【摘要】 利用体外发酵法研究了4种粗精比(10∶0、8∶2、6∶4和4∶6)底物对山羊瘤胃细菌产量、15NH3-N利用效率的影响。结果表明:混合培养液的pH值与氨态氮浓度在8h内急剧下降,而后至24h呈缓慢下降;经24h培养的细菌产量在8∶2、6∶4和4∶6组中差异不显著(P>0.05),但都极显著地高于10∶0组(P<0.01);细菌体15N丰度以8∶2及4∶6组较高,显著高于10∶0和6∶4组(P<0.05);细菌体15N富集量以8∶2组最高,底物547.43μg15N中有120.44μg被细菌体富集,显著高于10∶0组(P<0.05),但6∶4、4∶6组与10∶0组间差异均不显著(P>0.05)。细菌赖氨酸的相对百分组成随精饲料比例的增加而显著增加,胱氨酸在粗饲料组(10∶0)显著高于其它组,但各精饲料添加组间差异不显著,组氨酸以8∶2组为最高,显著高于10∶0组,但与其它精饲料添加组间差异不显著(P>0.05)。更多还原

【Abstract】 An in vitro system was used to investigate the influence of different roughage and concentrate ratio substrates on utilization of ammonia-N by mixed ruminal bacteria in vitro. The treatments were four roughage and concentrate ratio substrates （10∶0, 8∶2, 6∶4 and 4∶6）. The pH and ammonia-N concentration rapidly decreased in first 8 h incubation, then the speed of decrease became slow in later incubation. At the end-point of incubation （24 h）, bacteria isolated from 8∶2, 6∶4 and 4∶6 groups had much higher biomass compared with that in 10∶0 group （P<0.01）. （）¹⁵N Atom % abundance of bacteria was much higher in 8∶2 and 4∶6 groups than that in 10∶0 and 6∶4 groups （P<0.05）. The highest level of （）¹⁵N-enrichment was observed in the 8∶2 group, of the 547.43 μg （）¹⁵N provided in the medium, 120.44 μg （）¹⁵N was utilized over the incubation period, much higher than that in 10∶0 group （P<0.05）, but no differences compared with the 6∶4 and 4∶6 groups （P>0.05）. The Lys content of bacteria increased with the level of concentrate feedstuff inclusion in the substrate, the content of （Cys）₂ was higher in 10∶0 group compared with other three groups, His content in 8∶2 group was at the highest level, no differences compared with the 6∶4 and 4∶6 groups, but much higher than that in 10∶0 group.更多还原