丙酸、乳酸菌添加对多花黑麦草青贮发酵品质的影响

Effect of Adding Propionic acid and Lactic Acid Bacteria on Fermentation Quality of Italian Ryegrass Silages

本试验旨在评价丙酸、乳酸菌及两者组合添加对意大利黑麦草(Lolium multiflorum Lam.)青贮发酵品质及残余水溶性碳水化合物(WSC)含量的影响。试验共六个处理:对照、乳酸菌(LAB)、0.4%丙酸(PA4)、0.5%丙酸(PA5)、0.4%的丙酸+乳酸菌(PA4+LAB)和0.5%的丙酸+乳酸菌(PA5+LAB),以鲜重为基础。结果表明:经过30 d青贮发酵,各处理组间DM含量差异不显著,各添加组pH值与对照相比有下降趋势,乳酸含量显著(P<0.05)高于对照,且PA5及其组合添加显著(P<0.05)高于PA4及其组合添加,但在相同PA添加量下,单独或组合添加组间差异不显著。对照组的乳酸/乙酸与LAB组间差异不显著,PA单独或组合添加组显著(P<0.05)高于对照和LAB处理组,但PA单独添加组又显著(P<0.05)高于PA组合添加组;PA单独或组合添加组乙酸、丁酸含量及氨态氮/总氮显著(P<0.05)低于对照和LAB组,丙酸及残留WSC含量显著(P<0.05)高于对照和LAB组;PA单独添加后残留WSC含量明显高于(P<0.05)PA+LAB组合添加;丙酸添加能有效地抑制有害微生物的活性,减少对WSC的消耗,促进乳酸菌发酵,改善意大利黑麦草青贮发酵品质。

The experiment was carried out to evaluate the effects Of adding propionic acid, lactic acid bacteria, and their combination on the fermentation quality and residual water soluble carbohydrate content of I- talian ryegrass （Loliurn multiflorurn Lain. ） silage. The treatments were as follows： Control （no addition） ; Lactic acid bacteria addition （LAB） ; Propionic acid addition at 0.4% （PA4） ; Propionic acid addition at 0.5%o （PAS） ; PA4 ＋ LAB; PAS＋ LAB; all the additions were made on the fresh weight basis of Italian ryegrass..The DM content was not significantly different among all treatments, however, the pH tended to decrease, and the lactic acid content showed significantly （P〈0.05） higher in all addition treat- ments in comparison with control. PA5 and PA5＋LAB treatments showed significantly （P〈0.05） higher lactic acid content than the PA4 and PA4 ＋LAB treatments and there were no significant difference between PA and PA＋LAB treatment with the same PA adding rate. PA and PA ＋LAB treatments showed significantly （P〈0.05） higher lactic acid/acetic acid than that of control and LAB addition, PA alone significantly （P〈0.05） higher than PA＋LAB treatment, and there was no significant difference between control and LAB treatment. PA and PA＋LAB treatments resulted in significantly （P〈0.05） lower contents of acetic acid and butyric acid and NHa-N/total N and significantly （P〈0.05） higher contents of pro- pionic acid and residual water soluble carbohydrate in comparison with control and LAB treatment. In summary, addition of propionic acid could depress the undesirable bacterial activities, decrease the watersoluble carbohydrates loss, and promote lactic acid fermentation.