摘 要：以装有永久性瘤胃瘘管的黄牛作为瘤胃液的供体动物，应用短期人工瘤胃发酵技术研究日粮组合效应对瘤胃液pH、NH3–N含量和不同发酵时间(2、4、8、12、24 h)产气量的影响。结果表明，pH实测值与加权平均值差异不显著(P＞0.05)，瘤胃液pH值间不存在日粮组合效应。NH3–N含量实测值与加权平均值差异极显著(P＜0.01)，瘤胃液NH3–N含量间存在极显著的日粮组合效应。饲料体外培养发酵2、4 、8、12、24 h产气量实测值和加权平均值的t检验结果表明，发酵2 h存在极显著的日粮组合效应；发酵4、8、12 h时的产气量实测值和加权平均值间无统计学意义；发酵24 h存在显著的日粮组合效应。 Abstract：The objective of this experiment is to investigate the associative effects of ruminant mixed feeds on pH, NH3–N and GP (gas production) 2, 4, 8, 12 and 24 h after in vitro incubation. One adult cattle fitted with a perpetual rumen cannula was used as the donor of rumen fluid. The animal was fed with a mixed ration twice daily and had free access to water. Regression analysis showed that there was a significant relationship between the calculated weighted mean value of pH(x) and those pH value measured by the in vitro incubation technique(y, 24 h incubation), and pH value was not significantly (P＞0.05) effected by mixed feeds based on t test. The NH3–N weighted mean value calculated(x) and those NH3–N value measured by the in vitro incubation technique(y, 24 h incubation) showed linear regression and t test showed NH3–N value was significantly (P＜0.01) effected by mixed feeds. And the GP calculated weighted mean value (x) also showed regression on those GP value measured by the in vitro incubation technique(y, 24 h incubation) and t test showed that GP value under 2 h and 24 h incubation was significantly effected by mixed feeds. Key words：cattle; associated effects; fermentation parameters of rumen; pH; ammonia nitrogen; gas production