青貯菌劑的篩選及對苜蓿半乾青貯品質的影響

本研究的目的在開發本土青貯菌劑，以協助不易青貯的芻料如豆科等之保存及利用。乳酸菌分離篩選來源包括：青貯料、醃漬食品、酸乳、水果、堆肥及動物糞便。分離總共獲得60株菌株，經生長耐性篩選後，以活性較佳的22株進行苜蓿青貯菌種初步篩選。篩選試驗利用不同含水率的苜蓿進行接種，並以商業菌株進行比較，藉由不同青貯時間的pH值變化及產氣情形評估各菌株接種效果。青貯8週後，未萎凋苜蓿以接種ST15處理的pH值4.61為最低（不接種對照為4.86），萎凋苜蓿中以接種ST12之pH值4.88為最低（不接種對照為5.45）；而D41青貯產氣最少。因此，繼續以ST15、ST12及D41菌株進行後續試驗。此三菌株經鑑定，D41為Lactobacillus casei、ST12及ST15均為Lactobacillus plantarum。將苜蓿萎凋至含水率56.9%，對照組不接種，接種處理分別為接種商業菌劑及D41、ST12及ST15，接種量均為1×10^6 cfu/g forage，青貯4、8、12週開封並測定發酵產物。對照組乳酸及乙酸含量分別介於0.26%DW-0.69%DW及0.29%DW-1.67%DW；接種處理則在0.64%DW-2.24%DW及0.29%DW-0.87%DW之間，顯示接種可促進乳酸發酵。對照組之青貯評分隨青貯時間下降，青貯12週時降至38分，而接種處理仍維持於82－89分之間。自行分離菌株在4週、8週的發酵及青貯評分均優於商業菌株，顯示自行分離菌株能有效促進發酵。

關鍵字

苜蓿半乾青貯；接種劑；乳酸菌

並列摘要

The purpose of this study was to develop domestic inoculants to improve the silage quality of those materials with poor fermentation characters like legumes. Sixty strains of lactic acid bacteria were obtained from diverse resources including silage, pickled foods, yogurt, fruit, compost and animal manure. After evaluation of acid and salt tolerance, 22 strains were selected to screen their effects on alfalfa ensiling. In the preliminary screening, alfalfa of two different moisture contents was used and a commercial inoculant was used as positive control and no inoculant as negative control. After ensiling of 8 weeks, un-wilted alfalfa inoculated by strain ST15 had the lowest pH value of 4.61 and that of no inoculant control was 4.86. While in wilted condition, the set of strain ST12 had the lowest pH value of 4.88 and that of no inoculant control was 5.45. The strain D41 had the least gas production. Therefore, strains S15, S12 and D41 were used for further experiment. D41 was identified as Lactobacillus casei, and ST12 and sT15 were L. plantarum. In experiment II, the moisture content of alfalfa was wilted to 56.9% and ensiled with or without inoculant. Laboratory silos were opened and analyzed at 4, 8, 12 weeks for pH and fermentation products. The acetic acid and the lactic acid of no inoculant control ranged 0.29%-1.67% and 0.26%-0.69% while inoculant treatments ranged 0.29%-0.87% and 0.64%-2.24%, respectively. The results showed that inoculants produced more lactic acid and lowered acetic acid/lactic acid ratio than control. The Fleig's score of no inoculant control at 12 weeks reduced to 38, and those of inoculation treatment still maintained among 82 to 89. In addition, the Fleig's score of strain D41, ST12 and ST15 sets were higher than commercial strain(Ecosyl)set at 4 and 8 weeks, indicated that the domestic strains can improve the fermentation effectively.

並列關鍵字

Alfalfa haylage ； Inoculate ； Lactic acid bacteria

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