Effects of  Entodinium caudatum  monocultures in an acidotic
environment on  in vitro  rumen fermentation

The study evaluated the effect of Entodinium caudatum on the prevention of subacute ruminal acidosis (SARA) in vitro. Different proportions of wheat and corn [100% wheat (W); 75% wheat and 25% corn (W75); 50% wheat and 50% corn (WC); 75% corn and 25% wheat (C75); and 100% corn (C)] were used to create an in vitro acidotic environment. The activity of E. caudatum was determined by adding defaunated rumen fluid and protozoan monocultures to the substrates. The effect of E. caudatum monoculture on pH was insignificant, while a significant influence of grain type was observed on ammonia (NH3-N) formation. E. caudatum inoculation decreased lactic acid concentration throughout the incubation period and shortened the fermentation start time (lag time). The specific fermentation rate (SFR), which increased with the wheat ratio, was reduced by E. caudatum culture. The total gas production varied depending on the substrate and was increased by E. caudatum. Protozoan monoculture decreased propionic acid levels, while it increased methane production. As a result, E. caudatum stimulated earlier fermentation, but decreased lactic acid production by reducing SFR. It is believed that the instantenuous phagocytosis of E. caudatum (iodophilic storage) to digest starch particles prevents rapid bacterial fermentation in the rumen fluid, and thus limit lactic acid production. The results of this work may support future in vitro studies requiring E. caudatum monoculture, as well as in vivo studies investigating the effect of E. caudatum on the inhibition of SARA formation.

FUNDING

This project was funded by the Selcuk University Scientific Research Projects Coordination Unit (No: 14401042).

CONFLICT OF INTEREST

The Authors declare that there is no conflict of interest.

METADATA IN OTHER LANGUAGES:

Chinese

酸性环境中单独培养尖尾内旋纤毛虫对瘤胃体外发酵的影响

关键词：尖尾内旋纤毛虫；体外酸性环境；原生生物；亚急性瘤胃酸中毒

摘要: 本研究采用体外实验评价了尖尾内旋纤毛虫（Entodinium caudatum，E. caudatum）对亚急性瘤胃酸中毒（Subacute ruminal acidosis，SARA）的预防作用。使用不同比例的小麦和玉米【100%小麦（W）；75%小麦 + 25%玉米（W75）；50%小麦 + 50%玉米（WC）；25%小麦 + 75%玉米（C75）；100%玉米（C）】来建立体外酸性环境。通过向底物中添加灭虫瘤胃液和原生动物单独培养基来测定E. caudatum的活性。E. caudatum单独培养对pH值的影响不显著，而谷物类型对氨氮（NH3-N）的形成有显著影响。接种E. caudatum降低了整个培养过程中的乳酸浓度，缩短了发酵开始时间（滞后时间）。E. caudatum的特定发酵速率（specific fermentation rate，SFR）随小麦比例的增加而降低。不同底物的总产气量不同，E. caudatum对总产气量有促进作用。原生生物的单一培养降低了丙酸水平，同时增加了甲烷产量。结果表明，E. caudatum能通过降低SFR而提前发酵，但降低了乳酸产量。普遍认为E. caudatum（嗜碘的贮存）对淀粉颗粒的瞬时吞噬作用阻止了瘤胃液中细菌的快速发酵，从而限制了乳酸的产生。该结果可能支持未来需要E. caudatum单一培养的体外研究，以及研究E. caudatum对抑制SARA形成的影响的体内研究。

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