Abstract: 【Objective】 Artemisinine is a kind of plant（Artemisia apiacea） extracts which is a potential feed additive to manipulate the rumen fermentation pattern in the future. The main purpose of this study was to search a novel rumen regulating agent and reveal its consequences of manipulation in the rumen. Experiments were conducted to investigate the effect of artemisinine on the rumen fermentation parameters and nitrogen recycling rate between protozoa and bacteria in the rumen. 【Method】 Four Xuhui goats fitted with rumen cannula were used in the experiment. Animals were randomly assigned into four dietary treatments (adding 0, 0.2%, 0.4% and 0.6% artemisinine in diets, respectively) in a 4 × 4 Latin square design. All animals were kept in individual pen and fed with ad libitum diet consisted of grinded corn, soybean meal and Chinese ryegrass hay mainly and had free access to clean drinking water. Protozoa engulf bacteria rate and ruminal nitrogen recycling were determined by a novel fluorescence-labeled bacteria technique dyed with 5-([4,6-Dichlorotriazin-2-yl]amino) fluorescein hydrochloride.【Results】The results showed that the extent of pH ranged from 6.85 to 7.16. The addition of artemisinine could decrease the concentration of NH₃-N concentration effectively; the consequences of ammonia concentration for 0.4% and 0.6% artemisinine treatments were significantly lower than that of the control group. It was shown that acetate, propionate as well as total volatile fatty acid (TVFA) concentration in the rumen were dramatically improved by adding artemisinine, and the ratio of acetate to propionate for artemisinine treatment groups was significantly lower than that of the control group(P＜0.05). With the increasing addition of artemisinine, bacterial protein yields tended to increase, and bacterial protein yield of the highest 0.6% group was very significantly higher than that of the control group(P＜0.01). Additionally, compared to the control group, no significant influence was detected in ruminal peptide nitrogen concentration. Additionally, artemisinine led to an increase of bacterial density, and a decrease of protozoal density. It was further observed that, the engulfing rate of rumen protozoa on bacteria was altered by artemisinine, and they were, 320.11cells/（cell h）, 313.94cells/（cell h）, 305.00cells/（cell h）, 278.14cells/（cell h）for A, B, C, D, respectively. 【Conclusion】 It was concluded that artemisinine was more effective at 0.6% DM proportion of diet. It could decrease ammonia concentration and influence on ruminal fermentation pattern accordingly. The addition of artemisinine in diet could drop the total protozoal density and alter protozoa genus profile in the rumen, where the percentage of Entodinium was decreased, and that of Diplodinium and Isotricha were increased. With adding at 0.6% artemisinine, the rate of microbial protein recycling was increased by decreasing engulfing bacteria rate of protozoa in the rumen of goats and dietary protein efficiency was improved potentially.

Key words: artemisinine, rumen fermentation, microbial nitrogen recycling, goats