in rumen, and a set of continuous culture system of artificial rumen was designed. [Method] With in vivo as control, the...[Objective] The paper was to study the dynamic changes of forage nutrient substance fermentation in rumen, and a set of continuous culture system of artificial rumen was designed. [Method] With in vivo as control, the simulating rumen fer- mentation effect in vitro culture system was evaluated. [Result] The simulation rumen fermentation test needed adaptive phase of 2-3 d, and the fermentation state was relatively stable within 3-9 d, with good effects. The test showed certain regularity variation with index value of rumen in vivo. [Conclusion] The continuous culture sys- tem of artificial rumen could be used as the ideal model to study the rumen fermen- tation in vivo.展开更多
The problem of equilibrium of non-linear dynamic system for microorganism in continuous culture is considered in this paper. The existence of equilibrium point is proved. The conclusion that the equilibrium is the con...The problem of equilibrium of non-linear dynamic system for microorganism in continuous culture is considered in this paper. The existence of equilibrium point is proved. The conclusion that the equilibrium is the continuous function of the dilution rate and substrate concentration in medium in a certain range is concluded. And the stability criterion of equilibrium is obtained. In theory, it explains the multiplicity shown in laboratory.展开更多
Rotifers are considered as one of the most important prey organisms in the culture of altricial fish larvae. However, high density rotifer culture is often problematic due to water quality problems which results in fr...Rotifers are considered as one of the most important prey organisms in the culture of altricial fish larvae. However, high density rotifer culture is often problematic due to water quality problems which results in frequent crashes. In the present study, the performance of a small-scale, continuous system was evaluated for culturing rotifers, Brachionus plicatilis, using concentrated nonviable green algae, Nannochloropsis oculeataas feed in a 160 L tank for a period of 90 days. The system configuration was simple and major components consisted of a protein skimmer and a pure oxygen delivery system. Although egg ratio increased from 3% on day 1 to 21.8% and 39.3% on days 7 and 9, respectively, rotifer growth was slow at start up and resulted in fluctuations in total number of rotifers between days 19-41. Rotifer densities remained 〈 400 until day 51 but increased at higher rates reaching 900 individuals/mL on day 55, 1,620 on day 60 and 2,127 on day 70. Rotifer density reached a maximum of 2,188 individuals/mL on day 85. Once the rotifer density exceeded 1,500 individuals/mL （day 60）, periodical harvesting （a total of 16 harvest events） produced a total of 369,920,000 rotifers corresponding to a daily production of 12,330,667 individuals/day during the next 30 days until the experiment was terminated at day 90. As a result of periodic harvesting, water makeup and continuous protein skimming, total settleable solids and NH3-N levels remained low and ranged between 4-22 mL/L and 0.4-2.2 mg/L, respectively. The authors＇ findings indicated that this inexpensive culture system can be successfully used for small-scale marine or freshwater ornamental fish production. Further work is required to minimize lag period at start-up and increase the production potential and yield by better management of suspended solids.展开更多
Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous ...Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous batch culture screening of various supplements identified selected mixtures with an enhanced potential to mitigate ruminal methane and ammonia formation.Among these,Q-2(named after quebracho extract and EOC blend 2,composed of carvacrol,thymol,and eugenol)and C-10(chestnut extract and EOC blend 10,consisting of oregano and thyme essential oils and limonene)have been investigated in detail in the present study with the semi-continuous rumen simulation technique(Rusitec)in three independent runs.For this purpose,Q-2 and C-10,dosed according to the previous study,were compared with a non-supplemented diet(negative control,NC)and with one supplemented with the commercial EOC-based Agolin^(R) Ruminant(positive control,PC).Results From d 5 to 10 of fermentation incubation liquid was collected and analysed for pH,ammonia,protozoa count,and gas composition.Feed residues were collected for the determination of ruminal degradability.On d 10,samples of incubation liquid were also characterised for bacterial,archaeal and fungal communities by high-throughput sequencing of 16S rRNA and 26S ribosomal large subunit gene amplicons.Regardless of the duration of the fermentation period,Q-2 and C-10 were similarly efficient as PC in mitigating either ammonia(-37%by Q-2,-34%by PC)or methane formation(-12%by C-10,-12%by PC).The PC was also responsible for lower feed degradability and bacterial and fungal richness,whereas Q-2 and C-10 effects,particularly on microbiome diversities,were limited compared to NC.Conclusions All additives showed the potential to mitigate methane or ammonia formation,or both,in vitro over a period of 10 d.However,several differences occurred between PC and Q-2/C-10,indicating different mechanisms of action.The pronounced defaunation caused by PC and its suggested consequences apparently determined at least part of the mitigant effects.Although the depressive effect on NDF degradability caused by Q-2 and C-10 might partially explain their mitigation properties,their mechanisms of action remain mostly to be elucidated.展开更多
Language classrooms should be seen as mini intercultural communities in which interactions take place. It is English teachers' responsibility to acquaint learners with cultural differences and strategies for cross...Language classrooms should be seen as mini intercultural communities in which interactions take place. It is English teachers' responsibility to acquaint learners with cultural differences and strategies for cross- cultural communication. While teaching linguistic features in college English classrooms, cultural bridge should be built to enhance cultural continuity and effective communication.展开更多
文摘[Objective] The paper was to study the dynamic changes of forage nutrient substance fermentation in rumen, and a set of continuous culture system of artificial rumen was designed. [Method] With in vivo as control, the simulating rumen fer- mentation effect in vitro culture system was evaluated. [Result] The simulation rumen fermentation test needed adaptive phase of 2-3 d, and the fermentation state was relatively stable within 3-9 d, with good effects. The test showed certain regularity variation with index value of rumen in vivo. [Conclusion] The continuous culture sys- tem of artificial rumen could be used as the ideal model to study the rumen fermen- tation in vivo.
文摘The problem of equilibrium of non-linear dynamic system for microorganism in continuous culture is considered in this paper. The existence of equilibrium point is proved. The conclusion that the equilibrium is the continuous function of the dilution rate and substrate concentration in medium in a certain range is concluded. And the stability criterion of equilibrium is obtained. In theory, it explains the multiplicity shown in laboratory.
文摘Rotifers are considered as one of the most important prey organisms in the culture of altricial fish larvae. However, high density rotifer culture is often problematic due to water quality problems which results in frequent crashes. In the present study, the performance of a small-scale, continuous system was evaluated for culturing rotifers, Brachionus plicatilis, using concentrated nonviable green algae, Nannochloropsis oculeataas feed in a 160 L tank for a period of 90 days. The system configuration was simple and major components consisted of a protein skimmer and a pure oxygen delivery system. Although egg ratio increased from 3% on day 1 to 21.8% and 39.3% on days 7 and 9, respectively, rotifer growth was slow at start up and resulted in fluctuations in total number of rotifers between days 19-41. Rotifer densities remained 〈 400 until day 51 but increased at higher rates reaching 900 individuals/mL on day 55, 1,620 on day 60 and 2,127 on day 70. Rotifer density reached a maximum of 2,188 individuals/mL on day 85. Once the rotifer density exceeded 1,500 individuals/mL （day 60）, periodical harvesting （a total of 16 harvest events） produced a total of 369,920,000 rotifers corresponding to a daily production of 12,330,667 individuals/day during the next 30 days until the experiment was terminated at day 90. As a result of periodic harvesting, water makeup and continuous protein skimming, total settleable solids and NH3-N levels remained low and ranged between 4-22 mL/L and 0.4-2.2 mg/L, respectively. The authors＇ findings indicated that this inexpensive culture system can be successfully used for small-scale marine or freshwater ornamental fish production. Further work is required to minimize lag period at start-up and increase the production potential and yield by better management of suspended solids.
基金partially funded with Ferrero 3P projectsupported by the European Union under the European Regional Development Fund(part of the Union’s response to the COVID-19 outbreak,AXIS VI—Investment Priority 13i—Action 3.1.1)。
文摘Background Dietary supplements based on tannin extracts or essential oil compounds(EOC)have been repeatedly reported as a promising feeding strategy to reduce the environmental impact of ruminant husbandry.A previous batch culture screening of various supplements identified selected mixtures with an enhanced potential to mitigate ruminal methane and ammonia formation.Among these,Q-2(named after quebracho extract and EOC blend 2,composed of carvacrol,thymol,and eugenol)and C-10(chestnut extract and EOC blend 10,consisting of oregano and thyme essential oils and limonene)have been investigated in detail in the present study with the semi-continuous rumen simulation technique(Rusitec)in three independent runs.For this purpose,Q-2 and C-10,dosed according to the previous study,were compared with a non-supplemented diet(negative control,NC)and with one supplemented with the commercial EOC-based Agolin^(R) Ruminant(positive control,PC).Results From d 5 to 10 of fermentation incubation liquid was collected and analysed for pH,ammonia,protozoa count,and gas composition.Feed residues were collected for the determination of ruminal degradability.On d 10,samples of incubation liquid were also characterised for bacterial,archaeal and fungal communities by high-throughput sequencing of 16S rRNA and 26S ribosomal large subunit gene amplicons.Regardless of the duration of the fermentation period,Q-2 and C-10 were similarly efficient as PC in mitigating either ammonia(-37%by Q-2,-34%by PC)or methane formation(-12%by C-10,-12%by PC).The PC was also responsible for lower feed degradability and bacterial and fungal richness,whereas Q-2 and C-10 effects,particularly on microbiome diversities,were limited compared to NC.Conclusions All additives showed the potential to mitigate methane or ammonia formation,or both,in vitro over a period of 10 d.However,several differences occurred between PC and Q-2/C-10,indicating different mechanisms of action.The pronounced defaunation caused by PC and its suggested consequences apparently determined at least part of the mitigant effects.Although the depressive effect on NDF degradability caused by Q-2 and C-10 might partially explain their mitigation properties,their mechanisms of action remain mostly to be elucidated.
文摘Language classrooms should be seen as mini intercultural communities in which interactions take place. It is English teachers' responsibility to acquaint learners with cultural differences and strategies for cross- cultural communication. While teaching linguistic features in college English classrooms, cultural bridge should be built to enhance cultural continuity and effective communication.
