添加剂对不同干物质含量的多花黑麦草青贮品质的影响

为分析不同添加剂类型与干物质含量对多花黑麦草(Lolium multiflorum)青贮品质的影响,本研究将3种添加剂处理——甲酸(formic acid,FA)、植物乳杆菌(Lactobacillus plantmentum,LP)、布氏乳杆菌(L.buchneri,LB)添加于3种干物质含量(20%、30%、40%)的多花黑麦草中,青贮60d后,测定不同处理青贮营养成分和发酵品质的相关指标。结果表明,甲酸处理组在3种干物质条件下,其pH均在4.3以下,氨态氮(NH3-N)均显著低于其他处理组(P0.05),而可溶性碳水化合物(water soluble carbohydrate,WSC)含量则显著高于其他处理组(P0.05)。在干物质含量为30%、40%的多花黑麦草中添加两种乳酸菌可以获得较好的发酵效果,其中,LB处理组乙酸含量显著高于其他处理组(P0.05),LP处理组乳酸含量显著高于其他处理组(P0.05)。就干物质含量而言,干物质30%和40%时发酵品质均优于干物质20%时同样的添加剂处理组,且在干物质20%时,对照组和乳酸菌处理组均含有大量的丁酸。因此,在制作多花黑麦草青贮时尽量凋萎使干物质含量保持在30%~40%,同时添加乳酸菌类添加剂是保证青贮料品质的关键。当没有条件凋萎,将鲜样直接青贮时,添加一定量的甲酸(4mL·kg~(-1))是保证青贮料发酵品质的有效手段。

Effect of additives on the quality of ryegrass silage with different dry matter content

The effects of different types of inocula on the quality of Italian ryegrass with different dry matter content were investigated.Three additives formic acid (FA),Lactobacillus plantmentum (LP),Lactobacillus buchneri (LB)] were used to ensile Italian ryegrass with different dry matter content (20％,30％,and 40％).The results showed that the pH in the FA-treatment of Italian ryegrass with three levels of dry matter content was below 4.3,and NH3-N/TN was significantly lower than that in the other treatments (P＜0.05).However,the content of water soluble carbohydrate was significantly higher than that in the other treatments (P＜0.05).Two types of lactic acid bacteria treatments (LP and LB) of Italian ryegrass with dry matter content of 3000and 40 ％ led to better ferment quality.The lactic acid content in the LP treatment was significantly higher than that in the other treatments (P＜0.05),whereas the acetic acid content of the LB treatment was significantly higher than that in the other treatments (P＜0.05).The ferment quality of Italian ryegrass with 30％ and 40％dry matter content was better than that of 20 ％ dry matter content in treatments with the same additive.Particularly,when the dry matter content was 40％,the pH of the control group was less than 4.2,which suggested that at this level of dry matter content,high quality silage can be prepared even without adding any additives.Evidently,wilting Italian ryegrass with a dry matter content of 30％ ～40％ treated with lactic acid bacteria can ensure high quality silage production.In unwilted Italian ryegrass,adding formic acid (4 mL · kg-1 FM) can preserve silage quality.