| The study was conducted to investigate the effect of tea (Camellia Sineis ) saponin on the productive performance of growing HuZhou-sheep(Expt.l) sand on ruminal fermentation in vitro(Expt.2). The Expt.l consisted of trial I and tria-l II. In trial I,thirty-two HuZhou lambs were used and randomly divided into four gr-oups (Cl,Til,T12,T13),eight lambs each. All animals were offered the same ration:400g concentration mixture,117g Rice straw meal and 2.5kg fresh ryegrass. Tea saponin was added at levels of 0,0.38,0.75 and 1.5g/d for Cl,Til,T12,and T13,respectively. The design of trial II was same as trial I:tea saponin was offered at levels of ?,0.75,1.5 and 3.0g for C2,T21,T22 and T23,respectively. Ingredient of the ration in trial 2 included 400g concentration mixture,160g Rice straw meal and 1.5kg fresh ryegrass. Each trial lasted for 45d,including 15d for adaptation. All animals had free access to drinking water.In trial I,the daily weight gain of the sheep receiving lower levels (0.38 and 0.75g/d) of tea saponin did not increase (p>0.05) compared to that in th-e control,while tea saponin did increase the daily gain of the sheep (13.9%) when added at higherlevel(1.5g/d). In trial II,the daily weight gain of sheep in T21,T22 and T23 was increased by 11.2,24.3 and 42.0%,respectively. Feed efficiency was increased by 11.2,23.2 and 40.8%,respectively. The highest level of tea saponin showed optimal effect. Tea saponin had little effect on feed intake.In Expt.2,gas syringes were used as incubators to investigate the effect of Tea saponin addition on ruminal fermentation. Four levels of tea saponin were 0,0.4,0.8 and 1.2% against substance (100mg,corn meal and 100mg,grass meal) in ruminal fluid. After incubation for 3,6,12,24 and 48h,the gas production were recorded and three syringes were removed. The pH,ammonia nitrogen (NHs-N),volatile fatty acids(VFAs),protozoa counts,microbial protein(MCP) were determined.Tea saponin addition reduced the pH of ruminal fluid,but all values were in the normal range. After 48h incubation,addition of 1.2% tea saponin reduced pH to the lowest level(6.50),compared to 6.77 in control.Inclusion of tea saponin in ruminal fluid in vitro reduced the NHa-N concentration. After 24h incubation,addition with 0.8 and 1.2% tea saponin reduced the NHs-N concentration by 7.7(p<0.01) and 7.5%(p<0.01),respectively,while 0.4% tea saponin had no significant effect on Nfy-N concentration. At other incubation time,the NHa-N showen the same trend.The gas production was increased significantly (P<0.01) at all levels of tea saponin except 3h incubation. After 24h incubation,the gas production in the control was 16.73mL,while inclusion 0.4,0.8 and 1.2% of tea saponin increased the gas production to 19.67,28.37 and 32.77mL,respectively.Concentrations of acetic,propionic,butyric and total VFAs were increased significantly by addition of tea saponin,and the 0.8% tea saponin had the greatest effect on the VFAs. After 24h incubation,addition 0,0.4,0.8 and 1.2% of tea saponin,the acetic acid was increased by 4.2 (p>0.05),28.4 (P<0.01) and 14.7% (P<0.01);propionic acid by 40.0 (p<0.05),51.8 (P<0.01) and 30.8%(p<0.05);butyric acid by 26.0 (p<0.05),30.2 ( p<0.05) and 11.4%(p>0.05);the total VFAs by 12.9( P<0.01),33.8( P<0.01) and 17.7%( P<0.01),respectively.Inclusion of tea saponin significantly (p<0.01) inhibited the protozoa growth in ruminal fluid. After 24h incubation,the protozoa counts were reduced to 10.56,6.40 and 5.00x1 oVmL from 18.50xl04/mL in the control,respectively. After 48h incubation,the highest level of tea saponin (1.2%) had the optimal effect,and the protozoa count was reduced to the lowest level (2.61xl04/mL vs 18.33xl04/mL). These results indicated that the protozoa may be inhibited by tea saponin,and reduced with the increasing level of tea saponin and prolong incubation time. The MCP determined at 24h incubation was increased by tea saponin addition. Compared to 0.709mg/mL in the control,the MCP yield was 6.6,49.4(p<0.05) and 19.2% higher with addition of 0.4...
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