| The present research was conducted to investigate the influence of saponins on rumen fermentation and methane production in vitro and growth performance of growing Boer goats. By developing the optimal measurement condition for ruminal fermentation products and comparing the effects of two different saponins (Yucca saponins and Quillaja saponins) on fermentation and methane production, the proper adding levels of saponins in vitro was estabilished. By using different incubation condition (including faunated and defaunated rumen fluid, different defaunated methods and different forage/concentrate ratio), we evaluated the effects of tea saponins (TS) on rumen fermentation and methane production in vitro. Furthermore, the effect of the TS addition on growth performance of growing Boer goats was investigated. The main results are shown as follows:1. By using the HP-INNOWAX, FID and nitrogen as the carrier, the optimal measurement condition for methane was established: nitrogen pressure at 130kPa, total and column flow rates at 30.2 and 1.7ml/min, and the column, injection and detection temperatures at 80, 100 and 120℃, respectively. The optimal condition for measurement of acetate, propionate and butyrate was: nitrogen pressure at 90kPa, total and column flow rates at 37.2 and 0.67ml/min, and column, injection and detection temperatures at 180, 200 and 220℃, respectively.2. Yucca saponins (steroid saponins) and Quillaja saponins (triterpenoid saponins) had similar effects on rumen fermentation and methane production in the syringe system, that is, saponins could moderate rumen fermentation, including increased the microbial protein (MCP) yield, decreased the ammonia-N level and methane emission, and inhibited the protozoa in rumen fluid.3. The effects of TS on rumen fermentation and methane emission were examined in Menke's syringe system. The TS were added at levels of 0, 2, 4, 6 and 8mg against 200mg mixture of corn meal and grass meal (1/1, w/w) in 30ml rumen fluid. The gas production (GP) was increased with the increasing level of TS except 8mg at 24h. TS decreased the methane emission, ammonia-N concentrations and inhibited theprotozoa growth in ruminal fluid significantly (P<0.01). Concentrations of volatile fatty acids (VFAs) were not effected by TS addition. The MCP was enhanced with the TS addition except at 2 mg level. It is suggested that TS could modify the rumen fermentation and inhibit the release of methane and ammonia in rumen fluid in vitro.4. Two different incubation systems were compared in the effects of TS on rumen fermentation and methane production in vitro. Four adding levels of TS (0, 0.2, 0.4, 0.8 mg/ml) were designed in the Menke's syringe and Mauricio's Reading Pressure Technique (RPT) system. Results showed that there were no significant difference in rumen fermentation parameters between the two systems, indicated that both systems could be used to simulate the rumen fermentation.5. Effects of TS on methane emission and rumen fermentation in different incubation status (including protozoa stuatus, defaunated method and forage/concentrate ratio in rumen fluid) were examined using RPT system. Results showed that: (1) TS addition and defaunation decreased methane emission in rumen fluid, but defaunation was much more effective than TS addition in inhibiting methane emission; Defaunation and TS addition lowered ammonia-N concentration and increase MCP yield; The beneficial effects of TS on methane production and rumen fermentation may not exclusively an effect of the associated depression on protozoa counts. (2) Defaunation method influenced methane emission in rumen fluid, defaunation in vitro was much more effective than in vivo in inhibiting methane emission. (3) TS may increase the 24h GP in the rumen fluid in rice straw-based substrates, whereas the TS may have adverse effect on rumen fermentation when the maize was above 50%. The TS had no effect on the methane production in forage-based diets, but may lower the methane emission in maize-based diets. The TS addition and rice straw/maize ratio affected the protozoa number, ammonia-N and MCP level. When 0.2mg/ml TS were included in the rumen fluid or the maize ratio was increased, the protozoa number and ammonia-N were greatly reduced and the MCP greatly increased. TS and rice straw/maize ratios also affected the VFAs concentration in rumen fluid.6. Twenty-seven growing Boer goats were used to evaluate the effects of the TSaddition on growth performance and serum biochemical parameters of the goats. The animals received the same basal diets, and added with the TS at levels of 0 (C), 3g (Ti) and 6 g (T2) per day. The experiment lasted for 60 days with the first 15 days for adaptation. Blood samples were obtained by jugular venipuncture before the morning feeding on the final day of the experiment. There is no different on dry matter intakes among the three treatments, but the average daily gain and feed conversion ratios in group Ti were higher than the other two. Serum total protein, albumin, high density lipoprotein cholesterol, Ca and P and alkaline phosphatase levels were higher in group T] than those in C and groupT2, whereas the blood urea nitrogen, creatinine and total cholesterol were lower in the TS-added groups. The concentrations of glucose, glutamic-oxaloacetic transaminase and glutamic-pyruvic transaminase were not affected by the TS. From the results obtained in this study, it is inferred that the TS could modify the rumen fermentation and that proper doses of TS may have some potentials in improving the animal growth performance.In summary, ruminal fermentation products may be determined by gas chromatogram rapidly. Steroid saponins and triterpenoid saponins had similar effects on rumen fermentation and methane emission. Menke's syringe and Mauricio's RPT system may be used to simulate the rumen fermentation. Tea saponins may moderate rumen fermentation, including increased the microbial protein yield, decreased the ammonia-N level and methane emission, and inhibited the protozoa in rumen fluid. In vitro incubation status affected the action of tea saponins on methane emission and rumen fermentation. Proper doses of tea saponins may have some potentials in improving the animal growth performance.
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