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试验采用体外瘤胃发酵法来研究肉牛日粮中不同比例精料与粗料间的组合效应(AE)。用注射器法将精料与玉米秸秆青贮、谷草以100∶0(CR100),80∶20(CR80),60∶40(CR60),50∶50(CR50),40∶60(CR40),20∶80(CR20),0∶100(CR0)的比例进行组合,分别测定产气量(GP)、干物质消失率(DMD)、氨态氮(NH_3-N)浓度、微生物蛋白(MCP)产量和挥发性脂肪酸(VFA)浓度及其组合效应值,确定最适宜的精粗比。结果表明,1)CR80组合的体外发酵GP最高,组合效应值最大;CR100组合的DMD最高;而CR50组合的单项组合效应值最大,NH_3-N浓度和MCP产量最高,产生了最大正组合效应。2)乙酸浓度随精料比例的降低呈先上升后下降的趋势,丙酸和丁酸浓度则随精料比例的下降而降低。3)综合分析各组合的多项组合效应指数(MFAEI),CR50组合最大(AE_(24h)0.56,AE_(48h)0.67,AE_(72h)1.00)。因此,在本试验条件下精粗比为50∶50的组合最有利于瘤胃发酵。
In vitro ruminal fermentation was used to study the combined effect (AE) of different proportions of concentrate and raw material in beef cattle diets. The concentrate was mixed with corn stover silage and asparagus at a ratio of 100: 0 (CR100), 80:20 (CR80), 60:40 (CR60), 50:50 (CR50), 40:60 (GP), DMD, NH_3-N concentration, microbial protein (MCP) yield and volatilization Sex Fatty Acid (VFA) concentration and its combined effect value, to determine the most appropriate concentrate ratio. The results showed that 1) CR80 had the highest GP in vitro and the highest combinatorial effect, while CR100 had the highest DMD. CR50 had the highest single combination effect, highest NH_3-N concentration and MCP yield, and produced the largest positive combinatorial effect. 2) The concentration of acetic acid firstly increased and then decreased with the decrease of the proportion of concentrate, while the concentration of propionic acid and butyric acid decreased with the decrease of the proportion of concentrate. (3) Comprehensive analysis of multiple combination effect index (MFAEI) of each combination, CR50 combination maximum (AE_ (24h) 0.56, AE_ (48h) 0.67, AE_ (72h) 1.00). Therefore, under the conditions of this test, the combination of fine and coarse ratio of 50:50 is most conducive to rumen fermentation.